Effect Of Severe Plastic Deformation Research Articles

An Overview on the Effect of Severe Plastic Deformation on the Performance of Magnesium for Biomedical Applications.

There has been a great interest in evaluating the potential of severe plastic deformation (SPD) to improve the performance of magnesium for biological applications. However, different properties and trends, including some contradictions, have been reported. The present study critically reviews the structural features, mechanical properties, corrosion behavior and biological response of magnesium and its alloys processed by SPD, with an emphasis on equal-channel angular pressing (ECAP) and high-pressure torsion (HPT). The unique mechanism of grain refinement in magnesium processed via ECAP causes a large scatter in the final structure, and these microstructural differences can affect the properties and produce difficulties in establishing trends. However, the recent advances in ECAP processing and the increased availability of data from samples produced via HPT clarify that grain refinement can indeed improve the mechanical properties and corrosion resistance without compromising the biological response. It is shown that processing via SPD has great potential for improving the performance of magnesium for biological applications.

Electrochemical behavior of ECAP-processed Sn–5Sb alloy

An attempt has been made in this research to evaluate the effects of severe plastic deformation (SPD) on the electrochemical and passivation response of Sn–5Sb alloy. The electrochemical response of severely deformed alloy through the equal channel angular pressing (ECAP) process has been studied by cyclic voltammetry (CV), potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), and Mott–Schottky in 0.1 M NaOH solution. The grain structure and corrosion product of samples have been evaluated by X-ray diffraction (XRD), atomic force microscopy (AFM) patterns, transmission electron microscopy (TEM), and field emission scanning electron (FESEM) micrographs. It has been revealed that imposing such a large strain yields specimens with finer grain structure resulting in higher corrosion resistance and higher protecting passive films.

Can Severe Plastic Deformation Tune Nanocrystallization in Fe-Based Metallic Glasses?

The effects of severe plastic deformation (SPD) by means of high-pressure torsion (HPT) on the structural properties of the two iron-based metallic glasses Fe73.9Cu1Nb3Si15.5B6.6 and Fe81.2Co4Si0.5B9.5P4Cu0.8 have been investigated and compared. While for Fe73.9Cu1Nb3Si15.5B6.6, HPT processing allows us to extend the known consolidation and deformation ranges, HPT processing of Fe81.2Co4Si0.5B9.5P4Cu0.8 for the first time ever achieves consolidation and deformation with a minimum number of cracks. Using numerous analyses such as X-ray diffraction, dynamic mechanical analyses, and differential scanning calorimetry, as well as optical and transmission electron microscopy, clearly reveals that Fe81.2Co4Si0.5B9.5P4Cu0.8 exhibits HPT-induced crystallization phenomena, while Fe73.9Cu1Nb3Si15.5B6.6 does not crystallize even at the highest HPT-deformation degrees applied. The reasons for these findings are discussed in terms of differences in the deformation energies expended, and the number and composition of the individual crystalline phases formed. The results appear promising for obtaining improved magnetic properties of glassy alloys without additional thermal treatment.

Omega Phase Formation and Mechanical Properties of Ti–1.5 wt.% Mo and Ti–15 wt.% Mo Alloys after High-Pressure Torsion

The paper analyzes the effect of severe plastic deformation by the high-pressure torsion (HPT) on phase transformations, in particular, on the formation of the ω-phase, and on mechanical properties, such as hardness and Young’s modulus, in Ti alloys with 1.5 and 15 wt.% Mo. Both alloys were pre-annealed at 1000 °C for 24 h and quenched. The microstructure of the initial Ti–1.5 wt.% Mo alloy consisted of the α-phase and α’-martensite, and the initial Ti–15 wt.% Mo alloy contained polycrystalline β solid solution. The hardness tests of the samples were carried out under the load of 10 and 200 mN. The annealed alloys were subjected to HPT, and the micro- and nanohardness of both deformed samples increased up to ~1 GPa compared to their initial state. It turned out that the values of hardness (H) and Young’s modulus (E) depend on the applied load on the indenter: the higher the applied load, the lower H and higher E. It was also found that the HPT leads to the 30% increase in E for an alloy with 1.5 wt.% Mo and to the 9% decrease in E for the alloy with 15 wt.% Mo. Such a difference in the behavior of the Young’s modulus is associated with phase transformations caused by the HPT.

Effect of surface severe plastic deformation on microstructure and hardness of Al alloy sheet with enhanced precipitation

The effect of severe plastic deformation on microstructure and hardness of 7075 aluminum alloy sheet presented different results from that of thick samples in previous study. Grains were not refined obviously, and precipitation phases MgZn2 were massively dissolved in the matrix in the region close to the surface. Varied density of dislocations were produced at different depths. The depth of severe plastic deformation layer was 40–70 μm, while the affected depth of hardness was much deeper. The maximum hardness enhancement, 16% increase compared to the core hardness, appeared at about 150–250 μm below surface. The hardness change depended on the competition between the roles of precipitation dissolution and dislocation multiplication.

Effect of Severe Plastic Deformation by Extrusion on Microstructure and Physical and Mechanical Properties of Mg–Y–Nd and Mg–Ca Alloys

Effect of Severe Plastic Deformation by Extrusion on Microstructure and Physical and Mechanical Properties of Mg–Y–Nd and Mg–Ca Alloys

Microstructure evolution and wear properties of ECAP-treated Al-Zn-Mg alloy: Effect of route, temperature and number of passes

In this study, the effect of severe plastic deformation on Al-Zn-Mg alloy was investigated by ECAP method. The ECAP process parameters were determined using Taguchi experimental design for different routes (A, B C and C), different temperatures (100, 150 and 200 °C) and different number of passes (2, 4 and 8). EBSD and TEM analysis were used for microstructural characterization of the samples and the dry sliding wear test was used to measure the mechanical strength. In the study of microstructural properties, it was determined that there was a direct relationship between the number of passes and temperature. With the increase in the number of passes and the decrease in the temperature, a severe decrease in grain size in the samples was observed. It was observed that the sample subjected to ECAP treatment with 8 passes at 100 °C in the B C route was microstructurally coaxial and had the smallest grain size, and the same sample showed the best wear properties.

Severe plastic deformation influence on the structure transformation of the amorphous Zr62.5Сu22.5Al10Fe5 alloy

The paper analyzes the effect of severe plastic deformation on the structure, mechanical and thermal properties as well as crystallization process of a Zr62.5Сu22.5Al10Fe5 alloy. High pressure torsion (HPT) induces local atomic changes and accumulates the formation of inhomogeneous chemical regions. The mechanically treated alloy structure is generally complex. The residual glassy matrix contains nanocrystalline particles. The structural changes observed during the HPT process lead to significant changes in the crystallization process. The effect of shear strain on crystallization of the Zr62.5Сu22.5Al10Fe5 alloy and its properties was studied in detail using transmission electron microscopy (TEM), X-Ray diffraction (XRD), and differential scanning calorimetry (DSC) methods.

Effect of Severe Plastic Deformation and Post-Deformation Heat Treatment on the Microstructure and Superelastic Properties of Ti-50.8 at.% Ni Alloy.

Severe plastic deformation via high-ratio differential speed rolling (HRDSR) was applied to the Ni-rich Ti-50.8Ni alloy. Application of HRDSR and a short annealing time of 5 min at 873 K leads to the production of a partially recrystallized microstructure with a small grain size of 5.1 μm. During the aging process for the annealed HRDSR sample at 523 K for 16 h, a high density of Ni3Ti4 particles was uniformly precipitated over the matrix, resulting in the formation of an R phase as the major phase at room temperature. The aged HRDSR sample exhibits excellent superelasticity and superelastic cyclability. This achievement can be attributed to an increase in strength through effective grain refinement and particle strengthening by Ni3Ti4 and a decrease in the critical stress for stress-induced martensite (B19') due to the presence of the R-phase instead of B2 as a major phase at room temperature. The currently proposed method for using HRDSR and post-deformation heat treatment allows for the production of Ni-rich NiTi alloys with excellent superelasticity in sheet form.

Effects of Severe Plastic Deformation and Ultrasonic Treatment on the Structure, Strength, and Corrosion Resistance of Mg-Al-Zn Alloy.

Nowadays, there is a great demand for increasing the strength and corrosion resistance of magnesium alloys for their wider use in machine engineering, oil industry, and medicine. This paper is devoted to a study on the effects of the combined process of reduction and equal channel angular pressing, as well as the subsequent ultrasonic irradiation on the structure, strength, and corrosion properties of the Mg-Al-Zn alloy. Deformation processing results in an increase of the strength up to 280 ± 10 MPa. A fine-grained structure is formed with a grain size of 10–20 µm and small recrystallized grains 1–2 µm in size. The corrosion resistance in the HCl medium falls down significantly. Action of ultrasound on the deformed specimen leads to an increased fraction of high-angle boundaries, in particular, the fractions of special, fully overlapping Σ13a boundaries and twin boundaries of Σ15b and Σ17a systems. Due to the ultrasonic treatment, the strength of the Mg-Al-Zn alloy increases up to 310 ± 5 MPa, while the corrosion resistance in HCl almost doubles.

Cyclic Extrusion Compression Process for Achieving Ultrafine-Grained 5052 Aluminum Alloy with Eminent Strength and Wear Resistance

Previous studies have yet to show a consistent effect of severe plastic deformation (SPD) processing on the wear behavior of different metals and alloys. To fill this scientific gap, this study investigated the effect of the cyclic extrusion compression (CEC) process, as one of the prominent SPD techniques, on the wear behavior of AA5052. In addition, the microstructure evolution and mechanical properties of the sample before and after the process were experimentally examined and studied. It was found that the yield and ultimate tensile strength of the AA5052 improved significantly after the first pass, while the elongation-to-failure decreased considerably. Further, the subsequent passes mildly changed the trend of increasing strength and reducing elongation-to-failure. SEM morphology indicated that the ductile mode of the initial annealed alloy changed to a combination of ductile and brittle failure modes, in which the level of the brittle failure mode increased with the addition of passes. TEM observations showed that the grain refinement during the CEC process included the formation of dislocation cell structures, subgrain boundaries, and low-angle grain boundaries, with the subgrain boundaries initially evolving into low-angle grain boundaries and, eventually, due to the imposition of additional plastic strain, into high-angle grain boundaries. Furthermore, the CEC process and its increased number of passes led to a significant improvement in wear resistance due to the enhanced tensile strength achieved through grain refinement. In this regard, the wear mechanism of the initial alloy was a combination of adhesion and delamination, with the plastic deformation bands changing to plowing bands with decreased adhesive wear during the process. Eventually, oxidization was found to be a mechanism contributing to wear under all conditions.

Tension-compression asymmetry of quadruple CuCoNiBe alloys processed by high-temperature multi-pass equal channel angular pressing (ECAP)

Abstract Among copper alloys, the precipitation (age) hardening quadruple CuCoNiBe alloys due to their superior mechanical properties in terms of the highest strength and elasticity achieved by peak aging have been used over the years in a wide range of industrial applications including aircrafts, coil systems, blast-proof materials, and molding dies. Combined thermomechanical treatment (i.e., equal channel angular pressing [ECAP] processing followed by post-ECAP aging) can result in a further enhancement of the strength of CuCoNiBe alloys due to the grain refinement and the formation of fine precipitates from α-Cu supersaturated solid solution. In this study, for the first time, the effect of severe plastic deformation by ECAP processing on the mechanical behavior of CuCoNiBe alloys is discussed thoroughly based on the material responses to tensile and compressive loading conditions. The results show that, besides a considerable strength enhancement, ECAP processing leads to a strong tension-compression asymmetry and significantly accelerated precipitation kinetics in CuCoNiBe alloys.

Regularities of Microstructure Evolution in a Cu-Cr-Zr Alloy during Severe Plastic Deformation.

The effect of severe plastic deformation by the conforming process of equal channel angular extrusion (ECAE-Conform) followed by cold rolling on the microstructures developed in a Cu-0.1Cr-0.1Zr alloy was investigated. Following the ECAE-Conform of 1 to 8 passes (corresponding strains were 0.8 to 6.4) cold rolling to a total strain of 4 was accompanied by substantial grain refinement and strengthening. An average grain size tended to approach 160 nm with an increase in the rolling reduction. An increase in the ECAE-Conform strain promoted the grain refinement during subsequent cold rolling. The fraction of the ultrafine grains with a size of 160 nm after cold rolling to a strain of 4 increased from 0.12 to 0.52 as the number of ECAE-Conform passes increased from 1 to 8. Correspondingly, the yield strength increased above 550 MPa. The strengthening could be expressed by a Hall–Petch type relationship with a grain size strengthening factor of 0.11 MPa m0.5.

Effect of Severe Plastic Deformation on Pre- and Post-Nitriding Conditions of 316 Stainless Steel

Effect of Severe Plastic Deformation on Pre- and Post-Nitriding Conditions of 316 Stainless Steel

Effect of Magnesium Powder Application on the Microstructure and Properties of Rods Extruded by the Forward-Backward Rotating Die Extrusion Method.

The effects of severe plastic deformation (SPD) with a forward-backward rotating die (KOBO extrusion) on pure magnesium, in the form of cold-compacted powder, sintered powder, or cast ingots as reference, were examined. This method is known to reinforce metals, but the role of the initial form of magnesium applied in the fabrication of metal-based rods, as well as related phenomena, has not been characterized until now. The problem is important in the potential processing of commercial metal powders, the recycling of metal shavings, and the fabrication of metal matrix composites with discontinuous reinforcing phases. In the presented experiments, rods of 8 mm in diameter and 400 mm in length were obtained, and the structural effects induced by KOBO that occurred on a macro- and microscale on the surface and cross sections were characterized. Changes in the size and orientation of α-Mg crystallites were determined by XRD. The porosity, hardness, tensile strength, and compressive strength were measured, and the mechanisms of decohesion dependent on starting metal form were analyzed. After KOBO extrusion, significant differences were observed in the microstructure and properties between the materials derived from cold-compacted powder, sintered powder, and reference cast magnesium. Due to the application of KOBO, apart from α-Mg grain refinement, the MgO derived from the initial powder’s surface was refined to fine regular particles surrounded by magnesium. Their bands curved in the perpendicular plane and were oriented with the extrusion direction of the formed network, which augmented some mechanical properties and changed the decohesion mechanism. The conducted experiments revealed that before extrusion by KOBO, the magnesium powder required sintering under pressure.

Effect of severe plastic deformation on the precipitation kinetics and the properties of CuCoNiBe alloys

The effect of the precipitation hardening by means of the conventional heat treatment and the combined thermomechanical treatment (i.e., equal channel angular pressing (ECAP) with subsequent aging) on the electrical conductivity, mechanical properties and precipitation kinetics of precipitation hardening, quadruple CuCo1Ni1Be alloy was investigated. No experimental studies on the effect of ECAP on the electrical conductivity and precipitation kinetics of CuCoNiBe alloys have been reported. Systematic microstructural and mechanical investigations show that both ECAP processing and post-ECAP aging result in a significant increase in the hardness and strength of the alloy due to the grain boundary strengthening by means of the grain refinement (and the formation of subgrains) and due to the precipitation hardening by means of the formed precipitates (primary and secondary beryllides) in the fine-grained structure, respectively. Moreover, the electrical conductivity of both solution treated and ECAPed alloys increases with increasing aging time due to the precipitation of the solute atoms in α-Cu matrix leading to decreasing electrical resistivity. However, the CuCo1Ni1Be alloys subjected to ECAP exhibit a lower conductivity than the solution treated ones, which can be attributed to an increase in resistivity caused by increased probability of electrons scattering by severe plastic deformation. The linear relationship between electrical conductivity and volume fraction of the precipitates according to the Martition's law and the empirical Avrami equation are used to investigate the precipitation kinetics of the CuCo1Ni1Be alloy. The S-shaped volume fraction of precipitates vs. aging time curves clearly indicate that the precipitation kinetics of the CuCoNiBe alloys can be significantly promoted by ECAP processing. The results of the present study provide new insights into the interaction of the severe plastic deformation, the kinetics of precipitation, and the microstructural, mechanical and physical properties of the CuCo1Ni1Be alloy.

Effect of severe plastic deformation on aging kinetics of precipitation hardening 17–4 stainless steel

Precipitation hardening (PH) stainless steels are high chromium, high nickel and low carbon stainless steels which were mainly developed to provide high strength and fracture toughness while maintaining good corrosion resistance. Precipitation hardening treatment involves solution annealing treatment followed by aging treatment which is applied on these steel to impart high hardness, fracture toughness and strength. The PH stainless steels develop high strength and toughness through additions of copper, aluminum, titanium, niobium, vanadium, and/or nitrogen, which form precipitates during aging heat treatment. In this work effect of severe plastic deformation (SPD) on aging kinetics of pH 17–4 stainless steel was investigated. Severe plastic deformation was applied on the surface of pH stainless steel specimens by shot-peening process. For comparison, aging of specimens with shot-peening and without shot-peening were done. After aging specimens were characterized by microhardness testing, optical and electron microscopy. The results showed considerably high hardness in the range of 617–649 HV for pH 17–4 stainless steel after aging on severely deformed specimens which is nearly 29% higher than the specimens which were aged without SPD.

Еffect of methods and modes of severe plastic deformation on structural features of ultrafine-grained aluminum alloys, which determine their increased mechanical properties

The effect of severe plastic deformation on the structure of aluminum alloys 1420 and V96T s1, as well as the nanostructure parameters of these metal systems, which determine their increased mechanical properties, is shown: tensile strength of 775 and 800 MPa, elongation of 14 and 20 %, respectively, for 1420 and V96Ts1 alloys.

Effects of severe plastic deformation on the microstructures, mechanical properties, and corrosion behavior of U-5.5Nb alloy

Equal-channel angular pressing (ECAP) and mechanical machining were employed to introduce large plastic shear strain into bulk and the surface layer of a U-5.5wt.%Nb (U-5.5Nb) alloy, respectively. Applying ECAP, the U-5.5Nb alloy exhibited a single yield feature on the stress-strain curve in comparison to the “double yield” feature in the water quenched (WQ) counterpart. The difference is attributed to the characteristics of severe plastic deformation (SPD) structures obtained by ECAP. Mechanical machining resulted in a further severe microstructure refinement of the SPD surface layer with nano-grains/subgrains, which is accompanied with a dramatic increase of both the hardness and the elastic modulus of the surface layer. It is further proposed that the suppression of the shape memory effect (SME) in the nanostructured U-5.5Nb alloy may be responsible for the enhanced elastic modulus. The results of corrosion rate and pitting susceptibility showed a microstructure dependency, where the ECAP sample exhibited a better pitting resistance than that of the WQ counterpart.

Evolution of the Zr42.5Сu42.5Al10Fe5 amorphous alloy structure during the HPT process

The paper analyzes the effect of severe plastic deformation on the structure, mechanical and thermal properties of a Zr42.5Сu42.5Al10Fe5 alloy. It was found that high pressure torsion induces phase separation of an amorphous matrix and causes formation of a complex structure containing nanocrystalline particles. The precipitation of nanocrystals leads to a change in the composition of the amorphous matrix and changes in the crystallization process and characteristic temperatures of the alloy. It is shown in the work that high pressure torsion significantly increases the hardness of the material, which is associated with the formation of nanocrystals in the structure and elastic stresses.