挤压ZK60镁合金的循环变形与疲劳行为研究

Cyclic deformation and fatigue properties for extruded ZK60 magnesium alloy

针对挤压ZK60镁合金在循环变形过程中变形机制开启的问题,在室温下对试样进行了应变控制(Rε=-1)下的单轴疲劳试验,得到了总应变幅为0.25%~5%下的半寿命时的稳定应力-应变滞回曲线和应变幅分别为4%、1%和0.35%时的应力-应变滞回曲线,采用超景深三维显微镜和扫描电子显微镜(SEM)观察试样的疲劳断口形貌,运用了宏观力学性能与微观结构分析相结合的研究方法分析其循环变形过程中的变形机理。研究结果表明:挤压ZK60镁合金的循环变形行为分可为3个不同的部分,应力-应变滞回曲线和疲劳断口形貌随应变幅的变化而变化明显,导致这些差异主要原因是循环变形过程中变形机制的不同。

Aimming at the problems of the deformation mechanism in cyclic deformation for extruded ZK60 magnesium alloy,strain-controlled（the strain ratio is Rε=-1） cyclic loading experiments were carried out at room temperature obtaining stabilized stress-strain hysteresis loops at half-fatigue lives with strain amplitude ranging from 0.25%~5% and cyclic stress-strain hysteresis loops at strain amplitudes of 4%,1% and 0.35%,respectively.The super depth of field three-dimensional microscope and the scanning electron microscope（SEM）were used to investigate the fatigue fracture,researching cyclic deformation mechanism by the analysis of macro-mechanical properties and microstructure.The experimental results show that the cyclic deformation behavior for extruded ZK60 magnesium alloy can be divided into three parts.The stress-strain curves and fracture morphology changed with strain amplitude obviously mainly because of the different deformation mechanism during cyclic deformation.