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研究了电脉冲连续退火对冷轧时效态AZ91镁合金带材显微组织和力学性能的影响。结果表明:电脉冲退火在较低的温度下快速完成了α-Mg基体的再结晶,可显著细化晶粒。当退火温度为210℃时,α-Mg基体发生完全再结晶,其平均晶粒尺寸由冷轧态的约30μm减小为约7μm,带材的抗拉强度由冷轧态的410 MPa减小至334 MPa,断后伸长率由冷轧态的3.7%增大至23%。电脉冲退火后带材的拉伸断裂方式由冷轧态的脆性沿晶断裂转变为韧性穿晶断裂。电脉冲在其热效应和非热效应的共同作用下快速完成再结晶过程以及β-Mg17Al12相阻碍α-Mg基体晶粒长大,是电脉冲退火细化晶粒的主要原因。
The effects of continuous annealing of electric pulse on the microstructure and mechanical properties of AZ91 magnesium alloy strip during cold rolling were studied. The results show that the electrical pulse annealing can rapidly recrystallize the α-Mg matrix at a lower temperature, which can remarkably refine the grains. When the annealing temperature was 210 ℃, the α-Mg matrix was completely recrystallized, the average grain size decreased from about 30μm in the cold-rolled state to about 7μm, and the tensile strength of the strip decreased from 410 MPa in the cold-rolled state To 334 MPa, the elongation at break increased from 3.7% in cold rolled state to 23%. After the electrical pulse annealing, the tensile fracture mode of the strip changes from brittle fracture along cold-rolled to ductile fracture. The rapid completion of the recrystallization process by the electrical pulse combined with its thermal and non-thermal effects and the β-Mg17Al12 phase hinders the grain growth of the α-Mg matrix are the main reasons for grain refinement by electrical pulse annealing.