GOALI: Warm Forming Studies of Magnesium Alloys under Uniaxial and Biaxial Deformation

该项目解决了成分，显微组织和加工对镁合金的可成形性的影响，用于运输行业的轻量化应用。一种改进的变形工艺称为多次压印/瓦楞和平整（MCF）将用于生产随机取向的超细晶粒，以改善成形特性，特别是在相对较低的温度下增加应变速率敏感性。本文的主要目的是对镁合金板材的微观组织、微观织构、拉伸流动响应和双向成形行为进行详细的分析。晶粒尺寸和晶粒取向差的分布的演变将被分析为加工步骤和温度的函数。特别注意变形机制，包括孪生和滑移，以及动态再结晶和晶粒长大的动力学。将在实验结果和现有理论的基础上寻求微观结构参数和应力-应变-应变率响应之间的定量关系，并描绘最佳成形性路径。标准AZ 31 B合金将被视为沿着通过添加稀土和过渡元素以改善耐腐蚀性和蠕变性的改性合金。沿着实验研究，基于物理的本构关系将被用于预测双向变形样品的成形极限曲线和变薄，以与实验数据进行比较。拟议的努力，共同分享的大学参与者和合作者，戴姆勒克莱斯勒公司和Thixomat公司，考虑了两种镁合金，探讨加工-微观组织-流动关系及其对成形极限的影响。这项基础研究的结果将更清楚地定义成分，微观结构和加工对镁合金可成形性的影响，这些镁合金可应用于运输和其他行业，其中轻质材料是先决条件。该项目涉及大学和工业实验室的研究人员。

The project addresses the effects of composition, microstructure and processing on the formability of Mg alloys for lightweight applications in transportation industry. A modified deformation processing known as multiple coining/corrugating and flattening (MCF) will be used to produce randomly-oriented ultra-fine grains for improved forming characteristics, in particular the increased strain-rate sensitivity at relatively low temperatures. A major objective is to perform detailed analyses of microstructure, microtexture, tensile flow response and biaxial forming behavior of Mg sheets. The evolution of distributions in grain size and grain misorientation will be analyzed as functions of processing steps and temperature. Particular attention will be paid to deformation mechanisms including twinning and slip, and the kinetics of dynamic recrystallization and grain growth. Quantitative relations between microstructural parameters and stress- strain-strain rate response will be sought on the basis of experimental results and existing theories, and optimum formability paths will be delineated. The standard AZ31B alloy will be considered along with a modified alloy by adding rare earth and transition elements for improved resistance to corrosion and creep. Along with the experimental studies, physically based constitutive relations will be used to predict forming limit curves and thinning in biaxially deformed samples, for comparison with experimental data.%%%The proposed effort, jointly shared by the University participants and collaborators, Daimler Chrysler Corporation and Thixomat, Inc., considers two Mg alloys to explore processing-microstructure-flow relations and their influence on formability limit. The results of this fundamental study will define more clearly the effects of composition, microstructure and processing on the formability of Mg alloys that find applications in transportation and other industries where lightweight materials are a prerequisite. The project involves researchers at the university and the industrial laboratories.***