AQ80M镁合金挤压板材微观组织与力学性能不均匀性的研究

Study on inhomogeneity of microstructure and mechanical properties of AQ80M magnesium alloy extruded plate

通过OM、SEM、XRD、EBSD和拉伸试验,研究AQ80M镁合金挤压板材微观组织及力学性能不均匀性。研究结果表明:AQ80M镁合金挤压板材主要由α-Mg基体和β-Mg17Al12相组成,边部β相分布弥散,再结晶程度比心部的高,心部存在粗大的未再结晶晶粒。经410℃/2 h固溶处理后β相溶入基体,屈服强度下降,断后伸长率上升。从心部到边部多数晶粒的c轴(<0001>轴)从平行于ND方向转变为平行于TD方向,在不同区域沿ND方向拉伸时的变形机制发生变化。沿ED方向拉伸柱面滑移施密特因子(SF)大于0.4的晶粒占比和平均SF比TD和ND方向的高,这是导致AQ80M镁合金挤压板材各向异性的主要原因。边部沿ED方向拉伸基面滑移SF大于0.4的晶粒占比和平均SF比心部的低,柱面滑移SF大于0.4的晶粒占比和平均SF比心部的高,导致边部屈服强度更高。

Inhomogeneity of microstructure and mechanical properties of the AQ80M magnesium alloy extruded plate were studied by OM,SEM,XRD,EBSD and tensile tests.The results show that the AQ80M magnesium alloy extruded plate mainly consists of theα-Mg matrix andβ-Mg17Al17 phase.Theβ-phase is dispersed in the outer region,in which the degree of recrystallization is higher than that in the inner region,containing coarse non-recrystallized grains.After solution treatment at 410℃for 2 h,theβ-phase dissolves into the matrix,the yield strength decreases while the elongation increases.From the inner to the outer region,the texture type shifts from<0001>//ND to<0001>//TD.The tensile deformation mechanism of different regions along the ND changes.Besides having a higher average SF,the proportion of grains with prismatic slip Schmid factors(SF)more than 0.4 along the ED is higher than those along the TD and ND,leading to the anisotropy of AQ80M magnesium alloy extruded plate.The proportion of grains with basal slip SF more than 0.4 and the average SF along the ED in the outer region are lower than those in the inner region,while the proportion of grains with prismatic slip SF more than 0.4 and average SF in the outer region are higher.Consequently,the yield strength in the outer region is higher.