Mg2Si含量对6061铝合金组织和力学性能的影响

Effects of Mg2Si Content on Microstructure and Mechanical Properties of Aluminum Alloy 6061

通过扫描电镜/能谱、金相显微镜分析及力学性能测试,研究了Mg2Si对6061铝合金热处理前后组织和力学性能的影响。结果表明:铸态组织中,Mg2Si主要以短棒状和长条状的结晶相的形式存在,随着Mg、Si元素的增多,长条状的Mg2Si结晶相在晶界处连续分布;Mg2Si含量低于1.80%时,基本能在均匀化处理中完全回溶,超过1.80%时,Mg2Si形貌发生球化转变;当Mg2Si含量为2.65%时,短棒状的Mg2Si相比圆点状的Mg2Si相造成更多Si的富集,在晶界处形成单质Si相;Mg2Si含量为1.58%时,合金T6态具有最优的力学性能,抗拉强度、屈服强度、延伸率分别为σb=348MPa,σ0.2=310MPa,δ=3.0%;Mg2Si含量的提高并不能进一步提升合金的强度,延伸率反而随之下降。

The effects of Mg 2Si on microstructure and mechanical properties of aluminum alloy 6061 before and after the heat treatment was investigated by means of scanning electron microscope/energy spectrum, metallographic microscope analysis and mechanical properties test. The results show that in the as-cast alloy, Mg 2Si mainly exists in the form of short rod precipitation phase and long strip crystalline phase. With the increase of Mg and Si, the long strip phases were continuously distributed at the grain boundaries. Mg 2Si could be completely dissolved in the homogenization treatment when its content was less than 1.80wt%, and its morphology turned to spherical shape when its content was over 1.80wt%. The short rod Mg 2Si leaded to such more enrichment of Si than spherical Mg 2Si when Mg 2Si content was 2.65wt% that Si phase formed at the grain boundary. When the Mg 2Si content was 1.58 wt%, the T6 alloy performed best in mechanical properties that tensile strength, yield strength, elongation were 348 Mpa, 310 Mpa,and 3.0% respectively. The increase of Mg 2Si content did not further increase the strength of the alloy, but the elongation decreased.