双辊铸轧和热轧处理AZ31B镁合金的动态拉伸性能（英文）

Dynamic tensile behaviors of AZ31B magnesium alloy processed by twin-roll casting and sequential hot rolling

研究双辊铸轧和热轧处理AZ31B镁合金板材在室温和应变速率从0.001 s^(-1)到375 s^(-1)条件下的动态拉伸力学行为,以及力学性能与显微结构之间的关系。实验发现,该镁合金板材具有很强的初始基面纤维织构,并且在高应变速率条件下机械孪生成为主要的变形机理。材料的屈服强度和拉伸极限强度随应变速率的提高而提高;然而,孪生诱导的软化效应导致应变强化指数随应变速率的提高而成比例地降低。在准静态拉伸条件下,断裂伸长率随应变速率的提高而明显地降低;而在动态拉伸条件下应变速率对断裂伸长率的影响却不明显。最后,应用扫描电镜对拉伸试样进行了断口形貌分析。分析结果表明,该加工状态下的AZ31B镁合金板材的拉伸断裂是一种韧性与脆性混合断裂模式。

The dynamic tensile behavior of twin-roll cast-rolled and hot-rolled AZ31B magnesium alloy was characterized over strainrates ranging from 0.001 to 375 s^-1 at room temperature using an elaborate dynamic tensile testing method, and the relationshipbetween its mechanical properties and microstructures. It is observed that the sheet has a strong initial basal fiber texture andmechanical twinning becomes prevalent to accommodate the high-rate deformation. The yield strength and ultimate tensile strengthmonotonically increase with increasing the strain rate, while the strain hardening exponent proportionally decreases with increasingthe strain rate due to twinning-induced softening. The total elongation at fracture distinctly decreases as the strain rate increasesunder quasi-static tension, while the effect of strain rate on the total elongation is not distinct under dynamic tension. Fractographicanalysis using a scanning electron microscope reveals that the fracture is a mixed mode of ductile and brittle fracture.