摘要
对AZ31镁合金进行固溶和均匀化处理后,再进行不同时间预时效和不同程度形变,最后进行相同的时效处理,研究预时效时间及形变量对金相显微组织和布氏硬度的影响。结果表明:固溶处理使绝大部分Mg_(17)Al_(12)相溶入了α-Mg基体,形变处理后,晶粒被拉长,颗粒相或杂质沿形变方向分布,出现明显的纤维组织,晶粒内部出现大量交错的形变孪晶;形变程度越大,加工硬化效果越显著,形变程度到20%时,硬度增长缓慢;形变前预时效增加了再结晶的形核,在随后的时效处理过程中,发生了再结晶,形变产生的纤维组织消失,生成了等轴晶粒;形变程度越大,再结晶后的等轴晶粒越细小。再结晶软化和时效析出强化的共同作用,使AZ31镁合金的硬度比时效前略有升高。因此,形变热处理前预时效能有效地改善AZ31镁合金的组织及力学性能。
The processes of thermomechanical treatment adopted on AZ31 magnesium alloy are solution treatment,pre-ageing, deformation and ageing. This paper focuses on the effects of the preageing and the sub- sequent deformation on its microstrueture and mechanical properties. The experimental results show that most second phase of MglTA112 dissolved into the substrate of a-Mg and thermomechanical treatment is one of effec- tive process to improve the property of AZ31 alloy. The effect of pre-ageing before deformation is to increase nucleation of recrystallization. The coarse grains are elongated and the second phaoes or impurities distributed along the direction of deformation, which calls fabric stucture. The work hardening is enhanced with increasing of deformation degree, and the hardness rises slowly when the deformation degree beyond 200//00. In addition, many the deformation twins occurred in the deformed grains. Recrystallization is happen during the subsequent ageing treatment, and the deformation belts consists of twins disappeared and changed into equiaxed grains. As deformation degree increasing, the equiaxed grains are finer. Both precipitation hardening and recrystallization softening take effect on its property,therefore the hardness of AZ31 magnesium alloy is increased slightly.
出处
《中原工学院学报》
CAS
2016年第4期53-56,79,共5页
Journal of Zhongyuan University of Technology
关键词
AZ31镁合金
预时效
形变热处理
布氏硬度
显微组织
AZ31 magnesium alloy
pre-ageing
thermo-mechanical treatment
Brinell hardeness
microstructure
