循环道次对高温叠轧AZ31镁合金板材组织与性能的影响

目的通过高温累积叠轧工艺制备出高强度的镁合金,并研究该过程中循环道次对AZ31镁合金板材的微观组织与性能的具体影响。方法对累积叠轧1～5次板材进行微观组织观察,并进行显微硬度的测试,得到不同板材的硬度值,通过X射线衍射分析得到不同板材的取向结果,最终进行力学性能实验,并对比分析。结果随着循环道次的增加,板材抗拉强度有明显改变。从260 MPa先增加至310 MPa,最后稳定在350 MPa左右;非基面织构比重增加;断裂伸长率先降低后升高并稳定在10%左右。结论累积叠轧工艺使得AZ31镁合金板材产生了加工硬化,并显著细化了晶粒。循环道次的增加、孪晶产生和晶界数量显著增多导致强度进一步提高。

Effects of Cyclic Passes on Micro-structure and Properties of AZ31 Magnesium Alloy Sheet Rolled at High Temperature

The paper aims to prepare high strength magnesium alloys with the high temperature cumulative overlapping rolling process, and study the specific effect of the cyclic passes on the microstructure and properties of AZ31 magnesium alloy sheet. Microstructure observation and micro-hardness test were carried out on accumulative rolled sheets for 1~5 times to obtain the hardness of different sheets. Orientation results of different sheets were obtained by X-ray diffraction analysis. Finally, mechanical properties were tested and compared. It was found that the tensile strength of the sheet changed obviously from 260 MPa to 310 MPa with the increase of the cyclic passes, the final became stable at about 350 MPa. The proportion of non-base texture increased, and the fracture elongation decreased firstly, then increased and stabilized at about 10%. The cumulative overlapping rolling process leads to work hardening and remarkable grain refinement of AZ31 magnesium alloy sheet. The strength is further improved with the increase of cyclic passes, the generation of twin crystal and the remarkable increase of grain boundary.