Sr及热处理对Al-Si-Mg合金共晶硅形貌与材料性能的影响研究

The Influence of Sr&Heat Treatment on the Morphology of Eutectic Silicon and Mechanical Properties of Al-Si-Mg Alloy

研究了Sr变质及不同热处理状态对Al-Si-Mg系合金组织构成、共晶硅形貌、力学性能及断裂模式等方面的影响,提出通过调控共晶硅形貌及减少Al(Fe,Mn)Si等硬脆相数量及尺寸,改善Al-Si-Mg系铸造合金塑性的途径。结果表明,添加Sr后,相互交叉呈“直片状”的共晶硅变质为“细小羽毛状”形态,合金断后伸长率提升137%,强度提升不明显;热处理可通过对共晶硅的熔断与球化,实现铝合金断裂模式与力学性能的改变,人工时效处理可提升合金屈服强度73%,固溶处理可提升合金断后伸长率97%,淬火温度对2#铝合金T6处理的力学性能影响较大,淬火温度为530℃时,经200℃人工时效处理后,铝合金抗拉和屈服强度分别较铸态提高14%和100%,断后伸长率与铸态持平,显示出较为优良的综合力学性能。

This paper analyzes the effects of Sr elements and different heat treatment states on the microstructure,eutectic silicon morphology,mechanical properties,and fracture mode of Al-Si-Mg alloy.The paper also proposes a way to improve the plasticity of Al Si Mg cast alloys by regulating the morphology of eutectic silicon and reducing the number and sizes of hard and brittle phases such as Al(Fe,Mn)Si.The results show that,after Sr modification,the straight sheet eutectic silicon is transformed into fine feather shaped eutectic silicon,the elongation of the aluminum alloy increases by 137%compared to unmodified,while the alloy strength doesn’t improve significantly.After heat treatment,eutectic silicon undergoes melting and spheroidization,changing the fracture mode and mechanical properties of the aluminum alloy.After artificial aging and solid solution treatment,the yield strength and the elongation of the aluminum alloy increase by 73%and 97%respectively compared to the cast state.The quenching temperatures have a significant impact on the mechanical properties of the 2#alloy by T6 treated.When the quenching temperature is 530℃,after artificial aging treatment,the tensile and yield strength of the aluminum alloy are increased by 14%and 100%respectively compared to the cast state,and the elongation remains unchanged,demonstrating superior comprehensive mechanical properties.