Effect of cold rolling and mode of annealing on textures,mechanical properties and formability limit diagrams in interstitial free steel sheets

Formability limit diagram (FLD) and strain limits are determined along with mechanical properties and the same are correlated with textural characterization as a function of degree of rolling in an interstitial free (IF) steel. Around 65–70% and 85–90% hot deformation were given in austenitic region. It was found that 85–90% deformation developed strong hot band texture and the texture was dominated by {112}〈110〉 and {332}〈113〉 orientations. Hot rolled steel sheets were then cold rolled to 50%, 70%, 80% and 90%, where the perfect α-fiber and γ-fiber textures were developed at 80% cold reduction. Excellent formability was obtained by batch as well as continuous mode of annealing. The new γ-fibers were developed after annealing. It was observed that IF steel sheet has to be cold rolled between 80% and 90%. From FLD plots, it was observed that IF steel sheets were highly formable.     

Orientation distribution function analysis of the recrystallization texture in a boron-treated deep-drawing steel

The textural components present in a boron-treated deep-drawing quality nonaging steel, processed and annealed in the mill, have been determined using the orientation distribution function (ODF) analysis technique. The main components are a 〈111〉 fiber parallel to sheet plane normal or normal direction, ND, and an incomplete 〈337〉∥ND fiber. Minor {110}〈001〉, {310}〈001〉, {001}〈110〉, and {110} 〈110〉 orientations were also found. The texture on the whole is somewhat similar to that in A1-killed steels, but not as strongly developed. It is expected that this boron-treated steel would be suitable for moderate forming applications.     

Evolution of texture and microstructure in a thermomechanically processed Al-Li-Cu-Mg alloy

The development of texture and microstructure in a thermomechanically processed quaternary Al-Li-Cu-Mg alloy has been investigated. Textures on both the surface (1/8 thickness (T)) and midthickness levels of specimens were measured using the conventional pole figure as well as the orientation distribution function (ODF) method. Microstructural characterization was carried out with the help of optical microscopy and transmission electron microscopy (TEM). The processing schedule involved hot cross rolling, followed by several stages of cold rolling (CR) with intermediate solution treatments (STs). A marked through-thickness texture inhomogeneity developed in the processed sheets during the course of thermo mechanical treatment (TMT). In general, the texture produced at the midthickness level was 2 to 3 times sharper than the texture at the surface. The alloy, after hot cross rolling, showed nearly equally strong Bs {110} 〈112〉 and Bs/S {168} 〈211〉 components at midthickness. After three cycles of cold rolling (CR) and solution treatments (STs), the overall texture intensity came down by a factor of nearly 2. The final processed sheet material showed a moderately strong Bs and a predominant S {123} 〈634〉 component at midthickness. Solution treatments did not produce much change in the texture of the cold-rolled materials. Microstructural evidence indicated extensive recovery and, at best, partial recrystallization of the deformed structure. No significant effect of second-phase particles in texture development was noticed.     

Effect of initial texture on texture evolution in 1050 Al alloys under simple shear

The effect of the initial textures prior to dissimilar channel angular pressing (DCAP) on the texture evolution of the 1050 Al alloy sheets, processed by the continuous confined strip shearing (C2S2) process, were studied. The four different specimens, i.e., cold rolled, heat treated, warm rolled, and as-cast 1050 Al alloy sheets, having various initial textures were prepared using different thermomechanical routes. Although the major texture types were significantly affected by the initial textures prior to DCAP, DCAP always promoted both the 〈111〉//normal direction (ND) textures and the {001}〈110〉 rotated cube texture regardless of the initial texture status. Effects of the texture evolutions due to equal channel angular pressing (ECAP) on deep drawbility and planar anisotropy were analyzed based on the -r value and the Δr value determined from the measured pole figures. A feasibility for producing the 1050 Al alloy sheets having high deep drawbility and low planar anisotropy was demonstrated.     

Twinning-induced sluggish evolution of texture during recrystallization in AISI 316L stainless steel after cold rolling

This paper deals with the evolution of texture in AISI 316L austenitic stainless steel during annealing after 95 pct cold rolling. After 95 pct cold rolling, the texture is mainly of the brass type {110}〈112〉, along with a scatter toward the S orientation {123}〈634〉 and Goss orientation {011}〈100〉. Weak evidence of Cu component is observed at this high deformation level. During annealing, recovery is observed before any detectable recrystallization. Recrystallization proceeds through nucleation of subgrain by twinning within the deformed matrix and, later, preferential growth of those to consume the deformed matrix. After recrystallization, the overall texture intensity was weak; however, there are some discernible texture components. There was no existence of the brass component at this stage. Major components are centered on Goss orientation and Cu component {112}〈111〉 as well as the BR component {236}〈385〉. Also, a few orientations come up after recrystallization (i.e., {142}〈2−11〉 and {012}〈221〉). With increase in annealing temperature, the textural evolution shows emergence of weak texture with another new component, {197}〈211〉. The evolution of texture was correlated with the deformation texture through twin chain reaction.     

Texture and anisotropy of the mechanical properties of an Al-Mg-Li-Zn-Sc-Zr alloy

The formation of rolling texture in the α solid solution and the δ′ phase in various sections of 1424 (Al-Mg-Li-Zn-Sc-Zr) alloy sheets 1.6–8 mm thick is studied using pole and inverse pole figures. The textures of the α solid solution and δ′ phase are shown to be characterized by similar changes in the orientations across the sheets. The medium layer in the sheets has a two-component {011}〈211〉 + {135}〈211〉 texture with the predominant first component. The anisotropy in the mechanical properties of the alloy sheets is characterized by a high yield strength and a low plasticity in the longitudinal and transverse directions as compared to direction at an angle of 45° to the rolling direction. A model for the calculation of the anisotropy in the yield strength of the alloy is proposed; it takes into account the texture in the alloy, the ratio of the volumes of the α solid solution and δ′ phase, and their relative strength. Original Russian Text ￠ A.A. Il’in, V.V. Zakharov, M.S. Betsofen, O.E. Osintsev, T.D. Rostova, 2008, published in Metally, 2008, No. 5, pp. 57–64.     

Evolution of strain-induced microstructure and texture in commercial aluminum sheet under balanced biaxial stretching

The evolution of surface topography and crystallographic texture was investigated under balanced biaxial stretching in sheets of the aluminum alloy 5052-H32. Two different lots of material, with an initial nominal thickness of 1 mm, were tested in the as-received condition. Samples with increasing levels of balanced biaxial strain were deformed using a modified Marciniak in-plane stretching test. In general, the sheet materials were microstructurally and crystallographically anisotropic. Between the two lots, the initial microstructure and mechanical properties were found to be equivalent; however, the sheet texture was appreciably different. This latter variation was observed to have an effect on the additional roughening of the surface subsequent to deformation. For a given lot of material, the surface roughness was found to be proportional to the magnitude of the strain. However, while the roughening rates for the two lots were comparable, the lot having a stronger initial {220} texture component was found to roughen to a higher degree. Corresponding changes in the sheet texture were observed to have two regimes as a function of the strain level. In the first regime, typically, for strains (ɛ) up to 0.05, the orientations were found to rotate quickly away from the initial cube {001}〈100〉 orientation observed in the as-received sheet toward positions along the α fiber. Above a strain level of 0.05, the {220} texture component continued to increase with deformation, but at a decreasing rate up to failure of the sheet. The difference in the grain rotation rates observed did not appear to have an effect on the surface roughening, as the relative change of the crystallographic orientations with increasing plastic strain was similar for both heats of material. Instead, it is believed that localized grain or grain-grouping interactions may play a more important role in the surface roughening process.     

The influence of rolling practice on notch toughness and texture development in high-strength linepipe

The mechanical properties and notch toughnesses of an X80 linepipe steel were determined for various test directions in the plane of sheet that had been finish rolled in the γ and in the intercritical (α+γ) regions. The anisotropies of yield strength (YS) and of impact energy are correlated to the presence of various texture components, as detected by the use of an orientation distribution function (ODF) analysis. The final microstructures were similar and consisted of polygonal and acicular ferrite. The textures were also similar; however, after rolling in the (α+γ) region, the intensity of the texture was significantly higher. These textures were mainly comprised of two fibers, the rolling direction (RD), 〈110〉//RD, and the normal direction (ND), 〈111〉//ND, fibers. The observations show that the RD fiber centered at {112}〈110〉 and the {110}〈001〉 orientation were responsible for the YS anisotropy. The relationships between notch toughness and texture were considered for the brittle or cleavage (−196 °C), mixed brittle-ductile (−60 °C), and ductile (room temperature (RT)) modes of fracture. This work shows that the anisotropy of impact energy associated with ductile fracture at the higher temperatures is caused by the {112}〈110〉 component, and that the {001}〈110〉 and {110}〈001〉 components (if present) are responsible for the anisotropy of the impact energy associated with cleavage at low temperatures. The lack of anisotropy of the impact energy observed at −196 °C and the increase in toughness at higher temperatures are interpreted in terms of the volume fractions of textured grains present in the sheet and the intensities of specific texture components.     

Through-thickness texture variation in cold-rolled AA 5182 aluminum alloy with an initial {001}〈110〉 texture

Through-thickness texture variation in cold-rolled AA 5182 aluminum alloy with an initial {001}〈110〉 texture was investigated by X-ray diffraction. A detailed quantitative analysis of texture volume fractions in several layers was performed. The effect of initial through-thickness texture gradient and roll-gap geometry on the texture evolution during multipass rolling was determined. A pronounced texture variation through the thickness was found in the initial material. The shear deformation produced by the friction between the roll and the sheet contact surface may be neglected in the present experiment with oil as a lubricant. At low strains with the l/h ratio from 0.9 to 2.0, the shear deformation caused by the roll-gap geometry slightly decreased the lattice rotation from the {001}〈110〉 orientation to the C orientation at the intermediate layer, while the roll-gap geometry did not produce a shear strain at large strains with higher values of the l/h ratio. The strong initial r-cube texture at the center layer stimulated the transformation from the r-cube orientation to the C orientation and the formation of the β fiber during rolling.     

A variant selection model for predicting the transformation texture of deformed austenite

The occurrence of variant selection during the transformation of deformed austenite is examined, together with its effect on the product texture. A new prediction method is proposed based on the morphology of the austenite grains, on slip activity, and on the residual stresses remaining in the material after rolling. The aspect ratio of pancaked grains is demonstrated to play an important role in favoring selection of the transformed copper ({311}〈011〉 and {211}〈011〉) components. The extent of shear on active slip planes during prior rolling is shown to promote the formation of the transformed brass ({332}〈113〉 and {211}〈113〉) components. Finally, the residual stresses remaining in the material after rolling play an essential part by preventing growth of the {110}〈110〉 and {100}〈uvw〉 orientations selected by the grain shape and slip activity rules. With the aid of these three variant selection criteria combined, it is possible to reproduce all the features of the transformation textures observed experimentally. The criteria also explain why the intensities of the transformed copper components are sensitive to the pancaking strain, while those of the transformed brass are a function of the cooling rate employed after hot rolling.     

Evolution of recrystallization texture from aluminum sheet cold rolled under unlubricated condition

The texture of cold-rolled aluminum sheet has been known to vary through thickness due to inhomogeneous deformation, which can be caused by a characteristic deformation zone geometry and friction between materials and rolls during rolling. The copper texture is obtained in the center layer, which is plane strain compressed, while the shear texture is in the surface layer, which is approximated by major {001}t〈110t〉 and minor {111}t〈112t〉 and {111}t〈110t〉 components. The recrystallization texture of the surface layer is approximated by {225}t〈10 5 2t〉. The evolution of the recrystallization texture has been explained by the maximum energy release theory, in which the absolute maximum normal stress direction in the deformed state becomes parallel to the minimum elastic modulus direction of the recrystallized grains.     

Crystallographic textures in rolled and annealed Fe-Ga and Fe-Al alloys

The feasibility of obtaining [001] preferred texture in polycrystalline Fe₈₅Ga₁₅ and Fe₈₅Al₁₅ magnetostrictive alloys containing 1 mol pct NbC using a low-cost conventional thermomechanical processing approach is shown in this work. Thermomechanical processing conditions examined consisted of a sequence of hot rolling, two-stage warm rolling at 400 °C with intermediate anneal at 900 °C and texture anneal in the temperature range of 900 °C to 1300 °C for time periods up to 24 hours. Textures present prior to and after texture annealing were characterized using orientation imaging microscopy in a scanning electron microscope. In the case of Fe₈₅Ga₁₅ alloy with 1 mol pct NbC, the deformation-induced texture after a two-stage warm rolling consists of mixed {100} 〈110〉 and {111} 〈110〉 type partial textures. Texture annealing of the Fe₈₅Ga₁₅ alloy with 1 mol pct NbC at 1150 °C for 2 hours changes the texture to a predominant texture that is close to {001}〈100〉. On increasing the annealing time to 24 hours, the texture shifts toward {110}〈100〉. While texture anneal at both 1150 °C and 1300 °C produces a [001] or near-[001] preferred orientation along the rolling direction in the Fe₈₅Ga₁₅ alloy with 1 mol pct NbC, 1150 °C-24 hour treatment was found to provide the strongest [001] orientation among the conditions examined. Similar trends are observed for the case of Fe₈₅Al₁₅ alloy with 1 mol pct NbC.     

Development of recrystallization textures in 0.08%C steel

The present work investigates the effect of cold deformation on the evolution of microstructure and textures during recrystallization in 0.08%C steel. The cold rolling texture consists of partial α-fiber (RD//〈110〉) and complete γ-fiber (ND//〈111〉) along with Goss ({110}〈001〉) and cube ({100}〈100〉}) texture components. The sharpness of α-fiber, γ-fiber and cube component increases with the increase in rolling reduction from 70 to 85% while that of Goss component decreases. After recrystallization (750 and 800°C), the textures were composed of α and γ-fiber along with significant Goss components. The strength of γ-fiber decreases after annealing. The presence of Goss component in recrystallization textures is attributed to preferential nucleation in {111}〈112〉 type deformed grains.     

Influence of transverse rolling on the

The influence of transverse rolling passes on the recrystallization texture was investigated in an effort to strengthen the {111} 〈uvw〉 type components and reduce the intensity of the {100} 〈0vw〉 components, improve the uniformity of the microstructure, and refine the grain size in high-purity tantalum plate. Tantalum, from three different ingot breakdown processes, received an additional 80 pct reduction in the transverse direction (perpendicular to the ingot centerline) in the processing schedule prior to final annealing. This work investigated the influence of the additional transverse rolling passes on the development of texture in the as-rolled tantalum and also in rolled plus annealed tantalum. After annealing, the tantalum plates had significantly strengthened {111} 〈uvw〉 crystallographic orientations, not only for the side forged process, but also for the upset and side forged tantalum. For tantalum processed by extrusion, the transverse rolling did not improve the final recrystallized texture.     

Texture in deep drawing columbium (Nb)-treated interstitial-free steels

The development of the crystallographic texture in hot-rolled, cold-rolled, and recrystallized Cb-treated interstitial-free steels was investigated using the crystallite orientation distribution analysis as well as X-ray pole figures. The influence of chemical composition of the steel and processing variables on texture and on normal and planar anisotropy of the γ-value of cold-rolled and annealed sheet are discussed and compared with those of aluminum-killed deep drawing steels. While, in terms of ideal orientation components, the re-crystallization texture of aluminum-killed steels can be described as having significant amounts of {lll}〈110〉 and {lll}〈112〉 components, Cb-treated steels show these components and in addition even stronger {554}〈225〉 and {322}〈296〉 components. Distinctions in the hot-rolled texture, the cold-rolled texture, and the recrystallization texture are described. Cb-treated steels have an entirely different planar distribution of γ values or plastic strain ratios compared with aluminum-killed steels. The resulting average γ value, γ_m, is significantly higher for Cb-treated steels and results in superior deep drawing characteristics. A. ELIAS is deceased.     

On the origin of the R orientation in the recrystallization textures of aluminum alloys

The crystallographic textures of most Al alloys, after rolling and recrystallization, are composed of two components, the cube orientation {001}〈100〉 and a component similar to the former rolling texture, the so-called R orientation {124}〈211〉. The R orientation can be retained from the rolling texture in cases where the stored dislocation energy is being reduced merely through extended recovery reactions, which is referred to as continuous recrystallization. In addition, R-oriented grains can form through genuine, discontinuous recrystallization by nucleation within S-oriented grains at the grain boundaries between the deformed bands and a subsequent growth selection as caused by orientation pinning. The strength of the R orientation in the recrystallization textures strongly depends on the pretreatment and processing parameters of the material and, in particular, on the alloy investigated. The present article gives a survey of the factors affecting the R orientation and reviews recent results on the formation mechanisms of this orientation, which have been obtained by local texture analysis. The results are discussed with regard to the competition of the R orientation with the cube orientation during the evolution of the recrystallization textures in Al alloys.     

A taylor model based description of the proof stress of magnesium AZ31 during hot working

A series of hot-compression tests and Taylor-model simulations were carried out with the intention of developing a simple expression for the proof stress of magnesium alloy AZ31 during hot working. A crude approximation of wrought textures as a mixture of a single ideal texture component and a random background was employed. The shears carried by each deformation system were calculated using a full-constraint Taylor model for a selection of ideal orientations as well as for random textures. These shears, in combination with the measured proof stresses, were employed to estimate the critical resolved shear stresses for basal slip, prismatic slip, 〈c+a〉 second-order pyramidal slip, and { } twinning. The model thus established provides a semianalytical estimation of the proof stress (a one-off Taylor simulation is required) and also indicates whether or not twinning is expected. The approach is valid for temperatures between ∼150 °C and ∼450 °C, depending on the texture, strain rate, and strain path.     

The growth of single crystal terfenol-D crystals

Rods of the highly magnetostrictive material, Terfenol-D, Tb_0.3Dy_0.7Fe₂, have been prepared by both Bridgman and float zone techniques. It is found that the dendritic growth front consists of parallel sheets of dendrites growing with a primary direction of 〈112〉 and sheet planes of {111}. Unseeded rods show a strong preference for 〈112〉 alignment of the grains. Seeding experiments have been successful for 〈112〉 orientations but not 〈111〉, and the cause of this difference is discussed. The 〈112〉 single crystal rods are seen to contain parallel {111} twin boundaries throughout their volume, growing near the central plane of the dendrite sheets. These results are analogous to those of Ge and Si. The role of the twin planes on domain wall motion and methods of eliminating the twins are discussed.     

Evolution of Microstructure and Texture During Hot Compression of a Ni-Fe-Cr Superalloy

Superalloys are being employed in more extreme conditions requiring higher strength, which requires producers to forge products to finer grain sizes with less grain size variability. To assess grain size, crystallographic texture, and substructure as a function of forging conditions, frictionless uniaxial compression testing characteristic of hot working was performed on INCOLOY 945 (Special Metals Corporation, Huntington, WV), which is a newly developed hybrid of alloys 718 and 925, over a range of temperatures and strain rates. The microstructure and texture were investigated comprehensively using light optical microscopy, electron backscatter diffraction (EBSD), electron channeling contrast imaging (ECCI), and transmission electron microscopy (TEM) to provide detailed insight into microstructure evolution mechanisms. Dynamic recrystallization, nucleated by grain/twin boundary bulging with occasional subgrain rotation, was found to be a dominant mechanism for grain refinement in INCOLOY 945. At higher strain rates, static recrystallization occurred by grain boundary migration. During deformation, duplex slip along {111} planes occurred until a stable 〈110〉 fiber compression texture was established. Recrystallization textures were mostly random but shifted toward the compression texture with subsequent deformation. An exception occurred at 1423 K (1150 °C) and 0.001 seconds⁻¹, the condition with the largest fraction of recrystallized grains, where a 〈100〉 fiber texture developed, which may be indicative of preferential growth of specific grain orientations.     

Observation of cold-rolling texture and partially recrystallized texture in polycrystalline 3 pct Si-Fe by high-resolution electron backscattered diffraction

Cold-rolling texture and partially recrystallized texture of polycrystalline 3 pct Si-Fe were investigated using high-resolution electron backscattered diffraction (EBSD) method. From the measurement on a deformed grain with {211}〈011〉∼{111}〈011〉 orientations, deformation bands with {12 4 1}〈014〉 orientation were found. It turned out that the orientation rotation relationship between deformation bands and surrounding deformed grain can be explained by the activation of the slip system, which has a common slip plane with an adjacent grain. Oriented nucleation of recrystallized grains with {12 4 1}〈014〉 orientation was observed in a deformed grain with {211}〈011〉∼{111}〈011〉 orientation. Exactly the same orientation relationship that was observed between deformed grain and the deformation bands was also observed between the deformed grain and the recrystallized grain. A hypothesis that recrystallization nuclei are generated directly from the deformation bands formed by an activation of the slip system that has a common slip plane of neighboring deformed grains was proposed from the present experimental results.