Elucidation of effect of hydrogen on giga-cycle fatigue mechanism and establishment of improvement method of fatigue strength reliability

氢对十次循环疲劳机理的阐明及疲劳强度可靠性改进方法的建立

基本信息

批准号：
14001002
负责人：
YUKITAKA Murakami
金额：
$ 292.86万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Specially Promoted Research
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2006
项目状态：
已结题

项目摘要

In recent years, a special concern has been raised about the development and commercialization of fuel cell (FC) systems to solve both the global warming and energy problems. Under such circumstance, the role of this research project has been significantly increasing to ensure the safety use of FC systems in the near future. In this project, the effect of hydrogen on giga-cycle fatigue mechanism in high strength steels has been studied as well as the effect of hydrogen on fatigue properties of candidate materials for FC systems. The obtained results are as follows:(1) The evidences of interaction of hydrogen on giga-cycle fatigue failure have been shown by the fatigue tests of hydrogen-content-controlled specimens, the secondary ion mass spectrometry and the tritium autoradiography.(2) The giga-cycle fatigue mechanism taking the hydrogen interaction into consideration has been proposed. It has been shown that the giga-cycle fatigue strength can be improved by controlling hydrogen content in materials, inclusion size and inclusion type.(3) A fatigue design method in giga-cycle regime has been proposed based on the area parameter model, the statistics of extremes and the growth curve of the optically dark area (ODA).(4) A number of reliable fatigue data on the effect of hydrogen has been obtained about the candidate materials for FC systems. In addition, some important findings about the degradation mechanism due to hydrogen have been given, e.g. the slip localization due to hydrogen and the effect of phase transformations on the crack-growth acceleration, etc.Considering all the results in this project, the following two significant conclusions have been obtained:(I) Hydrogen does not cause so-called "embrittlement" of materials, but facilitates the dislocation mobility resulting in the slip concentration.(II) The role of hydrogen trapped by inclusions in giga-cycle fatigue mechanism is to cause the microscopic slip concentration even at the lower stress.

近年来，为了解决全球变暖和能源问题，燃料电池（FC）系统的开发和商业化受到了特别关注。在这种情况下，该研究项目的作用显着增强，以确保不久的将来FC系统的安全使用。在该项目中，研究了氢对高强度钢的十次循环疲劳机制的影响，以及氢对FC系统候选材料疲劳性能的影响。得到的结果如下：(1)通过控氢试件的疲劳试验、二次离子质谱和氚放射自显影，证明了氢相互作用对十次循环疲劳失效的影响。(2)提出了考虑氢相互作用的千兆循环疲劳机制。结果表明，通过控制材料中的氢含量、夹杂物尺寸和夹杂物类型，可以提高千兆周疲劳强度。(3)提出了基于面积参数模型的千兆周疲劳设计方法， (4)针对燃料电池系统的候选材料，获得了许多关于氢影响的可靠疲劳数据。此外，还给出了一些关于氢降解机制的重要发现，例如考虑到本项目的所有结果，得到以下两个重要结论：（一）氢不会引起所谓的“脆化” (II)在千兆周疲劳机制中，夹杂物捕获的氢的作用是即使在较低应力下也会引起微观滑移集中。