Cross-rolled Sheets Research Articles

Effect of rolling method on the recrystallization behavior and recrystallization texture of Al-Mn alloy

CC AA 3003 aluminum alloy hot strip was cold-rolled to various thinning degrees along the original rolling and crosswise, followed by annealing at 399 °C and 427 °C for various periods of times. Investigations were conducted on the impact of rolling method on recrystallization and recrystallization texture. The findings demonstrate that the straight-rolled (i.e., in the original rolling direction) sheets annealed at 399 °C have recrystallization textures that are characterized by the M {1 1 3}< 1 1 0 > and P {0 1 1}< 4 5 5 > components, with the M component significantly strengthening with increasing rolling reduction and the P component only slightly strengthening. The M texture diminishes noticeably when the annealing temperature increases from 399 °C to 427 °C, but the P texture weakens very marginally. When the rolling reduction approaches 60% to 70%, the r-cube recrystallization texture is formed in the annealed cross-rolled (i.e., along the original transverse direction) sheets, and the strength of the r-cube texture declines with increasing rolling reduction. The 90% cross-rolled sheet that has been annealed at 399 °C forms the comparatively strong M and extremely weak P textures in comparison to the 90% straight-rolled sheet. With increasing rolling reduction, an increase in the size of recrystallized grains is observed in plates annealed at 399 °C, but it shrinks in sheets that are annealed at 427 °C.

Tailoring the Mechanical Properties of Copper‐Added Transformation‐Induced Plasticity‐Aided Multiphase Steel by Thermomechanical Processing

Herein, the microstructure and mechanical properties of a low‐alloy Cu‐bearing transformation‐induced plasticity (TRIP) steel and their dependence on the processing history are investigated. The distributions of the retained austenite and bainite are found to be dependent on the initial cold‐rolled microstructure, which can be tailored by the preceding hot‐rolling route (unidirectional/cross rolling) and the subsequent cooling rate (furnace/air cooling). Mechanical properties and TRIP effect strongly depend on the initial microstructure, where the air‐cooled sheet shows remarkable mechanical properties; while the cross‐rolled sheet shows isotropic properties. The addition of copper results in an increase in the amount of the retained austenite, enhancement of strength‐ductility balance, and improvement of the hardening behavior of TRIP‐assisted high‐performance steel.

Deformation mechanism, orientation evolution and mechanical properties of annealed cross-rolled Mg-Zn-Zr-Y-Gd sheet during tension

Mg-6.75Zn-0.57Zr-0.4Y-0.18Gd (wt.%) sheet with typical basal texture was produced by cross rolling and annealing. Room temperature tensile tests were subsequently conducted along rolling direction (RD), transverse direction (TD), and diagonal direction (RD45). Deformation mechanism and orientation evolution during the tension were investigated by quasi-in-situ electron backscatter diffraction observation and in-grain misorientation axis analysis. The results indicate that the activation of deformation mechanism mainly depends on the initial grain orientation. For RD sample, prismatic <a> slip plays an important role in the deformation of grains with <0001> axis nearly perpendicular to the RD. With the <0001> axis gradually tilted towards the RD, basal <a> slip becomes the dominant deformation mode. After the tensile fracture, the initial concentrically distributed {0001} pole is split into double peaks extending perpendicular to the RD, and the randomly distributed {101¯0} pole becomes parallel to the RD. The evolution in {0001} and {101¯0} poles during tension is related to the lattice rotation induced by basal <a> slip and prismatic <a> slip, respectively. TD and RD45 samples exhibit similar deformation mechanism and orientation evolution as the RD sample, which results in the nearly isotropic mechanical properties in the annealed cross-rolled sheet.

Prediction of Earing of Cross-Rolled Al Sheets from {h00} Pole Figures

The plastic anisotropy of rolled Al sheets is the result of a crystallographic texture. It leads to the formation of uneven cup heights during deep-drawing, which is called earing. A new, simple and rapid method had been previously developed by the authors to predict earing directly from {h00} pole figures. In the present manuscript, this method is applied to cross-rolling for the first time. 5056 type aluminum sheets were unidirectionally- (conventionally) and cross-rolled from 4 to ~1 mm thickness in 6 or 12 passes. Earing was predicted from recalculated {200} pole figures obtained after X-ray diffraction texture measurements. The results were validated by deep-drawing tests. It is shown that the proposed method predicts the type (locations of ears) and magnitude of earing with satisfactory results. However, a different scaling factor must be used to calculate the magnitude of earing for cross-rolling than for unidirectional rolling even if all other parameters (including cold rolling, texture measurements, and deep-drawing) are the same. This is because the cross-rolled sheets exhibit a similar type but weaker earing compared to the unidirectionally rolled samples.

Microstructure, texture and mechanical anisotropy of Mg-Gd-Y-Zr sheets processed via different rolling routes and reductions

The dependence of microstructure, texture and mechanical anisotropy of Mg-Gd-Y-Zr alloy sheets on rolling routes (unidirectional rolling (UR) and cross rolling (CR)) and reductions (10% and 30% pass reduction) was investigated. Results show that the rolled sheets with pass reduction of 10% mainly consist of coarse deformed grains and 101¯2101¯1 tensile twins, and the UR sheet possesses twins with larger size and higher area fraction. With pass reduction increased to 30%, dynamic recrystallization (DRX) occurred in both UR and CR sheets, therein the CR sheet exhibited the lower DRX ratio due to the high degree of dynamic recovery induced by the CR route. Meanwhile, texture and deformation modes of the rolled sheets also exhibit rolling reduction dependence. For the case of 10% pass reduction, CR and UR sheets show the similar basal texture type and intensity, and thus prismatic ⟨a⟩ slip dominates plastic deformation during tensile tests. For the case of 30% pass reduction, CR sheet possesses a multiple-peak texture with more obvious peak inclination and spreading, while UR sheet shows a single-peak and weaker basal texture. The difference in texture results in the difference in deformation modes during tensile tests, i.e., prismatic ⟨a⟩ slip for UR sheet and basal ⟨a⟩ slip for CR sheet, respectively. Above differences further bring distinction to the mechanical anisotropy of the rolled sheets. For 10% pass reduction, CR and UR induce similar anisotropy. For 30% pass reduction, CR causes a more significant anisotropy than UR.

Anisotropic tensile and ratcheting behavior of commercially pure titanium processed via cross rolling and annealing

Microstructures, crystallographic textures, and mechanical properties for two different orientations along the rolling direction (RD) and transverse direction (TD) have been investigated in grade 2 commercially pure titanium sheet processed via cross rolling and annealing. The stress-strain curve has been simulated based on Viscoplastic self consistent (VPSC) model and relative slip/twin activity has been calculated for tensile and ratcheting deformation. The predicted slip/twin activity has been complemented with electron backscatter diffraction (EBSD) based deformation microstructure so as to shed light on the underlying micro-mechanism of anisotropic deformation behavior of cross rolled and annealed commercially pure titanium. The as received (AR) sheet exhibits equiaxed alpha grains with typical TD-split basal texture. After cross rolling, cross rolled (CR) sheet developed distinctly different RD-split texture. Both AR and CR sheet exhibit lower yield strength, higher elongation and higher ratcheting life for RD compared to TD orientation. However, the anisotropy in tensile properties have been found to be lower in CR sample, whereas the anisotropy in ratcheting properties have been found to be higher in CR sample compared to AR sample. VPSC simulation of tensile stress-strain response in the plastic regime reveals prism slip system {101¯0}<112¯0>, which acts as the primary mode of deformation in titanium gets suppressed with increase in strain, while basal and pyramidal slip activity rises in RD orientation and the situation is exactly reverse in case of TD orientation of cross rolled samples. In addition, electron backscatter diffraction based characterization of deformation microstructure reveals suppression of twinning activity too in CR samples. The manifestation of basal slip activity under controlled cyclic stress applied during ratcheting has been attributed for the augmentation of higher anisotropy in ratcheting response in CR samples.

Microstructure and mechanical properties of Mg-6.75%Zn-0.57%Zr-0.4%Y-0.18%Gd sheets by unidirectional and cross rolling

Microstructure and mechanical properties of the Mg-6.75%Zn-0.57%Zr-0.4%Y-0.18%Gd sheets processed by unidirectional and cross rolling were investigated. Compared with the unidirectional rolling (UR) sheet, cross rolling (CR) sheet exhibits finer grain size, weaker basal texture, higher recrystallized volume fraction and higher strength. Meanwhile, the UR sheet shows strong mechanical anisotropy, while the approximate mechanical isotropy is successfully achieved in the CR sheet. Cross rolling effectively reduced the anisotropy of mechanical properties. The finer grains in the CR sheet are responsible to its higher yield strength. The anisotropy of yield strength results from the basal <a> slip, while the activation of prismatic <a> slip reduced this anisotropy. The recrystallized components in the CR sheet weaken basal texture, thereby reducing anisotropy.

Mechanical anisotropy and deep drawing behaviors of AZ31 magnesium alloy sheets produced by unidirectional and cross rolling

Magnesium AZ31 sheets were produced by rolling on the as-extruded plates with two rolling techniques: cross rolling (CR), a laboratory process wherein the rolling direction is changed by 90° after each rolling pass, and conventional unidirectional rolling (UR) wherein the rolling direction is unchanged. The microstructure and texture, tensile mechanical properties in terms of strength and elongation, and also the anisotropy of the UR and CR sheets were investigated at room temperature. As expected, the UR sheet has obvious planar anisotropy from the strong basal-type texture; however, the CR sheet shows improved ductility of 28% elongation-to-fracture and low r value close to 1 which enhances drawing capability. Deep drawing tests carried out at 150°C reveals that the UR cups show obvious earing corresponding to a large negative value of planar anisotropy Δr, while earing of the CR cups is negligible due to a positive value of Δr. Moreover, the CR sheet produces a deeper drawn cup than the UR sheet as a result of its lower normal anisotropy r¯ value and larger elongation compared with the UR sheet.

The Role of Oriented Growth in P Texture Development in Al-Mn-Mg Aluminum Alloy

The deformation and recrystallization textures in straight-rolled and cross-rolled AA 3105 aluminum alloy were investigated by x-ray diffraction to determine the role of oriented growth in the formation of the P recrystallization texture. A very strong P texture was developed in the straight-rolled sheet after recrystallization annealing. In contrast, the cross-rolled sheet did not develop the P texture on annealing even though the cross-rolling (i.e., rolling along the original transverse direction) texture contained more orientations close to the P orientation than the straight-rolling texture. The formation of the P texture in aluminum alloys requires the presence of the C component, since the P orientation has a 31.1°〈122〉 orientation relationship with respect to the C orientation. The recrystallization texture in the cross-rolled sheets was in excellent agreement with the oriented growth theory.

Microstructure and mechanical properties of annealed Mg–0.6 wt%Zr sheets by unidirectional and cross rolling

The microstructure and mechanical properties of annealed Mg–0.6wt%Zr sheets processed by unidirectional and cross rolling were investigated. Compared with the unidirectional rolling sheet, the cross rolling sheet showed a more uniform microstructure, larger grain size and weaker texture intensity. Meanwhile, the cross rolling sheet displayed lower yield strength, ultimate tensile strength and higher elongation. Both sheets exhibited strong mechanical property anisotropy and the stronger anisotropic mechanical properties were showed for unidirectional rolling sheet. The yield strength and ultimate tensile strength of both sheets along the rolling direction were lowest and those along transverse direction were highest. In addition, the highest elongation was found along 45° direction for two sheets. Taking into account of {0001} 〈11−20〉 plastic deformation mechanism, the yield strength anisotropy for both sheets could be explained by the microscopic crystal plasticity theory.

Texture and mechanical properties of Al-0.5Mg-1.0Si-0.5Cu alloy sheets manufactured via a cross rolling method

The relationship between the texture and mechanical properties of 6xxx aluminum alloy sheets processed via cross rolling was investigated. The microstructures of the conventional rolled and cross rolled sheets after annealing were analyzed using optical micrographs (OM). The texture distribution across the thickness in the Al-Mg-Si-Cu alloy, conventional rolled sheets, and cross rolled sheets both before and after annealing was investigated via X-ray texture measurements. The texture was analyzed in three layers from the surface to the center of the sheet. The β-fiber texture of the conventional rolled sheet was typical of the texture obtained using aluminumoll ring. After annealing, the typical β-fiber orientations were changed to recrystallization textures: cube{001}〈100〉 and normal direction (ND)-rotated cubes. However, the texture of the cross rolled sheet was composed of an asymmetrical, rolling direction (RD)-rotated cubes. After annealing, the asymmetrical orientations in the cross rolled sheet were changed to a randomized texture. The average R-value of the annealed cross rolled sheets was higher than that of the conventional rolled sheets. The limit dome height (LDH) test results demonstrated that cross rolling is effective in improving the formability of the Al-Mg-Si-Cu alloy sheets.

Influence of anisotropy of the magnesium alloy AZ31 sheets on warm negative incremental forming

Single point incremental forming of the magnesium alloy AZ31 sheets, which were fabricated by hot extrusion, slab + hot/cold rolling, strip-casting rolling and cross-rolling, respectively, was investigated at elevated temperatures. The results show that the anisotropy of the sheets fabricated by casting slab + hot/cold rolling and cross-rolling is not remarkable, and the formability is improved significantly. The circular, square and rotary cone parts were performed with satisfactory surface quality and without any microcracks successfully, and which is superior to those of the extruded sheet and the one-way rolled sheet. Therefore, anisotropy of the sheets has remarkable effects on the surface quality of the formed parts, and the effect becomes weakened with increasing temperature. It is proposed that cross-rolling sheet is much more suitable for warm SPIF process.

Effect of pseudo cross-rolling on the recrystallization texture of a continuous cast Al–Mg alloy

The hot band of a continuous cast Al–Mg alloy was cold-rolled to different reductions along the original rolling direction and the original transverse direction, and then annealed at 399 °C for 3 h. The effect of the cross-rolling on recrystallization texture was investigated by X-ray diffraction. The cross-rolled sheet appears to be a continuous recrystallization texture transition from the cube component through the {4 0 7}〈7 3 4〉 component to the R component when the cross-rolling reduction increases from 0% to 91%.

Texture in Hot Extruded, Hot Rolled and Laser Welded Magnesium Base Alloys

In this work the textures of MgAl9Zn1, MgAl6Zn1, MgAl3Zn1 and MgAl2Mn alloys have been studied, using individual grain orientation measurement (“ACOM”) in the SEM. Hot extruded billets, unidirectional, reverse and cross-rolled sheet metals as well as laser welding seams have been investigated. In the shaft of a partial extrudate through a circular die orifice, a &lt;0001&gt; ring fiber texture has formed which continuously changes into a spiral fiber texture in the bottom neck. The unidirectional and the reverse hot rolled MgAl2Mn specimens show an R type &lt;0001&gt; texture with a small asymmetrical split whereby the basal poles are tilted by about ±12° from the sheet normal direction to the rolling direction. In the hot cross rolled specimens, the basal poles are slightly spread both in the first and second rolling directions. Texture in the laser welding seams is weak and distinctly different from that of the sheet material. There is almost no heat affected zone at the margins of the welding seams.

微細粒組織を有する７４７５系アルミニウム合金温間圧延板の材料特性

7xxx alloy fine grained sheets produced by a warm rolling method were investigated on its micro structure and bulk properties comparing with cold rolled sheets of AA7475 alloy. The warm rolled sheets kept the fine structure less than 3 μm after solution heat treatment. This structure was recognized by EBSP measurement as a sub-grain structure with a high proportion of low-angle boundary less than 15° while the cold rolled sheets had a high proportion of high-angle boundary over 15°. It was also a unique property that the texture of the warm rolled sheets consisted mainly of the β–fiber after solution heat treatment. A cross rolling method was applied for reducing anisotropy on polarized optical micrograph and led to successful results. In addition, it was found that the {011} orientation was formed strongly by the cross rolling. The {011} orientation was kept after solution heat treatment in the warm cross rolled sheets, but the cold cross rolled sheets formed a recrystallization texture without any strong components. The strength of the warm rolled sheets aged at 120°C increased about 10% comparing with that of the cold rolled sheets. The most important result in this study was that the property of resistance to SCC of the warm rolled sheets improved considerably. The reason of the above result was probably due to intermittent precipitation at grain boundaries on the warm rolled sheets in T6 condition.

Ｍｏ板の２次再結晶粒成長速度について

The growth kinetics of secondary recrystallized grains with specific orientations in the 90% hot rolled molybdenum sheets doped with CaO and MgO were investigated. Specific grains which are developed exclusively during secondary recrystallization in straight-and cross-rolled sheets have two kinds of orientaions with near {112} and {335} , and near {123} and {126} respectively. The activation energies for the growth of secondary recrystallized grains with specific orientations were estimated to be 69-78 kcal/mol in the temperature range 1900-2200°C. The temperature dependence of the grain growth rate G was described by G=3.0×104 exp (-73000/RT) cm sec-1 for the {112} orientation and G=5.4×103 exp (-70000/RT)cm sec-1 for the {123} orientation. Moreover, the growth rates of secondary recrystallized grain are closely related to the crystallographic orientation relation between secondary and primary recrystallized grains, and the size of grains obtained for primary recrystallized sheets as results of rolling procedures.

Effect of binder and process parameters on carbon content of injection mooulded steel : A. Pest et al (FHG-Fraunhofer Inst., Germany)

The hot band of a continuous cast Al–Mg alloy was cold-rolled to different reductions along the original rolling direction and the original transverse direction, and then annealed at 399 °C for 3 h. The effect of the cross-rolling on recrystallization texture was investigated by X-ray diffraction. The cross-rolled sheet appears to be a continuous recrystallization texture transition from the cube component through the {4 0 7}〈7 3 4〉 component to the R component when the cross-rolling reduction increases from 0% to 91%.

Computer modelling of the effect of rolling schedule on the plastic anisotropy of cold-rolled aluminium sheets

Metal sheets produced by rolling bring about dramatic changes in the mechanical properties and are characterized by the crystallographic textures (or preferred orientation of grains) which give rise to anisotropic properties. Computer modelling of the rolling texture formation offers a systematic and efficient way of exploring the relationship between the process variables and the state of plastic anisotropy of sheet products. The simulated results show that in general a high overall rolling reduction coupled with a small number of rolling pass will give a sheet with high normal anisotropy. Cross-rolled sheets possess higher average plastic strain ratios and lower planar anisotropy than those of the straight-rolled sheets. The higher plastic strain ratio is found to be associated with the {110} rolling plane texture components of the cross-rolling textures.

Effects of heat treatment on microstructure and texture in Ti24at%Al-11at%Nb

Hot cross-rolled sheets of Ti-24at.% -11at.%Nb are subject to heat treatments in the α 2 + β phase field and in the β phase field. Changes in microstructure are monitored by metallography while crystallographic texture is evaluated by pole figure analysis. Annealing in the α 2 + β regime produces equiaxed α 2 grains and intergranular β with little modification to the starting texture. Annealing in the β regime results in a Widmanstätten structure whose lamellar spacing depends on the cooling rate. A much sharper texture in the α 2 phase is observed. The sharpness of the β phase texture correlated with the sharpness of the α 2 texture. Hardness measurements indicate that the highest strength occurs in the fine Widmanstätten structure where rapid cooling from the β regime produces the greatest amount of microstructural refinement.

２次再結晶法によるＭｏ巨大双結晶板の製造

In order to obtain a large-scale bicrystal in sheet molybdenum by means of secondary recrystallization, the effects of rolling reductions and procedures on the secondary grain growth behavior were investigated texturally and optically.It has been found that the development of secondary grain from both surfaces or a surface of sheet is strongly dependent on the rolling reductions. For the case of straight-rolled sheet having rolling reductions of 73%-93%, an abnormal grain growth from both surfaces occurred after an anneal at 1850°C and a large-scale bicrystal was obtained. In contrast, the abnormal grain growth from both surfaces occurred for the cross-rolled sheet having rolling reductions of 86%-93%.These behaviours can be explained in relation to the texture gradients, and the shape and size of grains in the thickness direction obtained for primary recrystallized sheets as results of rolling reductions and procedures.