Effect Of Severe Plastic Deformation Research Articles

Multi-field coupling finite element analysis for determining the influence of temperature field on die service life during precision-forming process of steel synchronizer ring

Failure analysis shows that increased die temperature caused by severe plastic deformation of material and heat conduction between hot billet and cavity significantly affects the distortion of gear cavity in steel synchronizer ring forging process. The forging process of steel synchronizer ring and die temperature distribution under different forging conditions are analyzed through finite element method. Simulation results show that severe plastic deformation occurs in the gear cavity. The improvement of lubrication condition results in decreased die temperature. When the initial billet temperature is high, the die temperature is also high. Increasing forging speed in a certain range facilitates the die temperature decrease. The distribution of die temperature in synthetic forming technology is more reasonable than that of one step forging. The synthetic forming technology is adopted in production to reduce the effects of severe plastic deformation caused by die temperature. The ejection mechanism and control system of the double disc friction press are improved to reduce the contact time between the hot billet and cavity. Experimental results show that synthetic forming technology is reasonable, and that the die service life is prolonged.

Metal Forming Aspects of Cyclic Severe Plastic Deformation of Ti-Ni Shape Memory Alloys Using MaxStrain Device

The effect of severe plastic deformation using MaxStrain (MS) device which is a part of the Gleeble thermo-mechanical simulator of rolling and forging processes on the structure and functional properties of Ti–50.0 at.% Ni shape memory alloy has been studied. The use of the MS module allows performing SPD of the material under isothermal conditions with precise control of the deformation parameters. The deformation temperature was lowered from 370 to 330 °C. The accumulated true strain varied from e=4.6 to 9.5. Structure features were studied by the transmission electron microscopy. The maximum completely recoverable strain was determined by a thermomechanical method using a bending mode for strain inducing. A mixed submicrocrystalline and nanosubgrained structure with average grain/subgrain size below 100 nm was formed using SPD at 330 °C. A very high completely reсoverable strain (9.3%) was obtained against a reference treatment (2.5%).

Structural and Phase Transformations in Internally Nitrided Corrosion‐Resistant Steel during Severe Plastic Deformation and Subsequent Annealings

The effect of severe plastic deformation (SPD) by high‐pressure torsion (HPT) and subsequent annealings on structural and phase transformations in 0.08C–18Cr–0.5Ti steel, which is preliminarily hardened by high‐temperature internal nitriding (the microhardness is 3.2 GPa), has been studied. The HPT results in the formation of nanostructure with an average structural‐element size of 55 nm and the refining and in part dissolution of Cr2N particles. After HPT, the microhardness of steel increases by 2.7 times (to 8.6 GPa at the midradius of samples), which is substantially higher than the microhardness of non‐nitrided steel after HPT. The hardening of the material remains during heating to a temperature of no less than 450 °С at the expense of precipitation of disperse Cr2N particles and despite of coarsening structural elements. HPT of nitrided steel leads to a shift of phase transformations, namely the temperature of chromium nitride precipitation decreases.

The Effect of Severe Plastic Deformation and Heat Treatment on CuCrZr Alloys

The Effect of Severe Plastic Deformation and Heat Treatment on CuCrZr Alloys

Microstructure and mechanical properties of two binary Al‐Mg alloys deformed using equal channel angular pressing

AbstractIn the present work, the effect of severe plastic deformation (SPD) on the mechanical properties of two binary Al−Mg alloys have been investigated. Because of the limited workability of the investigated material, both alloys were subjected to the heat treatment (precipitation treatment) before plastic deformation using equal channel angular pressing (ECAP). Results of investigation show that the increased magnesium content result in a decrease in workability, however, the heat treatment improves ability for plastic working. It was also observed that a combination of heat treatment with severe plastic deformation causes an increase in mechanical properties when compared to the initial material. In order to characterize structural changes that occur after plastic deformation, scanning electron microscopy and transmission electron microscopy were used.

Strength, corrosion resistance, and biocompatibility of ultrafine-grained Mg alloys after different modes of severe plastic deformation

The effect of severe plastic deformation on the structure, mechanical properties, corrosion resistance, and biocompatibility of the WE43 (Mg-Y-Nd-Zr) alloy earmarked for applications as bioresorbable material has been studied. The alloy was deformed by rotary swaging (RS), equal channel angular pressing (ECAP), and multiaxial deformation (MAD). The microstructure examination by transmission electron microscopy showed that all SPD modes lead to the formation of ultrafine-grained structure with a structural element size of 0.5-1 µm and the Mg12Nd phase particles 0.3 µm in size. The microstructure refinement by all three treatments resulted in strengthening of the alloy. ECAP and MAD also raised ductility to up to 12-17%, while RS increased the ultimate tensile strength to up to 415 MPa. The study of the corrosion properties showed that SPD does not affect the electrochemical corrosion of the alloy. Its biocompatibility in vitro was estimated after incubation of the samples with red blood cells (hemolysis study), white blood cells (cell viability assay), and mesenchymal stromal cells (cell proliferation analysis). The biodegradation rate in fetal bovine serum was also evaluated. ECAP and MAD were found to cause some deceleration of biodegradation by slowing down the gas formation in the biological fluid and, compared to MSC, to improve the biocompatibility of the WE43 alloy.

Effect of severe plastic deformation on the structure and properties of Ni-Cu alloys

The structure of Ni-Cu alloys processed by high pressure torsion by 5 revolutions at room temperature (saturation stage) has been studied by the methods of transmission electron microscopy and microhardness measurements. It is demonstrated that moving from copper possessing lower melting temperature and lower stacking fault energy (SFE) to nickel the melting temperature and SFE of which are considerably higher, the submicrocrystalline structure of alloys is markedly refined (by about a factor of 2), whereas the microhardness increases by more than 1.5 times. The simultaneous effect of two factors (changing of homological temperature and SFE) results in the non-linear dependence of these parameters (crystallite sizes and microhardness) on alloy composition.

The effect of severe plastic deformation on the microstructure and mechanical properties of (TiB+TiC) reinforced titanium matrix composites

Equal-channel angular pressing (ECAP) was successfully applied to in-situ synthesized particulate reinforced titanium matrix composites. The results prove that the ultrafine-grained structure can be effectively obtained in the titanium matrix composite by ECAP at different temperatures and passes. Formation of homogenous TiB and TiC particles with ultrafine grains and sub-grains were obtained after 4 ECAP passes, which indicates that the reinforcement-induced ultrafine grains. The lamellar α phases are also twisted obviously due to the shear stress, which can reduce the average thickness of lamellar α phases to less than 1μm. After ECAP at relatively low temperature, dislocation pile-ups, dislocation tangling and plenty of cell structures with size of about 500nm can be observed in the matrix. While many newly formed ultrafine grains with clear grain boundaries and size of 100~500 nanometers have formed. The tensile test results show that the yield strength is improved by ECAP pressing and saturate after 4 ECAP passes to a value of 1150MPa, and the ductility is much higher compared with the first ECAP pass.

Effect of Severe Plastic Deformation and Subsequent Silicon Spheroidizing Treatment on the Microstructure and Mechanical Properties of an Al–Si–Mg Alloy

This study investigated the synergetic effects of severe plastic deformation and subsequent heat treatment on the characteristics of an A356 alloy. The severe deformation by accumulative back extrusion (ABE) at 300 °C substantially refined the α–Al primary phase and Si particles, but did not homogeneously redistribute the Si particles. ABE also improved the strength but did not enhance the ductility. To make a compromise between strength and ductility, a subsequent heat treatment at 540 °C was carried out. It was shown that severe plastic deformation substantially accelerated the silicon spheroidization. Heat treatment increased the ductility of the material from ∼8% (in the deformed condition) to ∼15%. This was discussed with emphasis on restoration of the matrix, spheroidization of the Si particles, and redistribution of the Si particles within the α–Al matrix.

Effect of Severe Plastic Deformation on Structure and Properties of Beta Titanium Alloy Using for Hip Implants

The Paper Deals with Microstructural and Mechanical Properties Changes during Severe Plastic Deformation Process in Beta Titanium Alloy Used for Hip Implants. Effect of Various Numbers of Passes through ECAP (Equal Chanel Angular Pressing) Die on Microstructure and Properties Have been Evaluated. Comparison between Virgin State Cast Alloy and Alloy after Several Steps of Severe Plastic Deformation Induced by ECAP Technology Have been Carried out. Mechanical Properties Have been Evaluated Using Miniaturized Specimens. from Experimental Work can Be Concluded Positive Effect of ECAP Technology both on Mechanical Properties (yield Stress as well as Tensile Strength) Including Grain Size.

Effect of Severe Plastic Deformation on Wear Properties of Aluminum Matrix Composites

Effect of Severe Plastic Deformation on Wear Properties of Aluminum Matrix Composites

Effect of the quasi-continuous equal-channel angular pressing on the structure and functional properties of Ti–Ni-based shape-memory alloys

The effect of severe plastic deformation by equal-channel angular pressing (ECAP) under normal and quasi-continuous regimes on the structure and the mechanical and functional properties of a Ti–50.2 at % Ni shape-memory alloy (SMA) has been studied. ECAP was carried out at an angle of intersection of channels of 120° in the normal regime with heating between passes at 450°C for 20 passes and in the quasi-continuous regime at the temperature of 400°C for three, five, and seven passes. The hot screw rolling with subsequent annealing at 750°C for 30 min and cooling in water was used as a control treatment (CT). A mixed submicrocrystalline and nanosubgrained structure was formed. The increase in the number of passes from three to seven led to a decrease in the average size of structural elements from 115 ± 5 to 103 ± 5 nm and to an increase in the fraction of grains/subgrains having a size less than 100 nm. After ECAP (seven passes) and post-deformation annealing at the temperature of 400°C for 1 h, a completely recoverable strain was 9.5%; after normal ECAP, 7.2%; after CT, 4.0%.

High-strength state of ultrafine-grained martensitic steel produced by high pressure torsion

The paper presents the study results on the effect of severe plastic deformation (SPD) via high pressure torsion (HPT) on the structure and properties of martensitic steel. The contribution of different strengthening mechanisms in the strength of steel has been analyzed. It is shown that independently of the deformation temperature the main contribution in hardening belongs to grain boundaries (about 50 %), whereas the dislocation and solid solution components achieve 15 and 25 %, respectively.

Effect of Severe Plastic Deformation on the Structure and Magnetic Behaviour of an Fe-Mn-Si Shape Memory Alloy

This work focuses on the relation between severe plastic deformation process via HSHPT and magnetic properties of an Fe–Mn–Si-Cr shape memory alloy. High speed high pressure torsion (HSHPT) was applied on cast state of alloy. Microstructure evolution of severe plastic deformed iron based alloy subjected to different deformation degree were investigated. The microstructure and phase compositions of alloy were characterized using optical microscopy, scanning electron microscopy and transmission electron microscopy. The magnetic properties are discussed on the basis of the severe plastic deformation process and the underlying martensitic transformation. Thermomagnetic curves, between 150 K and 390 K and magnetic hysteresis loops at 300 K temperatures were measured. The thermo-resistivity measurements were done by standard four-probe. The magnetic properties are interpreted and correlated with microstructure.

Effect of severe plastic deformation on the biocompatibility and corrosion rate of pure magnesium

It is well established that magnesium has a considerable potential for use as a biodegradable material. This report describes the effect of processing by severe plastic deformation (SPD) on the grain refinement, mechanical behavior, biocompatibility and corrosion behavior of commercial purity magnesium. The material was received as cast slabs and processed by rolling, equal-channel angular pressing and high-pressure torsion to produce samples with average grain sizes in the range of ~0.5–300 μm. The results show that severe plastic deformation does not affect the biocompatibility. However, the corrosion behavior is affected by the processing route. Specifically, SPD processing leads to general corrosion as opposed to localized corrosion in the as-cast and hot-rolled condition.

Effect of Severe Plastic Deformation on Shape Memory and Mechanical Properties of Nanostructured Cu-Zn-Al Alloy

Effect of Severe Plastic Deformation on Shape Memory and Mechanical Properties of Nanostructured Cu-Zn-Al Alloy

Influence of Zr on intergranular corrosion of cast and cryorolled D16 aluminum alloy

Effects of severe plastic deformation by isothermal сryorolling at a temperature of liquid nitrogen with a strain of e~2 and subsequent natural and artificial aging on the evolution of structure, hardness and resistance to intergranular corrosion (IGC) of the preliminary quenched D16 aluminum alloys of conventional and Zr modified compositions, were investigated. It was found that the natural aging of alloys had slight effect on corrosion resistance due to formation of Guinier-Preston-Bagaratsky zones. Because of their coherency to matrix, difference in their electrochemical potential was low, causing slight effect on corrosion resistance. Artificial aging to the maximum strength, performed at 190ºC for 12 hrs in accordance to conventional T1 route, in both rolled and non-rolled states of the alloys of both compositions led to strong decrease of IGC resistance due to precipitation of strengthening phases instead of zones, formed at natural aging. Modification of the alloy composition, via substitution of Mn by twice less amounts of Zr and decrease in impurity contents, had a minor influence on its structure and hardness in the initial and rolled conditions. However, it significantly enhanced corrosion resistance, reducing its depth and intensity, in both naturally and artificially aged conditions studied. It was concluded that the main factors, determining the alloy microstructure changes, mechanical and corrosion behavior, are the volume fraction and morphology, and spatial distribution of second phases - excess phases and precipitates.

Фазовые изменения в композиционном сплаве АК12ММгН-18%SiCp после интенсивной пластической деформации и отжига

The effect of severe plastic deformation by high pressure torsion (HPT) on the structure of AK12MMgN-18%SiCp composite alloy was investigated. A liquid-forged billet was taken as an initial material. Samples 8 mm in diameter and 0.45 mm in thickness were deformed by torsion in a Bridgman anvil at room temperature up to 5 turns under the pressure of 4 GPa. After deformation the samples were annealed in the temperature range of 300-500°C for 5 minutes. The average area and volume fraction of particles in the initial, HPT-processed and annealed samples were evaluated. The change of the concentration level of a solid solution in the states under study was analyzed. It was shown that HPT led to a fragmentation of particles and a reduction of their average area: silicon particles from 4.4±0.1 to 0.32±0.02 μm2, intermetallic particles from 5.2±2.6 to 0.20±0.02 μm2, and SiC from 37.6±0.9 to 3.9±0.02 μm2. At the same time, a partial dissolution of excess phases occurred that resulted in the formation of a supersaturated solid solution. Post-HPT annealing led to a dissolution of the supersaturated solid solution with a separation of secondary phases of different morphology not typical to the alloy: globular silicon, rod shaped phase enriched by Ni, Si and Fe and a more compact phase containing Si and Cu. The higher the annealing temperature, the more intensive was the process of supersaturated solid solution decomposition and the higher was the volume fraction of silicon and intermetallic particles. Their average area increased with annealing temperature. No changes in the average area and volume fraction of SiC particles during annealings of HPT-processed alloy were observed.

Formation of a state with high strength and electrical conductivity in the Cu-0.5%Cr-0.2%Zr alloy

The effect of severe plastic deformation by high pressure torsion (HPT) and subsequent aging on the formation of a high-strength state with sufficient electrical conductivity in the Cu-0.5%Cr-0.2% Zr (wt.%) alloy is investigated. It is shown that as a result of HPT and subsequent aging a high-strength state with a tensile strength of ≈ 900 MPa and a conductivity of 70% IACS can be formed.

Effect of severe plastic deformation and post-annealing on the mechanical properties and bio-corrosion rate of AZ31 magnesium alloy

Abstract In this work, the effect of fine grain sizes on the mechanical and bio-corrosion properties of AZ31 magnesium alloy was studied. Bio-corrosion refers to the accelerated degradation of metal within the human body. Fine-grained (~1.5 µm) AZ31 was obtained through Severe Plastic Deformation (SPD) via three cycles of Constrained Groove-Pressing (CGP) under elevated temperature. The effects of CGP and post-annealing (at 473 K for 15 and 30 min) on bio-corrosion were preliminarily investigated by potentiodynamic polarization measurements and constant immersion tests. Results obtained show that the as-processed samples with annealing exhibited improvements in yield strength and ductility while the bio-corrosion rate in Hank’s solution remains fairly similar during the early stage.