变形率及退火制度对Al-Mg合金薄板力学性能及微观组织的影响

Effects of reduction and annealing on mechanical properties and microstructure of Al-Mg alloy sheet

通过力学性能测试及显微组织观察,研究了不同变形率的Al-Mg合金薄板在120～400℃进行2～8 h退火后的强度及显微组织的变化规律。力学性能测试结果表明:在回复阶段,不同变形率板材的强度随退火温度的升高近似线性降低。在同一温度退火时,保温时间对力学性能的影响较小,强度降低在10 MPa以内。只有变形率为71%的板材在220～240℃退火时随着保温时间的延长强度下降较多约20 MPa。变形率为23%和71%时,再结晶开始和结束温度分别为260℃、280℃和220℃、260℃,并且保温时间对再结晶温度没有影响。通过显微组织观察发现,再结晶完成之后板材的平均晶粒尺寸随变形率的增加而减小,由45μm减小到15μm,并且不随退火温度的升高及保温时间的延长而增加。当变形率大于71%时晶粒尺寸不再随变形率的增加而减小。

The strength and microstructure of Al-Mg alloy sheet with different cold rolling reduction after annealing at 120-400℃for 2-8 h were investigated by means of mechanical properties test and microstructure morphology inspection.During the recovery stage,the strength of sheets with different cold rolling reduction decreases linearly with the raise of annealing temperature,but at the same temperature,the holding time has little effect on the strength,except for the sheets with reduction 71%.When annealed at 220-240℃,the drop of its strength is about 20 MPa,a little bigger than the others whose decrease is within 10 MPa.The starting and ending temperatures of recrystallization are 260℃,280℃for the sheet with 23%reduction,and 220℃,260℃for the other,both are independent with the holding time.After recrystallization,with the increase of cold rolling reduction,the average grain size decreases from 45μm to 15μm,and it is independent with the annealing treatment.But when the reduction is larger than 71%,the grain size does not decrease continually.