Microstructure and texture of high manganese steel subjected to dynamic impact loading

ABSTRACT

Dynamic impact response of high Mn-steel at a strain rate of 3000?s^?1 was investigated using the Split Hopkinson Pressure bar. The investigated steel depicted continuous yielding at high strain rates. Additionally, the yield stress displayed a positive strain-rate sensitivity with an increasing strain rate. Microstructural evaluations displayed that strain-induced martensitic transformation and dislocation multiplication during slip were dominant plastic deformation mechanisms in the absence of deformation twinning which contributes to the strain hardening. Adiabatic shear band and martensite to austenite reversion or dynamic recrystallisation were also attributed to strain softening during impact deformation. The {001}<110> R-cube, {011}<110> R-Goss, and ({111}<110>) E texture components were strengthened after impact loading compared with as-received condition, while the intensities of Cube, Cupper, Brass, and S texture components were decreased.     

Characterization of microstructure,texture and magnetic properties in twin-roll casting high silicon non-oriented electrical steel

An Fe-6.5 wt.% Si-0.3 wt.% Al as-cast sheet was produced by twin-roll strip casting process, then treated with hot rolling, warm rolling and annealing. A detailed study of the microstructure and texture evolution at different processing stages was carried out by optical microscopy, X-ray diffraction and electron backscattered diffraction analysis. The initial as-cast strip showed strong columnar grains and pronounced < 001 >//ND texture. The hot rolled & warm rolled sheets were characterized by large amounts of shear bands distributed through the thickness together with strong < 110 >//RD texture and weak < 111 >//ND texture. After annealing, detrimental < 111 >//ND texture almost disappeared while beneficial {001}<210 >, {001}<010 >, {115}<5 − 10 1 > and {410} < 001 > recrystallization textures were formed, thus the magnetic induction of the annealed sheet was significantly improved. The recrystallization texture in the present study could be explained by preferred nucleation and grain growth mechanism.     

Through-thickness texture gradient in AA 7055 aluminum alloy

Through-thickness texture gradient in AA 7055 aluminum alloy rolled plate has been investigated using the electron back-scattered diffraction (EBSD) technique. Quantitative analyses of texture in five layers from the surface to the center of the plate were performed. A pronounced texture variation through the plate thickness was found. In the center layer, a typical β fiber texture running from {112} <111> orientation through {123} <634> orientation to {011} <211> orientation was found. Near the surface, in contrast, shear type textures including {001} <110> orientation, {112} <110> orientation and {111} <110> orientation were dominating. In particularly, when the shear type textures reached the maximum in both intensity and content, the β fiber became minimums.     

Effect of asymmetrical rolling and annealing the mechanical response of an 1050-o sheet

The asymmetrical rolling process has been studied as a way to promote intense shear deformations across the sheet thickness. These shear deformations may lead, given the proper conditions, to the development of shear texture components ({001}<110>, {111}<110> and {111}<112>) and also grain refinement. In this work, a 1050-O sheet is asymmetrically rolled and annealed. Conventional rolling is also performed, for comparison purposes. Shear texture components are obtained for the asymmetrically rolled specimens, and seem to be retained after annealing. Differences in mechanical response between asymmetrical and conventionally rolled specimens, as well as texture evolution after heat treatment processing are inferred based on experimental tensile and shear tests. Numerical simulations are used to help explain the differences found on experimental tests. It is proven that it is difficult to spread shear texture through the entire sheet thickness from a general asymmetric rolling process. Based on the fact, future research is discussed at closure.     

Texture effect on serrated flow in 2090 Al‐Li alloy

Tensile specimens of 1×6×25 mm in gauge dimension were cut from the surface and centre of 12.7 mm thick 2090 Al‐Li alloy plate, which were solution treated at 550 °C for 30 min, peak‐aged at 190 °C for 18 h, or reversion‐treated at 275 °C for 2 min. The flow stress of the centre layer was higher than that of the surface layer, regardless of the heat treatments. The textures of the surface and centre layers were approximated by the {001}<110> and {011}<211> orientations, respectively. The solution‐treated specimens gave rise to extensive serrations in their flow curves at a strain rate of 2×10^‐4 s^‐1. The serration amplitude was drastically reduced after the specimens were peak‐aged or reversion‐treated. However, for the peak‐aged alloy, the surface‐layer specimens underwent complex, serrated flows, whereas the flow curve of the centre‐layer specimen was almost devoid of serration. The serration, especially fine‐type serration in the peak‐aged and reversion‐treated specimens tended to disappear with increasing strain rate. The tensile behavior was explained in terms of the texture and strain rate.     

温轧温度对Cr-Ti-B系低碳钢组织与织构的影响

使用扫描电镜、电子背散射衍射、透射电子显微镜和固体内耗仪研究了温轧温度对Cr-Ti-B系低碳钢组织和织构的影响.结果 表明,温轧后钢的组织由变形铁素体和少量珠光体所组成,随着温轧温度的提高铁素体晶内剪切带的含量呈现先提高后降低的趋势,在450℃温轧剪切带的含量最高.剪切带的形成,与Ti和B元素的偏聚密切相关.在350℃...     

Influence of Widening on the Rolling and Recrystallization Texture in High Purity Al with Initial Cube Texture

The influence of widening and initial Cube tex-ture on formation of rolling and recrystallizationtexture was investigated in high purity Al.With in-creasing widening the initial Cube texture has ro-tated more around rolling direction(RD)and lessaround transverse direction(TD).Therefore,moreorientations rotate in x-fibre between G{110}<001>and B{110}<112>positions,and less inS{124}<211>texture component,which showsthe widening plays an important role in the forma-tion of S component during rolling.The relation-ship between rolling and recrystallization texturecomponents is discussed.Though the transitionband predicted by Dillamore and Katoh is alwaysformed during rolling,the most important factor in-fluencing recrystallization texture should be the ori-ented growth according to the changes of volumefractions and scatter widths of texture componentswith widening.     

EBSD study on microstructure and texture of friction stir welded AA5052-O and AA6061-T6 dissimilar joint

Friction stir welded AA5052-O and AA6061-T6 dissimilar joint has a more obvious impact on microstructure and texture evolution compared to single material welding due to differences in physical and chemical parameters between two aluminum alloys. Microstructure, texture evolution and grain structure of AA5052-O and AA6061-T6 dissimilar joint were investigated by means of OM,EBSD and TEM measurements. Experimental results showed that FS weld was generalized in four regions–nugget zone (NZ),thermomechanically affected zone (TMAZ),heat affected zone (HAZ) and base metals (BM), using standard nomenclatures. NZ exhibited the complex structure of the two materials with flowing shape and mainly composed of the advancing side material Subgrain boundaries in weld nugget zone gradually transformed into high angle grain boundaries by absorbing dislocation and accumulating misorientations. Grain refinement of weld nugget zone was achieved by dynamic recrystallization. In the friction stir welding process, the presence of the shear deformation in weld made {001} < 100 > C cube texture, {123} < 634 > S texture in BM gradually transformed into {111} < 1(−)12(−) > A1¹ shear texture. HABs distribution were most significant in nugget followed by RS and then by AS. In TMAZ and NZ, numerous precipitates and lots of dislocations were observed.     

Texture evolution in Fe–3% Si steel treated under unconventional annealing conditions

The present work investigates texture evolution stages in grain-oriented steel heat-treated using unconventional conditions. The Fe–3%Si steel taken after final cold rolling reduction from an industrial line was subjected to a laboratory isothermal annealing at different temperatures. The annealing temperatures were varied in a range of 850–1150 °C. During the annealing each specimen was heated at 10 °C/s and kept at the stated temperature for 5 min. Development of microstructure and texture in the annealed specimens were followed by the DC measurements of magnetic properties. The grain oriented steel, taken from the same industrial line after final box annealing was also analyzed and compared with the laboratory annealed specimens. It was shown that there is an optimal temperature region that, with combination of a fast heating rate, led to the best conditions of a drastically reduced development time of the {110} < 001 > crystallographic texture in the cold rolled grain-oriented steel. Materials heat treated below the optimum temperature region account for a primary recrystallization, while applying heat above this region leads to a secondary recrystallization without abnormal grain growth. Moreover, in the optimum temperature range, there was a particular temperature leading to the most optimal microstructure and texture. The magnetic properties, measured after the optimal heat treatment, were close to that measured on specimens taken after the final box annealing. The electron back scattered diffraction measurement technique revealed that sharpness of the {110} < 001 > crystallographic texture, developed at the optimum temperature is comparable to the steel taken after the industrial final box annealing. This fact is evidence that there is a temperature where the abnormal grain growth proceeds optimally.     

Interfacial bonding and microstructural evolution of Al in kinetic spraying

Bonding and microstructural evolution of Al particles in kinetic spraying (cold gas dynamic spraying) result from ultra-high strain rate plastic deformation during supersonic single and successive collisions of the particles. The coating formation of kinetic spraying is composed of three stages (an individual particle impact + subsequent impacts + isothermal heating during full coating). When a single particle impacts, interfacial shear strain location under adiabatic state produces inter-particle bonding and grain refinement at narrow zone (<220 nm) by continuous dynamic recrystallization. After the individual particle impact, successive supersonic in-flight particle impact results in static recovery and static recrystallization at un-refined area using the heat energy converted from the kinetic energy as activation energy. In this study, the bonding state and microstructure of individually impacted Al particle and full Al coating were analyzed using a focused ion beam technique and a transmission electron microscopy. The mechanisms of interfacial bonding and microstructural evolution of Al particle during kinetic spraying were suggested.     

Analysis of the microstructure,texture and magnetic properties of strip casting 4.5 wt.% Si non-oriented electrical steel

The microstructure, texture and magnetic properties of 4.5 wt.% Si electrical steel fabricated by the processes of twin-roll casting, warm-rolling and final annealing were systematically investigated with the aim of introducing a remarkable and promising electrical steel with extensive potential applications. The results show that unusually sharp {411} < 148 > texture is obtained in addition to common Cube, rotated Cube, Goss and {111} < 112 > orientation after final annealing. Excellent magnetic inductions of 1.518 T (B₈) and 1.703 T (B₅₀), and iron losses of 24.92 W/kg (W_10/400) and 24.47 W/kg (W_5/1000) have been achieved.     

Texture evolution during hot-rolling and recrystallization in B2-type FeAl, NiAl and CoTi intermetallic compounds

The texture evolution during the hot-rolling and the recrystallization of B2-type Fe–48Al, Ni–50Al and Co–50Ti (expressed by at.%) intermetallic compounds were investigated. By hot-rolling at 973 K, Fe–48Al showed a microstructure with coarse grains elongated along rolling direction, while Ni–50Al and Co–50Ti showed a deformed microstructure featured by the heavily distorted (elongated) grains and/or the deformation bands. The hot-rolling texture of Fe–48Al was composed of {111}<uvw>, while those of Ni–50Al and Co–50Ti were composed of {111}<110> and {111}<112>, respectively. After annealing, the recrystallized grains were preferentially nucleated at the grain boundaries for Fe–48Al, and in the heavily distorted regions or the deformation bands for Ni–50Al and Co–50Ti. The orientations of the recrystallized grains were similar with those of the deformed matrix, especially for Ni–50Al and Co–50Ti. The recrystallization textures were generally more dispersive than the hot-rolling texture. Based on these results, the texture evolution during the hot rolling and the recrystallization of the B2-type intermetallic compounds were discussed.     

Deformation textures in wire drawn perlitic steel

In this study, we followed the deformation microstructure and texture evolution during the cold wire drawing of a perlitic steel wire intended for civil engineering applications. The deformation level effect on the microstructure evolution and on the texture evolution is characterized. Wire drawing induces the lengthening of the perlitic grains along the drawing axis and leads to a strong hardness increase. X-ray texture measurements were performed. The reference state (initial wire) revealed an isotropic texture. The quantitative analysis show the development of the α fibre (<110>//ND (ND // wire) with the deformation. Moreover, the {001}?<?110?>?orientation (rotated Cube) is also present. The experimental techniques used in this study are the: Optical Microscopy (OM), the Electron Back Scattered Diffraction (EBSD), the X-ray diffraction, the Neutron diffraction and the Vickers microhardness.     

Influence of Rolling Reductions on Recrystallization Texture in Commercially Pure Al

The recrystallization texture in commerciallypure Al is investigated after the samples are rolleddifferently and annealed.The samples with low rol-ling reductions could be generally recovered orrecrystallized in situ and characterized by the re-tained G{110}<001>component.This recoveryprocess decreases during annealing with the increaseof reduction.The appearance of the B/R{359}.<132>and R{123}<634>components de-pending on the rolling reduction is investigated andthe less developed Cube{100}<001>componentin commercially pure ahninium is also discussed.     

Texture evolution in Copper film at high temperature studied in situ by electron back-scatter diffraction

Changes in texture and microstructure during the thermal treatment of Cu films have been studied in situ using electron back-scatter diffraction (EBSD). A partially recrystallized Cu film which still had its microstructure evolving at room temperature was investigated using orientation imaging microscopy. Two separate investigations were conducted—the first one at different locations of the film and at different temperatures and a second one at the same location of the film and at different temperatures. The orientation of the (111), (110) and (100) grains within the plane of Cu film was investigated from the orientation distribution functions. There was an increased tendency of the (111) and (110) grains to form either {111}<112> or {111}<110> and {110}<100> texture respectively at higher temperature. The impact of elastic strain energies and dislocation glide in formation of these textures at higher temperatures has been analyzed in the light of some recent observations reported in literature. The variation in the area fraction of different fiber texture components, as a function of temperature, has been discussed in correlation with the measured mean grain size, grain boundary misorientation distribution and stress states. Stress state during the entire thermal cycle was monitored by wafer curvature technique and the traces of additive impurities at the surface were measured using X-ray photoelectron spectrometry. The possible role of impurities in affecting the behavior of texture components at high temperature is discussed. Comparison was made between the EBSD and X-ray diffraction texture data.     

Texture gradient,average texture,and plastic anisotropy in various AI–Li sheet alloys

Abstract

The variation of texture through the thickness and the average texture of sheet material of recrystallised AA 8090 and unrecrystallised AA 8090 (crossrolled) and AA 2090 AI–Li alloys have been investigated. Conventional (lithium free) AA 2024 alloy in the annealed condition was used as a reference material. The quantitative orientation distribution functions were determined via X -ray diffraction and neutron diffraction techniques. Using X -ray diffraction, textures of layers at various distances from the surface to the centre of the sheets were examined to achieve the texture gradients. The average textures were determined either via neutron diffraction using cylindrical stacked specimens or by summing the texture results obtained via the X-ray techniquefor the various layers. It is shown that the intensity of the common rolling textures, i.e. {112} <111>, {123} <634>, {110} <112>, and shear texture {100} <011> markedly varied through the thickness of unrecrystallised AA 8090 and AA 2090 AI–Li sheets. Also, in recrystallised AA 8090 AI–Li and AA 2024, a variation of the recrystallisation texture components {001} <100> and {011} <100> through the thickness was found. The quantitative texture data in conjunction with Taylor theory were used to predict the plastic anisotropy in terms of the plastic strain ratio as afunction of the angle a between the rolling and tensile directions. This prediction shows that the effects of texture can explain well the anisotropy in recrystallised AI–Li material (AA 8090). For unrecrystallised materials (AA 8090, AA 2090), a correct trend in plastic anisotropy is predicted; however, the calculated values in the 45° direction are larger than those determined experimentally.

MST/1910     

Grain morphology and texture evolution of TC21 titanium alloy during annealing with different time

A homogeneous equiaxed‐structure TC21 titanium alloy is hot rolled and annealed for different time ranging from 1 h to 6 h. The grain morphology and texture evolution of α and β phases during annealing are mainly investigated using the electron back‐scattered diffraction characterization. In the early annealing stage, the α grain mainly maintains the elongated morphology generated in the rolling. With increasing annealing time, more and more elongated α grains become equiaxed due to enhanced static recrystallization and boundary splitting. Differently, the β grain exhibits a fully equiaxed morphology all the time due to the sufficient static recrystallization, and get a coarsening with increasing annealing time. The α phase exhibits a (0001) basal texture in the early annealing stage, and then forms a TD‐split texture with increasing annealing time. The β phase exhibits the {001}<110> texture at every annealing time. Based on the analysis about the texture of different grain sizes, the effects of recrystallization nucleation and oriented growth on texture evolution are discussed. It suggests that TD‐split texture in α phase is originated from both the recrystallization nucleation and oriented growth. The formation of {001}<110> texture in β phase is mainly originated from the oriented growth.     

Microstructure evolution and mechanical properties of friction stir welded FeCrNiCoMn high-entropy alloy

To investigate the microstructural development and mechanical properties of friction stir welded high-entropy alloy, the stirring process and the air cooling period were separated for discussion. The texture component developed from A* {111}<112> to A {111}<110> in the stirring stage, and finally changed to B {112}<110> in the subsequent air cooling stage caused by the multiple mechanisms including discontinuous dynamic recrystallization, continuous dynamic recrystallization, static recovery and selected grain growth. This work also demonstrated that the static recovery and the selected grain growth during the air cooling stage remarkably deteriorated the microstructure and mechanical properties which is produced during the stirring stage, and it cannot be neglected when investigating the microstructure transformation and mechanical properties during the friction stir welding.     

Texture evolution during deformation of an Al-6%Cu-0.4%Zr superplastic alloy

Texture measurements of the as-received rolled Al-6%Cu-0.4%Zr alloy revealed that a copper component, {311}<233>, is developed at the surface and a S component, {631}<113>, is formed at the middle of the sheet. During early stages of superplastic deformation at 480 °C/5×10⁻⁴ s⁻¹ the intensity of the Cu component increases slightly whereas the S component changes toward the brass component Bs, {110}<112>, by a slip process. For larger strains, both components decrease by a grain boundary sliding mechanism.     

Effect of hot-rolling temperature on microstructure and texture of an ultra-low carbon Ti-interstitial-free steel

Effect of finishing temperature in hot-rolling on the microstructure and texture of a cold-rolled and continuously annealed ultra-low carbon Ti-interstitial-free steel has been investigated. The finishing temperature in hot-rolling was varied from 900 °C in austenite region to 750 °C in ferrite region. Lankford value of the annealed sheet was decreased with a decrease in the finishing temperature to the ferrite region. This might be related to both the stronger {100} <011> texture of the annealed sheet and the texture inhomogeneity in the through-thickness direction of the hot bands rolled in ferrite region. The major component of the recrystallization texture was near {554} <225> irrespective of the hot-rolling temperature, but the intensity of {100} <011> texture was increased with the decrease in the finishing temperature in hot-rolling.