Effect of Cu addition on overaging behaviour,room and high temperature tensile and fatigue properties of A357 alloy

添加Cu对A357合金过时效行为及室温、高温拉伸和疲劳性能的影响

The aims of the present work are to evaluate the overaging behaviour of the investigated Cu-enriched alloy and to assess its mechanical behaviour,in terms of the tensile and fatigue strength,at room temperature and at 200℃,and to correlate the mechanical performance with its microstructure,in particular with the secondary dendrite arm spacing(SDAS).The mechanical tests carried out on the overaged alloy at 200℃ indicate that the addition of about 1.3 wt.%Cu to the A357 alloy enables to maintain ultimate tensile strength and yield strength values close to 210 and 200 MPa,respectively,and fatigue strength at about 100 MPa.Compared to the quaternary(Al−Si−Cu−Mg)alloy C355,the A357−Cu alloy has greater mechanical properties at room temperature and comparable mechanical behaviour in the overaged condition at 200℃.The microstructural analyses highlight that SDAS affects the mechanical behaviour of the peak-aged A357−Cu alloy at room temperature,while its influence is negligible on the tensile and fatigue properties of the overaged alloy at 200℃.

本研究的目的是通过研究富铜合金在室温和200℃下的抗拉强度和疲劳强度以评估合金的过时效行为,并将力学性能与其显微组织,尤其是二次枝晶臂间距(SDAS)相关联。在200℃下对过时效合金进行力学性能测试,结果显示,在A357合金中添加1.3%(质量分数)Cu能够使其极限抗拉强度、屈服强度和疲劳强度分别保持在近210、200和100 MPa。与四元(Al−Si−Cu−Mg)C355合金相比,A357−Cu合金具有更高的室温力学性能和相当的高温(200℃)力学性能。显微组织分析表明,SDAS对峰值时效A357−Cu合金的室温力学行为有影响,而对过时效合金在200℃的拉伸和疲劳性能影响甚微。