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there is a need worldwide to develop materials for advanced power plants with steam temperatures of 700°c and above that will achieve long-term creep-rupture strength and low cO2 emissions. the creep resistance of actual 9-12cr steels is not enough to fulfil the engineering requirements above 600°c. in this paper, the authors report their advances in the improvement of creep properties of this type of steels by the microstructural optimization through nano-precipitation using two methodologies. 1) Applying a high temperature austenitization cycle followed by an ausforming step (thermomechanical treatment, tMt ) to G91 steel, to increase the martensite dislocation density and, thus, the number density of MX precipitates (M = v,Nb; X = c,N) but at the expense of deteriorating the ductility. 2) compositional adjustments, guided by computational thermodynamics, combined with a conventional heat treatment (no tMt ), to design novel steels with a good ductility while still possessing a high number density of MX precipitates, similar to the one obtained after the tMt in G91. the microstructures have been characterized by optical, scanning and transmission electron microscopy, eBSD and atom probe tomog- raphy. the creep behaviour at 700°c has been eval- uated under a load of 200 N using small punch creep tests.

An overview of modern material science problems is presented for ultralightweight highmodulus commercial Al-Li-based alloys in historical retrospect. Numerous particular examples of the Soviet and Russian aviation whose various designs were made of these alloys confirm their successful innovative potential. The key regularities of multicomponent alloying are discussed for the master alloys and modern commercial Al-Li-based alloys of the latest generation; the features typical of their microstructures, phase composition, and properties formed during aging are analyzed. The main mechanisms of phase formation are generalized for standard thermal and thermomechanical treatments. Recent original achievements have been obtained in designing of unique structural and phase transformations in these commercial alloys by means of methods of severe plastic deformations followed by heat treatment and storage. Using the example of three Russian commercial alloys of last generation, the basic principles of creating and controlling an ultrafine-grained structure, the origin and growth of stable nanophases of various types and chemical composition that determine the physicomechanical properties of alloys are established. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

In this study, the mechanical and microstructural properties of Al-Zn-Mg-Cu-Zr cast alloy with 0.1% Sc under homogeneous, dissolution, and T6 and thermomechanical treatments with the aim of increasing the volume fraction of MgZn2. Al-3(Sc,Zr) reinforcing precipitates were examined by hardness, microscopic examinations, tensile tests and software analysis. The results showed that, firstly, the hardness results are well proportional to the results of the tensile properties of alloys and, secondly, the strength of the alloy with thermomechanical treatments compared to T6 treatments increased from 492 MPa to 620 MPa and the elongation increased from 8% to 17% and was 100% upgraded. Microstructural and fracture cross section investigations showed that Al-3(Sc,Zr) nanosize dispersoids were evenly distributed among MgZn2 dispersoids and the alloy fracture was of semi-ductile type and nanosize dispersoids less than 10 nm were observed at the end of the dimples in the fracture section. The volume fraction of nanosize dispersoids in the whole microstructure of thermomechanical treatment samples was also much higher than that of T6 heat treated samples, so that the percentage of Al-3(Sc,Zr) precipitates arrived from less than 1% in T6 operation to 8.28% in the quench-controlled thermomechanical operation (with 50% deformation). The quality index (QI) in thermomechanical treatment samples is 19% higher than T6 samples, so that this index has increased from 641 in T6 operation to 760 in samples under thermomechanical treatment due to precipitate morphology, volume fraction of precipitates, their uniform distribution in the matrix, and nano sized precipitates in samples under thermomechanical treatment., QC 20220210

The mechanical strength and electrical conductivity (EC) in Al–Mg–Si 6xxx conductor alloys are key characteristics but mutually exclusive properties. This review paper critically elaborates the methods to enhance the mechanical strength and electrical conductivity. These methods include an optimization of the main alloying elements (Mg and Si), the addition of the other alloying elements, melt treatment, applying the modified thermomechanical treatments, and maximizing the area reduction (severe plastic deformation) in the wire drawing. Besides, the impact of the various microstructural features on the mechanical and electrical properties is addressed in detail using strength and electrical resistivity models. A principal conclusion drawn in this review is that the strength ought to be enhanced by creating barriers (such as sessile dislocations and precipitates) for dislocation movement while having a less detrimental effect on the electrical conductivity. Considering the potential of Al–Mg–Si conductor alloys, future directions are outlined.

There is a need worldwide to develop materials for advanced power plants with steam temperatures of 700 °C and above that will achieve long-term creep-rupture strength and low CO2 emissions. The creep resistance of actual 9-12Cr steels is not enough to fulfil the engineering requirements above 600 °C. In this paper, the authors report their advances in the improvement of creep properties of this type of steels by the microstructural optimization through nano-precipitation using two methodologies. 1) Applying a high temperature austenitization cycle followed by an ausforming step (thermomechanical treatment, TMT) to G91 steel, to increase the martensite dislocation density and, thus, the number density of MX precipitates (M = V,Nb; X = C,N) but at the expense of deteriorating the ductility. 2) Compositional adjustments, guided by computational thermodynamics, combined with a conventional heat treatment (no TMT), to design novel steels with a good ductility while still possessing a high number density of MX precipitates, similar to the one obtained after the TMT in G91. The microstructures have been characterized by optical, scanning and transmission electron microscopy, EBSD and atom probe tomography. The creep behaviour at 700 °C has been evaluated under a load of 200 N using small punch creep tests.

There is a need worldwide to develop materials for advanced power plants with steam temperatures of 700°C and above that will achieve long-term creep-rupture strength and low CO2 emissions. The creep resistance of actual 9-12Cr steels is not enough to fulfil the engineering requirements above 600°C. In this paper, the authors report their advances in the improvement of creep properties of this type of steels by the microstructural optimization through nano-precipitation using two methodologies. 1) Applying a high temperature austenitization cycle followed by an ausforming step (thermomechanical treatment, TMT) to G91 steel, to increase the martensite dislocation density and, thus, the number density of MX precipitates (M = V ,Nb; X = C ,N) but at the expense of deteriorating the ductility. 2) Compositional adjustments, guided by computational thermodynamics, combined with a conventional heat treatment (no TMT), to design novel steels with a good ductility while still possessing a high number density of MX precipitates, similar to the one obtained after the TMT in G91. The microstructures have been characterized by optical, scanning and transmission electron microscopy, EBSD and atom probe tomography. The creep behaviour at 700°C has been evaluated under a load of 200 N using small punch creep tests.

The mechanisms driving variant selection phenomena in ausformed bainitic microstructures are not fully controlled yet. Previous results are not congruent among them, as they cannot be explained by the same rule. In this work, we aimed to understand the mechanisms governing variant selection in a medium carbon-high silicon steel subjected to ausforming treatments. To do so, the microstructural characterization in different regions of barreled samples has been combined with the simulation of the stress and strain state at the macro and micro level, by finite elements simulations and crystal plasticity simulations, respectively. The main conclusion is that the variant selection shown in these microstructures can be explained by understanding the distribution of the plastic strains at the macro and micro level. The selection of crystallographic variants is more pronounced in the regions which have been more deformed. Also, the deformation distributes along deformation microbands, where the most promoted variants seem to grow, in good agreement with previous results in ausformed lath martensite., Team Jilt Sietsma

The bainitic ferrite plate thickness is the main parameter that controls the strength of this type of microstructures. Such thickness has been proved to mainly depend on the austenite yield strength, the driving force for the transformation and the transformation temperature. However, no research has focused on how these parameters evolve throughout the transformation and how this evolution can affect the outcome. In this study, thermal and thermomechanical treatments have been performed in three selected steels. The treatments have been designed in such a way that all the mentioned parameters are comparable, aiming to obtain similar microstructures in terms of bainitic ferrite plate thickness. However, significant differences have been found among the microstructures, with variations in plate thickness larger than 100 nm. These results indicate that there might be other factors that take part in the scale of bainitic microstructures. To explain these differences and based on the kinetics of the transformation and on the carbon content of austenite at the end of the transformation, a possible explanation has been proposed., Team Jilt Sietsma

The mechanisms driving variant selection phenomena in ausformed bainitic microstructures are not fully controlled yet. Previous results are not congruent among them, as they cannot be explained by the same rule. In this work, we aimed to understand the mechanisms governing variant selection in a medium carbon-high silicon steel subjected to ausforming treatments. To do so, the microstructural characterization in different regions of barreled samples has been combined with the simulation of the stress and strain state at the macro and micro level, by finite elements simulations and crystal plasticity simulations, respectively. The main conclusion is that the variant selection shown in these microstructures can be explained by understanding the distribution of the plastic strains at the macro and micro level. The selection of crystallographic variants is more pronounced in the regions which have been more deformed. Also, the deformation distributes along deformation microbands, where the most promoted variants seem to grow, in good agreement with previous results in ausformed lath martensite., Team Kevin Rossi

The bainitic ferrite plate thickness is the main parameter that controls the strength of this type of microstructures. Such thickness has been proved to mainly depend on the austenite yield strength, the driving force for the transformation and the transformation temperature. However, no research has focused on how these parameters evolve throughout the transformation and how this evolution can affect the outcome. In this study, thermal and thermomechanical treatments have been performed in three selected steels. The treatments have been designed in such a way that all the mentioned parameters are comparable, aiming to obtain similar microstructures in terms of bainitic ferrite plate thickness. However, significant differences have been found among the microstructures, with variations in plate thickness larger than 100 nm. These results indicate that there might be other factors that take part in the scale of bainitic microstructures. To explain these differences and based on the kinetics of the transformation and on the carbon content of austenite at the end of the transformation, a possible explanation has been proposed., Team Kevin Rossi

The mechanisms driving variant selection phenomena in ausformed bainitic microstructures are not fully controlled yet. Previous results are not congruent among them, as they cannot be explained by the same rule. In this work, we aimed to understand the mechanisms governing variant selection in a medium carbon-high silicon steel subjected to ausforming treatments. To do so, the microstructural characterization in different regions of barreled samples has been combined with the simulation of the stress and strain state at the macro and micro level, by finite elements simulations and crystal plasticity simulations, respectively. The main conclusion is that the variant selection shown in these microstructures can be explained by understanding the distribution of the plastic strains at the macro and micro level. The selection of crystallographic variants is more pronounced in the regions which have been more deformed. Also, the deformation distributes along deformation microbands, where the most promoted variants seem to grow, in good agreement with previous results in ausformed lath martensite.

The industrial requirement for low density, high strength, and desirable electrical conductivity (EC) have led to the development of Al-Mg-Si conductor alloys for the power transmission line. The precipitates, dislocations, solute atoms, and grain boundaries result in strengthening the Al-Mg-Si conductor alloys. However, these give rise to electrical resistivity due to disruptions in atomic periodicity in a crystal structure. Accordingly, the parameters improving the strength cause the electrical resistivity in Al-Mg-Si conductor alloys, showing conflicting behaviors of strength and EC. Therefore, the concurrent improvement in strength and EC turns out as a challenging issue. In this study, better combinations of strength and EC in Al-Mg-Si conductor alloys were obtained through (a) optimum principal alloying elements (Mg and Si); (b) natural aging and the modification of the thermo-mechanical treatment; (c) additional alloying elements (Ag and Cu). In the first part of this study, the effect of the various Mg/Si ratios (2, 1.5, 1, 0.86) on the strength and EC of Al-Mg-Si conductor alloys was investigated. The Mg content was kept constant (0.65 wt.%) while the Si amounts were changed. It was found that the peak strength increased with decreasing the Mg/Si ratio while the corresponding EC reduced. Therefore, a longer aging time was required for the alloys with a lower Mg/Si ratio to fulfill the minimum required EC (52.5 %IACS). The alloy with an Mg/Si ratio of 0.86 showed the highest peak strength among all alloys. However, prolonging the aging time (>34 h) was essential to exceed EC (52.5 %IACS), causing a significant drop in the strength with a narrow window of strength and EC. The alloy with Mg/Si ratio of ~ one showed the highest strength in the range of EC (52.5-54 %IACS). The developed strength model exhibited that the higher strength of this alloy could correspond to the higher contributions of the precipitate strengthening, strain hardening, and solute harden

The bainitic ferrite plate thickness is the main parameter that controls the strength of this type of microstructures. Such thickness has been proved to mainly depend on the austenite yield strength, the driving force for the transformation and the transformation temperature. However, no research has focused on how these parameters evolve throughout the transformation and how this evolution can affect the outcome. In this study, thermal and thermomechanical treatments have been performed in three selected steels. The treatments have been designed in such a way that all the mentioned parameters are comparable, aiming to obtain similar microstructures in terms of bainitic ferrite plate thickness. However, significant differences have been found among the microstructures, with variations in plate thickness larger than 100 nm. These results indicate that there might be other factors that take part in the scale of bainitic microstructures. To explain these differences and based on the kinetics of the transformation and on the carbon content of austenite at the end of the transformation, a possible explanation has been proposed.

In the work, the effect of thermomechanical treatment, including solid solution treatment, cold rolling and subsequent artificial aging, on the microstructure and mechanical properties of the high-strength aluminum alloy AA2519 (Al–5,64Cu–0,33Mn–0,23Mg (wt. %) was studied. Prestraining significantly increases the pefromance of alloy mechanical properties. However, as a consequence of ageing (at 190 °C), it was found that precipitates of stable θ-phase (Al2Cu) nucleate at the deformation bands., В работе было исследовано влияние термомеханической обработки, включающей обработку на твердый раствор, закалку, холодную прокатку и последующее искусственное старение, на микроструктуру и механические свойства высокопрочного алюминиевого сплава АА2519 (Al–5,64Cu–0,33Mn–0,23Mg (вес. %)). Искусственное старение (190 °C) после прокатки с обжатием 80 % приводит к выделению стабильной θ-фазы (Al2Cu) по границам деформационного происхождения.

Ova doktorska disertacija obuhvatila je istraţivanja na aluminijumskim legurama iz serije 6000 (Al-Mg-Si legure, komercijalne aluminijumske legure EN AW-6060 i EN AW-6082). Na pomenutim legurama sprovedena je različita termomehanička obrada, nakon čega je ispitivan uticaj reţima prerade na mehanička, fizička, toplotna i strukturna svojstva. Ispitivanja su raĎena u cilju karakterizacije ispitivanih legura i sagledavanja uticaja prisutnih legirajućih elemenata (hemijskog sastava) na njihove strukturne, mehaničke, fizičke i toplotne karakteristike čime je dat i odreĎeni naučni i stručni doprinos boljem poznavanju ispitivanih Al-Mg-Si legura nakon starenja (prirodnog i veštačkog), kao i nakon termomehaničke obrade koja je sprovedena u cilju proučavanja njenog uticaja na efekat ojačavanja starenjem. Ciljevi istraţivanja usmerili su ovu disertaciju tako da doprinese boljem poznavanju uticaja reţima primenjene termomehaničke obrade na strukturu i osobine ispitivanih Al-Mg-Si legura, što će uz nesumnjiv teorijski doprinos omogućiti i proširenje njihove primene u najsavremenijim industrijama, gde je trenutno velika potraţnja za materijalima sa aluminijumskom osnovom sa poboljšanim osobinama. Doktorska disertacija je podeljena u osam poglavlja. U uvodnom delu dat je kratak osvrt na veliku potraţnju u industriji u poslednjim decenijama za materijalima koji po odreĎenim osobinama mogu zameniti materijale iz oblasti crne metalurgije, s obzirom na to da njihova proizvodnja iziskuje veliku potrošnju energije i dovodi do zagaĎivanja ţivotne sredine, kao i na ulogu aluminijuma i njegovih legura u ovom domenu. Osnovne napomene o aluminijumu i legurama na njegovoj osnovi, uz kratak osvrt na primenljivost ovih legura u industriji, kao i kratak opis uticaja postupaka prerada na strukturu i karakteristike aluminijuma i njegovih legura prikazan je u drugom poglavlju. U trećem poglavlju opisane su osnovne teorijske postavke i uslovi za pojavu precipitacionog ili taloţnog ojačavanja (ojačav, This doctoral dissertation included the investigation of aluminium alloys from 6000 series (Al-Mg-Si alloys, commercial aluminium alloys EN AW-6060 and EN AW-6082). Various thermomechanical treatments (TMT) were applied to these alloys, after which the influence of these regimes on the mechanical, physical, thermal and structural properties was examined. The investigations were performed in order to characterize the alloys and to investigate the influence of alloying elements (chemical composition) on structural, mechanical, physical and thermal properties. These investigations also gave a certain scientific and professional contribution to better understand the investigated Al-Mg-Si alloys after ageing (natural or artificial), as well as after the thermomechanical treatment that was applied in order to study its effect on the precipitation hardening process. The research aim in this doctoral dissertation was to contribute to a better understanding of the influence of applied thermomechanical treatment on the structure and properties of the investigated Al-Mg-Si alloys. This will undoubtedly give the theoretical contribution and the expansion of the use of these alloys in modern industry, where currently there is a high demand for aluminium-based materials with improved properties. The doctoral dissertation is divided into eight chapters. The introductory section gives a brief overview of the great demand in the industry for materials that can replace materials in the field of ferrous metallurgy, since the production of ferrous metals requires high energy consumption and leads to environmental pollution, as well as to the role of aluminium and its alloys in this domain. Basic notes on aluminium and its alloys, with a brief overview of the applicability of these alloys to the industry, as well as a brief description of the impact of processing operations on the structure and characteristics of aluminium and its alloys, are presented in Chapter Two. The third chapter

Дисертація присвячена вирішенню важливої науково-технічної проблеми розробки та виготовлення високощільнихекономнолегованих порошкових матеріалів на основі заліза з високими фізико-механічними характеристиками для роботи в екстремальних умовах експлуатації. Проведено комплексні дослідження процесу плакування залізного порошку міддю та кобальтом та встановлено залежність фізичних та технологічних характеристик порошку від товщини плівки покриття. Досліджено вплив умов навантаження, природи та фізичних властивостей порошків на ступінь ущільнення під час пресування. Досліджено вплив термодеформаційного оброблення на процеси ущільнення, фазовий склад, мікроструктуру та властивості порошкових матеріалів. Досліджено вплив хімічної та структурної досконалості пресовок на механічні властивості економнолегованих сталей та композитів. Вперше встановлено вплив типу пористої 3D каркасної структури, а саме орієнтацію елементарних комірок, на характер деформації матеріалів. Розроблено матеріали для високоструменевих контактів на основі відходів металообробки важких сплавів просочених міддю, що мають ерозійну стійкість на рівні промислових псевдо сплавів. Відпрацьовано технологію отримання твердосплавних сердечників, що пройшли балістичні випробування, які підтвердили, що розроблені сердечники можуть застосовуватись для виробництва бронебійних боєприпасів стрілецької зброї.

Дисертація присвячена вирішенню важливої науково-технічної проблеми розробки та виготовлення високощільнихекономнолегованих порошкових матеріалів на основі заліза з високими фізико-механічними характеристиками для роботи в екстремальних умовах експлуатації. Проведено комплексні дослідження процесу плакування залізного порошку міддю та кобальтом та встановлено залежність фізичних та технологічних характеристик порошку від товщини плівки покриття. Досліджено вплив умов навантаження, природи та фізичних властивостей порошків на ступінь ущільнення під час пресування. Досліджено вплив термодеформаційного оброблення на процеси ущільнення, фазовий склад, мікроструктуру та властивості порошкових матеріалів. Досліджено вплив хімічної та структурної досконалості пресовок на механічні властивості економнолегованих сталей та композитів. Вперше встановлено вплив типу пористої 3D каркасної структури, а саме орієнтацію елементарних комірок, на характер деформації матеріалів. Розроблено матеріали для високоструменевих контактів на основі відходів металообробки важких сплавів просочених міддю, що мають ерозійну стійкість на рівні промислових псевдо сплавів. Відпрацьовано технологію отримання твердосплавних сердечників, що пройшли балістичні випробування, які підтвердили, що розроблені сердечники можуть застосовуватись для виробництва бронебійних боєприпасів стрілецької зброї., The dissertation is devoted to the solution of an important scientific and technical problem of development and manufacturing of high-density economically alloyed powder materials on the basis of iron with high physical and mechanical characteristics for application under extreme conditions of operation. Comprehensive studies of the plating process of iron powdersby copper and cobalt are conducted, and the dependence of physical and technological characteristics of the powders on the coating film thickness is found out. The main parameters which affect the process of deposition of the coatings on iron powder particles are determined. The possibility tocontrol the coating thickness (in the range of 12–20 μm) by changing the deposition kinetics is found out.The process of compaction of composite iron powders in the conditions of static pressing is analyzed by means of the mathematical equations which describe the density dependences on the pressure of compaction. The possibility of fabrication of materials for electrotechnical application on the base of composite powders of the Fe–Co system with high density and high magnetic characteristics with low total losses upon magnetization reversal at a level of 19–21 W/kg is shown, that allows to use the materials for production of magnetic circuits designed for operation in both constant and variable fields of industrial frequency. The influence of loading conditions, nature and physical properties of the powders on the degree of compaction during pressing is studied. The process of second compaction of the powder systems in the conditions of static pressing is investigated, and the main factors affecting the efficiency of compact densification are revealed. It is found out that the second compaction of iron–graphite mixes enhances the strength of the compacts by 5 times, that is caused both by higher density and increase in the surface area of iron–iron contacts. The possibility of manufacturing long semi-products by stati, Диссертация посвящена решению важной научно-технической проблемы разработки и изготовления высокоплотных экономно легированных порошковых материалов на основе железа с высокими физико-механическими характеристиками для работы в экстремальных условиях эксплуатации. Проведены комплексные исследования процесса плакирования железного порошка медью и кобальтом и установлена зависимость физических и технологических характеристик порошка от толщины пленки покрытия. Исследовано влияние условий нагрузки, природы и физических свойств порошков на степень уплотнения при прессовании. Исследовано влияние термодеформационной обработки на процессы уплотнения, фазовый состав, микроструктуру и свойства порошковых материалов. Исследовано влияние химического и структурного совершенства прессовок на механические свойства экономно легированных сталей и композитов. Впервые установлено влияние типа пористой 3D каркасной структуры, а именно ориентацию элементарных ячеек, на характер деформации материалов. Разработаны материалы для высокотоковых контактов на основе отходов металлообработки тяжелых сплавов пропитанных медью, имеющих эрозионную устойчивость на уровне промышленных псевдо сплавов. Отработана технология получения твердосплавных сердечников, прошедших баллистические испытания, которые подтвердили, что разработанные сердечники могут применяться для производства бронебойных боеприпасов стрелкового оружия.

There is a worldwide need to develop materials for advanced power plants with steam temperatures of 700°C and above which have the capacity to achieve high efficiency and low CO2 emissions. This request involves the development of new grades of 9-12Cr heat-resistant steels, with a nanostructured martensite, mainly focusing on the long-term creep rupture strength of base metal and welded joints, creep-fatigue properties, and microstructure evolution during exposure at such elevated temperatures. The main shortcomings of actual 9-12Cr high-chromium steels are that the creep resistance is not enough to fulfill the engineering requirements at temperatures higher than 600°C and the material undergoes a cyclic softening. Creep strength at high temperature could be improved by a microstructural optimization through nano-precipitation, guided by computational thermodynamics, and thermomechanical control process optimization.

TEMPO-oxidized thermomechanical pulp (TMP) prepared at low-oxidized and highly oxidized levels was compared with untreated TMP to observe the advantage of each pulp on paper properties. While the low oxidized pulp and non-oxidized pulp gave similar properties, highly oxidized TMP significantly increased tensile strength and decreased tear strength. Brightness was negatively affected by oxidation. In order to improve the paper optical properties, the use of a conventional mineral filler retention system was studied, using clay as filler. The high charge induced by the oxidized pulp significantly modified the pulp retention behavior. Moreover, paper made from pulp containing oxidized pulp and clay presented considerably better tensile strength with a loss in tear resistance for the same brightness target, which could be interesting for some paper applications. © 2019, North Carolina State University.

Thermomechanically treated (TMT) carbon steel bars, often known as TempCoreTM bars, are commonly used as reinforcements in concrete structures. TMT causes the formation of a martensite case in the outer surface of the bars, increasing their hardness, while the remaining ferritic-perlitic core maintains the typical ductility of hot rolled bars. In this work, the effect of this TMT induced microstructure on the development of pitting attacks in chloride media has been analyzed in depth. Electrochemical impedance spectroscopy (EIS) measurements and polarization curves have been carried out in simulated pore solutions to understand the effect of the presence of different phases in the microstructure and to quantify the strength of the galvanic couple that the outer martensite can form with the inner core. Moreover, accelerated corrosion tests in chloride contaminated concrete slabs have been performed. Bars from six different slabs where corrosive attack has been forced for different times have been studied. The shape of the main pits in the bars corroded in concrete has been analyzed through optoelectronic microscopy and the results obtained prove that the depth of the attack is related to the microstructure of the TMT bars.

In recent years, multicomponent alloys with shape memory effects (SMEs), based on the ordered intermetallic compounds B2-TiNi, L21-Ni2MnGa, B2- and D03-Cu-Me (Me = Al, Ni, Zn), which represent a special important class of intelligent materials, have been of great interest. However, only a small number of known alloys with SMEs were found to have thermoelastic martensitic transformations (TMTs) at high temperatures. It is also found that most of the materials with TMTs and related SMEs do not have the necessary ductility and this is currently one of the main restrictions of their wide practical application. The aim of the present work is to design and develop multicomponent alloys with TMTs together with ways to improve their strength and ductile properties, using doping and advanced methods of thermal and thermomechanical treatments. The structure, phase composition, and TMTs were investigated by transmission- and scanning electron microscopy, as well as by neutron-, electron- and X-ray diffraction. Temperature measurements of the electrical resistance, magnetic susceptibility, as well as tests of the tensile mechanical properties and special characteristics of SMEs were also used. Temperature-concentration dependences for TMTs in the binary and ternary alloys of a number of quasi-binary systems were determined and discussed. It is shown that the ductility and strength of alloys required for the realization of SMEs can be achieved through optimal alloying, which excludes decomposition in the temperature range of SMEs' usage, as well as via various treatments that ensure the formation of their fine- (FG) and ultra-fine-grained (UFG) structure. © 2019 by the authors.

TEMPO-oxidized thermomechanical pulp (TMP) prepared at low-oxidized and highly oxidized levels was compared with untreated TMP to observe the advantage of each pulp on paper properties. While the low oxidized pulp and non-oxidized pulp gave similar properties, highly oxidized TMP significantly increased tensile strength and decreased tear strength. Brightness was negatively affected by oxidation. In order to improve the paper optical properties, the use of a conventional mineral filler retention system was studied, using clay as filler. The high charge induced by the oxidized pulp significantly modified the pulp retention behavior. Moreover, paper made from pulp containing oxidized pulp and clay presented considerably better tensile strength with a loss in tear resistance for the same brightness target, which could be interesting for some paper applications. © 2019, North Carolina State University.

The microstructural degradation and the creep fracture behavior of conventionally and thermomechanically treated Grade 91 steel were investigated after performing Small Punch Creep Tests. A remarkable reduction in creep ductility was observed for the samples thermomechanically treated in comparison to those conventionally treated under the tested conditions of load (200 N) and temperature (700 ºC). A change in the fracture mechanism from a ductile transgranular fracture to a brittle intergranular fracture was observed when changing from the conventionally treated to the thermomechanically treated processing condition, leading to this drop in creep ductility. The change in the fracture mechanism was associated to the localized concentration of creep deformation, close to coarse M23C6 carbides, at the vicinity of prior austenite grain boundaries (PAGB) in the thermomechanically treated samples. The preferential recovery experienced at the vicinity of PAGB produced the loss of the lath structure and the coarsening of the M23C6 precipitates. The electron microscopy images provided suggest that the creep cavities nucleate in these weak recovered areas, associated to the presence of coarse M23C6. After the coalescence of the cavities the propagation of the cracks was facilitated by the large prior austenite grain size produced during the austenitization which favors the propagation of the cracks along grain boundaries triggering the intergranular brittle fracture. This fracture mechanism limits the potential use of the proposed thermomechanical processing routes.

Thermomechanically treated (TMT) carbon steel bars, often known as TempCoreTM bars, are commonly used as reinforcements in concrete structures. TMT causes the formation of a martensite case in the outer surface of the bars, increasing their hardness, while the remaining ferritic-perlitic core maintains the typical ductility of hot rolled bars. In this work, the effect of this TMT induced microstructure on the development of pitting attacks in chloride media has been analyzed in depth. Electrochemical impedance spectroscopy (EIS) measurements and polarization curves have been carried out in simulated pore solutions to understand the effect of the presence of different phases in the microstructure and to quantify the strength of the galvanic couple that the outer martensite can form with the inner core. Moreover, accelerated corrosion tests in chloride contaminated concrete slabs have been performed. Bars from six different slabs where corrosive attack has been forced for different times have been studied. The shape of the main pits in the bars corroded in concrete has been analyzed through optoelectronic microscopy and the results obtained prove that the depth of the attack is related to the microstructure of the TMT bars.

The so-called ausformin thermomechanical treatment consists in plastically deforming a fully austenitized steel prior to either a martensitic o a bainitic transformation. This treatment could be an alternative to obtain nanoestructured bainite in medium carbon steels. However, befores this alternative is implemented, it is important to study the effect of the plastic deformation on the transformation, especially when steels are deformed at medium ol low temperatures. In this paper, the effect of the plastic deformation on the bainitic transformation has been studied in a medium carbon steel (0.4 mass content in %) by means of high-resolution dilatometry, scanning electron microscopy and X-Ray diffraction.

The microstructural degradation and the creep fracture behavior of conventionally and thermomechanically treated Grade 91 steel were investigated after performing small punch creep tests. A remarkable reduction in creep ductility was observed for the samples thermomechanically treated in comparison to those conventionally treated under the tested conditions of load (200 N) and temperature (700 °C). A change in the fracture mechanism from a ductile transgranular fracture to a brittle intergranular fracture was observed when changing from the conventionally treated to the thermomechanically treated processing condition, leading to this drop in creep ductility. The change in the fracture mechanism was associated to the localized concentration of creep deformation, close to coarse M23C6 carbides, at the vicinity of prior austenite grain boundaries (PAGB) in the thermomechanically treated samples. The preferential recovery experienced at the vicinity of PAGB produced the loss of the lath structure and the coarsening of the M23C6 precipitates. The electron microscopy images provided suggest that the creep cavities nucleate in these weak recovered areas, associated to the presence of coarse M23C6. After the coalescence of the cavities the propagation of the cracks was facilitated by the large prior austenite grain size produced during the austenitization which favors the propagation of the cracks along grain boundaries triggering the intergranular brittle fracture. This fracture mechanism limits the potential use of the proposed thermomechanical processing routes.

TEMPO-oxidized thermomechanical pulp (TMP) prepared at low-oxidized and highly oxidized levels was compared with untreated TMP to observe the advantage of each pulp on paper properties. While the low oxidized pulp and non-oxidized pulp gave similar properties, highly oxidized TMP significantly increased tensile strength and decreased tear strength. Brightness was negatively affected by oxidation. In order to improve the paper optical properties, the use of a conventional mineral filler retention system was studied, using clay as filler. The high charge induced by the oxidized pulp significantly modified the pulp retention behavior. Moreover, paper made from pulp containing oxidized pulp and clay presented considerably better tensile strength with a loss in tear resistance for the same brightness target, which could be interesting for some paper applications. © 2019, North Carolina State University.

The major challenge in a heat-resistant steel is to generate thermally stable microstructures that allow increasing the operating temperature, which will improve the thermal efficiency of the power plant without diminishing strength or time to rupture. The strengthening mechanism in tempered martensitic 9Cr steels comes mainly from the combination of solid solution effect and of precipitation hardening by fine MX carbo-nitrides, which enhance the sub-boundary hardening. This work is focused on the effect of ausforming processing on MX nanoprecipitation, on both their distribution and number density, during the subsequent tempering heat treatment. The creep strength at 700 oC was evaluated by small punch creep tests. The creep results after ausforming were compared to those obtained after conventional heat treatment concluding, in general, that ausforming boosts the creep strength of the steel at 700 oC. Therefore, conventional ausforming thermomechanical treatment is a promising processing route to raise the operating temperature of 9Cr heat-resistant steels.

The best contribution to the strength of bainitic microstructures is due to the scale of the bainitic ferrite plates. In order to improve this strength, it is important to understand and control the parameters that define the final bainitic microstructure. Among them, the strength of the austenite from where the bainite grows and the driving force of the transformation are the most influential parameters. Historically, controlling the transformation temperature and the chemical composition has been the common way of increasing both, the strength of the austenite and the driving force of the transformation. Recently, the viability of increasing both magnitudes has been tested by a process called ausforming, that consists on applying plastic deformation prior to the transformation, obtaining in this way not only thinner bainitic ferrite plates, but also an acceleration of the bainitic transformation. In this project the viability of this thermomechanical treatment and the influence of the parameters that define it (deformation, deformation temperature and transformation temperature) on the bainitic transformation will be tested., [ES] La mayor aportación a la resistencia de las microestructuras bainíticas viene del tamaño de las placas de ferrita. Cualquier mejora de la misma pasa por tanto por el conocimiento y el control de los parámetros que definen la escala final de la microestructura bainítica, entre ellos la resistencia de la austenita a través de la cual crece la ferrita bainítica y la fuerza motriz de la transformación, directamente relacionados con la temperatura de transformación y la composición química del material. Recientemente, se ha comprobado que la aplicación de deformación plástica previa a la transformación, ausforming, permite conseguir de esta manera no solo placas de ferrita bainítica más delgadas, sino también una aceleración de la transformación bainítica. En este trabajo se comprobará la viabilidad de este tratamiento termomecánico, y la influencia que los parámetros que lo definen (deformación, temperatura de deformación y de transformación), tienen en la transformación bainítica.

Ausforming is the process by which austenite is plastically deformed prior to bainitic or martensitic transformation. The advantages of such a process on the kinetics of the bainitic transformations have already been reported, but little is found about the effect on the morphology and crystallography of the final microstructure, and in most cases the studies deal with high C steels. Since ausforming has been suggested to be an alternative to transfer the concept of nanostructured bainite to medium carbon contents, the necessity to study the effect of prior plastic deformation on the subsequent bainitic transformation in those steels arises. By means of techniques such as high-resolution dilatometry, scanning electron microscopy, electron backscatter diffraction and X-Ray diffraction, it has been proven that, in a medium carbon steel (0.4 wt%), the macroscopic isotropy that characterizes the bainitic transformation can be altered, under certain conditions, by plastically deforming austenite prior to transformation. The alteration is such that, at low temperatures, the interpretation of the dilatometric response or the plate thickness measurements can be hindered. In addition, the final microstructure is also affected, presenting highly ordered bainitic ferrite plates, most of them correspondent to specific crystallographic variants.

В работе исследовали свойства проволоки сплава Ti–Ni с эффектом памяти формы, из которой изготавливали термочувствительные элементы для термозапорных газовых клапанов. Проволока обладала нехарактерным для околоэквиатомного сплава низким значением сопротивления деформации, из-за чего клапан закрывался при комнатной температуре. В работе пытались увеличить сопротивление деформации проволоки путем проведения дополнительного волочения при пониженных температурах с целью увеличения деформационного наклепа, регулируя при этом температурный интервал восстановления формы и степень восстановления формы последеформационным отжигом., The properties of an industrial Ti–Ni wire with shape memory effect, that was used for making temperature sensing elements for thermal shutoff valves, were studied. Due to the low deformation resistance, which is untypical for near equi-atomic Ti–Ni alloys, the valve was closed at room temperature. There was an attempt to increase the deformation resistance, repeating the wire drawing at lower temperatures. The functional properties of the wire were regulated using the post-deformation annealing.

В работе исследовано влияние термомеханической обработки, включающей обработку на твердый раствор, закалку, прокатку при комнатной температуре и последующее искусственное старение при Т = 190°С, на микроструктуру и механические свойства высокопрочного алюминиевого сплава АА2519 (Al–5,64Cu–0,33Mn–0,23Mg–0,11Ti–0,08Fe–0,08Zn–0,1V–0,2Zr (вес. %)). Применение холодной пластической деформации значительно ускоряет процесс распада пересыщенного твердого раствора. После 40 % обжатия и старения на максимальную прочность сплав демонстрирует -0.2 = 496 МПа и -B = 536 МПа, при этом пластичность остаётся на приемлемом уровне (- - 10 %)., The effect of the thermomechanical treatments on the phase composition and mechanical properties of heat-treatable AA2519 aluminum alloy (Al–5.64Cu–0.33Mn–0.23Mg–0.11Ti–0.08Fe–0.08Zn–0.1V–0.2Zr) has been investigated. The heat treatment included solution heat treatment, cold rolling with reduction of 40 % and final artificial ageing at T = 190°C. Processing of T840 is lead to significant acceleration of solid solution decomposition, qualitatively changes in phase composition and increasing in strength.

Рассмотрено влияние термической и термомеханических обработок, включающих обработку на твердый раствор, закалку, 7%-правку растяжением (Т87) либо холодную прокатку со степенью обжатия 10 % (T810) и последующее искусственное старение при Т = 190 °С на микроструктуру и механические свойства высокопрочного алюминиевого сплава 2519 (Al-5,64Cu-0,33Mn-0,23Mg-0,11Ti-0,08Fe-0,08Zn-0,1V-0,2Zr (вес. %)). По сравнению со стандартной термической обработкой (Т6), применение обработок типа Т8 в значительной мере изменяет стадийность распада твердого раствора, повышает прочностные характеристики материала (σ0,2 на 35 %, а σ B на 11 %), при этом пластичность остается на приемлемом уровне (δ >10 %)., The effect of the thermomechanical treatments on the microstructure, phase composition, and mechanical properties of heat-treatable AA2519 aluminum alloy (Al-5.64Cu-0.33Mn-0.23Mg-0.11Ti-0.08Fe-0.08Zn-0.1V-0.2Zr) has been considered. The heat treatment included solution heat treatment, quenching, cold plastic deformation in tension with strain of ~7 % (T87) or rolling with reduction ~10 % (T810) and final artificial ageing at T = 190 °C. Processing of T8 type are lead to significant acceleration of solid solution decomposition, qualitatively changes in phase composition and increasing in mechanical properties level.

Istrаţivаnjа u okviru ove doktorske disertаcije obuhvаtila su eksperimentаlnа ispitivаnjа sinterovаnih i livenih bakarnih legurа nominalnog sastava Cu-4аt.%Au, kao i sinterovanog i livenog bаkrа radi uporeĎenja poboljšanja svojstava legura. Na sinterovanom i livenom bakru kao i na Cu-Au legurama je sprovedena kompleksna termomehanička obrada po istoj proceduri, koja je u Cu-Au legurama stvorila uslove za pojavu originalnog mehanizma ojačavanja - efekta ojačavanja ţarenjem. Sinterovani bakar i Cu-Au legura su dobijeni posle jednostranog presovanja homogene smeše prahova pritiskom od 360 MPa i sinterovanja na temperaturi od 850oC u trajanju od 1 h u redukcionoj atmosferi vodonika. Dobijanje livenih uzoraka bakra i Cu-Au legure je realizovano preko topljenja i livenja proračunate količine polaznih sirovina, homogenizacionog ţarenja odlivaka na 800oC u trajanju od 24 h i sečenja odlivaka. Tako dobijeni uzorci sinterovanog i livenog bakra i Cu-Au legura su bili podvrgnuti termomehaničkoj obradi po istovetnoj proceduri, koja se sastojala iz više etapa. Izvršene su sledeće etape termomehaničke obrade: predzavršno valjanje na proračunate visine - ţarenje na 500oC u trajanju od 45 minuta i kaljenje u vodi sa ledom - završno valjanje stepenima deformacije od 0 %, 20 %, 40 % i 60 % - izohrono ţarenje na vazduhu na temperaturama iz intervala od 60 oC do 700oC u trajanju od po 30 minuta i izotermalno ţarenje na 250oC u vremenskom intervalu od 1 minut do 100 sati. Sprovedena termomehanička obrada na opisani način je imala za cilj proučаvаnje rаzličitih mehаnizаmа ojаčаvаnjа sa osvrtom na legirаnje, hlаdnu plаstičnu deformаciju ostvarenu predzavršnim i završnim valjanjem, ali je najveća paţnja posvećena istraţivanju efekta ojačavanja ţarenjem, koji se javio kod sinterovanih i livenih Cu-Au legura, no različitog intenziteta. Zа kаrаkterizаciju sinterovanog i livenog bakra i Cu-Au legura u toku sprovedene termomehаničke obrаde je korišćeno više savremenih, standardizovanih, visoko r, The research conducted in this PhD thesis includes the experimental study of sintered (PM) and cast (IM) copper based alloys with nominal composition Cu- 4at.%Au, as well as PM and IM copper in order to compare the improvements of the alloy properties. An identical procedure of thermomechanical treatment was performed on PM and IM copper and Cu-Au alloys, which created the conditions for the occurrence of original mechanism of hardening (anneal hardening effect) in alloys. PM copper and Cu-Au alloys were obtained after one-sided pressing of the homogeneous powder mixture using the pressure of 360 MPa, and sintering at the temperature of 850°C for 1 h in a hydrogen reducing atmosphere. IM samples of copper and Cu-Au alloys were obtained through melting and casting of the calculated amount of the raw materials, as well as ingot homogenization at 800oC for 24 h, and ingot cutting. The obtained samples of PM and IM copper and Cu-Au alloys were subjected to thermomechanical treatment using the identical procedure consisting of several stages. The following stages of thermomechanical treatment were performed: prefinal rolling on a calculated height - annealing at 500°C for 45 minutes and quenching in the ice water - the final rolling with 0 %, 20 %, 40 % and 60 % reductions - isochronal annealing in air in the temperature interval of 60oC to 700°C for a period of 30 minutes, and isothermal annealing at 250°C in a time interval from 1 minute to 100 hours. The above described thermomechanical treatment was used in order to analyze different strengthening mechanisms such as alloying, cold plastic deformation by prefinal and final rolling, and most of all, the anneal hardening effect, occurring with different intensity in PM and IM Cu-Au alloys. For the characterization of the PM and IM copper and Cu-Au alloys during the thermomechanical treatment,many modern, standardized, high resolution methods and analytical techniques were used. Mechanical properties testing included the

In this work a novel finite element technology based on a three-field mixed formulation is presented. The Variational Multi Scale (VMS) method is used to circumvent the LBB stability condition allowing the use of linear piece-wise interpolations for displacement, stress and pressure fields, respectively. The result is an enhanced stress field approximation which enables for stress-accurate results in nonlinear computational mechanics. The use of an independent nodal variable for the pressure field allows for an adhoc treatment of the incompressibility constraint. This is a mandatory requirement due to the isochoric nature of the plastic strain in metal forming processes. The highly non-linear stress field typically encountered in the Friction Stir Welding (FSW) process is used as an example to show the performance of this new FE technology. The numerical simulation of the FSW process is tackled by means of an Arbitrary-Lagrangian-Eulerian (ALE) formulation. The computational domain is split into three different zones: the work.piece (defined by a rigid visco-plastic behaviour in the Eulerian framework), the pin (within the Lagrangian framework) and finally the stirzone (ALE formulation). A fully coupled thermo-mechanical analysis is introduced showing the heat fluxes generated by the plastic dissipation in the stir-zone (Sheppard rigid-viscoplastic constitutive model) as well as the frictional dissipation at the contact interface (Norton frictional contact model). Finally, tracers have been implemented to show the material flow around the pin allowing a better understanding of the welding mechanism. Numerical results are compared with experimental evidence., Postprint (published version)

Severe plastic deformation has been carried out in some iron aluminide alloys by repeated hightemperature forging and used to refine the dispersion of cast-in second phase particles. The second phases considered range from brittle Laves phases to tougher boride phases, with both apparently refined in the same way by the forging. It appears that refinement is mostly determined by the initial morphology of the second phase particles, with elongated particles being broken towards an equiaxed shape. A relatively uniform distribution of fine second phase particles, such as would be needed for good high-temperature creep resistance, requires very high levels of imposed plastic strain on initially fine elongated particles.

This thesis considers two related problems where heat conduction is accompanied by phase transformation during the cooling of carbon steels — phenomena which are fundamental to modern thermomechanical treatment processes. In the first problem, a non-linear heat equation formulation is described which includes linkage between irreversible diffusive and diffusionless phase transformation processes and thermophysical properties. A family of numerical schemes using finite difference methods with diagonally implicit Runge-Kutta method integrators for solving this formulation is present. Sample calculations using these schemes are presented for a mild steel cooled under range of industrially relevant heat transfer conditions. These calculations illustrate the need for careful scheme design and solver selection when coupled heat conduction and microstructure evolution equations become non-linear and stiff. The second section of the thesis extends this heat conduction formulation into the realm of inverse analysis. The problem of temperature reconstruction and boundary condition estimation using temperature measurements obtained thermocouples embedded into laboratory samples undergoing phase transformation is considered. A solution method based on iterative regularization is described for solving the resulting ill-posed problem. An analysis of extremely high rate cooling experiments made on a pilot-plant descaling unit using the inverse method is presented. This analysis highlights some of the practical issues associated with embedded thermocouple temperature measurements made in this fashion., Tiivistelmä Väitöstyössä tutkitaan kahta ongelmaa liittyen hiiliteräksen termomekaanisen käsittelyn numeeriseen mallintamiseen. Työssä tarkastellaan teräksessä tapahtuvaa lämmönsiirtoa ja faasimuutoksia jäähdytyksen aikana, eli ensisijaisen tärkeitä ilmiöitä kehittynyttä teräksen valmistusta ja prosessointia ajatellen. Ensimmäisenä ongelmana tutkitaan epälineaarisen energiayhtälön muodostaminen huomioiden teräksen termofysikaaliset materiaaliominaisuudet, diffuusion kontrolloimat ja diffuusiosta riippumattomat irreversiibelit faasimuutokset. Lisäksi huomioidaan näiden väliset kytkennät. Yhtälöt ratkaistaan numeerisesti ja käytetyt menetelmät esitellään differenssimenetelmien ja diagonaalisesti implisiittisten Runge-Kutta-menetelmien osalta. Väitöstyössä näiden käyttöä havainnollistetaan simuloimalla niukkahiilisen teräksen käyttäytymistä teollisia olosuhteita vastaavan jäähdytyksen aikana. Laskentatulokset osoittavat ratkaisumenetelmän suunnittelun ja valinnan tärkeyden erityisesti silloin, kun lämmönjohtuminen, mikrorakenteen kehittyminen ja termofysikaaliset materiaaliominaisuudet muuttavat ratkaistavan ongelman epälineaariseksi ja jäykäksi. Toisena ongelmana tutkitaan edellä esitetyn lämmönsiirtomallin käyttöä osanainversioanalyysiä. Laboratoriokokeiden, termopareilla suoritettujen lämpötilamittausten, työssä kehitetyn lämmönsiirtomallin ja suoritetun inversioanalyysin avulla rekonstruoidaan teräskappaleiden lämpötila- ja faasimuutoskäyttäytymistä sekä estimoidaan mallin reunaehtoja. Näin luotu inversio-ongelma on kuitenkin matemaattisesti tarkasteltuna ns. huonosti asetettu ongelma, ja sen ratkaisemiseksi käytetään iteratiiviseen säännöllistämiseen perustuvaa menetelmää. Väitöstyön inversioanalyysiä havainnollistetaan pilot-mittakaavan kokeiden avulla, joissa hilsepesuria käyttäen koekappaleen jäähtymisnopeus saadaan erittäin korkeaksi. Tulokset nostavat esille inversio-analyysiin liittyviä ongelmia ja rajoitteita nopeaan jäähtymiseen sekä lämpötilamittauksiin l

A comparative study of some of the most important effects of the diverse microalloying elements on austenite and ferrite microstructure of hot rolled microalloyed steels is carried out. The values of different aspects such as pinning and driving forces, size of precipitates, activation energies or diffusion coefficients are discussed. Titanium is the most effective element to control grain growth at high reheating temperatures and a weight Ti/N ratio close to 2 is recommended. Aluminum can help to control grain growth at medium temperatures, but its addition to Ti steels can promote abnormal grain growth. Niobium is the most effective element to inhibit static recrystallization of austenite, due to the adequate precipitation temperature range at deformation temperatures and the strong pinning effect of Nb carbonitrides. Finally, the preferential nucleation of intragranular ferrite on particles such as vanadium carbonitrides enhances the ferrite grain refinement.

The effects of cold work and different heat treatments on the stress corrosion cracking (SCC) behavior of Al-Mg6.8% alloy were studied using slow strain rate testing (SSRT). The results have indicated high SCC susceptibility for hard and soft tempers. After different heat treatments in the range of dual phase (a+(3) structure, a high SCC resistance has experienced. The presented results indicated the possibility of a serious improvement of SCC resistance in such a highly alloyed high strength Al-Mg alloy sheet., Metodom jednoosnog zatezanja sa malom brzinom deformacije (SSRT) ispitivanje uticaj strukture na otpornost prema naponskoj koroziji (SCC) Al-Mg legure sa 6.8%Mg. Utvrdjeno je da ispitivana legura u deformisanom, i meko žarenom stanju, pokazuje veliku osetljivost prema naponskoj koroziji. Pri ispitivanju u korozionom rastvoru, duktilnost se značajno smanjuje, a indeks osetljivosti prema naponskoj koroziji ima visoku vrednost, I.scc- 81-91%. Posle žarenja u dvofaznoj (a+P) oblasti, otpornost prema naponskoj koroziji ispitivane legure, znatno se poboljšava. U tom slučaju, duktilnost se neznatno menja pri ispitivanju u korozionoj sredini, a indeks osetljivosti prema naponskoj koroziji ima nisku vrednost, Iscc- 6-13%. Rezultati pokazuju daje izborom odgovarajuće termomehaničke obrade (TMO) moguće postizanje strukture u Al-Mg6.8% leguri koja je otporna prema naponskoj koroziji.

The effects of cold work and different heat treatments on the stress corrosion cracking (SCC) behavior of Al-Mg6.8% alloy were studied using slow strain rate testing (SSRT). The results have indicated high SCC susceptibility for hard and soft tempers. After different heat treatments in the range of dual phase (a+(3) structure, a high SCC resistance has experienced. The presented results indicated the possibility of a serious improvement of SCC resistance in such a highly alloyed high strength Al-Mg alloy sheet., Metodom jednoosnog zatezanja sa malom brzinom deformacije (SSRT) ispitivanje uticaj strukture na otpornost prema naponskoj koroziji (SCC) Al-Mg legure sa 6.8%Mg. Utvrdjeno je da ispitivana legura u deformisanom, i meko žarenom stanju, pokazuje veliku osetljivost prema naponskoj koroziji. Pri ispitivanju u korozionom rastvoru, duktilnost se značajno smanjuje, a indeks osetljivosti prema naponskoj koroziji ima visoku vrednost, I.scc- 81-91%. Posle žarenja u dvofaznoj (a+P) oblasti, otpornost prema naponskoj koroziji ispitivane legure, znatno se poboljšava. U tom slučaju, duktilnost se neznatno menja pri ispitivanju u korozionoj sredini, a indeks osetljivosti prema naponskoj koroziji ima nisku vrednost, Iscc- 6-13%. Rezultati pokazuju daje izborom odgovarajuće termomehaničke obrade (TMO) moguće postizanje strukture u Al-Mg6.8% leguri koja je otporna prema naponskoj koroziji.

Physical and metallurgical basis of historical steel development and some modern solutions for specific applications, together with predictions and projections of future development are reviewed in this paper. Undoubtedly, in future, steel will remain absolutely most used construction material due to the best relationship properties/price. Dominant place is reserved for steels for welded constructions, and their further development will be provided by application of concept of Total Thermomechanical Control Processing (TTCMP). Simultaneously, predictions consider intensive Development in the field of welding procedures, filler materials, modeling of TMCP and welding, with aim to provide fabrication of welded constructions with improved safety., U radu su izložene fiziko-metalurške osnove istorijskog razvoja čeličnih materijala, primeri savremenih rešenja čelika za specifične namene i pretpostavke daljeg razvoja. Nedvosmisleno, u budućnosti, čelični materijali će ostati suvereno najrasprostranjeniji konstrukcioni materijal, zbog najboljeg odnosa kvalitet/cena. Dominantno mesto će zauzimati čelici predviđeni za izradu zavarenih konstrukcija, a njihov razvoj će biti omogućen konceptom totalne termomehaničke prerade. Uporedo, predviđa se intenzivan razvoj na polju tehnologija zavarivanja, dodatnih materijala, matematičkog modeliranja termomehaničke prerade i zavarivanja, sa ciljem da se obezbedi izrada zavarenih konstrukcija povišene sigurnosti.

Physical and metallurgical basis of historical steel development and some modern solutions for specific applications, together with predictions and projections of future development are reviewed in this paper. Undoubtedly, in future, steel will remain absolutely most used construction material due to the best relationship properties/price. Dominant place is reserved for steels for welded constructions, and their further development will be provided by application of concept of Total Thermomechanical Control Processing (TTCMP). Simultaneously, predictions consider intensive Development in the field of welding procedures, filler materials, modeling of TMCP and welding, with aim to provide fabrication of welded constructions with improved safety., U radu su izložene fiziko-metalurške osnove istorijskog razvoja čeličnih materijala, primeri savremenih rešenja čelika za specifične namene i pretpostavke daljeg razvoja. Nedvosmisleno, u budućnosti, čelični materijali će ostati suvereno najrasprostranjeniji konstrukcioni materijal, zbog najboljeg odnosa kvalitet/cena. Dominantno mesto će zauzimati čelici predviđeni za izradu zavarenih konstrukcija, a njihov razvoj će biti omogućen konceptom totalne termomehaničke prerade. Uporedo, predviđa se intenzivan razvoj na polju tehnologija zavarivanja, dodatnih materijala, matematičkog modeliranja termomehaničke prerade i zavarivanja, sa ciljem da se obezbedi izrada zavarenih konstrukcija povišene sigurnosti.

En la I parte de este trabajo, se presentó, a modo de revisión, las características generales del llamado Modelo Dinámico de Materiales mediante el cual se determinan los mapas de procesado. En esta II parte, siguiendo la metodología descrita en la I parte, se desarrollan los mapas de procesado de un acero microaleado de contenido medio de carbono en el intervalo de temperaturas 900-1.150 °C y de velocidades de deformación ¿ = 10-4-10 s-1. El análisis de los mapas indica que el acero estudiado sufre recristalización dinámica, con un máximo de eficiencia del 33 %, en el dominio situado a 1.150 °C y 10 s-1 y restauración dinámica en el entorno de 900 °C y 0,1 s-1. Part 1 of this work presents a revisión of the general characteristics of the so called dynamic materials model on which processing maps are developed. In this part following the methodology described in part 1, processing maps of a microalloyed médium carbón steel are developed over a temperature range varying from 900 to 1.150 °C at different true strain rates ranging from 10-4 to 10 s-1. The analysis of these maps revealed a domain of dynamic recrystallization centred at about 1.150 °C and strain rate 10 s-1 and a domain of dynamic recovery centred at 900 °C and 0,1 s-1., Peer Reviewed, Postprint (published version)

Soviet efforts in thermomechanical treatments (TMT) have continued unabated during the last decade. The predominant strengthening mechanisms have been firmly established and procedures for simplifying the processing requirements have been developed. Substructural stabilization and hereditary treatments have received particular attention. Pilot plant and some production processing by TMT have been reported, though the type of end items involved has not substantially changed from earlier years. The typical applications involve processing of small volumes, while the TMT of large complex components is still not technically feasible. There are a number of small, simple components that have been successfully processed and evaluated in service. Surface hardening, particularly by roller burnishing, is one technological area where a wide range of specific hardware has been TMT processed. The background developed in all phases of TMT should enable Soviet designers to incorporate TMT into less publicized applications, as in military or aviation hardware, where the increased costs inevitably associated with TMT can be better tolerated. (Author)

Summarizing a decade of internal and sponsored uranium research at DREV, this paper covers more than 25 reports on in-house and research investigations made under contracts and university grants. The paper, which gives a broad overview of Canadian achievements in this area, is divided into five parts. The first is concerned with alloy developments, i.e. the heat-treatment responses of more than 100 binary, ternary and quaternary uranium alloys, whereas the second and the third cover more extensive investigations of the two most promising alloys, the quaternary U-1Mo-1Zr-1Nb and the binary U-2Mo. Various other aspects of uranium metallurgy, such as powder metallurgy, grain growth, pyrophoricity and directional casting, are briefly described in the fourth section. A list of the most important results obtained during the course of these investigations is presented in the final section., Attached summary in French.

The patent describes a process for treating 7000 series aluminum alloys whereby their stress-corrosion resistance is greatly increased. In accordance with the process, the alloy is pre-aged, deformed at room temperature, and then subjected to two aging steps. The alloy so treated has a high resistance to stress corrosion while retaining satisfactory strength properties., Supersedes AD-164 591.

Contents: Effect of the barrier layer on certain properties of aluminized medium carbon steel; Effect of electromechanical hardening on resistance of drill pipes to corrosion fatigue failure; Corrosion-crack trajectory in biaxial plane state of stress; Effect of anodizing on fatigue limit and corrosion-fatigue strength of duraluminum sheets with stress concentrators; Effect of structure on fatigue strength of certain titanium alloys., Trans. of Fiziko-Khimicheskaya Mekhanika Materialov, n7 p10- 15, 18-21, 87-91 1971.

The memorandum was adpted from a talk given by the author at a subgroup meeting of The Technical Cooperation Program (TTCP), London, April 1970. The author's primary theme is that there are sufficient data already available to permit the use of thermomechanical treatment (TMT) routinely in the manufacture of some alloy products. The use of TMT for products of low carbon steels, aluminum alloys, maraging steels, titanium alloys, nickel-base alloys and high-alloy steels is discussed briefly. Most of the memorandum deals with TMT of alloy steels. The future of TMT is forecast briefly, particularly with respect to alloy steels. An extensive bibliography includes sources in several languages, primarily English and Russian. A few sources in French, German, Czech, Serbo-Croatian, and Japanese are also cited.

The effect of thermomechanical treatment on the stress corrosion cracking susceptibility of Beta III (Ti-11.5Mo-6Zr-4.5Sn) alloy was investigated. Specimens of the alloy were cold worked 0, 2, 5, 10, 20, and 50% and precipitation hardened prior to fabrication into tensile test specimens. Five specimens of each thermomechanical treatment condition were tensile tested in order to obtain yield strengths. The remaining specimens were exposed to an alternate wet/dry environment of 3.5 w/o NaCl solution at ambient temperature under a load of 80% of yield. (Author Modified Abstract)

An investigation is being conducted to study the synergistic effects of thermal treatment and explosive shock loading on the microstructure and mechanical properties of Udimet 700 and Inconel 718. The influence of such shock thermomechanical processing (TMP) is compred with that of thermal processing alone and of conventional TMP by cold rolling to a recuction equivalent to the transient shock strain. Shock TMP of Udimet 700 led to improvements in tensile strengths at testing temperatures up to 1400F, tensile ductility, toughness, stress-rupture life at 1200 and 1400F, and microstructural stability. Room- temperature strength and toughness of Inconel 718 were increased due to shock TMP. (Modified author abstract), See also report dated Jan 72, AD-737 310.