POWRE: A Fundamental Study of Microstructual Evolution in Titanium Alloy Friction Stir Welds

POWRE：钛合金搅拌摩擦焊微观结构演变的基础研究

• 批准号: 0074267
• 负责人: Mary Juhas
• 金额: $ 7.45万
• 依托单位: Ohio State University Research Foundation -DO NOT USE
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-06-01 至 2003-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0074267&HistoricalAwards=false
• 关键词: POWRE; Fundamental; Study; Microstructual; Evolution

This project is aimed at greater understanding of fundamental mechanisms of high temperature deformation and microstructural evolution in titanium alloy friction stir welds. Two alloys have been selected, pure(CP) titanium and Ti-6Al-4V, a + b alloy. CP titanium, used for its corrosion resistance especially in the chemical process industry, was chosen for its good formability. Ti-6Al-4V is widely used in a variety of aerospace and marine applications in welded and unwelded conditions. In addition to "normal" welds, interrupted welds, where the tool is retracted before reaching the end of the two plates to be joined, will also be evaluated. In this way, the micro-structures of the thermomechanically-affected and heat-affected zones will be compared with material just ahead of the weld. These in turn will be compared with microstructures of the stir zone (the actual dynamically recrystallized weld) and the base material. Samples will be obtained for metallographic examination in both the transverse and longitudinal directions to reveal each distinct microstructural zone and serve as a map for the eventual location of TEM foils. A dual beam (electron beam + ion beam) Focused Ion Beam (FIB) will be used to remove TEM foils at precisely designated locations within the welds. This will greatly improve the chances of obtain-ing a foil with the desired microstructural information. Diffraction contrast techniques will be used on a Philips CM 200 and CM 300 Field Emission Gun TEMs to determine the details of the deformation processes, i.e., the development of deformation substructure (e.g., sub-grains and sub-bands), the occurrence of dynamic recovery and recrystallization, annealing effects, and phase transformations. Scanning electron microscopy will be performed on a Philips XL-30 FEG instrument using Orientation Imaging Microscopy to reveal possible microtexture that may be residual from the base material. The results of these microstructural studies will be used to complement process optimization and mechanical property data.%%% This is a research enhancement grant made under the Professional Opportunities for Women in Research and Education (POWRE) program. The PI plans to realign her career after a four-year hiatus in an administrative capacity. Prior to working as Aerospace Team Leader at Edison Welding Institute and Associate Director for the Center for the Accelerated Maturation of Mate-rials (CAMM) at the Ohio State University, she led an active technical career for 15 years. The research is expected to contribute basic materials science knowledge at a fundamental level of special relevance to the behavior of metals. The project is co-supported by the Division of Mate-rials Research, and the MPS OMA(Office of Multidisciplinary Activities). ***

该项目的目的是对钛合金摩擦搅拌焊缝中高温变形和微观结构进化的基本机制有更深入的了解。选择了两种合金，纯（CP）钛和Ti-6al-4V，A + B合金。 CP钛用于其耐腐蚀性，尤其是在化学过程行业中，因此被选为其良好的形成性。 TI-6AL-4V在焊接和未成年条件下的各种航空航天和海洋应用中广泛使用。除了“正常”焊缝外，还将评估在达到两个板的末端之前将工具缩回的焊缝中断的焊缝。以这种方式，将将受力学影响和受热区域的微结构与焊接前的材料进行比较。这些反过来将与搅拌区（实际动态重结晶焊接）和基本材料的微观结构进行比较。将在横向和纵向方向上获得金属学检查的样品，以揭示每个不同的微观结构区，并用作最终位于TEM箔的位置的地图。双光束（电子束 +离子束）聚焦离子束（FIB）将用于去除焊缝内精确指定位置的TEM箔。这将大大提高获得所需的微观结构信息获得箔的机会。衍射对比技术将用于Philips CM 200和CM 300场发射枪中的TEMS，以确定变形过程的细节，即，变形子结构的发展（例如，亚细粒和子频带），动态恢复和再结晶，死亡，死亡效应，以及相位转换。扫描电子显微镜将使用定向成像显微镜在飞利浦XL-30 FEG仪器上进行，以揭示可能是基本材料中残留的微纹解量。这些微观结构研究的结果将用于补充过程优化和机械属性数据。%%％这是研究和教育女性专业机会（POWRE）计划的研究增强补助金。 PI计划以行政身份进行四年休假后的职业生涯。在担任爱迪生焊接研究所的航空航天团队负责人和俄亥俄州立大学伴侣河流成熟（CAMM）中心副主任之前，她领导了一项活跃的技术职业15年。预计该研究将在基本材料科学知识中与金属行为的特殊相关性贡献。该项目由Mate-Rials Research和MPS OMA（多学科活动办公室）共同支持。 ***