温轧对6061铝合金铸轧板材显微组织和力学性能的影响

Effect of Warm Rolling on Microstructure and Mechanical Properties of 6061 Aluminum Alloy Cast-Rolled Sheet

采用温轧对双辊铸轧6061铝合金板材进行处理,观察不同温轧温度及累积压下量对铸轧板材的影响。采用光学显微镜(OM),扫描电镜(SEM),X射线衍射仪(XRD),显微硬度仪和万能试验机等,表征了铸轧板材及温轧板材的显微组织,获得了材料的硬度、强度和延伸率等力学性能。研究表明,铸轧6061合金中主要含有耐热相Al0.7Fe3Si0.3、Al9Fe0.84Mn2.16Si及少量强化相Mg2Si。合金中第二相随温轧道次的递增逐渐由网格状、片状转变为沿轧制方向的线条状,最终变为细小的颗粒状。经过温轧后,产生新的析出相Al0.5Fe3Si0.5且Mg2Si析出相增多。铸轧板材温轧后,硬度随压下量的增大呈线性递增,且当温轧温度为370℃时,硬度曲线斜率最大为2.42114。此时细小的AlFeSi类析出相及Mg2Si强化相均匀弥散分布于合金中,板材的硬度最大,可达842.8MPa,抗拉强度、屈服强度和延伸率分别为209.34 MPa、79.09 MPa和20.11%。

The effect of different warm rolling temperatures and cumulative reductions on microstructure and mechanical properties of 6061 aluminum alloy sheet rolled by twin-roll casting was studied.Multi-scale characterization techniques were employed to study the microstructures of cast-rolled and warm-rolled sheets.The mechanical properties such as hardness,strength and elongation were also measured.The results show that the cast-rolled 6061 alloy mainly contains heat-resistant phase Al0.7Fe3Si0.3,Al9Fe0.84Mn2.16Si,and a small number of strengthening phase Mg2Si.With increasing the rolling passes,the shape of second phases gradually changes from a mesh and a sheet shape to a line shape along the rolling direction,and finally becomes a fine granular shape.After warm rolling,the amount of new precipitates Al0.5Fe3Si0.5 and Mg2Si increases.Additionally,the hardness linearly increases with increasing the reduction,and the maximum slope(2.42114)of hardness curves is found at the warm rolling temperature of 370℃.At this temperature,fine AlFeSi precipitates and Mg2Si phases are uniformly dispersed in the alloy,the highest hardness of^842 MPa is obtained for plate,and the tensile strength,yield strength and elongation are 209.34 MPa,79.09 MPa and 20.11%respectively.