AZ31镁合金热轧边裂预判模型研究

PREDICTED EDGE CRACK MODEL OF HOT ROLLING FOR AZ31 MAGNESIUM Alloy

摘要:

本文采用等压法,通过等温热压缩实验获得了AZ31镁合金变形温度和应变速率分别在473-673K和0.005-5s_-1条件下对临界断裂应变的影响规律,以及Zener—Hollomon表达式,据此针对AZ31建立了临界断裂应变与变形温度和应变速率间的基本模型；在此基础上,基于镁合金轧制边裂的基本机理,引入Cockcroft Latham断裂准则,建立了含有材料变性激活能和基本轧制工艺参数的AZ31镁合金轧制边裂预判模型；并通过相同条件下有限元模拟和热轧实验分别得到沿板宽方向损伤值和边部裂纹深度,以此对所建立的边裂预判模型进行验证,结果显示所建立边裂预判模型的预测值和实测值平均误差为11.3%。

Abstract:

Base on equal pressure method, isothermal compression tests of AZ31 magnesium alloy at different strain rates of 0.005-5 s?1 and different deformation temperatures of 473-673K were performed by using Gleeble-1500 simulator. The in?uences of deformation temperature and strain rate on the ?ow stress and critical fracture strain were investigated, and established the basic model of critical fracture strain of AZ31. And then the predicted edge cracking model of hot rolling for AZ31 was obtained based on the basic principles of magnesium alloy rolling edge cracking and fracture criterion of Cockcroft Latham, which contains the material deformation activation energy and the technology parameters of rolling. In order to verify the correctness of the predicted edge cracking model was established ,the corresponding relationship was obtained between damage value and edge crack depth along the width direction by the finite element simulation and rolling experiments in the same conditions. The results showed that the average error was 11.3% between predicted values and measured values .