大应变量冷轧AA1050铝合金微观组织与织构的演变

MICROSTRUCTURE AND TEXTURE EVOLUTIONS OF AA1050 ALUMINUM ALLOY COLD ROLLED TO HIGH STRAINS

采用ECC和EBSD技术研究了AA1050铝合金冷轧到大应变量下微观组织和织构的演变规律。结果表明,AA1050合金冷轧到大形变量时,微观组织由低应变下的胞块组织结构转变成典型的层片状界面(LBs)结构,其内部的LBs基本与轧向(RD)平行;主要存在两种转变机制,即由于轧制变形(机制Ⅰ)和借助于S-bands结构的剪切作用(机制Ⅱ),从而导致GNBs逐渐旋转到与RD平行,且以机制Ⅰ为主。变形过程中,由于晶粒的分裂形成大量的大角度界面,随应变的增加,大角度界面的间距逐渐减小、数目逐渐增多;当冷轧到90%应变量时,除原始晶界外,约为47%的大角度界面起源于变形诱导的界面。冷轧变形主要形成典型的Brass+S+Copper轧制织构,且强度随应变的增加而逐渐增加。

The evolutions of the microstructure and texture of AA1050 alloy cold rolled to large strains have been investigated using electron channeling contrast （ECC） imaging and electron backscattered diffraction （EBSD） techniques. It is found that the microstructure evolves from a cell block structure at low strains into a lamellar structure at high strains, within which most of lamellar boundaries （LBs） are parallel to rolling direction （RD）. Two mechanisms contribute to the microstructure transition, i.e., a gradual reorientation of the cell-block boundaries toward to RD due to the cold rolling deformation （Mechanism Ⅰ, which is the dominant importance） and the realignment of boundaries to RD as a result of the shearing introduced by S bands structure （Mechanism Ⅱ）. During this process a significant number of high angle boundaries （HABs） is created, about 47% HABs originate from deformation induced boundaries at 90% reduction. The number of HABs increases and the spacing decreases with the increase of strains. The texture evolves into typical cold rolling deformation texture components of Brass＋S＋Copper, and the intensity of the texture increases with the increase of strain.