热扭转下AZ31镁合金微观组织和力学性能研究

Study on microstructure and mechanical properties of AZ31 magnesium alloy under hot torsion

为了研究热扭转变形温度对AZ31镁合金微观组织和力学性能的影响,利用TTM103型微机控制电子扭转试验机对挤压态AZ31镁合金棒材进行了25~300℃的热扭转试验。结果表明:在同一变形区域内,随着变形温度的升高,孪晶密度先升高后降低;在变形温度达到250℃时,有动态再结晶产生,之后随变形温度的持续升高,动态再结晶体积分数逐渐增大,抗扭强度逐渐降低,塑性逐渐提高,硬度先增大后减小;在同一变形温度下,扭转边缘区域至中心区域的孪晶密度和动态再结晶体积分数逐渐降低,平均晶粒尺寸逐渐增大,而硬度逐渐减小;热扭转变形在200~300℃下的断裂方式以韧-脆性断裂方式为主,其它温度下以脆性断裂为主。

To study the effects of hot torsional deformation temperature on the microstructure and mechanical properties of AZ31 magnesium alloy,the computer controlled TTM103 electronic torsional testing machine was used to perform hot torsional tests on extruded AZ31 magnesium alloy bars at 25-300℃.The results show that in the same deformation region,with the increase of deformation temperature,the twin density firstly increases and then decreases.Dynamic recrystallization occurs when the deformation temperature reaches 250℃and then the dynamic recrystallization volume fraction increases with the increase of deformation temperature,the torsion strength gradually decreases,and plasticity gradually increases,and the hardness first increases and then decreases.At the same deformation temperature,the twin density and dynamic recrystallization volume fraction from the torsional edge region to the central region gradually decrease,the average grain size gradually increases,and the hardness gradually decreases.The fractur mode of hot torsional deformation is mainly tough-brittle fracture at 200-300℃,and brittle fracture at other temperatures.