挤压铸造零件沿流程方向的成分偏析及组织偏聚

采用挤压铸造(液态模锻)工艺制备了A357铝合金螺旋线试件,使用化学成分分析和金相分析方法研究了流程长度对合金成分偏析及组织偏聚的影响.结果表明:在沿流程方向上,流程的开始端和流程末端的Si元素和Mg元素含量大于流程中段的含量.合金的初始α晶粒尺寸随着流程长度的增加先增大后变小.初生固相率随着流程长度的增大呈现波动变化.造成流程成分偏析和组织变化的原因是在挤压铸造凝固阶段中补缩液相的强迫运动.

Microstructure and composition segregation along the fluidity length of aluminum alloy in squeeze casting

This study investigated the spiral line sample of A357 prepared by the squeeze casting (liquid die forging) process and the influence of the fluidity length on the composition segregation and microstructure segregation through chemical composition and metallographic analyses.The results show that the Si and Mg mass fractions of the start and the end of the spiral line sample along the flow length are greater than that in the middle of the spiral line sample.The initial grain size of α first increases, then decreases with the increase of the fluidity length.Meanwhile, the phase rate of the primary solid shows a fluctuating change with the increase of the fluidity length.The composition segregation and the microstructure change are caused by the forced flow of the filling liquid in the squeeze casting process.