Quantitative Evaluation of Environmental Effects on Irreversibility of Cyclic Plastic Deformation by STM Observation

利用STM观测定量评价环境对循环塑性变形不可逆性的影响

基本信息

批准号：
06650774
负责人：
KUMAI Shinji
金额：
$ 1.22万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06650774/
关键词：
Metal fatigue Environmental effects Crack growth STM き裂発生

项目摘要

To get a better understanding of the enviromental influence on fatigue, a study has been undertaken on the fatigue crack growth in various kinds of gaseous environments. Constant load amplitude fatigue crack growth tests were performed in titanium, 8090Al-Li alloys and Fe-3%Si alloys under laboratory air with controlled humidity, nitrogen, argon and vacuum. Increased fatigue crack growth rates were obtained in any gaseous environments compared to that for the vacuum condition. Constant DELTAK fatigue crack growth tests were also performed for the 8090 Al-Li alloys under the controlled laboratory air condition to evaluate the effect of water vapor on the fatigue crack growth. The relative humidity (RH) of the laboratory air were systematically changed in the range of 0.01% to 40%. Fatigue crack growth rates were increased as increase in the relative humidity. However, the increase was observed in the range of 0.01% to 30%RH,and over the 30%RH the crack growth rates were unchanged. No crack delamination was observed in the vacuum condition. Precise observation and quantitative evaluation of the fatigue surface morphology of Fe-3%Si alloys have been made using an STM (Scanning Tunneling Microscope). Further experimental research using AFM is strongly required in order to evaluate the environmental effects on the fatigue crack initiation and growth.

为了更好地了解环境对疲劳的影响，对各种气体环境中的疲劳裂纹扩展进行了研究。在控制湿度、氮气、氩气和真空的实验室空气下，对钛、8090Al-Li 合金和 Fe-3%Si 合金进行恒载荷幅疲劳裂纹扩展试验。与真空条件相比，在任何气体环境中都获得了增加的疲劳裂纹扩展速率。还在受控的实验室空气条件下对 8090 铝锂合金进行了恒定 DELTAK 疲劳裂纹扩展试验，以评估水蒸气对疲劳裂纹扩展的影响。实验室空气的相对湿度（RH）在0.01%至40%的范围内系统地变化。疲劳裂纹扩展速率随着相对湿度的增加而增加。然而，在0.01％至30％RH范围内观察到裂纹扩展率增加，并且超过30％RH裂纹扩展率没有变化。在真空条件下未观察到裂纹分层。利用STM（扫描隧道显微镜）对Fe-3%Si合金的疲劳表面形貌进行了精确观察和定量评价。强烈需要使用 AFM 进行进一步的实验研究，以评估环境对疲劳裂纹萌生和扩展的影响。