【作者】 何国球； 莫德锋； 朱正宇； 胡正飞； 刘晓山； 张卫华；

【Author】 He Guoqiu~①Mo Defeng~①Zhu Zhengyu~①Hu Zhengfei~①Liu Shaoshan~①Zhang Weihua~②(①.School of Materials Science and Engineering,Tongji University,Shanghai China;②State Key Laboratory of Traction Power,Southwest Jiaotong University,Chengdu China)

【机构】 同济大学材料科学与工程学院； 西南交通大学牵引动力国家重点实验室；

【摘要】 在等效应变幅为0.22%时,研究了Al-7Si-0.3Mg铸造铝合金在比例与非比例载荷下的循环变形行为,并用透射电子显微镜镜(TEM)观察了疲劳失效试样的位错结构。结果表明:在多轴加载条件下,材料均表现出循环硬化现象,循环硬化的速度和程度对加载路径有依赖性;非比例载荷下材料的疲劳寿命远小于比例加载时的寿命,且非比例加载下的疲劳寿命对各种非比例加载路径也有依赖性;位错在不同的加载路径下形成不同的组态结构,位错与强化相、晶界及位错间的交互作用是铸造铝合金发生循环硬化的主要原因。更多还原

【Abstract】 Multi-axial fatigue tests were conducted on cast Al-7Si-0.3Mg alloy under both proportional and nonproportional loading with the same equivalent strain amplitude of 0.22%.TEM was used to investigate the dislocation structure of the fatigue failure specimens.Cyclic hardening is found in this material,but the rate and extent of cyclic hardening is quite dependent on particular loading paths used.The fatigue life under nonportional loading is much lower than that under proportional loading,and it shows different under nonportional loadings when different nonportional loading paths are used.The interaction among dislocation,particle and grain boundary is the main reason for cyclic hardening,and the structure and density of dislocation in fatigue failure specimens under different loading paths exhibit quite different.更多还原