A Fundamental Study of Flow Processes in High-Pressure Torsion

高压扭转流动过程的基础研究

• 批准号: 1160966
• 负责人: Terence Langdon
• 金额: $ 60万
• 依托单位: University of Southern California
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1160966&HistoricalAwards=false
• 关键词: Fundamental; Study; Flow; Processes; Pressure

TECHNICAL SUMMARYThe processing of metals through the application of severe plastic deformation provides an opportunity for achieving exceptional grain refinement. In high-pressure torsion (HPT), where a disk is subjected to a pressure and concurrent torsional straining, it is often feasible to reduce the grain size of a metallic alloy to the nanometer range (100 nm). These ultrafine-grained materials exhibit very high strength and a potential for use in superplastic forming processes. Experiments will be conducted to address four major issues in HPT processing. First, experimental parameters that are needed to achieve a fully homogeneous microstructure using HPT will be evaluated. Second, both experimental and theoretical factors that determine the equilibrium grain sizes achieved in HPT will be investigated. Third, the origin of unusual flow patterns, including the presence of swirls and vortices, that have been reported in materials processed by HPT will be investigated. Fourth, HPT will be combined with a surface mechanical attrition treatment (SMAT) to evaluate the opportunity for producing hardened disks that will have considerable use in industrial applications.NON-TECHNICAL SUMMARYThe grain size of a polycrystalline metal is a critical parameter because it determines fundamental properties such as strength and flow characteristics. The processing of metals by high-pressure torsion (HPT) is a relatively new procedure that provides an opportunity for producing bulk metals with extremely small grain sizes. These metals have a very high strength and also exhibit other attractive properties such as excellent formability and good wear resistance. The proposed research is designed to investigate some of the fundamental properties of the HPT processing technique with the objective of optimizing the technique so that it can be used to produce materials of interest for industrial applications. The research group will contain one post-doctoral fellow and at least one student, and they will have an opportunity to participate in a major and important research activity. We will also collaborate with several international groups in Japan, Brazil and Europe, and this will provide the students with an international experience.

技术概要通过应用剧烈塑性变形来加工金属提供了实现异常晶粒细化的机会。 在高压扭转 (HPT) 中，圆盘同时承受压力和扭转应变，通常可以将金属合金的晶粒尺寸减小到纳米范围 (100 nm)。 这些超细晶材料表现出非常高的强度和在超塑性成型工艺中的应用潜力。 将进行实验来解决 HPT 处理中的四个主要问题。 首先，将评估使用 HPT 实现完全均匀的微观结构所需的实验参数。 其次，将研究决定 HPT 中达到的平衡晶粒尺寸的实验和理论因素。 第三，将调查在 HPT 加工的材料中报告的不寻常流动模式的起源，包括漩涡和漩涡的存在。 第四，HPT 将与表面机械磨损处理 (SMAT) 相结合，以评估生产在工业应用中具有大量用途的硬化盘的机会。非技术摘要多晶金属的晶粒尺寸是一个关键参数，因为它决定了强度和流动特性等基本特性。 通过高压扭转 (HPT) 加工金属是一种相对较新的工艺，为生产晶粒尺寸极小的块状金属提供了机会。 这些金属具有非常高的强度，并且还表现出其他有吸引力的特性，例如优异的可成形性和良好的耐磨性。 拟议的研究旨在研究 HPT 加工技术的一些基本特性，目的是优化该技术，使其可用于生产工业应用感兴趣的材料。 研究小组将包含一名博士后和至少一名学生，他们将有机会参与重大且重要的研究活动。 我们还将与日本、巴西和欧洲的多个国际团体合作，这将为学生提供国际经验。