热扭转变形温度对AZ80镁合金微观组织的影响

Effect of Hot Torsion Deformation Temperature on Microstructure of AZ80 Magnesium Alloy

利用Gleeble-3500热模拟试验机对AZ80镁合金进行了热扭转变形试验,变形温度分别选取为300、340和380℃,扭转角速度为0.7 rad/s。利用光学显微镜(OM)和电子背散射衍射技术(EBSD)对AZ80镁合金在扭转变形条件下的显微组织和微观织构演变规律进行了研究。结果表明:热扭转变形能够显著细化晶粒,当扭转角速度一定时,升高温度能够促进动态再结晶(DRX)的产生,提高变形组织的均匀性。同时,小角度晶界所占比例随着变形温度的升高而逐渐减小,表明有连续性动态再结晶(CDRX)的发生。此外,热扭转变形能够显著调整合金的微观织构,织构极密度随着温度的升高呈现出先降低而后升高的趋势,在340℃时取得最小值18.476。

The thermal-torsional transformation test of AZ80 magnesium alloy was carried out by Gleeble-3500 thermal simulation test machine, and the deformation temperatures were 300 ℃, 340 ℃and 380 ℃, respectively, the torsional angular velocity was 0.7 rad/s. The microstructure and microtexture evolution rules of AZ80 magnesium alloy under torsional deformation were studied by optical microscope(OM) and electron backscatter diffraction(EBSD) technique. The results show that the thermal torsional deformation can significantly refine the grains. As the torsional angular velocity is constant,increasing temperature can promote the production of dynamic recrystallization(DRX) and increase the uniformity of deformed microstructure. At the same time, the proportion of small angle grain boundary decreases with the increase of deformation temperature, which indicates that a continuous dynamic recrystallization(CDRX) occurs. In addition, the thermo-torsional transformation can significantly adjust the microtexture of the alloy. With the increase of temperature, the polar density of texture decreases first and then increases, the minimum value at 340 ℃ is 18.476.