GOALI:Deformation Mechanisms and Microstructure Evolution in Thermo-Mechanical Processing of Mg Alloys for Structural Automotive Applications

目标：汽车结构应用镁合金热机械加工中的变形机制和微观结构演变

• 批准号: 1006784
• 负责人: Surya Kalidindi
• 金额: $ 45万
• 依托单位: Drexel University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-15 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1006784&HistoricalAwards=false
• 关键词: GOALI; Deformation; Mechanisms; Microstructure; Evolution

TECHNICAL SUMMARY: Although it has been widely observed that deformation twinning plays a dominant role in the deformation response of Mg alloys at room and elevated temperatures, its precise role on the ductility of these alloys is not yet understood. Establishing the physics of the underlying deformation mechanisms in Mg alloys has been complicated by many factors, including (i) the dramatic morphological and strain hardening rate differences between the two families of deformation twins observed in Mg alloys, (ii) the strong influence of grain size and temperature on the extent of deformation twinning, (iii) the activation of dynamic recrystallization during plastic deformation at elevated temperature, (iv) the activation of rotational dynamic recrystallization in some coarse-grained Mg alloys in certain temperature ranges, and (v) the potentially different influences of extension and contraction twins on the recrystallization processes. It is proposed to undertake a detailed experimental and modeling study to develop quantitative insights into the underlying deformation mechanisms in thermo-mechanical processing of two specific Mg alloys: AZ31 and Mg-0.2wt% Ce. Experimental investigations will include room and high temperature simple compression tests which will be interrupted for detailed microstructure investigations using orientation image microscopy and measurements of the local stored energy at the grain scale in plastically deformed samples. It is also proposed to develop and validate new physics-based elastic-viscoplastic crystal plasticity models to predict the anisotropic stress-strain response and the evolution of the microstructure in thermo-mechanical deformation of these alloys. These models will be subsequently employed to develop novel processing routes for cost-effective manufacture of structural automotive parts made from Mg alloys.NON-TECHNICAL SUMMARY: Strong but light magnesium (Mg) alloys offer tremendous potential for dramatic increases in the fuel efficiency of automobiles, with corresponding reductions in automotive CO2 emissions. The primary impediment to widespread application of these alloys is their very limited room temperature ductility, which prevents successful manufacture of the desired automotive structural components by standard inexpensive wrought processing methods. This proposal aims to produce the fundamental physical data sets and computational models of Mg alloy structure which are needed to find ways to improve the room temperature ductility of these alloys. The proposed interdisciplinary collaboration between researchers at Drexel University and at the General Motors Global R&D Center will result in the development of better Mg alloys for the automotive industry and may also have implications for the processing of other metals with similar crystalline structures. This project will produce two PhDs skilled in interdisciplinary research involving novel material characterization techniques, advanced computational mechanics, and applied mathematics. The project will expose numerous domestic undergraduate and graduate students, especially members of underrepresented groups in science and engineering, to cutting edge research methodologies and equipment.

技术摘要：尽管人们已经广泛观察到变形孪生在镁合金在室温和高温下的变形响应中起主导作用，但其对这些合金延展性的确切作用尚不清楚。建立镁合金潜在变形机制的物理过程因许多因素而变得复杂，包括（i）在镁合金中观察到的两个变形孪晶家族之间显着的形态和应变硬化率差异，（ii）晶粒的强烈影响尺寸和温度对变形孪晶程度的影响，（iii）高温塑性变形过程中动态再结晶的激活，（iv）某些粗晶镁合金在某些温度范围内旋转动态再结晶的激活，以及(v) 拉伸和收缩孪晶对再结晶过程的潜在不同影响。建议进行详细的实验和建模研究，以定量了解两种特定镁合金：AZ31 和 Mg-0.2wt% Ce 热机械加工中的潜在变形机制。实验研究将包括室温和高温简单压缩测试，这些测试将被中断，以使用定向图像显微镜进行详细的微观结构研究，并测量塑性变形样品中晶粒尺度的局部存储能量。还建议开发和验证新的基于物理的弹粘塑性晶体塑性模型，以预测这些合金热机械变形中的各向异性应力应变响应和微观结构的演变。这些模型随后将用于开发新颖的加工路线，以经济高效地制造由镁合金制成的结构汽车零件。非技术摘要：高强度但轻质的镁 (Mg) 合金为大幅提高汽车燃油效率提供了巨大的潜力，汽车二氧化碳排放量相应减少。这些合金广泛应用的主要障碍是它们非常有限的室温延展性，这阻碍了通过标准的廉价锻造加工方法成功制造所需的汽车结构部件。该提案旨在产生镁合金结构的基本物理数据集和计算模型，以找到提高这些合金的室温延展性的方法。德雷塞尔大学和通用汽车全球研发中心的研究人员之间拟议的跨学科合作将为汽车行业开发出更好的镁合金，并且也可能对具有类似晶体结构的其他金属的加工产生影响。该项目将培养两名擅长跨学科研究的博士学位，涉及新型材料表征技术、高级计算力学和应用数学。该项目将使众多国内本科生和研究生，特别是科学和工程领域代表性不足的群体的成员，接触到最先进的研究方法和设备。