淬火速率对砂铸Al-7Si-0.4Mg合金拉伸性能及疲劳裂纹扩展行为的影响

Effects of quenching rate on tensile properties and fatigue crack growth of sand casting Al-7Si-0.4Mg alloy

研究了淬火速率对峰值时效状态下的砂铸Al 7Si 0 .4Mg合金拉伸性能及疲劳裂纹扩展行为的影响。结果表明 ,随着淬火速率的提高 ,合金的抗拉强度、屈服强度以及α(Al)相的显微硬度均有提高 ,抗拉强度和屈服强度与淬火速率的对数值近似成线性关系。淬水速率对合金的延伸率影响较小 ,但对合金的室温疲劳裂纹扩展速率有明显影响 。

The effects of quenching rate on the tensile properties and fatigue crack growth of the peak aged sand casting Al 7Si 0.4Mg alloy were studied. The results show that as the quench rate increases, the ultimate tensile strength, yield strength and Vickers hardness of the α (Al) matrix of the alloy all increase remarkably; with the peak aged condition, both σ b and σ 0.2 are logarithmic functions of the quenching rate; the quenching rate has little influence on the total elongation of the alloy, but obviously affects the fatigue crack growth of the alloy at room temperature; higher quenching rate can improve the resistance to fatigue crack growth of the alloy.