耦合电脉冲与磁场的降低残余应力方法及其机理的研究

项目名称： 耦合电脉冲与磁场的降低残余应力方法及其机理的研究

项目编号： No.50805085

项目类型： 青年科学基金项目

立项/批准年度： 2009

项目学科： 金属学与金属工艺

项目作者： 蔡志鹏

作者单位： 清华大学

项目金额： 21万元

中文摘要： 通过脉冲电流或磁场可以改变金属材料的塑性，采用特定的外场参数能够实现残余应力的明显降低，但目前尚未见同时施加脉冲电流和磁场的处理方法的报导。从理论上分析耦合脉冲电流和磁场的复合处理方法可能存在增益效应，因而极有开展探索性研究的价值。此外，与外场改变残余应力直接相关的电致塑性和磁致塑性的机理尚需深入研究，特别是微观结构在外加场作用下发生改变的规律还需要实验支持，采用何种观测手段研究微观变化仍是其中的关键问题。本申请拟开展的工作是在现有处理方法的基础上,摸索同时耦合脉冲电流与磁场的复合处理方法对残余应力的作用规律。同时，利用核磁共振技术,探讨电脉冲处理、磁处理及复合电磁处理对材料微观结构影响的相似和不同之处。由于铁磁性材料核磁共振分析技术可以提供磁畴、畴壁及缺陷处的原子结构的多种信息，此项技术的引入有望为电脉冲处理和磁处理的机理研究提供新的实验支持。

中文关键词： 残余应力；核磁共振；电脉冲处理；磁处理

英文摘要： Residual stress can be remarkably decreased through either pulsed electrical current or magnetic field since the plasticity of metals is increased with the external fields. However, the effects of coupling both pulsed electrical current and magnetic field have not been reported yet. The extreme plasticity caused by the coupling external fields would have lots of potential for various applications if it does exits. In this application the possibility is analyzed and deduced and the possible effects are also presented. On the other hand, the mechanism of both electroplastic effects and magnetoplastic effects are being studied in the world wide and the exact connections are still not clear. How to detect micro variations caused by the external fields has became a key point in this field. In this application Nuclear Magnetic Resonance ( NMR ) would be adopted for the observation of micro variations, which is new and would probably provide useful information for the electoplastic effects and magnetoplastic effects. From the reasons above, two key points are presented in this application. One is focused on the study of coupling effects of both pulsed electrical current and magnetic field at the same time, the other is to use NMR to investigate mechanism of both electoplastic and magnetoplastic effects. On the first point, a new method of decreasing residual stress may be developed and used for manufacturing to prolong serving life or improve reliability. As for the second point, NMR would provides details on magnetic domain, domain walls, dislocations, grain boundary and other micro structures, which would be very helpful for the approach of eletroplastic and magnetoplastic effects. New phenomena and theories in this field may be brought out through the technology of NMR.

英文关键词： Residual stress; Nuclear Magnetic Resonance; elecropulsing treatment; magnetic filed treatment