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研究了Mg含量、冷却速度、固溶处理对Al-6.8Mg-0.3Mn、Al-3.8Mg-0.3Mn两种合金力学性能的影响。结果表明,随着Mg含量提高,晶界相增多。当Mg含量提高到6.8%时,晶界出现网状组织;随着Mg含量升高,合金强度提高,塑性下降;通过砂型铸造空冷、金属型铸造空冷、金属型铸造淬火来实现不同的冷却速度,发现金属型淬火试样的金相组织中,在晶界附近没有析出网絮状或颗粒状第二相,而强度和伸长率要高于其他两种工艺。两种合金经过430℃×60h固溶处理后,合金的综合力学性能得到大幅度提高。Al-6.8Mg-0.3Mn金属型铸造空冷试样固溶后抗拉强度由280MPa提高到335MPa,伸长率由10.4%提高到20%。
The effects of Mg content, cooling rate and solution treatment on the mechanical properties of Al-6.8Mg-0.3Mn and Al-3.8Mg-0.3Mn alloys were studied. The results show that with the increase of Mg content, the grain boundary phase increases. When the Mg content increases to 6.8%, the grain boundaries appear reticular structure; with the increase of Mg content, the strength of the alloy increases and the ductility decreases; different cooling rates are achieved by sand casting air cooling, metal casting air cooling and metal casting quenching It was found that in the microstructure of the metal quenched sample, no networked or granular second phase was precipitated in the vicinity of the grain boundaries, while the strength and elongation were higher than the other two processes. After the two alloys have been treated at 430 ℃ for 60h, the comprehensive mechanical properties of the alloy have been greatly improved. The tensile strength of the Al-6.8Mg-0.3Mn metal cast-casting air-cooled specimens increased from 280MPa to 335MPa and the elongation increased from 10.4% to 20%.