Experimental study of micro-cracking in Mg alloys based on the deformation response under dynamic loading

基于动加载下单轴拉压试验数据，采用有限元模拟方法设计了双剪试件。采用纯镁和Mg-Y合金挤压体，沿挤压方向有4种剪切面进行双剪切加工。结果表明，裂纹起裂处的剪切应力和剪切位移与取样方向密切相关。添加钇溶质可减弱各向异性，从而增强了合金的塑性和韧性。结果表明，微裂纹萌生频率与基面分布有关。韧性增强的趋势与细晶高强镁合金基体织构减弱导致韧性增强的趋势相似。

A double-shear specimen was designed by FEM simulation based on experimental data of uniaxial tension and compression under dynamic loading. The double-shear specimen was machined from pure magnesium and Mg-Y alloy extrusions having four kinds of shear plane against the extruded direction. As a result, shear stress and shear displacement at crack initiation strongly depended on the sampling direction. The enhanced ductility and toughness was attributed to weakened anisotropy by adding the yttrium solute. It was found that the frequency of micro-crack initiation depended on the basal plane distribution. The trend in the toughness enhancement was similar to the fact that weakened basal texture led to toughness enhancement in high strength Mg alloys having fine-grained structure.