均匀化处理对A390铝合金微观组织和硬度的影响

Effect of homogenization treatment on microstructure and hardness of A390 aluminum alloy

通过分析比较共晶硅和析出相的数量、尺寸、形貌变化,研究了均匀化温度、均匀化时间和均匀化后的冷却速率对A390铝合金微观组织演变及布氏硬度的影响规律。结果表明:析出相的析出数量增加是均匀化处理后A390铝合金布氏硬度降低的主要原因,而共晶硅尺寸、形貌的改变对其影响较小。合金中析出相的析出数量主要受均匀化处理后的冷却速率影响,同一均匀化温度和时间下,随均匀化冷却速率的减小,析出相数量增多,布氏硬度迅速降低。均匀化处理后,共晶硅熔断粒化,Al2Cu相发生分解和球化,Al5Cu2Mg8Si6相数量增加。

Effects of homogenizing treatment parameters including temperature,time and cooling rate on microstructure and Brinell hardness of A390 aluminum alloy were investigated by comparing the variation of size and morphology of eutectic silicon and intermetallics phases.The results indicate that the increase of amount of precipitated phase is responsible for the decline of Brinell hardness of the alloy after homogenizing treatment.However,no significant effect of the changes of eutectic silicon size and morphology on the hardness of the alloy is observed after the homogenizing annealing.The amount of precipitated phase is affected significantly by the cooling rate after homogenizing treatment.Under the condition of the same homogenizing temperature and time,Brinell hardness of the alloy has a sharp decrease with the decline of the homogenizing cooling rate for the formation of more precipitated phases.After homogenization,eutectic silicon tends to be round,Al2 Cu particles are observed to be remarkably spheroidized,as well as the amount of Al5Cu2Mg8Si6 particles increases significantly.