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This study determines how untreated recycled concrete aggregates (URA), thermally treated recycled concrete aggregates (TRA), and recycled concrete aggregates developed through an integrated thermomechanical treatment process (TmRA) perform in concrete relative to each other. A concrete composed of 100% recycled aggregates (RCA) with Portland pozzolana cement has been successfully developed in the present study. The compressive strength, split tensile strength, flexural strength, fracture energy, and modulus of elasticity of TmRC is observed higher than URC by 18.62%, 8.20%, 40.72%, 24.18%, and 54.99%, and those TRC by 7.54%, 28.57%, 29.78%, 24.12%, and 34.35%, respectively. The split tensile strength, flexural strength, fracture energy, and modulus of elasticity of these concretes are strongly correlated with their compressive strength. TmRC material properties match NAC, standard requirements, and reported values closely. URC and TRC chloride-ion penetrations are around 3.51- and 2.42-times greater than TmRC. Among these concretes, only TmRC meets corrosion protection requirements like NAC. The abrasion resistance of TmRC is observed 52.03% greater than URC and 43.07% greater than that of TRC. TmRC has substantially lower sorptivity compared to URC and TRC and is close to NAC. TmRC has around 32.65% and 16.67% less weight loss in drying than URC and TRC, respectively. URC and TRC have around 1.99- and 1.82-times less abrasion resistance than TmRC. An optimal reduced adhered-mortar volume, the minimized porosity and microcracks, dense and uniform surface texture, strengthened interfacial transition zones leads the performance of TmRA superior to URA and TRA, and close to or superior to parent aggregates. [ABSTRACT FROM AUTHOR]

The evolution of the microstructure and mechanical properties of Al–5.76Zn–1.77Mg–0.33Fe−0.45Ni (wt pct) alloy bars produced by hot extrusion (HE) followed by radial shear rolling (RSR) and heat treatment (quenching + aging) has been studied. The results show that the suggested thermomechanical treatment (TMT) allows one to produce a specific type of microstructure. HE provides for defect-free deformation of the initial cast structure, while RSR leads to the formation of a fine microstructure due to unique temperature–strain conditions. During deformation, insoluble Al9NiFe eutectic phase crystals are refined to a size of about 100 nm. These crystals are localized along the grain and subgrain boundaries and act as effective barriers to the migration of high-angle and low-angle grain boundaries. As a result, the formation of a deformed structure with an extensive network of low-angle grain boundaries (especially in the near-surface region where the equivalent strain is about 15) is observed in the central part and in the near-surface region of the obtained bars. The formation of a structure with an average characteristic subgrain size (~ 2 to 3 μm) comparable to that of grains produced by severe plastic deformation processes provides for a favorable combination of mechanical properties (UTS ~ 416 MPa, YS ~ 293 MPa, δ ~ 8.4 pct), which are comparable to the mechanical properties of a similar alloy after equal channel angular pressing. [ABSTRACT FROM AUTHOR]

Ferritic–martensitic (F–M) steels are widely used for high‐temperature pressure vessels and reactor cladding structures in power plants. The high operating temperatures and pressures, as well as the radiation environment, significantly challenge the mechanical stability of these steels. Here, the degradation mechanisms in F–M steels during creep and thermal aging under these harsh environments are reviewed. The exceptional mechanical properties of F–M steels are mainly attributed to their well‐constructed microstructures and chemical compositions. Microstructural barriers such as dislocations, solid solution atoms, and precipitates play key roles in resisting degradation. During the long‐term service, the microstructures undergo gradual evolution, resulting in a deterioration of mechanical properties at the macrolevel. In addition to the degradation mechanisms, some recent advancements in strengthening methods, including microalloying strengthening, thermomechanical treatment (TMT), and oxide dispersion strengthening, are summarized, aimed at the development of next‐generation F–M steels. The strengthening of the F–M steels is mainly achieved by enhancing the thermal stability of their microstructures. Insight into both the deterioration mechanisms and strengthening methods of F–M steels may pave the way for new approaches in developing high‐performance steels for applications in next‐generation power plants operating at ultrahigh operating temperatures and pressures. [ABSTRACT FROM AUTHOR]

Before artificial ageing, extruded aluminium profiles are subjected to stretching with a small cold deformation in the range of 0.5–2%. This deformation improves the geometrical stability of the extruded product and causes changes in the microstructure of the profile, which leads to the strain hardening of the material after artificial ageing. The work has resulted in the creation of the prototype of an original device, which is unique in the world, for the dynamic stretching of the extruded profiles after quenching. The semi-industrial unit is equipped with a hydraulic system for stretching and a pneumatic system for cold dynamic deformation. The aim of this research paper is to produce advantageous microstructural changes and increase the strength properties of the extruded material. The solution of the dynamic stretching of the profiles after extrusion is a great challenge and an innovation not yet practised. The paper presents the results of microstructural and mechanical investigations carried out on extruded AlMgSi(Cu) alloys quenched on the run-out table of the press, dynamically stretched under different conditions, and artificially aged for T5 temper. Different stretching conditions were applied: a static deformation of 0.5% at a speed of 0.02 m/s, and dynamic deformation of 0.25%, 0.5%, 1%, and 1.5% at speeds of 0.05 and 2 m/s. After the thermomechanical treatment of the profiles, microstructural observations were carried out using an optical microscope (OM) and a scanning electron microscope (SEM). A tensile test was also carried out on the specimens stretched under different conditions. In all the cases, the dynamically stretched profiles showed higher strength properties, especially those deformed at a higher speed of 2 m/s, where the increase in UTS was observed in the range of 7–18% compared to the classical (static) stretching. The microstructure of the dynamically stretched profiles is more homogeneous with a high proportion of fine dispersoids. [ABSTRACT FROM AUTHOR]

An approach for the crystallographic mapping of two‐phase alloys on the nanoscale using a combination of scanned precession electron diffraction and open‐source python libraries is introduced in this paper. This method is demonstrated using the example of a two‐phase α/β titanium alloy. The data were recorded using a direct electron detector to collect the patterns, and recently developed algorithms to perform automated indexing and analyse the crystallography from the results. Very high‐quality mapping is achieved at a 3 nm step size. The results show the expected Burgers orientation relationships between the α laths and β matrix, as well as the expected misorientations between α laths. A minor issue was found that one area was affected by 180° ambiguities in indexing occur due to this area being aligned too close to a zone axis of the α with twofold projection symmetry (not present in 3D) in the zero‐order Laue Zone, and this should be avoided in data acquisition in the future. Nevertheless, this study demonstrates a good workflow for the analysis of nanocrystalline two‐ or multi‐phase materials, which will be of widespread use in analysing two‐phase titanium and other systems and how they evolve as a function of thermomechanical treatments. [ABSTRACT FROM AUTHOR]

In this paper, the effect of thermomechanical treatment process on the hardening behavior, grain microstructure, precipitated phase, and tensile mechanical properties of the new high-strength and high-ductility Al-10.0Zn-3.0Mg-2.8Cu alloy was studied, and the optimal thermomechanical treatment process was established. The strengthening and toughening mechanisms were revealed, which provided technical and theoretical guidance for the engineering application of this kind of high strength-ductility aluminum alloy. Al-10.0Zn-3.0Mg-2.8Cu alloy cylindrical parts with external longitudinal reinforcement were prepared by a composite extrusion deformation process (reciprocal upsetting + counter-extrusion) with a true strain up to 2.56, and the organizational evolution of the alloys during the extrusion deformation process and the influence of pre-stretching treatments on the subsequent aging precipitation behaviors and mechanical properties were investigated. The results show that firstly, the large plastic deformation promotes the fragmentation of coarse insoluble phases and the occurrence of dynamic recrystallization, which results in the elongation of the grains along the extrusion direction, and the volume fraction of recrystallization reaches 42.4%. Secondly, the kinetic study showed that the decrease in the activation energy of precipitation increased the nucleation sites, which further promoted the diffuse distribution of the second phase in the alloy and a higher number of nucleation sites, while limiting the coarsening of the precipitated phase. When the amount of pre-deformation was increased from 0% to 2%, the size of the matrix precipitated phase decreased from 5.11 μm to 4.1 μm, and when the amount of pre-deformation was increased from 2% to 7%, the coarsening of the matrix precipitated phase took place, and the size of the phase increased from 4.1 μm to 7.24 μm. The finalized heat treatment process for the deformation of the aluminum alloy tailframe was as follows: solution (475 °C/3 h) + 2% pre-stretching + aging (120 °C/24 h), at which the comprehensive performance of the alloy was optimized, with a tensile strength of 634.2 MPa, a yield strength of 571.0 MPa, and an elongation of 15.2%. The alloy was strengthened by both precipitation strengthening and dislocation strengthening. After 2% pre-stretching, the fracture surface starts to be dominated by dense tough nest structure, and most of them are small tough nests, and small and dense tough nests are the main reason for the increase in alloy toughness after 2% pre-stretching deformation. [ABSTRACT FROM AUTHOR]

This study demonstrates an integrated thermomechanical treatment process to produce high quality recycled concrete aggregate (RCA) for structural concrete. RCA is mechanically treated after 90 min of heating at 250 °C in this process. The material properties of RCA produced through 15 combinations of charges and drum revolutions are compared using a statistical method. The highest ranking of an RCA identifies it as a high-quality class. Concrete composed of 100% RCA (recycled aggregate concrete, RAC) has 1.7% higher compressive strength than natural aggregate concrete (NAC). RAC has tensile and flexural strengths of 0.95 and 1.03 in fraction of NAC. RAC meets durability criteria such as UPV greater than 4.4 km/s, rapid chloride ion penetration test (RCPT) less than 1000 C, electrical resistivity greater than 208 Ohm-m, and sorptivity closer to NAC. Water absorption and abrasion resistance are similar to or superior to those of NAC. Coherent and uniform surface morphology of RCA enhances the ITZ microstructure in RAC. [ABSTRACT FROM AUTHOR]

In the present work, the corrosion behaviour of 2A97 Al-Cu-Li alloy with different thermomechanical treatments is investigated using electron microscopy and electrochemical measurements. The various thermomechanical treatments allowed the assessment of the individual and synergistic influence of local plastic deformation and precipitation on the corrosion susceptibility and mechanism of the alloy. It is found that in NaCl solution, corrosion of the alloys in T3 and T4 tempers occurs in the form of intergranular corrosion, which is closely associated with stored energy distribution. By contrast, the alloys in T6 and T8 tempers exhibit mainly intragranular corrosion due to high volume fractions of precipitates formed by artificial ageing.

Without homogenization or special micro-alloying treatment, the tensile strength and electrical conductivity of a commercial Cu–Ni–Si alloy can achieve 813 MPa and 51.2% IACS, respectively. The excellent combination properties were achieved by regulating the thermomechanical treatment to obtain a critical status of precipitates and dislocation densities. Although a short time pre-aging process can increase the mechanical strength, the electrical conductivity was not dramatically enhanced due to the limited precipitation process. A long-time pre-aging process or a too-high density of dislocations is not favorable to the nucleation of new precipitates, which, instead, causes the coarsening of pre-precipitates, resulting in a limited increase in strength. A critical dislocation density can be determined to boost the nucleation sites of precipitates to simultaneously maximize the mechanical and electrical properties of Cu–Ni–Si alloys. The obtained mechanical and electrical properties can meet the requirements for very large-scale lead frames. Thus, our investigation not only provides a new route for manufacturing high-performance Cu–Ni–Si alloys but also new insights into the role of dislocations in enhancing the mechanical properties of age-hardening alloys.

Cu–3Zr alloy was prepared by powder metallurgy and two-stage thermomechanical process, and the microstructure evolution and properties were investigated. The results show that the microstructure of as-sintered Cu–3Zr alloy is consisted of the coarse Cu–Zr intermetallic compounds and equiaxed Cu grains. After extrusion, the second phase is smaller in cross section, while deformation texture of the Cu matrix can be seen from longitudinal section. After further drawing, the Cu grains are elongated and the Cu–Zr intermetallic phase is broken into fine particles. The yield strength (YS), ultimate tensile strength (UTS) and electrical conductivity are 593 MPa, 684 MPa, and 74%IACS, which are respectively increased by 38%, 34% and 21% as compared to the as-sintered Cu–3Zr alloy. Phase analysis and microstructural characterization demonstrate that the Cu5Zr, Cu8Zr3, and Cu10Zr7 precipitates are uniformly distributed in the Cu matrix. Cu5Zr/Cu and Cu8Zr3/Cu are combined in the form of coherent relation. Cu10Zr7/Cu are combined in the form of semi-coherent relation. The enhanced mechanical properties can be attributed to the multiple synergistical strengthening effect. The elongated Cu grains and fine Cu–Zr precipitation phases block the movement of dislocation, resulting in the remarkable enhancement of strength. Moreover, the elongated Cu grains can provide fast channel for the electron transport, giving rise to simultaneous increase of the electrical conductivity.

Friction stir processing (FSP) is the most effective severe plastic deformation process for creating materials with very fine grains and good properties. The target of the present research is to investigate the influence of FSP on the microstructure and mechanical properties of homogenized 2024 aluminum alloy with and without rare-earth (RE) and thermomechanically treated conditions (TMT). The rare-earth elements used were Ce and La in the form of a master alloy containing (50% Ce + 50% La). The casting of 2024 aluminum alloys, both with and without (Ce + La), was carried out using the conventional stir cast technique. Part of the obtained alloys was homogenized, whereas the other part was thermomechanically treated (TMT). The homogenized 2024 material was exposed to FSP with multiple passes (one, two, and three) to obtain the suitable pass number. After that, the best pass number was performed on the 2024 aluminum alloy refined with RE (Ce + La) and TMT materials. The microstructures in different conditions (homogenized and stir friction) were examined by optical and scan microscopes attached with EDS and Map analyzer. At the same time, a tensile test was conducted to assess the mechanical properties. The findings indicated that the microstructures were significantly refined after adding RE (Ce + La) or applying the TMT technique. Whereas, the microstructures were greatly improved after applying FSP to both conditions. Ultra-fine grains were observed for both TMT and RE-containing alloys after FSP. On the other hand, the results of mechanical properties were significantly increased after applying multiple passes of FSP. The optimum results were obtained when two passes of stir friction were applied to the TMT alloy condition. [ABSTRACT FROM AUTHOR]

• The hierarchical structure was fabricated by a novel thermomechanical treatment. • The combination of grain-twin-precipitation hierarchical structure was realized on Mg-15Gd-1Zn-0.4Zr alloy. • The hierarchical structure had the effect of synergistically improving the strength and ductility of Mg-15Gd-1Zn-0.4Zr alloy. Currently, the hierarchical structure is one of the most effective means to enhance the strength and plasticity of metal materials, since the strain localization can be effectively delayed by the coordination of the unique microstructure. In this study, a hierarchical structure of Mg-15Gd-1Zn-0.4Zr (GZ151K) alloys containing grain, twin, and precipitation structural units was prepared by ultrasonic surface rolling process (USRP) and recrystallization annealing (RU). The results showed that the stress gradient generated by USRP formed a twin gradient structure, which will activate the twin-assisted precipitation (TAP) effect and twin-induced recrystallization (TIR) effect during RU. Then, the twin gradient structure transformed into a twin-precipitation gradient structure, and finally into a hierarchical structure with grain-twin-precipitation as the increasement of recrystallization degree. Besides, the dual gradient structure with twin and precipitation structural units had the highest strength and microhardness owing to the precipitation strengthening. However, the hierarchical structure with grain, twin, and precipitation structural units exhibited the most excellent combination of strength and plasticity under grain refinement and precipitation strengthening. [ABSTRACT FROM AUTHOR]

The industrial Ti–6Al–4V alloy, obtained almost in the single-phase α state by the thermomechanical treatment including hot rolling, is studied by the methods of X-ray diffraction analysis, optical and transmission and scanning orientation electron microscopy. It is revealed that the layered fine-grained microstructure in the plate's transverse section (TD) along the rolling direction (RD) is characterized both in the rolling plane (ND) and in the transverse section perpendicular to the RD by the texture selection and consistent distribution of globular α grains over the orientation Burgers relations and twinning orientations. The special crystallographic orientation of α grains and the mechanisms of generation of microtexture regions in the studied plate's transverse section (TD) of the alloy correlate with the similar data established for the plate in the plane (ND) and in the transverse section. The results obtained in three mutually orthogonal sections of the plate agree with each other, determining the texture of the globular α phase. [ABSTRACT FROM AUTHOR]

The microtexture and microstructure of the industrial Ti–6Al–4V alloy almost in the single-phase α state, obtained using the thermomechanical treatment including the hot rolling, are studied by the X-ray diffraction analysis method and optical and transmission and scanning electron microscopy. It is established that the layered fine-grained microstructure in the cross section of the plate perpendicular to the rolling direction is characterized by selection of equiaxed globular α grains that obey Burgers orientation relationships and twinning orientations. The revealed distributions of α grains over dimensions and crystallographic orientations in the plate's cross section are related to the peculiarities of distributions established for the plane of plate rolling. The structural mechanisms of generating the microtexture regions in the alloy are discussed. [ABSTRACT FROM AUTHOR]

To improve the high-temperature mechanical properties of the commercial high-chromium ferritic/martensitic (F/M) steel P92, the steel was subjected to a thermomechanical treatment (TMT) involving a warm rolling with 93 pct deformation at 650 °C and a tempering at 650 °C for 1 hour. The TMT-strengthened steel was subjected to 3.5 MeV Fe13+ ion irradiation at 400 °C to 0.68 dpa in order to study irradiation effects on the precipitates of high-chromium F/M steel after TMT. Precipitates in the TMT-strengthened steel before and after irradiation were investigated using transmission electron microscopy. Cr-rich M23C6, Nb-rich MX (NbC type) and nano-sized Cr-rich M2X as dominant precipitate phases pre-existing in the TMT-strengthened steel were also identified in the irradiated specimens. The irradiation resulted in a partial dissolution of nano-sized Cr-rich M2X precipitates and a coarsening of precipitates including undissolved nano-sized precipitates and relatively large-sized precipitates. After irradiation, the composition of Cr-rich M23C6 precipitates exhibited an increase in Cr and W, but a decrease in Fe. Seven types of irradiation-induced phases were identified in the irradiated specimens. They are Cr-rich M2C and Nb-rich MX(NbN type) with a hexagonal crystal structure, Fe-rich M3C and Fe-rich M2C as well as Cr-rich M2N0.39C0.61 with a simple orthorhombic crystal structure, Nb-rich M6C5 with a base-centered monoclinic crystal structure, and σ-FeCr with a simple tetragonal crystal structure. These irradiation-induced phases are also discussed. [ABSTRACT FROM AUTHOR]

The development of deformation and fracture in titanium alloy VT22 in the temperature range of 293–823 K is studied in the presence of ~0.1 wt.% hydrogen. It has been shown that the formation of the structure consisting of β-transformed grains with thin lamellar structure and particles of the primary α-phase increases the resistance of the hydrogenated VT22 alloy to localized plastic deformation at the macrolevel and promotes the transition of the alloy fracture from brittle-ductile to ductile during tension at room temperature. At elevated temperatures (653–823 K), the presence of dissolved hydrogen in the solid solution in the VT22 alloy reduces its resistance to localized plastic deformation at the macrolevel and the deformation value to failure. [ABSTRACT FROM AUTHOR]

In this work there is evaluation of the life of hot strengthened die steel with controlled austenitic transformation during exploitation. For this purpose thermomechanical treatment of specimens is conducted according to a compression scheme, which consists of a preliminary hot hardening stage (in the range of 450–750 °C) and a stage of long-term (9 cycles with e ~0.02 per cycle) hot deformation (at 750 °C). It is established that during long-term hot deformation the relative value of specimen weakening is only about 8%. The results obtained make it possible to predict stable operation of a stamping tool made of steel with controlled austenitic transformation during exploitation at temperatures of 450–750 °C. [ABSTRACT FROM AUTHOR]

This paper investigates the effect of thermomechanical treatments, including deformation by radial shear rolling or severe plastic deformation by abc pressing with subsequent aging at 773 K, on the structural-phase state, deformation behavior, and mechanical properties of commercial near β titanium alloy VT22 (Ti–5Al–5Mo–5V–1Cr–1Fe). The structure of the alloy after radial shear rolling and subsequent aging consists of transformed β grains with a lamellar α + β structure and primary α-phase particles. Severe plastic deformation of the alloy followed by aging causes the formation of a grain-subgrain α + β structure with an average characteristic size of 0.23 µm. It is found that, after the thermomechanical treatments, the strength characteristics of the alloy at room temperature increase by ~40% compared to the as-received alloy. The alloy after radial shear rolling and aging retains a 40–20% higher strength in the temperature range of 293–823 K. The strength of the alloy after severe plastic deformation and aging becomes lower than that of the as-received alloy already at a temperature of 773 K. Analysis of creep parameters at 743 K shows that the creep deformation of the alloy in the state after radial shear rolling and aging occurs by the motion of dislocations (glide + climb). The creep deformation of the alloy in the state after severe plastic deformation and subsequent aging is largely contributed by grain boundary sliding. [ABSTRACT FROM AUTHOR]

The structure and mechanical properties of rolled sheets with a thickness of 40 mm made of low-carbon low-alloyed steel after thermomechanical treatment of different modes are investigated. The structural factors that affect obtaining high mechanical properties are established. It is shown that a complex treatment including quenching from the rolling temperature and high-temperature tempering with a subsequent additional cycle of quenching and tempering leads to formation of rolled sheet uniform over the cross section with a fragmented bainite structure with disperse niobium carbides and carbides of cementite type. Such structure provides a yield strength of no less than 630 MPa in combination with high values of the impact energy at negative temperatures and a level of plasticity of δ ≈ 20%. [ABSTRACT FROM AUTHOR]

Printed circuit boards (PCBs) are the main components of e-waste. In order to reduce the negative impact of waste PCBs on human health and the environment, they must be properly disposed of. A new method is demonstrated for recycling waste PCBs. It is referred to as the high-temperature thermo-mechano-chemical gasification (TMCG) of PCBs by the detonation-born gasification agent (GA), which is a blend of H2O and CO2 heated to a temperature above 2000 °C. The GA is produced in a pulsed detonation gun (PDG) operating on a near-stoichiometric methane–oxygen mixture. The PDG operates in a pulsed mode producing pulsed supersonic jets of GA and pulsed shock waves possessing a huge destructive power. When the PDG is attached to a compact flow reactor filled with waste PCBs, the PCBs are subject to the intense thermo-mechano-chemical action of both strong shock waves and high-temperature supersonic jets of GA in powerful vortical structures established in the flow reactor. The shock waves grind waste PCBs into fine particles, which undergo repeated involvement and gasification in the high-temperature vortical structures of the GA. Demonstration experiments show full (above 98%) gasification of the 1 kg batch of organic matter in a setup operation time of less than 350 s. The gaseous products of PCB gasification are mainly composed of CO2, CO, H2, N2, and CH4, with the share of flammable gas components reaching about 45 vol%. The solid residues appear in the form of fine powder with visible metal inclusions of different sizes. All particles in the powder freed from the visible metal inclusions possess a size less than 300–400 μm, including a large fraction of sizes less than 100 μm. The powder contains Sn, Pb, Cu, Ni, Fe, In, Cd, Zn, Ca, Si, Al, Ti, Ni, and Cl. Among these substances, Sn (10–20 wt%), Pb (5–10 wt%), and Cu (up to 1.5 wt%) are detected in the maximum amounts. In the powder submitted for analysis, precious elements Ag, Au, and Pt are not detected. Some solid mass (about 20 wt% of the processed PCBs) is removed from the flow reactor with the escaping gas and is partly (about 10 wt%) trapped by the cyclones in the exhaust cleaning system. Metal inclusions of all visible sizes accumulate only in the flow reactor and are not detected in powder samples extracted from the cyclones. The gasification degree of the solid residues extracted from the cyclones ranges from 76 to 91 wt%, i.e., they are gasified only partly. This problem will be eliminated in future work. [ABSTRACT FROM AUTHOR]

In this work, thermomechanical treatment (single-pass rolling at 800 °C and solution treatment) was applied to nuclear-grade hot-rolled austenitic stainless steel to eliminate the mixed grain induced by the uneven hot-rolled microstructure. By employing high-temperature laser scanning confocal microscopy, microstructure evolution during solution treatment was observed in situ, and the effect of single-pass rolling reduction on it was investigated. In uneven hot-rolled microstructure, the millimeter-grade elongated grains (MEGs) possessed an extremely large size and a high Schmid factor for slip compared to the fine grains, which led to greater plastic deformation and increased dislocation density and deformation energy storage during single-pass rolling. During subsequent solution treatment, there were fewer nucleation sites for the new grain, and the grain boundary (GB) was the main nucleation site in MEGs at a lower rolling reduction. In contrast, at a higher reduction, increased uniformly distributed rolling deformation and more nucleation sites were developed in MEGs. As the reduction increased, the number of in-grain nucleation sites gradually exceeded that of GB nucleation sites, and in-grain nucleation preferentially occurred. This was beneficial for promoting the refinement of new recrystallized grains and a reduction in the size difference of new grains during recrystallization. The single-pass rolling reduction of 15–20% can effectively increase the nucleation sites and improve the uniformity of rolling deformation distribution in the MEGs, promote in-grain nucleation, and finally refine the abnormally coarse elongated grain, and eliminate the mixed-grain structure after solution treatment. [ABSTRACT FROM AUTHOR]

The purpose of this research is to manufacture steel rebars per the obligations declared in ASTM A615/615M Grade-60 via hot rolling of steel billets and thermomechanical treatment process installed at the manufacturing facility. Afterward, to understand the effect of processing parameters on the microstructure and mechanical properties of the finished product. The characterization of rebars include the chemical analysis of the final product. Moreover, the average yield strength, ultimate tensile strength, yield strength and ductility were examined. Furthermore, 180° bend testing, Charpy V-notch test, hardness, scanning electron microscopy (SEM) and optical microscopy were also explored. The results show the product perfectly endorses the demand of the standard and the values are within the specified range. But the material demonstrates menial impact energy and the characteristic features of the brittle fracture. Furthermore, hardness testing, optical microscopy and SEM corroborate the existence of dissimilar microstructures in the vicinity of core and case areas. The results shows the material satisfy the ASTM A615/615M grade-60 standard, but exhibit inferior energy absorption capabilities. [ABSTRACT FROM AUTHOR]

Biomedical Ti-22Nb-6Zr, Ti-18Zr-15Nb, and Ti-41Zr-12Nb (at.%) shape memory alloys were subjected to cold rolling (CR) and subsequent post-deformation annealing (PDA). The evolutions of phase and structure states, crystallographic texture, and crystallographic limit of recovery strain were studied using EBSD, TEM, and XRD analyses. The study found that CR (e = 1.5) and PDA at 800 °C for 30 min results in fine- and coarse-grained structures. Severe CR (e = 3.0) and PDA at 550 °C for 5 min results in a recrystallized, equiaxed, predominantly ultrafine-grained structure of the β-phase with a small amount of low-angle boundaries. Increasing the degree of CR from moderate (e = 0.3) to severe (e = 3.0) results in a favorable strong {111}β<110>β recrystallization texture. Alloys with low Zr content are more susceptible to this type of crystallographic texture formation during TMT, primarily due to a higher Nb content. The Ti-41Zr-12Nb alloy shows the highest crystallographic limit of recovery strain (εrmax ≈ 6%). The limit decreases to ≈5% (for Ti-18Zr-15Nb) and ≈3% (for Ti-22Nb-6Zr) when transitioning from high- to low-Zr alloys. The transition of Ti-Zr-Nb alloys from coarse-grained to ultrafine-grained structures of the β-phase and a decrease in grain size do not affect the crystallographic limit of recovery strain in the studied grain size ranges. [ABSTRACT FROM AUTHOR]

This study delved into exploring microstructural states in a Ti–7Ag alloy to achieve targeted functional and structural properties. Specifically, the focus was on attaining a homogeneously precipitated state and a solid solution, known for their potential to combine functional traits like corrosion resistance and antibacterial activity with structural properties such as mechanical strength. However, obtaining these optimized microstructures presents challenges due to kinetic considerations. A key finding of this study was the crucial role of a pre-deformation stage, prior to heat treatment, to create an even distribution of fine Ti2Ag precipitates. Moreover, we demonstrated that starting from this precipitated state, a controlled dissolution step could yield a single-phase solid solution with similar grain size. Therefore, a tailored set of thermomechanical treatments was developed to achieve both microstructures, and these metallurgical states were fully characterized combining SEM (BSE imaging and EDS analysis), TEM, and XRD. Associated mechanical properties were also assessed by tensile testing. In addition, the process was proven to be robust enough to overcome potential industrial problems, such as slow cooling rates when water-quenching large ingots. Considering the limited existing documentation on microstructural features in Ti–Ag alloys, this work on this model alloy significantly advanced our current understanding of the broader Ti–Ag alloy system by providing new data and showcasing a tailored approach involving thermomechanical treatments. [ABSTRACT FROM AUTHOR]

The objective of the present paper is the assessment of the healing efficiency of a thermomechanical treatment (microwave heating and re-compaction) on cold recycled asphalt mixtures. The asphalt mixture specimens were fabricated with different electric arc furnace slag (EAFS) contents to improve the mixtures' microwave susceptibility. The healing response was then assessed in terms of recovery of their initial indirect tensile strength. Furthermore, statistical analysis was conducted by means of a three-way analysis of variance to determine the influence of temperature, re-compaction energy, and EAFS content on the healing capability of the mixtures. Although re-compaction and heating in the ranges studied do not themselves cause healing, the combination of both produced excellent healing performance. The optimal content of EAFS was established at 5% of EAFS over the weight of the asphalt mixture. [ABSTRACT FROM AUTHOR]

One of the most effective ways to increase the processing plasticity of advanced superalloys (heat-resistant nickel-based alloys) is the formation of an ultrafine-grained (UFG) microstructure in bulk semi-finished products. Such a microstructure is a necessary condition for the manifestation of the structural superplasticity effect in the technological processes of manufacturing products from such superalloys. One of the most promising methods for producing UFG microstructures is thermomechanical treatment (TMT) according to the multiple isothermal forging scheme. It has been shown that the EK79 superalloy after TMT, with a gradual decrease in the processing temperature from 0.88 to 0.62 Ts (where Ts is the strengthening phase dissolution temperature) leads to the transformation of the initial microduplex fine-grained microstructure into a mixed UFG microstructure. Such a mixed UFG microstructure consists of: 1) relatively coarse (inherited from the fine-grain microstructure) particles – γ'-phase with a size of 3.0±0.8 μm; 2) γ-grains, and incoherent γ'-phase particles with a size of 0.3–0.5 μm; 3) strengthening coherent intragranular γ'-phase particles with a size of 0.05–0.1 μm, released upon cooling from the TMT temperature to room temperature. During uniaxial compression tests, the EK79 superalloy with such microstructure, demonstrates low-temperature superplasticity in the temperature range of 800–1000 °C. It has been found that an increase in the deformation temperature up to 1000 °C, leads to the increase of γ-phase grains to micron size. The maintenance of superplastic properties in the presence of relatively coarse incoherent particles in the microstructure of the second phase (γ'-phase) is apparently related to the fact that the deformation is localised in the UFG component.

Abstract Post-weld heat treatment (PWHT) and solid-state thermomechanical treatment (TMT) via friction stir processing (FSP) have been shown to enhance the mechanical properties of aluminum alloys. The current work investigates the effects of PWHT and TMT on the microstructure and mechanical performance of AA6082-T6 welded butt joints welded using the MIG process. The 5 mm thick AA 6082-T6 plates were joined in butt configuration using MIG welding with ER 5356 filler wire, 120 A current, 0.3 mm/s weld speed, and argon shielding gas at 15 L/min flow rate. PWHT was performed on the MIG welds per the T6 temper procedure. TMT was implemented via FSP using a pinless tool rotating at 800 rpm and traversing speed at 200 mm/min with a 3° tilt angle. Microstructural analysis, hardness mapping, tensile testing, and fracture surface evaluation were utilized to characterize the as-welded, PWHT, and TMT samples. The results demonstrate that both PWHT and TMT significantly refine and homogenize the microstructures of the welded joints. However, the TMT samples displayed superior hardness and tensile strength compared to the as-welded and PWHT conditions. The TMT-processed welds achieved approximately 99% joint efficiency versus only 69% and 85% for the as-welded and PWHT samples. In summary, PWHT and especially TMT via FSP are effective at enhancing the mechanical properties of MIG welded AA6082-T6.

Purpose: To compare the effect of thermomechanical aging on implant abutment color change when using different abutment backgrounds. Materials and Methods: In this study, three separate experimental groups (n = 10) with different implant abutment materials were used: zirconia, modified polyether ether ketone (MPEEK), and polyether ketone ketone (PEKK). Equal-sized glass-ceramic incisor crowns were cemented to the abutments using transparent dual-curing resin cement. The specimens were then subjected to the thermomechanical aging process for the clinical equivalent of 5 years of use. The color values of each specimen in the middle third and the incisal third were recorded by a digital spectrophotometer in the CIE L*a*b* color coordinates both before and after the aging process. Color differences between groups were compared using one-way analysis of variance (ANOVA), while Tukey test was used to compare differences within the groups (P = .05). Results: In terms of color change (Î"E00) values, the zirconia group was found to show statistically more color changes only in the middle third (P < .000), but there was no significant difference between the the MPEEK and PEKK groups. In all groups, the Î"E00 value was clinically acceptable (Î"E00 < 1.8). Conclusion: After the aging process, high-performance polymer abutments caused less color change than zirconia. Therefore, esthetically satisfying results can be obtained in the anterior region, especially when highly translucent crown materials are used. [ABSTRACT FROM AUTHOR]

We propose pathways to produce high-strength thermal resistant Mg-doped Al–Zr-based conductors to be manufactured in the form of ultrafine-grained wires via deliberate thermomechanical treatment, including aging, continuous equal-channel angular pressing and cold drawing. Al–0.97Mg–0.35Zr and Al–1.17Mg–0.34Zr (wt.%) alloys were chosen as objects for investigation to reveal the effect of Mg on the alloys' properties in the processed states. Prior to deformation, the initial rods of the studied alloys were aged at 400 °C for 72 h to attain precipitation of nano-sized particles of the metastable phase Al3Zr (L12) in the aluminum matrix. The following refinement of microstructure in the aged alloys by severe straining followed by cold drawing allows achieving a promising combination of ultimate tensile strength over 320 MPa, plasticity with elongation to failure over 2% and electrical conductivity about 50% IACS. We show that the produced wires exhibit thermal resistance similar to that of the commercial high-strength heat-resistant aluminum alloy (KTAL) type AT2 wire, but with a markedly superior strength. The Mg concentrations and parameters of thermal and mechanical processing that maintain a reasonable trade-off between high strength and acceptable electrical conductivity are discussed on the basis of the presented and earlier reported data to produce high-performance heat-resistant UFG Al–Mg–Zr wires. [ABSTRACT FROM AUTHOR]

A new amorphous alloy (Al74Cu16Mg10)99,7Zr0.3 was prepared the applying a melt-spinning technique. Temperature dependence of viscosity of the alloy was determined using data from a PerkinElmer TMS2 thermo-mechanical analyzer processed according to a methodology based on the Free Volume Model (FVM). The strength of the alloy was calculated according to the Yang equation and the glass-forming ability was calculated according to the values of the Angell index mA. The activation energy of crystallization and the activation energy of the glass transition were computed using data from differential scanning calorimetry and thermomechanical experiments respectively. The activation energy of crystallization Еx=168±3.7kJ/mol, was found to be higher than the activation energy of the glass transition Еg=156±1.4kJ/mol, which means a dominant contribution of the atomic transport barrier, compared to the nucleation barrier. The relatively high temperature interval of the supercooled melt state Tx-Tg=32K and the low viscosity values in the same range ƞ(Тg)=3.40E+11Pa.s and ƞ(Тx)=1.87E+10 Pa.s would allow thermomechanical treatment of the alloy in the temperature range of supercooled melt. [ABSTRACT FROM AUTHOR]

Copyright of Foundry Technology (1000-8365) is the property of Foundry Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Foundry Technology (1000-8365) is the property of Foundry Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A new amorphous alloy (Al74Cu16Mg10)99,7Zr0.3 was prepared the applying a melt-spinning technique. Temperature dependence of viscosity of the alloy was determined using data from a PerkinElmer TMS2 thermo-mechanical analyzer processed according to a methodology based on the Free Volume Model (FVM). The strength of the alloy was calculated according to the Yang equation and the glass-forming ability was calculated according to the values of the Angell index mA. The activation energy of crystallization and the activation energy of the glass transition were computed using data from differential scanning calorimetry and thermomechanical experiments respectively. The activation energy of crystallization Еx=168±3.7kJ/mol, was found to be higher than the activation energy of the glass transition Еg=156±1.4kJ/mol, which means a dominant contribution of the atomic transport barrier, compared to the nucleation barrier. The relatively high temperature interval of the supercooled melt state Tx-Tg=32K and the low viscosity values in the same range ƞ(Тg)=3.40E+11Pa.s and ƞ(Тx)=1.87E+10 Pa.s would allow thermomechanical treatment of the alloy in the temperature range of supercooled melt. [ABSTRACT FROM AUTHOR]

Background: This study aimed to compare the effect of heat treatment on the cyclic fatigue resistance of three different nickel-titanium rotary file systems: TruNatomy, HyFlex CM, and NeoEndo flex in simulated curved canals at two different radii of curvatures. Materials and Methods: A total of 60 NiTi rotary files of three types were used, and the samples were divided into three groups TruNatomy, HyFlex CM, and NeoEndo flex. All the instruments were subjected to cyclic fatigue testing using a stainless steel custom-made canal model with a 60° angle of curvature and two radii of curvature 5 mm and 3 mm; the number of cycles to fracture and length of the fractured segment was measured. The separated instruments were subjected to fractographic analysis under scanning electron microscope. Results: The number of cycles to failure to fracture a file at a 3 mm radius of curvature is significantly less as compared to a 5 mm radius of curvature (HCM > TRN > NE). Conclusion: Within the limitation of the present study, there was a positive correlation between the radius of curvature and fatigue life of NiTi files. [ABSTRACT FROM AUTHOR]

An investigation was conducted to examine the photothermal and thermomechanical effects of short-pulse laser irradiation on normal tissues. This study analyzed the impact of short-pulse laser radiation on the heat-affected region within tissues, taking into consideration a set of laser variables, namely wavelength, intensity, beam size, and exposure time. The beam size ranged between 0.5 and 3 mm, and the intensity of the laser radiation ranged from 1 to 5 W/mm2 at wavelengths of 532 and 800 nm. A three-layered, three-dimensional model was implemented and studied in a polar coordinate system (r = 10 mm, z = 12 mm) in COMSOL Multiphysics (version 5.4, COMSOL Inc., Stockholm, Sweden) to perform numerical simulations. The Pennes bioheat transfer model, Beer-Lambert, and Hooke's law are integrated to simulate the coupled biophysics problem. Temperature and stress distributions resulting from laser radiation were produced and analyzed. The accuracy of the developed model was qualitatively verified by comparing temperature and mechanical variations following the variations of laser parameters with relevant studies. The results of Box-Behnken analysis showed that beam size (S) had no significant impact on the response variables, with p-values exceeding 0.05. Temperature (Tmax) demonstrates sensitivity to both beam intensity (I) and exposure time (T), jointly contributing to 89.6% of the observed variation. Conversely, while beam size (S) has no significant effect on stress value (Smax), wavelength (W), beam intensity (I), and exposure time (T) collectively account for 71.6% of the observed variation in Smax. It is recommended to use this model to obtain the optimal values of the laser treatment corresponding to tissue with specified dimensions and properties. [ABSTRACT FROM AUTHOR]

Rapid economic growth implicated the developing multiple industry sectors, including the automotive branch, increasing waste generation since recycling and utilization methods have not been established simultaneously. A very severe threat is the generation of enormous amounts of post-consumer tires considered burdensome waste, e.g., due to the substantial emissions of volatile organic compounds (VOCs). Therefore, it is essential to develop novel, environmentally friendly methods for their utilization, which would hinder their environmental impacts. One of the most promising approaches is shredding, resulting in the generation of ground tire rubber (GTR), which can be introduced into polymeric materials as filler. The presented work is related to the thermomechanical treatment of GTR in a twin-screw extruder with zinc borate, whose incorporation is aimed to enhance shear forces within the extruder barrel. Modified GTR was introduced into flexible polyurethane (PU) foams, and the impact of modification parameters on the cellular structure, static and dynamic mechanical performance, thermal stability, as well as thermal insulation, and acoustic properties was investigated. Emissions of VOCs from applied fillers and prepared composites were monitored and evaluated. Depending on the treatment parameters, beneficial changes in foams' cellular structure were noted, which enhanced their thermal insulation performance, mechanical strength, and thermal stability. It was proven that the proposed method of GTR thermomechanical treatment assisted by zinc borate particles might benefit the performance of flexible PU foamed composites and hinder VOC emissions, which could broaden the application range of GTR and provide novel ways for its efficient utilization. [ABSTRACT FROM AUTHOR]

This work studies the influence of thermomechanical processing modes, including rotary forging and post-deformation annealing at various temperatures and holding times, on the structure and mechanical properties of titanium nickelide alloy with shape memory effect of near-equiatomic composition. Rotary forging was carried out at a temperature of 450 °C from 12 to 5 mm with a true accumulated strain of e = 1.8. Post-deformation annealing was carried out in the temperature range from 450 to 550 °C for 0.5–1 h. The structure of the alloy following rotary forging and post-deformation annealing was studied using transmission electron microscopy. Mechanical properties were studied by tensile testing. Functional properties were determined using the thermomechanical method under bending deformation. It was found that rotary forging leads to the formation of an ultrafine-grained structure in the TiNi alloy with a high density of defects and sizes of structural elements in the range of 100–250 nm. Post-deformation annealing at 450 °C results in no increase in the average size of structural elements. At the same time, the dislocation density visually decreases. After rotary forging, the TiNi SMA rod is characterized by strong strain hardening compared to the state after reference treatment (annealing at 750 °C, 30 min, cooling in water), since a sharp increase in strength characteristics is observed. Post-deformation annealing leads to a slight decrease in strain hardening, and with an increase in the post-deformation annealing temperature and holding time, a more noticeable decrease in strength characteristics occurs. After inducing 7% strain, there is no residual strain following all considered rotary forging and post-deformation annealing regimes, with the exception of annealing at a temperature of 550 °C for 1 h, which is a confirmation of a significant increase in the shape recovery characteristics as a result of the applied processing modes. [ABSTRACT FROM AUTHOR]

Temperature has a great influence on the mechanical properties of ductile cast iron or nodular cast iron. A thermomechanical treatment was carried out at various elevated temperatures of 450 °C, 750 °C and 850 °C using a universal testing machine with a tub furnace. Specimens were held at these temperatures for 20 min to ensure a homogeneous temperature distribution along the entire length of the specimen, before a tensile load was applied. Specimens were deformed to various levels of uniform strain (0%, 25%, 50%, 75%, and 100%). These degrees of deformation were measured with a dial gauge attached to a movable cross plate. Three strain rates were used for each specimen and temperature: 1.8 × 10 − 4   s − 1 , 9 × 10 − 4   s − 1 and 4.5 × 10 − 3   s − 1 . A simple analytical model was extracted based on the CT tensile test geometry and yield stress and a 0.2% offset strain to measure the fracture toughness (JIC). To validate the analytical model, an extended finite element method (XFEM) was implemented for specimens tested at different temperatures, with a strain rate of 1.8 × 10 − 4   s − 1 . The model was then extended to include the tested specimens at other strain rates. The results show that increasing strain rates and temperature, especially at 850 °C, increased the ductility of the cast iron and thus its formability. The largest percentage strains were 1 and 1.5 at a temperature of 750 °C and a strain rate of 1.8 × 10 − 4   s − 1 and 9 × 10 − 4   s − 1 , respectively, and reached their maximum value of 1.7 and 2.2% at 850 °C and a strain rate of 9 × 10 − 4   s − 1 and 4.5 × 10 − 3   s − 1 , respectively. In addition, the simple and fast analytical model is useful in selecting materials for determining the fracture toughness (JIC) at various elevated temperatures and different strain rates. [ABSTRACT FROM AUTHOR]

In the present study, various defects such as dislocations were controlled in Ti-V-Al-based shape memory alloy by thermomechanical treatment and introduction of interstitial oxygen (O) atom to optimize the performances. The results revealed that the Ti-V-Al-O shape memory alloys gradually evolved from α" martensite phase to the β parent phase with increasing annealing temperature. Moreover, the degree of lattice distortion can be tailored by changing annealing temperatures. Upon the annealing temperature reached 900 °C, masses of ω precipitates and a nano-sized ordered domain, characteristic of strain glass, can be found. As a result of suppression effect of multiple varieties of defects to the martensitic transformation, no obvious endothermic and exothermic peaks were observed in differential scanning calorimetry curves. The yield strength and maximum tensile fracture strength of the Ti-V-Al-O shape memory alloy increased with the increase of annealing temperatures. Meanwhile, Ti-V-Al-O shape memory alloys annealed at 900 °C possessed superior strain recovery characteristics and corrosion resistance. The excellent performances in Ti-V-Al-O shape memory alloys annealed at 900 °C can be attributed to the formation nanoscale nanodomain. [ABSTRACT FROM AUTHOR]

Duplex stainless steels, well known for their excellent mechanical properties and high corrosion resistance, are used in high concentration chloride environments. However, the formation of intermetallic phases when they are exposed to high temperatures for extended periods limits their application in such scenarios. Hence, to determine their mechanical behavior, a study was conducted to determine the optimum parameters for obtaining good strength and hardness in duplex stainless steel. The Gleeble Physical testing system was used to test 2002 duplex stainless steel under hot compression while varying strain, strain rate, and temperature. Using an L9 orthogonal array, the optimal parameters for achieving high strength and hardness were arrived at using Taguchi techniques. It was identified that, at 1000 °C, a 10 s−1 strain rate in samples strained to 60% provided the best results. Lastly, the microstructure was analyzed and correlated with the experimental results. [ABSTRACT FROM AUTHOR]

The impact of thermomechanical treatment on the structure, electrical resistance, and hardness of the Al–4% Cu–3% Mn alloy, which was obtained by casting in an electromagnetic crystallizer, has been investigated using computational and experimental methods. It has been shown that at the cooling rate of more than 1000 K/s, the whole amount of manganese and half of the copper content are dissolved in the aluminum solid solution. This enables the formation of a structure with the maximum possible number of Al20Cu2Mn3 dispersoids after subsequent thermomechanical treatment, resulting in a significant improvement in the thermal resistance compared to the known alloys of Al–Cu–Mn system. [ABSTRACT FROM AUTHOR]

The microstructural evolution of Al-Zn-Mg-Cu alloy under different stress and aging temperature was studied using cold compression and heat treatment. The relationship between the process parameter and the microstructure of the material was analyzed by OM, EBSD, and TEM. The results showed that the grain size decreased and the recrystallization fraction increased with the increase of compression. Textures of ||X (cubic), //Y, Goss have higher intensity after solution treatment, but their intensity and proportion also decrease with the increase of compression. η' is the main precipitate in the alloy aged at 140 °C, while η is the main precipitate in the alloy aged at 160°C. Precipitation coarsening and grain refinement affect the microhardness of the alloy together.