重复搅拌摩擦加工对铸态L2纯铝组织性能影响

Effect of Accumulation of Friction Stir Processing on Microstructure and Properties of Cast Pure Aluminum L2

对铸态L2纯铝分别进行了单道次和2,3次重复搅拌摩擦加工处理,研究了搅拌摩擦加工次数对L2纯铝组织性能的影响。结果表明:剧烈的塑性变形促使粗大的枝状晶显著破碎,形成了细小且均匀分布的再结晶组织,重复加工次数对再结晶晶粒的尺寸影响较小。重复搅拌摩擦加工后,铸态L2纯铝的最大显微硬度值提高了17 HV,最大抗拉强度及延伸率分别提高了39 MPa和22%,试样的拉伸断口呈现出微孔聚合韧性断裂特征。随着重复加工次数的增加,相邻道次间的显微硬度、抗拉强度和延伸率差值均减小。

Single pass, 2-pass and 3-pass of friction stir processing （FSP） were conducted on cast pure aluminum L2. Effect of FSP times on microstructure and properties of cast pure aluminum L2 was studied. The results show that intense plastic deformation results in significant breakup of the coarse dendrites and creates a fine, uniform recrystallized microstructure; accumulative processing times have a little effect on the size of recrystallized grain. The highest microhardness, ultimate tensile strength and elongation increase by 17 HV, 39 MPa and 22% , respectively after accumulation of FSP; the surface fracture of the FSPed tensile specimens exhibit a typical ductile dimple-fracture. The differences of microhardness, ultimate tensile strength and elongation between adjacent passes are reduced with more accumulative processing times.