Development of Aluminum Alloy Sheet with Excellent Formability through Texture Control by Asymmetric rolling

采用2道次差辊速轧制，成功地在1050铝板中引入了大于4.0的大剪切应变。在整个厚度范围内均存在以{111}<110>、{112}<110>和{001}<110>为主的剪切织构，而在任何厚度区域均未观察到{112}<11>或{123}<634>取向的常规轧制织构。剪切分量的强度随剪切应变的增加而增加。第二道次轧制方向对变形织构影响不大。1050铝板在再结晶退火后，剪切织构成分得到保留，r值不受辊速比的影响，但Δr随辊速比的增大而略有减小。2道次差速轧制的道次制度对r值影响不大，2道次等压下量轧制时r值最大。通过2道次反向剪切轧制轧制的板的r值，其中板绕其ND转动180度 ...更多信息 第二道次轧制前的TD轴的r值略高于第二道次单向剪切轧制的r值，在第二道次单向剪切轧制中，板在第二道次轧制前围绕其TD轴旋转180度。5182铝合金板的r值随辊速比增加而增加，并且在辊速比为1.8时为0.9。在没有润滑的情况下通过常规（对称）轧制轧制的板达到了0.85的r值，其高于商业5182合金板。即使在常规轧制中，当在高摩擦条件下进行轧制时，在轧制板的表面附近引入大的剪切应变。在常规轧制条件下，板材表面附近产生剪切织构，其<111>轴与ND轴平行，而<111>在差速轧制条件下，其轴稍向轧制方向倾斜。常规轧制板和非对称轧制板的r值之间的小差异可能是由于轴向的这种差异<111>。然而，这些r-值高于通过常规轧制与润滑轧制的板。实验结果表明，剪切应变对r值的影响是有效的，再结晶晶粒尺寸随辊速比的增大而减小。本研究中获得的最小晶粒尺寸为4μm。强度随辊速比的增加而提高，但塑性不受影响。采用差速轧制，由于能在整个厚度范围内引入剪切变形，从而提高了铝合金板材的冲压成形性和强度。结果表明，差速轧制是一种通过控制组织和织构来提高板材物理机械性能的有效方法。该工艺不仅适用于铝合金，也适用于其它金属材料。少

Large shear strain exceeding 4.0 was successfully introduced in 1050 aluminum sheet by 2-pass differential roll speed rolling. The shear texture of which main components were {111}<110>, {112}<110> and {001}<110> prevailed throughout the thickness, and conventional rolling texture such as {112}<11> or {123}<634> orientation was not observed in any part of thickness. The intensity of shear component increased with shear strain. The rolling direction of the second pass exerts a little effect on the deformation texture. After recrystallization annealing, shear texture components are retained.The r-value of 1050 aluminum sheet was not affected by roll speed ratio, however Δr slightly decrease with increasing roll speed ratio. The pass schedule of 2-pass differential speed rolling slightly had an influence on r-value which becomes maximum in 2-pass equal reduction rolling. The r-value of the sheet rolled by 2-pass reverse shear rolling, in which the sheet was turned 180 degree around its ND … More axis before second pass rolling, was slightly higher than that of 2-pass unidirectional shear rolling, in which the sheet was turned 180 degree around its TD axis before second pass.The r-value of 5182 aluminum alloy sheet increased with roll speed ratio, and was 0.9 at the roll speed ratio of 1.8. The sheet rolled by conventional (symmetric) rolling without lubrication attained the r-value of 0.85 that is higher than of commercial 5182 alloy sheet. Even in conventional rolling, large shear strain is introduced near the surface of rolled sheet when rolling is conducted under high friction condition. Near the surface of conventionally rolled sheet, shear texture of which <111> axis is just parallel to the ND axis develops, whereas <111> axis slightly inclines towards rolling direction in differential speed rolling. The small difference between r-values of conventionally rolled sheet and asymmetrically rolled sheet is probably due to this difference of <111> axis direction. However the these r-values are higher than that of the sheet rolled by conventional rolling with lubrication. The effect and usefulness of shear strain on the r-value was confirmed.The recrystallized grain size decreased with increasing roll speed ratio. The smallest grain size attained in the present study was 4μm. The strength also inereased with roll speed ratio without loss of ductility.We have succeeded in improving press formability and strength of aluminum alloy sheet by differential speed rolling, bay which shear deformation can be introduced throughout the thickness of rolled sheet. It is proved that the differential speed rolling is promising process for improving physical and mechanical properties of rolled sheet by microstructure and texture control. This process can be applied not only for aluminum alloy but also for other metallic materials. Less