Influence Of Cold Deformation Research Articles

Influence of cold deformation on the structure, texture, elastic and microdurometric properties of biocompatible beta-titanium alloys based on the Ti–Nb–Zr system

The influence of cold rolling with degrees of 85, 90% on the structural and textural state, microdurometric and elastic properties of hardened biocompatible -titanium alloys (at.%) Ti-26%Nb-3%Zr, Ti -26%Nb-5%Zr, Ti-26%Nb-6%Zr, Ti-26%Nb-3%Zr-1%Sn, Ti-26%Nb-3%Zr-1%Sn-0.7Ta . It is shown that an increase in the degree of deformation during cold rolling contributes to the formation of a more pronounced two-component texture {001}, {112} an increase in microhardness and a decrease in the values ​​of the elastic modulus in the rolling plane . A good agreement between the calculated and experimental values ​​of the modulus of elasticity of alloys in the quenched and cold-rolled states has been established.The influence of alloying and anisotropic state of alloys (through the molybdenum equivalent and the Zener anisotropy factor, respectively) on the level of their microhardness, contact modulus of elasticity E, including the difference in E in different sections of a cold-rolled sheet, is considered. It has been established that the minimum average value of Е=51±2 GPa in the rolling plane is given by the Ti-26Nb-3Zr alloy rolled with ε=90%, and the minimum level of average values Е (52±2 GPa in the rolling plane and 62±1 GPa in cross section) is typical for the Ti-26Nb-3Zr-1Sn alloy after rolling with ε= 85%

Influence of cold deformation on microstructure, crystallographic orientation and tensile properties of an experimental austenitic Fe–26Mn-0.4C steel

The correlation between microstructure, crystallographic orientation and grain boundaries characteristics of an austenitic high manganese steel was systematically investigated. The as-received and cold-rolled specimens with 50% and 70% reduction were analyzed using Scanning Electron Microscopy (SEM), Electron Back-Scattered Diffraction (EBSD) and X-ray diffraction techniques. A significant increase in the fraction of low-energy Σ3 twin boundaries, from 16.21% to 24.41%, was found in the 70% deformed sample. This was coupled with the formation of {011} austenitic structure, and occurrence of twinning-induced plasticity. The ductile-brittle fracture mode observed in the 70% cold rolled sample, which can be attributed to the formation of the high fraction of low-energy Σ3 twin boundaries, minimized both the localized stored strain energy and lattice misfit and promoted dislocation glide. A potential employment of the investigated steel in the petroleum industry is discussed.

Effect of cold deformation before heat treatment on the hydrogen embrittlement sensitivity of high-strength steel for marine risers

Herein, the effects of cold deformation before heat treatment on the hydrogen diffusion and hydrogen embrittlement sensitivity of low-alloy high-strength steel for marine risers were investigated. The influence of cold deformation on hydrogen diffusion and hydrogen embrittlement was elucidated by electrochemical hydrogen permeation test and slow strain rate tension test. A tempered martensitic structure was gradually refined by increasing the cold deformation amount. This phenomenon increased the density of hydrogen traps in the steel sample, decreasing the hydrogen effective diffusion coefficient and prolonging the hydrogen penetration time. Due to the high deformation, the hydrogen embrittlement sensitivity index of the tempered martensite decreased significantly and the brittle fracture characteristics of slow strain rate tensile fracture were insignificant. The ability of the microstructure to resist hydrogen embrittlement failure was effectively enhanced. In addition, the refinement of the martensitic structure increased the number and homogeneity of hydrogen traps in the tested steel, thereby enhancing the hydrogen solubility of the microstructure. The hydrogen content at the hydrogen traps could not attain to the critical value, inhibiting the initiation and propagation of hydrogen embrittlement cracks.

FORMATION OF LOW-CARBON WIRE ROD STRUCTURE UNDER SHS CONDITIONS USING MAGNETIC COERCIMETRIC CONTROL

The article discusses the use of a self-propagating high-temperature synthesis of SHS ofsolid chemical compounds – it is a new technological process that possible to obtain a materialwith a given structure based on carrying out an exothermic reaction of interaction of reagents inthe combustion regime. The influence of cold deformation and intermediate annealing underSHS conditions on the structure, magnetic and mechanical properties of low-carbon steel is determined.The use of magnetic coercimetric control possible to control changes in the structureand mechanical properties of during technological cycle for low-carbon welded wire in productionconditions.

Microstructure, mechanical and corrosion properties of Mg–Zn–Nd alloy with different accumulative area reduction after room-temperature drawing

Good mechanical properties and corrosion resistance are the key factors for the application of biodegradable magnesium alloy wires as new medical implant materials. This study is aimed at investigating the influence of microstructural evolution on mechanical and corrosion properties of Mg–2Zn–0.5Nd alloy (ZN20) during room-temperature drawing. The decreases in the cross-sectional area of ZN20 alloy during drawing refined the grains from 10 to 5 μm under the influence of cold deformation, the basal texture was rotated around radius direction, the basal texture became dominant, and the texture transformed from drawing direction (DD)// $$ $$ to a point between $$ $$ and $$ $$ parallel to DD. The ultimate tensile strength of the wire was increased by 44.7% compared with that of the extruded alloy due to grain boundary strengthening, hard orientation and work hardening during drawing process, while the elongation was decreased by 85% under the influence of work hardening. The corrosion resistance of the alloy was improved after drawing due to grain refinement, while it was sensitive to prismatic texture.

Influence of Cold Deformation on the Aging Behavior of the Al-Mg-Si Alloy

Influence of Cold Deformation on the Aging Behavior of the Al-Mg-Si Alloy

Influence of Cold Deformation and Phase Transformation on the Electrochemical Corrosion Behavior of Nitrogen‐Alloyed Stainless Steel in Chloride Solution

Nitrogen‐alloyed stainless steels exhibit outstanding corrosion resistance in chloride solution. However, cold deformation and phase transformation can influence the materials surface properties and, therefore, corrosion behavior. A nitrogen‐alloyed stainless steel with 20 wt% chromium, 0.13 wt% nitrogen, and subject to plastic deformation of up to 36% is electrochemically tested in a 5 wt% sodium chloride solution by linear polarization and electrochemical impedance spectroscopy. The steel's corrosion behavior is distinctly influenced by its deformation state. Before polarization, a negative influence of plastic deformation on the corrosion resistance of the alloy can be determined. However, after anodic polarization, the susceptibility to corrosion due to cold deformation and phase transformation decreases. While the electrochemical resistance of the protective surface film decreases due to deformation‐induced film rupture and the formation of anodes at the surface, the permeability of the double layer also decline. This is caused by the increased activation of the surface due to the formation of local anodes and, therefore, an increase in the formation of protective species that retard further dissolution processes. In addition, increasing plastic deformation results in the surface ratio between anodes and cathodes becoming more favorable, and in a decrease in the anodic current density.

Influence of cold deformation and annealing on hydrogen embrittlement of cold hardening bainitic steel for high strength bolts

The influence of cold drawing and annealing on hydrogen embrittlement (HE) of newly developed cold hardening bainitic steel was investigated by using slow strain rate testing (SSRT) and thermal desorption spectrometry (TDS), for ensuring safety performance of 10.9 class high strength bolts made of this kind of steel against HE under service environments. Hydrogen was introduced into the specimen by electrochemical charging. TDS analysis shows that the hydrogen-charged cold drawn specimen exhibits an additional low-temperature hydrogen desorption peak besides the original high-temperature desorption peak of the as-rolled specimen, causing remarkable increase of absorbed hydrogen content. It is found that cold drawing significantly enhances the susceptibility to HE, which is mainly attributed to remarkable increase of diffusible hydrogen absorption, the occurrence of strain-induced martensite as well as the increase of strength level. Annealing after cold deformation is an effective way to improve HE resistance and this improvement strongly depends on annealing temperature, i.e. HE susceptibility decreases slightly with increasing annealing temperature up to 200°C and then decreases significantly with further increasing annealing temperature. This phenomenon is explained by the release of hydrogen, the recovery of cold worked microstructure and the decrease of strength with increasing annealing temperature.

On the influence of cold deformation on liquid metal embrittlement of a steel in a liquid zinc bath

The influence of cold deformation on liquid metal embrittlement of a steel in a liquid zinc bath was studied. A typical construction steel was cold deformed with different degrees. The microstructure of the different material conditions were investigated as well as their mechanical properties at 450 °C in hot air. Tensile tests with different strain rates were made in a 450 °C hot zinc bath. For each specimen the reduction in area was determined and the fracture surfaces were studied. It can be shown that the strain rate has a large effect on liquid metal embrittlement. An increasing degree of deformation leads to a decrease on liquid metal embrittlement which is caused by the change of microstructure through deformation.

Development of Forming Processes for MoNiCr Alloy

Nickel based super alloy MoNiCr was developed as the material with high corrosion and creep resistance against aggressive molten fluoride salt environment. This medium is used by Fluoride salt cooled High temperature Reactor (FHR) and Molten Salt Reactor (MSR) systems. The elements Mo, Cr and Fe are most important alloying elements accompanied by very low amount of Al + Ti. Necessity to prepare hot formed semi products such as sheets, bars, wires and tubes was the motivation for this new experimental program execution searching for suitable hot forming conditions. In the case of MoNiCr components forming, recrystallization is a crucial process allowing successful forming. Special attention was paid to this process after finding out, that this process is running very slowly or even not running at all, if inappropriate conditions are met. Proper temperature and strain rate range were determined and furthermore the influence of cold deformation on recrystallization progress was determined. It was found that cold deformation before hot forming as well as after hot forming can be successfully implemented into technological chain. Almost fully recrystallized microstructure can be achieved using synergy of both cold and hot deformation.

Influence of cold deformation and Ti element on the microstructure and properties of Cu–Cr system alloys

Abstract

Influence of cold deformation on the corrosion behavior of Ni–Fe–Cr alloy 028

Ni–Fe–Cr alloy 028 (a nickel based super alloy also known as UNS N08028) was subjected to different degree of cold deformation by laboratory rolling to investigate the influence of microstructure on corrosion behavior under two simulated environments, (0.5M NaCl and 1M H2SO4). Experimental results showed that texture had influence on the corrosion rate of this alloy. The corrosion rate under both environments significantly decreased with increase in the ND//〈110〉 orientation. Significant differences in the corrosion rate with increased degree of deformation were mainly related to different amount of the CSL (coincident site lattice) Σ3 boundaries in the ND//〈110〉 oriented grains. The present study contributes to discussion on the CSL boundary formation for improved corrosion resistance.

Structural changes in Hadfield steel under cold deformation

The influence of cold deformation on the structure of Hadfield (110G13L) steel is analyzed. The steel hardening is demonstrated to be caused by the formation of dislocation clusters and the generation of stacking faults and twins. It is found that regions with nanocrystalline structures with FCC and hexagonal close-packed lattices are created at large degrees of compression.

A model for releasing of stored energy and microstructure evolution during recrystallization by phase-field simulation

A format of f(ik,jk ) = Es (ide )2(1-(jre )2) to express cold deformed stored energy is suggested in a phase-field model for simulating recrystallization in alloys. Using AZ31 magnesium alloy as an example, the recrystallization process is simulated by the new model, and the simulation results are in good agreement with experimental measurements. The nucleation process of recrystallization is realized for the first time by the model based on the physical background. The simulation results show that the grain growth of a cold deformed alloy in the annealing process indicates automatically two stages: recrystallization driven by the restored energy and thermal growth driven by boundary energy. A theoretical time spent in finishing recrystallization, obtained by simulation, is found to be 2/3 of that obtained by industrial practice. The mechanism and the experimental results about the influence of cold deformation on subgrain size and stored energy are examined, and the experimental results are introduced into the simulation. The common experimental phenomenon shows that there is a peak at the critical strain on the curve of recrystallized grain size versus cold strain. A theoretical explaination to the mechanism of the peak occurrence is also discussed.

Influence of cold deformation and aging on the relaxation of strengthened low-carbon steel

Attention focuses on relaxation phenomena, including the rate of stress relaxation in the uniaxial extension of low-carbon steel samples strengthened by cold deformation (extension and torsion) with subsequent aging to 400°C. The relaxation effects that arise with identical and different loading configurations in the strengthening treatment and in relaxation tests are discussed.

Influence of Cold Deformation on the Aging Behaviour of Al-Cu-Si-Mg Alloy

The present study deals with the effect of cold deformation and subsequent aging on the microstructure and mechanical properties of Al-Cu-Si-Mg alloy. Differential scanning calorimetry indicates that precipitation occurs in the temperature range of 258-272°C for the as quenched wrought alloy. The activation energy value estimated by Kissinger method for the aforesaid precipitation reaction is obtained as 106 kJ/mol. 45% cold deformation prior to aging indicates the first dissolution reaction at about 50°C and the precipitation reaction at a temperature of about 82°C. Microstructural investigations have revealed the formation of fine precipitates within the matrix after aging of the cold deformed sample. As-quenched alloy reveals prominently the aging response. The increase in hardness, yield and tensile strength with simultaneous decrease in elongation in the deformed alloy is found to be primarily due to the deformation strengthening and not due to the precipitation hardening.

Study of decomposition of ferrite in a duplex stainless steel cold worked and aged at 450–500 °C

The influence of cold-deformation on ferrite decomposition in duplex stainless steel during heat treatment at 450–500 °C was investigated using micro-hardness measurements and transmission electron microscopy. It was found that cold-deformation can change the mechanism of the α → α + α′ phase separation in the ferrite from nucleation and growth to spinodal decomposition. This finding is discussed in terms of the influence of an increased dislocation density on coherency strains.

Influence of cold deformation on martensite transformation and mechanical properties of Ti–Nb–Ta–Zr alloy

Abstract Ti–35Nb–2Ta–3Zr alloy was fabricated by vacuum consumable arc melting furnace and hot pressing. Microstructure and phase transformation of solution-treated (ST) and cold-rolled (CR) plates of Ti–Nb–Ta–Zr alloy were observed. Different microstructure of strain-induced martensite transformation during cold deformation were investigated. With the increase of reduction of cold rolling, microstructure of α″-phase changed from acicular martensite to butterfly shaped martensite and showed variant crossed and cross-hatched when the reduction of cold rolling was over 60%. Mechanical properties and SEM images of the fracture surface indicated that the alloy fabricated by cold deformation showed favorable strength and plasticity. Owing to the excellent cold workability and biomedical safety of elements of Nb, Ta and Zr, Ti–Nb–Ta–Zr alloy contributed much to medical applications.

Characterization of prior cold worked and age hardened Cu–3Ti–1Cd alloy

The influence of cold deformation by 50%, 75% and 90% on the age-hardening behavior of a Cu–3Ti–1Cd alloy has been investigated by hardness, tensile tests and light optical as well as transmission electron microscopy. The hardness of Cu–3Ti–1Cd alloy increased from 111 Hv in the solution-treated condition to 355 Hv in 90% cold worked and peak aged condition. The yield and ultimate tensile strengths of Cu–3Ti–1Cd alloy reached maxima of 922 MPa and 1035 MPa, respectively, on 90% deformation and peak aging. The microstructure of the deformed alloy exhibited elongated grains and deformation bands. The maximum strength on peak aging was brought about by the precipitation of ordered, metastable, coherent β′ Cu 4Ti phase, in addition to high dislocation density and deformation twins. Both the hardness and the strength of the alloy decreased on overaging due to the development of the incoherent equilibrium phase β Cu 3Ti in a cellular structure form. However, the morphology of the discontinuous precipitation was changed to globular form at high deformation levels.

Structure of the Bonding Zone in Explosively Welded Austenitic and Ferrite-Pearlitic Steel / Gefüge der Verbundzone in sprengplattiertem austenitischem und ferritisch-perlitischem Stahl

The structure of the bonding zone in explosively welded joints of ferrite-pearlite steel (0,3 % C, 1,4 % Mn) as a target and austenitic nitrogen steel (0,64 % N, 18 % Cr, 12 % Mn) as a flyer was studied by transmission electron microscopy. For the observation of the flyer a model joint was prepared using equal plates of the Cr-Mn-N steel for the flyer and the target. The structure of both joints had a layer character. The bonding was realized by a thin layer containing ultra-fine equiaxial recrystallized grains: ferritic in the real joint and austenitic in the model joint. The flyer structure was built up by parallel layers of plastically deformed austenite. A combined action of plastic deformation and heating was found in the regions of target close to the interface. Depending on the local conditions it caused formation of dislocation cell structure, polygonisation or recrystallisation in the ferrite, partial dissolution of cementite and secondary precipitation of dispersed carbides. The structure of the target suffered only the influence of cold deformation at a distance larger than 0,3 to 0,5 mm from the interface, which caused martensitic transformation in the layer between 0,5 and 1,0 mm from the interface.