挤压铸造A356.2铝合金发动机悬置支架的组织与性能

以挤压铸造A356.2铝合金发动机悬置支架为研究对象,对支架铸态组织、不同固溶时效热处理后的显微组织与力学性能,以及内部缺陷进行了分析研究。结果表明,挤压铸造A356.2铝合金铸态组织由α-Al相和Al-Si共晶组成,晶粒尺寸约为148μm,二次枝晶间距约为20μm;经固溶时效处理后,共晶Si一部分溶入α-Al相中,一部分以粒状、球状形式分布在α-Al晶界;固溶时间、时效温度和时效时间对A356.2合金的力学性能有一定影响。试样经过535℃×6h固溶+8min水淬+170℃×6h时效处理后,抗拉强度为340.5MPa,屈服强度为274.5MPa,伸长率为10%,满足支架整体力学性能要求。

Forming Process and Mechanical Properties of Squeeze Casting A356.2 Aluminum Alloy Engine Mounting Bracket

The microstructure,mechanical properties under different solid solution and aging conditions and internal defects of the squeeze casting A365.2 aluminum alloy engine mount bracket were investigated.The results reveal that microstructure of the heat-treated A356.2 alloy is composed mainly ofα-Al matrix,eutectic Si phase and Mg2Si phase with a grain size of about 148μm and the secondary dendrite spacing around 20μm.After solution aging treatment,part of the eutectic Si phase is dissolved into theα-Al matrix,and the other is distributed in the form of granular or spherical particle at theα-Al grain boundary.The solution time,aging temperature and aging time can affect the mechanical properties of A356.2.It is found that with solution at 535 ℃ for 6 hand water quenching for 8 min+ aging at 170℃for 6 h,the tensile strength,yield strength and elongation of the squeezing casting aluminum alloy bracket reach 340.5 MPa,274.5 MPa and 10%,respectively,meeting the mechanical properties standard required by the engine bracket.