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In recent years, Magnesium alloy has gained big interest to be developed as orthopedic implant material due to its good biocompatibility and mechanical properties that are closest to human bones. Nevertheless, the rapid degradation of magnesium is still becoming an obstacle to its clinical orthopedic applications. Therefore, it needs several treatments to increase strength and corrosion resistance. This paper will review the effect of thermomechanical treatment with the hot rolling method for improving the mechanical properties of Mg-Li-Al alloy. Furthermore, this review will also discuss the effect of the percentage of rolling reduction and the addition of lithium (Li) and aluminum (Al) as alloying elements on structural changes and strengthening mechanisms that occur in magnesium alloys. [ABSTRACT FROM AUTHOR]

Low Ni-Cr-Mo alloy with refined grain belongs to the group of high-strength martensitic-bainitic working steel and is the most commonly used material for the screw. The microstructure and corrosion properties of the low alloy 36NiCrMo16 quench-tempered after hot forging is discussed. Two steel plates were subjected to two different thermomechanical treatment procedures, with and without hot forged. Both steel plates were intercritically annealed at 750°C for 10 minutes, and subsequently, water quenched and tempered at 250 and 400°C. All microstructures contain martensite temper, ferrite, and bainite phases with various volume fractions. The hot forging significantly affects the hardness and corrosion rate of 36NiCrMo16. After hot forging followed by tempering process, the grain size reduced to 15.19 and 16.74 µm for HF-QT250 and HF-QT400. The final microstructure of these samples were bainite, martensite temper, and ferrite. HF-QT250 obtains the highest hardness (∼45.94 HRc). Additionally, the hardness and corrosion rate decreased after tempering by reduction of plastic deformation that induces residual stress. The forging addition generated higher corrosion rates in 3.5% NaCl solution, up to up to 9.211 mmpy (HF-QT250) and 4.075 mmpy (HF-QT400). Whereas, the sample without tempering process has a lower corrosion rate, near to 5.367 mmpy (QT250) and 3.442 mmpy (QT400) due to the grain size was larger than the other samples. [ABSTRACT FROM AUTHOR]

To date, the restoration of parts and assemblies of pyrolysis reactors have been determined by methods of modifying the contacting surfaces. As is known, there are three modification methods: methods of chemical and physical deposition of contacting coatings, as well as thermomechanical treatment. The choice of a particular method, as a rule, is determined by the scope of application of technological equipment. Another important factor affecting the quality of the contacting surface after modification is the residual stresses that occur in the coatings during cooling after application. In this study, a finite element method is proposed for quantifying thermal stresses using the Klein equation. This equation makes it possible to predict stresses in both single-layer and multi-layer contact surfaces. For simplicity of modeling, the contacting surface is represented by the "substrate-coating" system. [ABSTRACT FROM AUTHOR]

In this work, the high entropy alloys based on the equiatomic CoCrFeMnNi and Fe40Mn40Cr10Co10 (in at.%), were doped with the similar amount of N (0.5 and 2.0 at.%). The alloys were examined in as-cast condition and after thermomechanic treatment. In the as-cast state, alloys had single fcc phase structure. Thermomechanical treatment in the form of cold rolling followed by annealing led to the development of static recrystallization in precipitation of nitrides (in the alloys doped with 2 at.% of N). The "base" alloy composition has barely affected the microstructure, yet the mechanical behaviour of the alloyc can be quite different, especially in cryogenic conditions. In particular, the Fe40Mn40Cr10Co10-based alloys demonstrate notably lower ductility in cryogenic temperatures. Meanwhile some of the program alloys can have very attractive properties at 77K, i.e. yield strength of 1100-1180 MPa, ultimate tensile strength of 1550-1570 MPa, and ductility of ∼25%. [ABSTRACT FROM AUTHOR]

The influence of high-temperature thermomechanical treatments on grain structure and carbide subsystem of reactor austenitic steel EK-164 is studied. It is shown that as a result of hot deformation the grains extend in the rolling direction and flatten in the rolling plane with a multiple decrease of their average size. The high-temperature thermomechanical treatments results in a change from the original cellular-lattice dislocation substructure to a banded dislocation substructure. The special high-temperature thermomechanical treatment conditions (high degrees of deformation and lowering of the deformation temperature in every stage of the treatment) increase the density of the banded substructure and reduce the cross-sectional dimensions of the bands. The dislocation density and the volume fraction of dispersed particles are estimated. An increase in the yield strength due to dispersed and substructural strengthening is discussed. [ABSTRACT FROM AUTHOR]

The fatigue failure beyond the traditional fatigue limit of 107 cycles, the so called very high cycle fatigue (VHCF) is constantly gaining attention due to the demand for long service life of highly stressed components to reach a better sustainability. While the underlying characteristic VHCF mechanism still needs to be fully understood, it is beneficial to investigate measures to improve the fatigue lifetime even in the VHCF range. For this purpose, a thermomechanical treatment (TMT) in the temperature range of maximum dynamic strain aging, for which an increase in fatigue strength in the high cycle fatigue (HCF) range was already shown for the steel SAE 52100, was applied to the steel SAE 4140H. The positive influence of TMT on fatigue results were found for HCF as well as VHCF-regime. The aim of this publication is to analyze as well as to substantiate the influence of TMT on the stress intensity factors (SIF) of failure-causing inclusions and on the forming characteristic of fine granular area (FGA) in the VHCF-regime. [ABSTRACT FROM AUTHOR]

The issues of developing a constitutive model focused on the description of martensitic transformations in steels during thermomechanical loading are considered. The description of the multilevel model general structure is given. The issues of choosing a phase transformation criterion for a homogeneous element of a material at the meso-level, its application for description of the thermomechanical treatment processes using the proposed constitutive model are analyzed. The modeling results and applicability assessment of the selected criterion are presented. [ABSTRACT FROM AUTHOR]

The results of studying the microstructure and mechanical properties of the V-W-Cr alloy after different regimes of thermomechanical treatment are presented. It is shown that the use of the modified regime promotes the formation of a more uniform grain structure, which provides an increase in strength properties at room temperature by more than 10%. Analysis and comparison of the results showed that the thermal stability and the level of strength properties of V-Me(Cr, W)-Zr(C, O, N)-system alloys are mainly provided by the effects of disperse strengthening with stable Zr-based particles. [ABSTRACT FROM AUTHOR]

The effect of carbon content on structure and mechanical properties of Fe65(CoNi)25Cr10 and Fe65(CoNi)25Cr9.5 C0.5 high-entropy alloys was studied. In addition, the effect of thermomechanical treatment on structure and properties of the Fe65(CoNi)25Cr9.5C0.5 alloy was investigated. Microstructure of the alloys in the as-cast conditions had a two-phase structure consisting of a face-centered cubic (fcc) and a body-centered (bcc) phases. An increase in the carbon content from 0 to 0.5 at % led to a decrease in the bcc phase amount from 90 to 35%. Besides the carbon addition resulted in higher plasticity without significant loss in strength. Cold rolling of the Fe65(CoNi)25Cr9.5C0.5 alloy to 80% thickness reduction leads to an increase in the bcc phase amount up to 40%. Subsequent annealing at 700–900°C for 10 min led to the development of a recrystallized microstructure with an increased volume fraction of the bcc phase, and the precipitation of M23C6-type carbides. Relationships between the chemical composition, processing, structure and mechanical properties of alloys are briefly discussed. [ABSTRACT FROM AUTHOR]

Thermo-mechanical treatment for a low-carbon 9% Cr martensitic steel was modeled with aim to obtain the stable secondary phase particles of Z-phase instead of non-equilibrium MX carbonitrides. Modeling of thermomechanical treatment consisting of normalizing at temperatures ranging from 1050 to 1200°C, forging at temperatures ranging from 600 to 680°C with various strains from 10 to 60%, annealing at temperatures ranging from 600 to 680°C with different durations and tempering at 750°C for 3 hrs was carried out using Thermo-Calc and Prisma software. Analysis of phase composition predicted by Thermo-Calc software together with growth kinetic of the Z-phase particles using Prisma software showed that the optimal normalizing temperature of 1200°C, forging/annealing temperature of 680°C and time annealing of 50 hrs must provide the formation of stable Z-phase with a mean size of about 50 nm. [ABSTRACT FROM AUTHOR]

The microstructure parameters of ferritic-martensitic steels EK-181 and EP-823 after quenching, traditional heat treatment and high-temperature thermomechanical treatment are investigated by an X-ray diffraction analysis. It is shown that lattice parameters, microdistorsions and dislocation density after these treatments in the experimental steels have similar values. The maximum values of these parameters are observed after quenching. After the treatments they decrease as a result of depletion of the solid solution for alloying elements and carbon and precipitation of dispersed carbide particles during tempering. The increased dislocation density, formed by high-temperature treatment of the steels, leads to an increase in strength properties compared to the traditional heat treatment. [ABSTRACT FROM AUTHOR]

The effect of warm deformation on the microstructure and mechanical properties of cold-deformed AISI 316 type austenitic steel is investigated. It is shown that cold deformation with a strain degree of ≈55% leads to the formation of a microtwin structure, with an average size of microtwin plates of ≈30 nm. Subsequent warm deformation (≈20%) with heating up to 600°C promotes the formation of localized deformation bands within the microtwin structure. The volume fraction of the localized deformation bands is ≈10%, and their width does not exceed 150 nm. These features of the microstructure provide high strength properties: yield strength ≈1000 MPa, with an elongation to failure of ≈10%. [ABSTRACT FROM AUTHOR]

The interaction between particles and grain boundaries responsible for a presence of restraining forces affecting grain boundary mobility is known as the Zener drag. The value of the total restraining force depends on the size, distribution, and volume fraction of particles present in the matrix. They could be easily modified in twin-roll cast Al-Fe-Si-based alloys by a high-temperature annealing. In order to create different types of dispersoids distributions a choice of a proper annealing temperature was done on a basis of several in-situ TEM annealing experiments. An estimation of an influence of the Zener drag on a recrystallization behavior in a twin-roll cast AA8079 alloy after different thermomechanical treatments was done. [ABSTRACT FROM AUTHOR]

The effect of thermomechanical treatments combined with plastic deformation at different temperatures and annealing conditions on the features of the microstructure and the mechanical properties of 17Cr18Mn2VN high-nitrogen austenitic steel are investigated. The deformation is carried out at low (including cooling in liquid nitrogen) and elevated temperatures (600–700°C) in various combinations. It is shown that an exposure to low-temperature and subsequent warm deformation leads to the formation of microstructure with high density of microtwin packets and shear bands. Similar microstructures are formed because of treatment combining warm deformation with plastic deformation at room temperature. This structure features provide high strength properties (yield strength up to ≈1180 MPa, tensile strength up to ≈1400 MPa) at low relative elongation (2–3%). It is demonstrated that annealing of the deformed structures in the temperature range of 550–650°C during 0.5–3 h, resulting in precipitation of the dispersed nitride particles, does not lead to significant changes in the microstructure and ductility of the material. At a higher annealing temperature (700°C, 1 h) the deformed structure in the material is observed to recrystallize, which is accompanied by intensive precipitation of Cr2N particles. A significant volume fraction of this phase provides low elongation values. Higher values of elongation under plastic deformation of high-nitrogen austenitic steel can be obtained by high-temperature thermomechanical treatments. [ABSTRACT FROM AUTHOR]

The effect of high-temperature thermomechanical treatment (HTMT) with plastic deformation in the austenitic region on the mechanical properties and fracture features of 12% chromium ferritic-martensitic steel EP-823 in the temperature range of 300–600°C is investigated. It is shown that at these temperatures the yield strength of the steel after HTMT exceeds the corresponding values after a traditional heat treatment (THT). In the temperature range of 300–500°C after HTMT the values of relative elongation at break are minimal; with an increase in the deformation temperature to 600°C this value increases by about 2 times. Low values of elongation at break and increased strength properties at 350–450°C may be associated with the dynamic strain aging processes. Fractographic investigations have shown that in the temperature range of 300–600°C, the fracture features of steel after two treatments are qualitatively similar. Despite the low values of relative elongation fracture occurs mainly by a viscous mechanism with the formation of pits. HTMT leads to the formation of microcracks and an increased proportion of brittle fracture by cleavage. [ABSTRACT FROM AUTHOR]

The features of microstructure and mechanical properties of an austenitic reactor steel with dispersed particles after high-temperature thermomechanical treatment with plastic deformation after heating to T = 1100 and 600°C are investigated. It is shown that as a result of processing with heating to T = 1100°C, plastic deformation develops in localized regions of the material and a fragmented microstructure with predominantly low-angle misorientation boundaries is formed. After deformation with heating to T = 600°C, fragmentation develops more intensively with the formation of both low- and high-angle misorientation boundaries. The elemental composition of dispersed carbide particles of the MC type in steel is studied. It is shown that these particles have a complex composition based on Ti, Nb, and Mo. The elemental composition of the matrix after the treatments corresponds to the nominal one, which indicates that a significant proportion of carbide-forming elements remains in the solid solution and does not participate in the formation of dispersed particles. These structural states provide an increase in the yield strength of steel up to ≈550– 740 MPa compared to the initial values with a relative elongation of ≈7–12.5%. It should be noted that the main contribution to strengthening (Δσ ≈ 350–540 MPa) is provided by the fragmented structure, while the contribution of dispersed particle hardening is Δσdisp≤35 MPa. [ABSTRACT FROM AUTHOR]

Residual stresses often become the cause of early damage to equipment or machinery. Residual stress generally appears on components as a result of improper equipment design and improper of manufacturing processes. Cold working processes on metals can provide plastic deformation. Plastic deformation that occurs will cause lattice distortion on the metal structure. This lattice distortion will cause residual stress. Greater the degree of cold working on the metal, greater the residual stress level in the metal. In this research, measurement of residual stress was carried out on as received specimen and treated specimens. The treatment given is cold work by rolling and thermomechanical treatment (cold work + normalizing). Residual stress measurement is carried out using the hole drilling method. The results show that when the deformation percentage is higher, the residual stress will be higher as well. One of the methods to relieve residual stresses in material is by heat treatment process. In this process, the residual stress on material will decrease significantly accompanied by changes in the microstructure inside the metal. However, if the application of the heat treatment process is not right, besides experiencing a decrease in residual stress, the metal will also experience decreasing in strength and therefore proper treatment process is needed through understanding the phenomena that occur during the process of heat treatment of metals that have high residual stress. For this reason, a detailed understanding about the effect of thermomechanical treatment on the residual stress level is important to investigate. [ABSTRACT FROM AUTHOR]

The structure, mechanical characteristics and mechanisms of plastic deformation of stainless austenitic steel 12Cr15Mn9NiCu after high-temperature cross and screw and cold longitudinal rolling are examined with the help of mechanical testing, X-ray diffraction and electron transmission microscopy. It is shown that deformation martensitic transformations are the main mechanisms of deformation at temperatures less than 20 °C. The modes of thermomechanical treatment, which allow to obtain a good combination of strength and plastic properties in steel have been found out. [ABSTRACT FROM AUTHOR]

The features of microstructure and mechanical properties of a high-nitrogen austenitic steel after high-temperature thermomechanical treatments with plastic deformation after heating to T = 1100 and 600°C are investigated. It is shown that these treatments result in plastic deformation in localized areas of the material and fragmented microstructure with low- and high-angle misorientation boundaries. Plastic deformation develops more intensively in δ-ferrite than in austenite. An additional warm deformation at T = 600°C (after deformation at T = 1100°C) contributes to more intensive fragmentation of the austenite microstructure. The structural states formed after high-temperature thermomechanical treatments provide an ≈300 MPa increase in the yield strength of steel compared to the initial values with the relative elongation ≈10%. The issues of strength and plasticity of the high-nitrogen austenitic steel after thermomechanical treatments are discussed. [ABSTRACT FROM AUTHOR]

To expand the practical use of high-entropy and material with shape memory effect (SME), we have developed a technology to form functionally oriented surface layers with five and six-component powder compositions CoCuTiZrHf, NiCoTiZrHf, NiCuTiZrHf, ZrCuNiCoTi, TiNiZrHfCoCu. The coatings were deposited under conditions of high-energy effects, including mechanical activation of the applied material, high-velocity oxygen-fuel spraying in a chamber with argon, followed by thermomechanical treatment in a single technological cycle on the patented equipment. Electron-microscopic and X-ray diffraction studies have shown that the obtained coatings correspond to SME materials with a grain size of 80–400 nm. In accordance with energy criterion, we have predicted the cyclic durability of steel samples with a surface layer made of multicomponent SME materials. We took into account the energy intensity of the coating material and the structural factor. The energy intensity of the alloy is determined by the thermodynamic characteristics and the state diagram of the systems. The structural factor is based on the analysis of the structural-phase state by the method of multifractal parametrization taking into account homogeneity, fractal dimensionality, adaptability. [ABSTRACT FROM AUTHOR]

The mechanical properties of heat-resistant low-activated 12% Cr ferritic-martensitic steel EK-181 are investigated during tensile tests at T = 20 °C and in the temperature range close to the operating temperatures of the nuclear reactor (T = 650 and 720 °C) after traditional heat (THT) and high-temperature thermomechanical treatments (HTMT). It is shown that the strength properties of steel after HTMT exceed the corresponding values after THT. The features of the steel microstructure near the neck of the samples deformed by tension at these temperatures using two processing methods are studied. It is shown that plastic deformation at T = 20 °C leads to the curvature and fragmentation of martensitic lamellae and the formation of new low-angle boundaries. Deformation near the operating temperature range contributes to the development of dynamic polygonization, recrystallization and increase in density and size of the precipitates. After HTMT these processes are less intensive compared to the structural state after THT. This is due to the higher density of nanosized precipitates of V(C, N) and the increased dislocation density after HTMT. [ABSTRACT FROM AUTHOR]

The effect of high-temperature thermomechanical treatment (HTMT) with deformation in the austenitic region on the microstructure and mechanical properties of 12% chromium ferritic-martensitic steel EP-823 is investigated. It is shown that the strength properties of steel after HTMT exceed the corresponding values after traditional heat treatment (THT) at the temperatures of 20 and 650 °C. The features of steel microstructure are studied by optical metallography and transmission electron microscopy. It is shown that under the HTMT conditions the original austenite grains are elongated in the rolling direction, while their dimensions perpendicular to the rolling direction decrease and are found to be ≈ 10 µm on average. HTMT provides the formation of a heterophase microstructure with high dispersion of such nanosized precipitates as MX and high dislocation density. These microstructure features of steel EP-823 after HTMT ensure higher strength properties than those after the THT. At an elevated deformation temperature (650 °C) the hardening effects are reduced. [ABSTRACT FROM AUTHOR]

Advanced composite materials are characterized by high strength and stiffness while keeping a low internal weight. For this reason, they are materials more and more frequently used in the aviation industry. One of the major disadvantages of composites is a significant decrease in mechanical properties in the case of any damage. Damage can be mechanical or thermomechanical. This problem is solved by combining composite materials with metal sheets. Metal-composite laminates (FML - Fibre Metal Laminate) have recently been the main interest of the aerospace industry in the field of materials used for aircraft construction [1]. The purpose of this article is to test the strength of a hybrid composite subjected to strong thermal loads. A laminar hybrid composite (FML) consisting of two layers is used in the research. FML composites are combinations of two materials with different mechanical and thermomechanical (thermal) properties. The first layer is made of a titanium sheet and the other layer was reinforced with carbon fibre with HTA/913 symbol. This material is made using an autoclave technique. In the experimental studies, a sample of material was gradually heated from a room temperature to an elevated temperature, which caused a change in the shape of its profile. Measurements of the deformation state of the sample were conducted at the following temperatures: 25.5°C, 50°C, 80°C, 110°C, 130°C. The deformation of the sample profile as a function of temperature was determined experimentally using optical deformation measuring method. The results of this work were used in FEM model development to estimate thermal stress distribution occurring in HTA/913 composite – titanium resulting from heat loading. [ABSTRACT FROM AUTHOR]

After almost 40 years of development, meshless methods are still treated as “new” numerical technique. Smoothed Particles Hydrodynamics (SPH) is not an exception. Number of publications shows still new applications of the method. One of such rather new area is analysis of coupled thermal – mechanical field. In the article, authors show results of comparative analysis of SPH and Finite Element Method (FEM) aimed to investigate usefulness of meshless approach in analysis of disk brake and lining interaction. [ABSTRACT FROM AUTHOR]

In this study, the results of the thermomechanical simulation of the process of the multi-stage plastic shaping of the 30CrMoV1211 tool steel with the application of the forging method in the form of the distributions of local values of the strain state, the stress state, temperature, and also the damage factor making it possible to predict a crack in a material in the course of plastic deformation, are presented. A numerical analysis was conducted with the application of the pre-developed spatial mathematical model upon the basis of the finite element method, and with the application of a professional program, DEFORM-3D. The analysis of the constituents of the strain state and the stress state, and also their changes in the course of completing the particular stages of deformation, made it possible to determine the areas of the largest plastic deformations and the places of the hypothetical cracks in a material, which provided the possibility of the preliminary predicting of the internal quality of a forging at the subsequent stages of forging with the increasing forging ratio. The results of numerical research were subjected to experimental verification. [ABSTRACT FROM AUTHOR]

Mono- and co-doped TiO2 photocatalyst were synthesized using sol–gel method followed with calcination process. The effect of Fe and/or N on the structural, morphological, and optical properties of TiO2 was studied. The samples were characterized using XRD, FESEM, and UV–visible diffuse reflectance spectroscopy to study the changes in the properties due to the presence of the dopants. XRD diffraction analysis shows anatase structure in all samples. FESEM images exhibit agglomerated particles with grain size of 30–40 nm. A slight shift of the absorption edge to higher wavelength up to 480 nm was observed due to the addition of mono- and co-doped Fe and/or N, respectively. The photocatalytic activity of all samples was assessed by testing the degradation of methyl orange (MO) under visible light. [ABSTRACT FROM AUTHOR]

Bone is chiefly composed of 20-30 wt% organic phase, 60-70 wt% inorganic phase and about 5 wt% of water. The organic phase is comprised mostly of collagen, but lipids and non-collagenous proteins are other compounds in small concentration. Elasticity, flexibility, and resistance to the bone are provided by organic phase while the main component of the inorganic phase is hydroxyapatite (HAP). The present work focuses on the X-ray diffraction (XRD) and Fourier transforms infrared (FTIR) study of A&B type carbonated HAP extracted from bovine bone at different calcination temperatures (600, 800, and 1000 °C) without the use of chemicals/solvents. Therefore, it is a green technology. The hydrothermal method followed by heat treatment at different calcination temperatures was used to extract the A&B type carbonated HAP in this research. The characterizations of raw and calcined HAP powder were done by using XRD and FTIR techniques. XRD data showed that the extracted HAP is highly crystalline. It has a hexagonal crystal structure and crystallite size is in the range of range of 3.95 nm to 83.12 nm (Raw-HAP to HAP-1000). Crystallite size and crystallinity degree gradually increased with the intensification of calcination temperature from 600-1000 °C. The FTIR results confirmed the presence of phosphate (PO4−3), hydroxyl (OH−1) and carbonate (CO3−2) groups in the HAP powder. It is also confirmed that the extracted HAP is A&B type carbonated HAP as indicated by the position of the peaks at 1456 cm-1 and 1541 cm-1. [ABSTRACT FROM AUTHOR]

In this paper with the use of optical and scanning electron microscopy were conducted investigations of the structure of the AA2024 alloy in adhesive friction zone at severe thermomechanical action. The conducted studies showed that the structure in the friction zone at severe thermomechanical action is similar to the structure observed at the friction stir welding. Depending on the shape of the counterbody, the formation of the main structural zones in the surface layers varies and is determined by the sliding speed and the stress state scheme at each particular point. [ABSTRACT FROM AUTHOR]

The physical dimension of solder joint plays an important role in the joint reliability during the surface mount technology (SMT) assembly process. During the SMT process, the thermal induced stress, strain and displacement is difficult to visualize and assess. The objective of the study is to tackle these problems via simulation analysis technique using the Finite element based software. A model of electronic package was considered and created in the simulation software. The effect of the solder joint height to stress, strain and displacement were investigated. The results revealed that the solder height crucially influence the maximum stress to the solder joint. Besides, solder height also affects the displacement and strain of the solder joint during the analysis. The increment of the solder height yielded the increment of the strain and displacement of the solder joint. The lowest maximum stress was found on the 0.45mm of solder joint. Thus, the results are expected to enhance the understanding the thermos-mechanical characteristics of solder joint in the electronic packaging research field. [ABSTRACT FROM AUTHOR]