摘要
用垂直剖面法研究了GC－4超高强度钢在NaCl水溶液中，不同电化学腐蚀条件下腐蚀疲劳（CF）裂纹亚稳扩展区断口表面的分维特征，并与机械疲劳断口进行了比较。结果发现，弱腐蚀条件下，断口分维值Df与裂纹亚稳扩展速率（da／dN）s之间存在良好的相关性，但相关规律依赖于测量码尺范围；强腐蚀条件下，Df与（da／dN）s之间无明确相关性。同时，Df具有方向性和部位差异性。
Some researchers found that the higher Df (fractal dimension)was, the more resistant was the material to the propagation of fatigue cracking. Other researchers found that such a conclusion could not be drawn. We did experimentai research on Chinese GC - 4 ultra - high strength steel and found after careful analysis that under certain conditions, which are usually satisfied in engineering application, such a conclusion can be drawn for corrosion fatigue cracking of GC - 4 steel.Ih our researeh, we selected landing gear GC - 4 steel and tension - tension fatigue loading and then concentrated on corrosion as the only varinble. When corrosion is slight (usually true in engineering application) and when, in determining the vaiue of Df, the ragged fracture surface is measured in small yardstick of several micrometers (mapnified to several mtheters and measured with a divider), we found that the larger Df is, the smaller is the rate of propagation of corrosion fatigue cracking of GC - 4 steel. We think that the physical meaning is quite clear: a measurement yardstick of severalμm corresponds to the step increase of several μm of crack in the most important initinl stage of crack propagation. We exercised painstaking care in determining value of Df, because we had to calculate a proper aversae value out of different values of Df at different locations and different directions on the frature surface.
出处
《西北工业大学学报》
EI
CAS
CSCD
北大核心
1998年第2期191-195,共5页
Journal of Northwestern Polytechnical University
基金
航空科学基金
国家自然科学基金
关键词
超高强度钢
腐蚀疲劳
分形维数
断口
ultra-high strength steel, fractal dimension (D_f), corrosion fatigue, measuring yardstick
