镁合金板形件扭-挤成形载荷的主应力法求解模型

Solution Model of Principal Stress Method for Torsion-extrusion Forming Load of Magnesium Alloy Plate

结合挤压工艺和高压扭转工艺的优势提出一种扭-挤成形工艺新方法及开发了模拟装置,该工艺不仅能够保证成形,而且还能够有效的细化晶粒。通过分析扭-挤成形工艺金属流动和变形区特点,建立了镁合金扭-挤成形载荷的主应力法求解模型,该模型将变形区划分为四个区域,依次推导了不考虑扭转和考虑扭转成形载荷的求解模型,剪切屈服强度考虑温度和应变速率的效应。通过与成形试验的载荷对比,模型计算结果与试验的结果误差在8%以内。采用该模型分析了不同参数对成形载荷的影响,结果表明随着扭转轴转速的增加,不仅坯料剪切变形增加,且成形载荷减小;成形载荷随坯料半径的增加而增加,随坯料高度的增加呈线性增加,随板件宽度的增加而减小,随板件高度的增加先骤减后平缓减小,且坯料半径和板件高度对成形载荷影响显著。

A new torsion-extrusion forming process and the corresponding simulation device are proposed and designed through considering the advantages of extrusion and high-pressure torsion processes.The developed process is suitable for the forming of the sheet magnesium alloy and is beneficial to the microstructure refinement.Based on the characteristics of metal flow in the deformation zone of the torsion-extrusion process,the principal stress method to solve the model of the torsion-extrusion load is established for magnesium alloy.This model divides the deformation zone into four regions.The model without torsion and the one with torsion are derived sequentially,meanwhile,the shear yield strength depends on the effects of temperature and strain rate.By comparing with the experimental load,the error between the computed and the experimental results is less than 8%.The influence of different deformation parameters on the forming load is analyzed through this model.As the rotation speed of the torsion shaft is increased,the shear deformation of the billet is increased and the forming load is decreased.The forming load is increased with the radius and height of the billet.The load is decreased with the increase of the plate width,moreover,it is decreased sharply and then slowly with the increase of the plate height.Furthermore,the billet radius and the plate height have a significant influence on the forming load.