时效对无铅易切削Al-Cu合金的微观组织结构与性能的影响

Effect of aging treatment on microstructure and properties of lead-free free-cutting Al-Cu alloy

采用力学性能测试、X射线物相分析、扫描电镜背散射和能谱分析、透射电子显微分析和金相实验方法,研究时效工艺对固溶-冷拉处理的Sn和Bi微合金化的无铅易切削Al-Cu合金棒材显微组织结构特征和力学性能的影响,并采用晶间腐蚀法研究合金的腐蚀性能。研究结果表明:合金最适宜的时效热处理工艺为160℃/6 h,在此工艺条件下,合金的抗拉强度、屈服强度和伸长率分别为473 MPa,391 MPa和11.2%。合金的物相组成为Al基固溶体,Al7Cu2Fe,CuAl2以及低熔点物质Bi,SnBi和Sn;合金的晶间腐蚀深度为0.4 mm,其综合性能与含铅2011合金的相当。

The effect of aging treatment on the microstructure and mechanical properties of solution treated and cold drawn Sn, Bi alloying lead-free free-cutting Al-Cu alloy rod was investigated using mechanical properties test, XRD analysis, SEM hack scattered and energy spectrum, TEM observation and OM, and the corrosive property was also studied by Huey test. The results show that the optimal aging technology of aUoy is 160 ℃/6 h, and under this condition, the tensile strength, yield strength and elongation of alloy bar can reach 473 MPa, 391 MPa and 11.2%, respectively. The phase compositions of alloy include Al-based solid solution, Al7Cu2Fe, CuAl2 and low melting point phase （Bi, Sn and SnBi）. The depth of intercrystalline corrosion is about 0.4 mm, and the overall property is equivalent to lead-containing 2011 alloy.