GOALI: Deformation Microscopy of Retained Austenite Transformation in TRIP Steels

GOALI：TRIP 钢中残余奥氏体转变的变形显微镜

• 批准号: 1507095
• 负责人: David Fullwood
• 金额: $ 45.55万
• 依托单位: Brigham Young University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-01 至 2019-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1507095&HistoricalAwards=false
• 关键词: GOALI; Deformation; Microscopy; Retained; Austenite

NON-TECHNICAL SUMMARY:The efficiency of modern vehicles critically affects individual and national prosperity, national energy independence, city pollution levels (and related health) and climate change. A key element in deciding this efficiency is vehicle weight. While many ongoing efforts aim at introducing lightweight materials (such as aluminum, magnesium and carbon composites) into automotive structures, the dominant constituent, by far, is still relatively heavy steel. Hence this project focuses on the alternative light-weighting strategy of developing advanced high strength steels with improved formability; this will allow less metal to provide the same structural and safety performance. New and emerging microscopy techniques are combined with simulation to reveal the relationships between microstructure and properties of modern high-strength steels. The resulting insights lead to the deeper levels of understanding and improved models that are required for the nascence of so-called third-generation steels and a step-change in vehicle weight and efficiency. Not only does this research project provide an environment for mentoring graduate and undergraduate students in a mixed academic / industrial setting (via a strong collaboration with General Motors), but high school education is being improved via an outreach program. Teachers from local high schools spend time on the project during the summer months while receiving help in developing new and relevant curriculum components for their classes.TECHNICAL SUMMARY:Many studies have been carried out on TRIP (Transformation Induced Plasticity) steels. However, there is still no systematic information concerning the influence of austenite chemistry and microstructure on the resulting transformation to martensite. Such knowledge is critical to the design of texture, morphology and volume fraction of retained austenite in order to enable low-alloy TRIP steels to achieve enhanced strength, formability, and fracture resistance necessary to achieve the desired automotive structure performance. Proposed retained-austenite and martensite identification technologies (based upon emerging electron-backscatter diffraction techniques), along with meso-scale dislocation characterization, are combined with micro-digital image correlation (DIC) to provide a new 'Deformation Microscopy' capability. The resultant framework allows for the assessment of interactions between dislocations and hard phase boundaries, while also precisely capturing the strains at which the various retained austenite islands transform. Knowledge of the fundamental links between microstructure and formability enables the formulation of a meso-scale model for transformation of austenite to martensite, and related deformation phenomena.

非技术摘要：现代车辆的效率严重影响个人和国家繁荣，国家能源独立性，城市污染水平（以及相关的健康）以及气候变化。决定这种效率的关键要素是车辆重量。尽管许多持续的努力旨在将轻质材料（例如铝，镁和碳复合材料）引入汽车结构，但到目前为止，主要成分仍然相对较重。因此，该项目重点介绍了具有提高的高强度高强度钢的替代轻度加权策略。这将允许较少的金属提供相同的结构和安全性能。新的和新兴的显微镜技术与模拟结合使用，以揭示显微结构与现代高强度钢的性质之间的关系。由此产生的见解导致了更深的理解和改进的模型，这些模型是所谓的第三代钢和车辆重量和效率的逐步变化所必需的。该研究项目不仅为在混合学术 /工业环境中的指导研究生和本科生提供了一个环境（通过与通用汽车的强有力合作），而且通过宣传计划改善了高中教育。来自当地高中的老师在夏季的几个月中花费了时间在项目上，同时在开发课程的新课程组件方面获得帮助。技术摘要：许多研究已经进行了旅行（转化诱导的可塑性）钢。 但是，仍然没有关于奥氏体化学和微观结构对产生的马氏体转化的影响的系统信息。这种知识对于保留奥氏体的纹理，形态和体积分数的设计至关重要，以便使低合金跳闸钢钢达到实现所需的自动动力结构性能所需的增强强度，表现性和断裂性。拟议的保留 - 厄斯特林和马氏体识别技术（基于新兴的电子 - 折线衍射技术）以及中尺度的脱位表征与微数数字图像相关（DIC）相结合，以提供新的'变形显微镜'能力。 最终的框架允许评估位错和硬相边界之间的相互作用，同时还可以精确捕获各种保留的奥氏体岛变换的菌株。了解微观结构与形成性之间的基本联系使得可以制定一个中尺度模型，以将奥氏体转化为马氏体，以及相关的变形现象。