Texture evolution and its simulation of cold drawing copper wires produced by continuous casting

The texture evolution of cold drawing copper wires produced by continuous casting was measured by X-ray diffractometry and electron back-scatter diffractometry,and was simulated using Taylor model.The results show that in the drawn poly-crystal copper wires produced by traditional continuous casting,111 and 100 duplex fiber texture forms,and with increasing strain,the intensities of 111 and 100 increase.In the drawn single-crystal copper wires produced by Ohno continuous casting,100 rotates to 111,and there is inhomogeneous distribution of fiber texture along radial direction of the wires,which is caused by the distribution of shear deformation.Compared with 100,111 fiber texture is more stable in the drawn copper wires.Comparison of the experimental results with the simulated results shows that the simulation by Taylor model can analyze the texture evolution of drawn copper wires.

Effect of electropulsing on deformation behavior of Ti-6Al-4V alloy during cold drawing

Electron backscattered diffraction （EBSD） and transmission electron microscopy （TEM） were used to investigate effect of electropulsing on microstructure and texture evolution of Ti-6Al-4V during cold drawing. Research results demonstrate that the electropulsing treatment （EPT） can enhance the deformability of the grains with unfavorable orientations, which makes the compatibility of deformation among grains much better. A comparison in texture evolution between conventional cold drawing and EPT cold drawing indicates that the EPT promotes prismatic 〈a〉 slip moving, restricts pyramidal 〈c＋a〉 slip occurring and accommodates the deformation with c-component by grain boundary sliding. The fraction decrease of low-angle grain boundaries for samples deformed with EPT reveals that the application of electropulsing restricts the formation of the incidental dislocation boundaries and the geometrically necessary boundaries.

Microstructure and texture evolution of cold drawing <110> single crystal copper

By means of electron backscattering diffraction and transmission electron microscopy the microstructure and texture of drawn single crystal copper with initial orientation （110） parallel to axial direction have been investigated in the present work. In or- der to analyze the effect of initial orientation on microstructure and texture of drawn copper, the results of the drawn （110） sin- gle crystal copper wires have been compared with （100） and （111） single crystal copper wires. It is found that the grain subdi- vision of （110） single crystal is more evident than that of （100） and （111）, and the textures consisting of （111） and （100） abruptly form in the drawn （110） single crystal. At high strains, due to shear strain, the distribution of fiber textures is imho- mogenous along the radial direction of drawn （110） single crystal copper wires. （100） is near the surface and （111） is at the center. The microstructure results of drawn （110） single crystal show that at low strains, it can be characterized as two kinds of geometrically necessary boundaries with noncrystalline character. At medium strains, S bands can be observed. At high strains, lamellar boundaries form. Mean misofientation and average spacing of dislocation boundary are larger in drawn （110） single crystal, as compared with （111） and （100）. In drawn （110） single crystal with high strains, the bimodal distribution forms at lower strains than in drawn （100） single crystal, which is because the dislocation boundaries with high angle are contributed by not only the boundary between （111） and （100） fiber textures but also the boundary in （111） or （100） texture.

Influence of Torsion Deformation on Textures of Cold Drawing Pearlitic Steel Wires

The influence of torsion deformation on textures of cold drawing pearlific steel wires was investigated by twisting the wires to different number of revolutions. Macro-texture （over the entire wire cross section） associated with torsion deformation was investigated by X-ray diffraction, while micro-texture （near the wire surface） was characterized by EBSD. The results show that the （110） macro-texture increases at the beginning of torsion and then decreases with increasing of torsion strain, while the （110） micro-texture decreases linearly with increasing of torsion strain. The relationships between the （110） fiber texture and the microhardness of the wires are also discussed.

Combination of cold drawing and cryogenic turning for modifying surface morphology of metastable austenitic AISI 347 steel

The application of components often depends to a large extent on the properties of the surface layer.A novel process chain for the production of components with a hardened surface layer from metastable austenitic steel was presented.The investigated metastable austenitic AISI 347 steel was cold-drawn in solution annealed condition at cryogenic temperatures for pre-hardening,followed by post-hardening via cryogenic turning.The increase in hardness in both processes was due to strain hardening and deformation-induced phase transformation from y-austenite to^-martensite.Cryogenic turning experiments were carried out with solution annealed AISI 347 steel as well as with solution annealed and subsequently cold-drawn AISI 347 steel.The thermomechanical load of the workpiece surface layer during the turning process as well as the resulting surface morphology was characterized.The forces and temperatures were higher in turning the cold-drawn AISI 347 steel than turning the solution annealed AISI 347 steel.After cryogenic turning of the solution annealed material,deformation-induced phase transformation and a significant increase in hardness were detected in the near-surface layer.In contrast,no additional phase transformation was observed after cryogenic turning of the cold-drawn AISI 347 steel.The maximum hardness in the surface layer was similar,whereas the hardness in the core of the cold-drawn AISI 347 steel was higher compared to that in the solution annealed AISI 347 steel.

Microstructure and mechanical properties of low carbon steel wires with serial and reverse-direction cold drawing

Low carbon steel wires were prepared by two processes,serial drawing(SD)and reverse-direction drawing(RD).Effects of the two processes on microstructure and mechanical properties in steel wires were investigated by field emissio scanning electron microscopy,electron backscatter diffraction(EBSD),X-ray diffraction and transmission electron microscopy(TEM).Residual compressive stress and more low-angle grain boundaries were introduced into the steel wire by the RD.As a result,the RD wires exhibited a greater tensile strength when drawing strain s<1.18.The SD encouraged grain refinement and texture formation in the wire.The SD wires exhibited a smaller average width of the elongated ferrite grain and a higher intensity of(110)fiber texture at all drawing strains.Therefore,the SD wires showed a bit greater tensile strength and 20%greater torsion performance than the RD wires at c=2.51.TEM and EBSD analysis indicated that dislocation tangle was formed easily in RD wires,and it transformed into twist boundary.This twist boundary impeded the grain refinement in the RD wires,and there were still non-fibrous grains in the RD wires even after heavy drawing.

Effect of surface layer softening from previous electrochemical corrosion on electrochemical cold drawing of Q235 steel bar

The effects of H_(2)SO_(4)concentration and current in electrochemical corrosion on surface layer softening or plasticizing of Q235 steel bar and their effects on subsequent electrochemical cold drawing(ECD)were investigated.The results indicate that the electrochemical corrosion can soften or plasticize the surface layer of Q235 steel bar and then make the subsequent ECD be conducted more easily.The softening degree and thickness of the surface layer are continuously enhanced with increasing corrosion rate,i.e.,increasing H_(2)SO_(4)concentration or current,due to the generation of more vacancy clusters in deeper regions of surface layer.These vacancy clusters then relax dislocations through being absorbed during ECD,and the formation and movement of additional dislocation flux are thereby enhanced,resulting in the further obvious decrease in the drawing force.It is also due to the enhanced formation and movement of additional dislocation flux that the dislocation density and thus the hardness of the surface layer are decreased,as well as that the texture structure is weakened.These behaviors are enhanced as the corrosion rate increases.

Microstructure Evolution and Its Effects on the Mechanical Behavior of Cold Drawn Pearlite Steel Wires for Bridge Cables

The microstructure evolution and its effects on the mechanical performance of 2000 MPa bridge cable steel wires were investigated by transmission electron microscope(TEM),electron backscatter diffraction(EBSD),X-ray diffractometer(XRD)and mechanical tests.Experimental results reveal that,with the increasing strain from 0 to 1.42,a fiber structure and a<110>fiber texture aligned with the wire axis are gradually developed accompanied by cementite decomposition and the formation of sub-grains;the tensile strength increases linearly from 1510 to 2025 MPa,and the reduction of the area is stable with a slight decline from 44%to 36%.After annealing at 450℃for different times,pronounced changes in the microstructure occur.Cementite lamella fragment into coarser globules corresponding to a remarkable spheroidization process,while ferrite domains recover and recrystallize,and this process is associated to modifications in the mechanical properties.Furthermore,based on the observations on dislocation lines crossing through cementite lamellae,a possible mechanism of cementite decomposition is discussed.

Influence of Fatigue Loading on the Residual Stress Distribution in Prestressing Steel Wires

This paper analyzes the influence of fatigue loading on the residual stress profile in high strength steel wires. To this end, different sinusoidal loads with diverse values of maximum loading level and number of cycles were simulated on wires in which several residual stress profiles had been previously introduced, some of them with a tensile state and others with a compressive state. An analysis was made of the evolution with time of such residual stress laws by comparing them at key instants of loading, that is, at initial instant, at maximum load, at minimum load and at final instant. Numerical results show only a minor influence of fatigue loading on the residual stress profile.

Microstructural Evolution and Service Performance of Cold-drawn Pure Aluminum Conductor Wires

Microstructures and service performance(mechanical and electrical properties) of the commercially pure Al conductor wires subjected to different cold drawing strains were investigated. The results show that the microstructures of the cold-drawn Al wires along the radial direction were inhomogeneous, i.e. the texture in the center region was strong <111> and weak <001> components, while that in the surface region shifted from the initial cubic texture to a <112> component and finally developed into a strong<111> component. The volume fraction of the high angle grain boundaries in the surface region was higher than that in the center region. The cold-drawing process greatly enhanced the yield strength of the pure Al wires while retained the acceptable electrical resistivity. The strengthening mechanism and the variation of electrical conductivity of the cold-drawn Al wires are discussed through correlating with microstructure evolution.

Effect of stress profile on microstructure evolution of cold-drawn commercially pure aluminum wire analyzed by finite element simulation

The evolution of microstructure in the drawing process of commercially pure aluminum wire （CPAW） does not only depend on the nature of materials, but also on the stress profile. In this study, the effect of stress profile on the texture evolution of the CPAW was systematically investigated by combining the numerical simulation and the microstructure observation. The results show that the tensile stress at the wire center promotes the formation of 〈111〉 texture, whereas the shear stress nearby the rim makes little contribution to the texture formation. Therefore, the 〈111 〉 texture at the wire center is stronger than that in the surface layer, which also results in a higher microhardness at the center of the CPAW under axial loading.2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science ＆ Technology.

Shortening the manufacturing process of degradable magnesium alloy minitube for vascular stents by introducing cyclic extrusion compression

Due to its excellent biocompatibility and biodegradability,Mg and its alloys are considered to be promising materials for manufacturing of vascular sent.However,the manufacture of high-precision and high-performance Mg alloys minitubes is still a worldwide problem with a long manufacturing processing caused by the poor workability of Mg alloys.To solve this problem,the cyclic extrusion compression(CEC)was used to pretreat the billet by improving the workability of Mg alloys,finally shortening the manufacturing process.After CEC treatment,the size of grains and second phase particles of Mg alloys were dramatically refined to 3.2μm and 0.3μm,respectively.Only after three passes of cold drawing,the wall thickness of minitube was reduced from 0.200 mm to 0.135 mm and a length was more than 1000 mm.The error of wall thickness was measured to be less than 0.01 mm,implying a high dimensional accuracy.The yield strength(YS),ultimate tensile strength(UTS)and elongation of finished minitube were 220±10 MPa,290±10 MPa and 22.0±0.5%,respectively.In addition,annealing can improve mechanical property and corrosion resistance of minitubes by improving the homogeneity of the microstructure and enhancing the density of basal texture.

Crystallization behavior in severely cold-drawn Ti_(50) Ni_(47) Fe_3 wire

The microstructures and crystallization behavior of Ti-47 at% Ni-3 at% Fe shape memory alloy wire under the condition of severe cold drawing at room temperature and different post-deformation annealing processes were intensively investigated using transmission electron microscope（TEM） and differential scanning calorimetry（DSC）. It is indicated that the amorphous phase is dominant in the Ti50Ni47Fe3 wire after the cold drawing of 78 % areal reduction. The critical temperature for recrystalization is determined at about 300 °C. The average grain size grows from 7 up to 125 nm when annealing temperature rises from300 to 500 °C. Post-deformation annealing process exerts significant influence on the crystallization temperature which climbs up with the increase of annealing temperature.

The application of back-scattered electron imaging for characterization of pearlitic steels

The microstructures of pearlitic steel wire rods and steel wires are commonly characterized by secondary electron imaging (SEI)technique using scanning electron microscopy(SEM).In this work,a back-scattered electron imaging(BSEI)method is proposed to determine the microstructures of undeformed and deformed pearlitic steels with nanometer scale pearlite lamellae.The results indicate that BSEI technique can characterize the pearlite lamellas veritably and is effective in quantitative measurement of the mean size of pearlite interlamellar spacing.To some extent,BSEI method is more suitable than SEI technique for studying undeformed and not severely deformed pearlitic steels.

Effect of Transverse Grain Boundary on Microstructure,Texture and Mechanical Properties of Drawn Copper Wires

In the present study, microstructure and texture of drawn copper wires with a large number of transverse grain boundaries have been characterized and their mechanical properties have been analyzed. The results show that the texture evolution is accelerated by transverse grain boundary and the saturation value 60% of volume fraction of 〈111〉 fiber texture component is reached rapidly with increasing strain. For the microstructure of drawn wires with a large number of transverse grain boundaries, the critical strain, where lamellar boundaries form, is less than that for wires with equiaxed grains or columnar grains （all grain boundaries parallel to axis direction）. Since transverse grain boundary accelerates grain subdivision and dislocation density increases rapidly in drawn wires with a large number of transverse grain boundaries, there are a higher flow stress and a higher work hardening rate.