挤压铸造和重力铸造A356铝合金低周疲劳行为研究  

Low Cycle Fatigue Behavior of A356 Aluminum Alloy Prepared by Squeeze Casting and by Gravity Die Casting

作　　者：郑成坤[1] 娄照辉[1] 程佩[1] 范建磊[1] 林波[1] 张卫文[1] 

机构地区：[1]华南理工大学机械与汽车工程学院

出　　处：《特种铸造及有色合金》2013年第8期735-739,共5页Special Casting & Nonferrous Alloys

基　　金：GD-NSFC联合基金资助项目(U1034001);国家科技支撑计划资助项目(2011BAE21B00);博士点基金资助项目(20120172110045)

摘　　要：通过低周疲劳试验,结合金相分析、静态力学性能测试、SEM等手段,对比研究了重力铸造和挤压铸造A356铝合金的低周疲劳行为。结果表明,两种制备工艺下的合金都表现为明显的持续循环硬化行为,但挤压铸造工艺下,压力使针状Si更加细小弥散,二次枝晶减小,缩松、气孔等铸造缺陷减少,组织致密度提高,使得循环应力响应曲线的最大值增加,且循环变形抗力和低周疲劳寿命提高。两种工艺下合金的循环塑性应变能密度都随着循环周次的增加而减小,在相同应变幅条件下,挤压铸造合金的循环周次增加,消耗的总能量增加。The low-cycle fatigue behavior of squeeze casting and gravity casting A356 alloys was investiga- ted by the strain-controlled fatigue experiment, tensile testing, optical microscope（OM）, scanning elec- tronic microscope（SEM）. The results show that the A356 alloy prepared exhibits cyclic strain hardening in both processing methods. With pressure, as a result of the smaller and dispersive needle-like silicon particles and the decrease of SDAS as well as elimination of the shrinkage and porosity in the squeeze casting alloy parts, the maximum values in cyclic stress response curve, the cyclic deformation resistance and low cycle fatigue life of the A356 alloy are increased. The plastic cyclic strain energy density is de- creased with the increase of cyclic time in the alloy prepared by two kinds of methods. However, the cy- clic time and the total energy consumption of the squeeze cast alloy are increased at the same strain am- plitude condition comparing with the gravity cast alloy.

关 键 词：挤压铸造 重力铸造 A356铝合金 低周疲劳 

分 类 号：TG249.2[金属学及工艺—铸造]