Effect Of Thermomechanical Treatment Research Articles

Effect of thermomechanical treatment on deformational behavior of ferromagnetic Fe–Ni–Co–Ti alloy under uniaxial tension

To improve the functional properties of a ferromagnetic shape memory alloy, a thermomechanical treatment that includes drawing followed by quenching and high-temperature annealing was proposed, as a result of which a nanostructured state is formed. Thermomechanical treatment (TMT) increases the alloy thermoelasticity, although it is accompanied by a large temperature hysteresis of martensitic transformation and results in a significant hardening of the matrix, which, in its turn, enlarges the effects of shape memory and superelasticity (or pseudoelasticity). It has been established that TMT of Fe–Ni–Co–Ti shape memory alloy contributes to an increase in reversible superelastic deformation up to ~ 3%. In a superelastic cycle with wide mechanical hysteresis, a large dissipation energy per loading–unloading cycle was gained, that favors the use of this alloy as a damper of mechanical oscillations.

The Influence of Heat and Mechanical Treatment of Concrete Rubble on the Properties of Recycled Aggregate Concrete.

Concrete is a building material commonly used for ages. Therefore, in the result of repairs or demolition of building structures, large amounts of concrete rubble are created, which requires appropriate management. The aim of the realized research was to determine the influence of heat and mechanical treatment of concrete rubble on the properties of recycled aggregate concrete. The research experiment included 12 series, with three variables: X1—roasting temperature (300, 600, 900 °C), X2—time of mechanical treatment (5, 10, 15 min), X3—content of coarse recycled aggregates (20, 40, 60% by volume). Two additional series containing recycled aggregate without treatment and natural aggregate were also prepared. Established properties of individual aggregates have confirmed a positive effect of thermo-mechanical treatment. Then, based on the results of compressive strength, flexural strength, Young’s modulus, volumetric density, water absorption, water permeability and capillarity, the most favourable parameters of heat and mechanical treatment of concrete were determined. The test results showed that appropriate treatment of concrete rubble allows to obtain high-quality coarse aggregate and valuable fine fraction. This was also confirmed by the macro- and microscopic observations of the aggregate and separated cement paste. Works realized on the concrete recycling method resulted in obtaining a patent PAT.229887.

The effect of thermomechanical treatment on the magnetic and mechanical properties of Fe-48Ni alloy

In the current study, the mechanical and magnetic properties of annealed Fe-48Ni alloy with different structures and grain sizes were investigated. Accordingly, the Fe-48Ni samples were prepared using vacuum induction melting and subsequent thermo-mechanical processes. Field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) were also employed to investigate the structural changes; then a vibrating sample magnetometer (VSM), and tensile and hardness tests were utilized to characterize the magnetic and mechanical properties of the cold-rolled and annealed samples, respectively. According to the obtained results, the grain sizes of the annealed samples were elevated with increasing the annealing temperatures. Growth of grains had different effects on the magnetic and mechanical properties. The results showed that the 80% cold-rolled sample required a lower annealing temperature for recovery and recrystallization. Coercivity and saturation magnetization of the cold-rolled and annealed Fe-48Ni samples were in the range of 2.5–4 Oe and 161–175 emu/gr, respectively. Both magnetic and mechanical properties of the samples were improved after annealing at 900°С for 20 min, and the optimum results for the magnetic and mechanical properties were obtained by 80% and 20% cold-rolling, respectively. In fact, the magnetic anisotropies and the increase of dislocations density during cold-rolling had destructive effects on the magnetic and mechanical properties of Fe-48Ni samples, which could be resolved by annealing at 900 °C for 20 min.

Effect of thermomechanical treatment on the microstructure and mechanical properties of a nickel base superalloy heavily alloyed with substitution elements

Effect of thermomechanical treatment on the microstructure and mechanical properties of a nickel base superalloy heavily alloyed with substitution elements

Влияние деформационно-термической обработки на микроструктуру и механические свойства нового высоколегированного никелевого сплава

Влияние деформационно-термической обработки на микроструктуру и механические свойства нового высоколегированного никелевого сплава

Effect of Thermomechanical Treatment on Subsequent Deformation Behavior in a Binary Z1 Magnesium Alloy Studied by the Acoustic Emission Technique

Pre‐straining of magnesium alloy modifies the final texture of the material and therefore leads to a different deformation behavior during subsequent loading. At the same time, heat treatment in the context of thermo‐mechanical procedures is used as softening mechanism, as well as for age hardening processing. In mechanical conditions with twin‐dominated deformation in textured magnesium alloys, the twin boundaries can be pinned if existing after a pre‐deformation of samples and therefore influence their mobility. The impact of the ongoing mechanical behavior is discussed. In the present paper, a procedure of pre‐compression and reverse tensile loading of extruded binary magnesium alloy Mg–1 wt% Zn (Z1) is used and intermediate aging at 200 °C is applied in two different routes. The effect of the heat treatment on the flow behavior during subsequent mechanical loading is correlated with the dominating deformation mechanisms revealed by in situ acoustic emission measurements and ex situ scanning electron microscopy. The pinning of twin boundaries can restrict their mobility in experimental environments that favor the recovery of the samples. As a result, new twins easily nucleate if the concurrent re‐orientation of the lattice is favorable for strain accommodation.

Effect of thermomechanical treatment on wear resistance of Hadfield’s steel

The technique of thermomechanical treatment of high manganese steel under high-temperature plastic deformation of cylindrical specimens with various degrees of reduction is presented. The experimental data on the wear of samples on granite and electrocorundum show that the use of the thermomechanical treatment method can significantly increase the abrasive wear resistance of high manganese steel by up to 50%, and the method itself can be recommended for the introduction into the technology of manufacturing wear parts of ore mining and processing equipment in order to increase their service life.

Effect of Thermo-Mechanical Treatments on the Microstructure and Mechanical Properties of the Metastable β-type Ti-35Nb-7Zr-5Ta Alloy

In this work, theoretical composition design and thermo-mechanical treatments were combined in order to improve the mechanical compatibility of a biomedical β-type titanium alloy. By applying a composition design theory, cold rolling and low temperature aging, a metastable β-type Ti-35Nb-7Zr-5Ta (wt%) alloy with an elastic modulus of 47 GPa and a yield strength of 730 MPa was successfully fabricated. This combination of high yield strength and low elastic modulus resulted in enhanced elastic recoverable strain of 1.7%, which is much higher than that of the conventional metallic biomaterials. The microstructure responsible for the much sought-after mechanical properties was observed to be mainly consisted of a homogeneous distribution of nanometer-sized ω- and α-precipitates in a β-phase matrix obtained via cold rolling plus short-time aging at low temperature, i.e. aging at 673 K for 20 min. These precipitates increase the strength of the material by hindering the motion of dislocations while the β-matrix with relatively low content of β-stabilizers gives rise to the observed low elastic modulus. By extending aging time, a higher strength is reached at the expense of an undesirable increasing in elastic modulus.

Effect of thermomechanical treatment on properties of an extruded Al-3.0Cu-1.2Mg/SiCp composite

Thermomechanical processing determines the practical applications of metal–matrix composites (MMCs) by contributing to the interrelationship between their microstructure and properties. In this study, we investigate the changes in Al-3.0Cu-1.2Mg/SiCp (40 vol%) caused by the tension applied at high temperatures and strain rates. The study shows the microstructural changes and mechanical characteristics resulting from the cold/warm and hot rolling of the extruded material. It is observed that hot rolling has a favorable effect on the restoration of the defects formed in parts of the extruded bar. The microstructural characteristics of the composite related to the deformation-induced redistribution of the secondary inclusions in the matrix and fracture of the reinforcement particles are shown. High-temperature uniaxial tensile testing of the studied composite conducted under high strain rates (10−1 and 10−2 s−1) indicates an increase in the ductility. The decrease in the stress of the tested samples is attributed to the refined grains in the matrix after the thermomechanical processing. The testing of the given material provides the stress–strain relationships, which indirectly assist in ranking the relative formabilities of the differently processed sheets of the MMCs with a high-volume fraction of the reinforcement particles. The proposed approach may be considered for the near net-shaped manufacturing of MMCs with high wear resistance and low thermal expansion coefficients.

Effect of Thermo-Mechanical Treatment with Various Annealing Hold Conditions on Al Alloyed TRIP Steel

Heat and thermo-mechanical treatment of TRIP (transformation induced plasticity) steels conventionally containes an annealing hold in the temperature region of bainitic transformation to obtain microstructure suitable for utilization of TRIP effect. The hold ensures stabilization of retained austenite and formation of sufficient amount of bainite.The conditions of this hold play an important role in obtaining good combination of high strength and total elongation of TRIP steel. This article deals with the effect of temperature and duration of a bainitic hold on the final microstructure and mechanical properties of TRIP steel processed by thermo-mechanical treatment. The holds in the interval of 350 - 500 °C were used with hold times of 25 - 1200 s. Tensile strengths of 815-976 MPa were obtained in combination with total elongations of 27-45%. The best combinations of tensile strengths around 850 MPa with total elongations above 40% were achieved for the holds at 450 °C.

Dynamic strain aging behavior of an ultra-fine grained Al-Mg alloy (AA5052) processed via classical constrained groove pressing

In this study, severe plastic deformation (SPD) was employed on an Al-Mg alloy (AA5052 series) in the annealed condition with sheet form geometry by using the classical constrained-groove pressing (CGP) process up to two passes at room temperature, and accordingly an equivalent plastic strain of ∼2.32 imposed into the sheets. In relation to the microstructural features (cellular structure formation and precipitates morphology), dynamic strain aging behavior of these processed Al-Mg alloys up to different passes were evaluated by elaborating the tensile property along rolling (RD) and transverse directions (TD) of sheets in terms of anisotropy. Also, the effects of thermo-mechanical treatment in H34-temper condition on the characteristics of Al-Mg alloy was elaborated and compared with the SPD processing, as well. The results showed refinement of coarse grain structure (∼50μm) for initial annealed alloy into the ultra-fine range (400–500nm) after implementation of two CGP passes with significant homogenous enhancement of mechanical property. Hardness, yield, and tensile strengths were continuously improved up to ∼55%, 110%, and 20%, respectively, with a considerable deterioration of elongation (>90%). Notably, the strengthening mechanisms were elaborated by dislocation-based models to establish a microstructure–mechanical strength relationship.

Precipitate phases in ferritic/martensitic steel P92 after thermomechanical treatment

Thermomechanical treatment (TMT) can effectively improve the mechanical properties of 9–12% Cr ferritic/martensitic (F/M) steels. To understand the effect of TMT on the creep properties of the steels, precipitate phases in the steels produced by TMT require investigations. A TMT process, including austenization at 1373 K (1100 °C) for 2 h, followed by warm-rolling at 923 K (650 °C) plus tempering at 923 K (650 °C) for 1 h, was applied on a commercial F/M steel P92. Precipitate phases in the steel after the TMT were investigated by transmission electron microscopy. Nano-sized Cr-rich M2(C,N) carbonitride with a high number density was the dominant phase. Large-sized Nb-rich M(C,N), (Nb0.8V0.13Cr0.05Mo0.02) (C,N), and nano-sized Nb-V-rich M(C,N) carbonitride phases with the same f. c.c. crystal structure were identified. Identified Cr-rich M23C6 carbides with a typical composition of (Cr0.68Fe0.25W0.04Mo0.03)23C6 have a large size and less amount. Modified Z-phase, Cr(V,Nb)N, with a body-centered tetragonal crystal structure, and Cr-rich M7C3 carbide with a simple orthorhombic crystal structure were also identified. The amount of Z-phase and Cr-rich M7C3 carbides was the least compared to other precipitate phases.

Effect of Thermo-mechanical Treatment on the Formation Behavior of Martensite in 316L Stainless Steel

Effect of Thermo-mechanical Treatment on the Formation Behavior of Martensite in 316L Stainless Steel

Effect of thermo-mechanical treatment on tensile properties of reduced activation ferritic-martensitic steel

Effect of thermo-mechanical processing on tensile behaviour of reduced activation ferritic martensitic (RAFM) steel has been assessed and compared with those of the normalized and tempered steel. The thermo-mechanical treatment (TMT) was carried out by performing hot rolling and ageing in the austenite phase field, air cooled followed by tempering. TMT of the steel increased its hardness compared to the normalized and tempered condition. Tensile strength of the steel increased on TMT over the investigated temperature range of 300–923 K and more importantly was accompanied with increase in ductility. The strength increase on TMT was accomplished with the refinement of microstructure of the steel having finer martensite lath size and intra-granular precipitates. The tensile flow behaviour of steel has been assessed in the frame work of Voce's constitutive equation. The strength related parameters of the constitutive equation i.e. initial stress and saturation stress increased on TMT, while the recovery related parameter (nv) decreased marginally. The enhancement of tensile strength and ductility of the steel on TMT is considered due to microstructural refinement and its enhanced stability as reflected in appreciable lower relaxation and creep rates and the delayed in onset of tertiary stage of creep deformation.

Superelastic properties of nanocrystalline NiTi shape memory alloy produced by thermomechanical processing

Abstract Effects of thermomechanical treatment of cold rolling followed by annealing on microstructure and superelastic behavior of the Ni50Ti50 shape memory alloy were studied. Several specimens were produced by copper boat vacuum induction melting. The homogenized specimens were hot rolled and annealed at 900 °C. Thereafter, annealed specimens were subjected to cold rolling with different thickness reductions up to 70%. Transmission electron microscopy revealed that the severe cold rolling led to the formation of a mixed microstructure consisting of nanocrystalline and amorphous phases in Ni50Ti50 alloy. After annealing at 400 °C for 1 h, the amorphous phase formed in the cold-rolled specimens was crystallized and a nanocrystalline structure formed. Results showed that with increasing thickness reduction during cold rolling, the recoverable strain of Ni50Ti50 alloy was increased during superelastic experiments such that the 70% cold rolled–annealed specimen exhibited about 12% of recoverable strain. Moreover, with increasing thickness reduction, the critical stress for stress-induced martensitic transformation was increased. It is noteworthy that in the 70% cold rolled–annealed specimen, the damping capacity was measured to be 28 J/cm3 that is significantly higher than that of commercial NiTi alloys.

Effect of thermomechanical treatment on mechanical and electrical properties of Cu-Cr-Zr alloy in continuous hybrid process

The effect of thermomechanical treatment on mechanical and electrical properties of the Cu-Cr-Zr alloy was experimentally investigated through the Vickers micro-hardness, tension tests, and four-point probe method at room temperature. Three sets of experiments were carried out employing a commercially available alloy that was solution treated at 980 ˚C for 1 h in an argon atmosphere and water quenched. The order of the wire drawing or continuous hybrid processing and aging was varied to determine the effect of the thermomechanical treatment condition on material properties. The three-pass wire drawing and two-pass continuous hybrid processes after aging at 450 ˚C produced 508.8 MPa with 80.1% IACS and 529.4 MPa with 78.6% IACS, respectively. In conclusion, the continuous hybrid process might be an alternative to achieve the economical manufacturing in meeting the requirements for better strength and comparable electrical conductivity of the existing material compared to the conventional wire drawing.

Comparative study on the effect of samarium additions on thermo-mechanical behaviour of shape memory alloys

In the present work, a comparative study of the shape memory and thermo-mechanical behaviour of four alloys containing different amount of samarium have been carried out at a strain rate of 0.08 × 10-6s-1. After hot rolling, annealing and solution treatment, the alloy samples were tensile deformed at room temperature from 1% to 5% and were then recovered at 600 °C for 20 minutes repeatedly for six times to complete six training cycles. It is found that thermo-mechanical treatment (training) results in improvement of shape memory effect and has a significant influence on mechanical parameters like proof stress (σ: 0.002), critical stress (σ: 0.0008) and strain hardening exponent. The improvement in shape memory effect by thermo-mechanical treatment can be regarded as the effect of reduction in the values of proof stress and critical stress during training which facilitates the formation of ε (martensite). It has also been noticed that excessive training may result in the formation of ά (martensite) due to continuous softening of the alloy during training, thus degrading the shape memory effect. Finally, it has also been noticed that the addition of samarium increases the values of proof stress, critical stress and strain hardening exponent. Although the addition of samarium increases the values of proof stress, critical stress and strain hardening exponent yet it has not an adverse effect on shape memory effect. In this paper, the effect of thermo-mechanical treatment on mechanical parameters such as proof stress, critical stress, strain hardening exponent and their influence on shape memory effect is discussed.

The effects of cold rolling and the subsequent heat treatments on the shape memory and the superelasticity characteristics of Cu73Al16Mn11 shape memory alloy

In the present study, the effect of thermo-mechanical treatments on the shape memory and the superelastic characteristics of Cu73Al16Mn11 (at%) shape memory alloy were investigated. 10%, 50% and 70% cold rolling and subsequent heat treatment processes were conducted to achieve strengthening via grain size refinement. 70% grain size reduction compared to the homogenized condition was obtained using 70% cold rolling and subsequent recrystallization heat treatment technique. Moreover, 10% cold rolling was applied to homogenized specimen to reveal the influence of the low percentage cold rolling reduction with no heat treatment on shape memory properties of Cu73Al16Mn11 (at%) alloy. Stress free transformation temperatures, monotonic tension and superelasticity behaviors of these samples were compared with those of the as-aged sample. Isobaric heating–cooling experiments were also conducted to see the dimensional stability of the samples as a function of applied stress. The 70% grain-refined sample exhibited better dimensional stability showing reduced residual strain levels upon thermal cycling under constant stress compared with the as-aged material. However, no improvement was achieved with grain size reduction in the superelasticity experiments. This distinctive observation was attributed to the difference in the magnitude of the stress levels achieved during two different types of experiments which were the isobaric heating–cooling and superelasticity tests. Intergranular fracture due to the stress concentration overcame the strengthening effect via grain refinement in the superelasticity tests at higher stress values. On the other hand, the strength of the material and resistance of material against plastic deformation upon phase transformation were increased as a result of the grain refinement at lower stress values in the isobaric heating–cooling experiments.

Effects of post-processing on the thermomechanical fatigue properties of laser modified NiTi

The multifunctional capabilities needed for advanced shape memory alloys (SMA) actuators has been shown to be achievable by locally tuning the properties through laser processing. Before the wide-spread use of these SMAs is realized, a detailed understanding on the long-term stability and functional life span of these material must be achieved. The current study systematically investigates the effects of thermomechanical treatment on laser modified NiTi wires, while comparing them to the original base material. Surface analysis was done using a scanning electron microscope (SEM), while microstructure analysis was performed using transmission electron microscopy (TEM). Mechanical properties were assessed using standard tensile tests and a custom built thermomechanical fatigue. Results showed that the coarse-grains, large inclusions and surface defects associated with as laser modified NiTi resulted in reduced mechanical performance. However, subsequent thermomechanical treatment restored the refined microstructure and mechanical performance similar to the base material while providing the added functionality, thus allowing for laser processed NiTi to be used for manufacturing multiple memory NiTi actuators.

Deformation mechanism and mechanical properties of a thermomechanically processed β Ti-28Nb-35.4Zr alloy.

The effects of thermomechanical treatment on the microstructure and mechanical properties of a newly developed β titanium alloy, i.e., Ti-28Nb-35.4Zr (wt%, hereafter denoted Ti-Nb-Zr) were investigated. The as-cast Ti-Nb-Zr alloy was subjected to solution treatment at 890°C for 1h, after which its thickness was reduced by 20%, 56%, 76%, and 86% via cold rolling. Results indicated that annealing at 890°C for 1h after cold rolling at a thickness reduction ratio of 86% resulted in a phase transformation from the stress-induced α" and ω into β, leading to a recrystallization of a uniform single β phase. The recrystallized Ti-Nb-Zr alloy exhibited a tensile strength of 633MPa, Young's modulus of 63GPa, and elongation at rupture of 13%, respectively. The cold rolled specimens showed a higher Young's modulus than that of the recrystallized specimen due to the stress-induced ω phase. Transmission electron microscopy (TEM) analysis revealed that ω, α" and β phases co-existed in the microstructure of the cold-rolled specimens. Electron backscatter diffraction analysis revealed that the deformation mechanisms during thermomechanical processing included kink bands, {332}<113> twins and shear bands; and the predominant deformation mechanism depended on the extent of CR deformation.