Sn微合金化无铅易切削Al-Mg-Si合金的组织与性能

Microstructure and properties of lead-free and free-cutting Al-Mg-Si alloy with minor Sn alloying

采用力学性能测试、X射线衍射物相分析、扫描电子显微分析、透射电镜分析和金相实验方法研究了不同处理态Sn微合金化的无铅易切削Al-Mg-Si合金棒材的显微组织与性能。研究结果表明:合金的最佳时效工艺为170℃／8 h,在此条件下,合金棒材的抗拉强度为351 MPa,屈服强度为336 MPa,延伸率为13．5％;合金的物相组成为铝基固溶体、主要强化相Mg2Si和CuAl2以及低熔点组织组成物Mg2Sn+Sn;低熔点组织组成物Mg2Sn+sn以及时效析出相Mg2Si和CuAl2使合金具有良好切削性能和较高强度。

The microstructure and mechanical properties of minor Sn alloying lead-free and free-cutting Al-Mg-Si alloy rod with different treatments were investigated using mechanical property test, XRD analysis, SEM and TEM. The results show that the best aging process is 170 ℃/8 h, and in this condition, the tensile strength, yield strength and elongation of the alloy bar are 351 MPa, 336 MPa and 13.5%, respectively. The phase composition includes Al-based solid solution, low melting point eutectic（Mg2Sn＋Sn） and Mg2Si and CuAl2 precipitates. The existence of low melting point substance （Mg2Sn＋Sn） Mg2Si and CuAl2 precipitation makes the alloy possess not only good machinability but also good strength.