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

摘要:

文主要是研究温轧对双辊铸轧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),显微硬度仪和万能拉伸机等设备,观察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84.28 HV,抗拉强度、屈服强度和延伸率分别为209.34 MPa、79.09 MPa和20.11％。

Abstract:

The effect of different warm rolling temperature and cumulative reduction on microstructure and mechanical properties of a 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 e.g. Al0.7Fe3Si0.3, and Al9Fe0.84Mn2.16Si, and a small amount of strengthening phase Mg₂Si.With increasing rolling passes, the shape of second phases gradually changes from mesh and sheet shape to line shape along the rolling direction, and finally to fine granular shape. After warm rolling, the amount of a new precipitate Al0.5Fe3Si0.5 and Mg₂Si increases. Additionally, the hardness linearly increases with increasing 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 84.28HV is obtained for plate. The tensile strength, yield strength and elongation are 29.34MPa, 79.09MPa and 20.11% respectively.