AZ31B镁合金带材热轧过程组织均匀性及性能研究

Study on the microstructure and properties of AZ31B magnesium alloy strip in hot rolling

本文开展了变形温度为300、350、400℃和总压下率分别为15%、30%、45%、60%的AZ31B镁合金带材热轧试验,分析了不同工艺参数对轧后带材的微观组织及力学性能的影响规律。研究表明:随着轧制温度的升高,再结晶百分数增加,晶粒细化显著,组织均匀性增强;当温度达到350℃时,由于中间退火保温导致再结晶晶粒长大,使温度进一步升高,对再结晶程度的影响减弱,轧后带材晶粒度和延伸率均有降低;相比温度参数,提升总压下率对晶粒细化效果更为显著,轧制温度为300℃,压下率为60%时近表面平均晶粒尺寸由10μm细化至3.7μm,中心层晶粒尺寸细化至4.9μm,组织分布较为均匀;压下率的增加有效改善了组织均匀性,使轧后带材延伸率显著增加,拉伸断口的韧窝增多,且逐渐加深。

Hot rolling process tests of AZ31B magnesium alloy strip with rolling temperatures of 300℃,350℃,and 400℃and rolling reductions of 15%,30%,45%,and 60%were carried out.Influences of different process parameters on the microstructure and mechanical properties of the strip after rolling were studied.Results show that with the increase of the rolling temperature,the percentage of the recrystallization was increased,the grain refinement became more significant,and the microstructure uniformity was enhanced.When the temperature reached 350℃,the recrystallization grain grew up due to the intermediate annealing holding,and the influence of the further increase of the temperature on the recrystallization degree was weakened.The grain size and the elongation of the strip were both decreased after rolling.Compared with temperature parameters,the total reduction rate was more significant for grain refining.The near-surface average grain size was refined from 10μm to 3.7μm and the central grain size was refined to 4.9μm at the rolling temperature of 300℃and the reduction rate of 60%,indicating a relatively uniform distribution of the microstructure.The microstructure uniformity was improved by increasing the reduction rate,the elongation of the rolled strip was increased significantly,and the dimple of the tensile fracture was increased and deepened gradually.