Al-7Si-0．3Mg合金低周疲劳行为及其机理  

Low Cycle Fatigue Behavior and Its Mechanism of Al-7Si-0.3Mg Alloy

作　　者：莫德锋[1] 何国求[1] 朱正宇[1] 胡正飞[1] 刘晓山[1] 张卫华[2] 

机构地区：[1]同济大学材料科学与工程学院 [2]西南交通大学牵引动力国家重点实验室

出　　处：《特种铸造及有色合金》2008年第7期493-495,共3页Special Casting & Nonferrous Alloys

基　　金：国家重点基础研究发展计划(973计划)资助项目(2007CB714705);国家自然科学基金资助项目(50771073)

摘　　要：研究了Al-7Si-0.3Mg铸造铝合金在不同等效应变幅值下循环加载时的低周疲劳行为,并用透射电镜(TEM)观察了疲劳失效试样的位错结构。结果表明,位错结构对应变幅值有很强的依赖性,疲劳失效试样的位错密度随应变幅值的增大而增大;由于位错间的交互作用及颗粒的钉扎作用,铸造铝合金表现出明显的循环硬化现象,高应变幅值下,硬化区可贯穿整个疲劳过程;试样的疲劳寿命随应变幅值的提高而下降,并且符合Manson-Coffin关系式。Low cycle fatigue behavior of Al-7Si-0.3Mg alloy was examined by mechanical fatigue testing with equivalent strain amplitude varied from 0.15% to 0.35%, and the dislocation evolution in the specimens was observed by TEM(transmission electron microscope). The results indicate that the dislocation structure is closely dependent on strain amplitude, and the density of dislocation in failure specimens is increased with increasing in equivalent strain amplitude. Cyclic hardening can be found as a result of the dislocation interaction and particle pinning, and hardening region can been throughout the entire fatigue process with the strain amplitude more than 0.35%. Fatigue life is decreased with the increase of the equivalent strain amplitude,confirming to the equation of the Manson-Coffin.

关 键 词：铸造铝合金 低周疲劳 位错 

分 类 号：TG146.21[一般工业技术—材料科学与工程]