大应变热轧过程中AZ31镁合金显微组织及织构的演变

摘要

在823 K下对工业用AZ31镁合金板材进行约70%压下量的单道次轧制实验。结果表明，细小的再结晶晶粒不仅分布在轧制板材的剪切带中，同时还存在于板材的表面。剪切带中再结晶晶粒尺寸在0.4~1μm之间。晶粒的显著细化主要来源于流变应力集中过程中所产生的动态再结晶。板材中部的织构为基面织构，织构强度在轧制变形前后未发生明显改变；然而，经过轧制后板材表面织构转变成双峰织构，基面沿板材横向发生倾转。双峰织构的相对强度为26.6，明显高于板材中部织构强度。变形应变的分配差异是板材内部不均匀再结晶及织构差异的主要原因。%Commercial AZ31 magnesium alloy sheets were rolled by nearly 70%thickness reduction in one rolling pass at 823 K. The results show that ultrafine grains are distributed in both shear bands and surfaces of the rolled sheets. The grain size of the refined grain in the shear bands is 0.4−1μm. The outstanding grain refinement is attained by dynamic recrystallization due to flow localization. The texture in middle layer of the sheet is basal texture with little change in intensity throughout the rolling process, while the texture on surface becomes a double-peak texture with basal poles splitting in the transverse direction (TD). The relative intensity of the double-peak texture is 26.6, which is quite higher than that of the texture in the middle layer. The inhomogeneous strain distribution is responsible for the exceptional grain refinement and texture evolution.