摘要
研究了3.5％NaCl溶液对恒应力强度因子范围△K控制下AISI 321不锈钢疲劳裂纹扩展过载行为的影响,与在空气中的结果比较表明,两种条件下存在相似的过载延缓效应,但是环境极大地削弱了过载对疲劳裂纹扩展的延缓效应,削弱程度随过载比不同而变化,以“损失循环数”表征约为40％—70％,以“过载影响区尺寸”表征则为30％—40％。分析表明,用“损失循环数”表征过载对裂纹扩展的延缓效应不够充分,无法区分环境对裂纹闭合的削弱和增强作用,“过载影响区尺寸”可以区分环境对过载塑性形变增强裂纹闭合的综合影响,对断口的SEM分析发现,过载造成的塑性形变在溶液中比在空气中受到更多的磨损,表明环境对过载延缓效应的削弱除了对裂尖的影响外,还包括对过载导致的塑性诱发裂纹闭合的影响。
The effects of 3.5% NaCl aqueous solution on the overload retardation behavior of AISI 321 stainless steel fatigued under constant ΔK was investigated. The results show that, compared with the air, the environment reduces the overload retardation effect significantly, although the overload behaviors in the air and environment are similar. The reducing level is approximately 40%-70% in terms of loss cycle number, and 30%-40% in terms of overload affecting zone size. The comparison of the above two parameters shows that the former is not a proper parameter to describe the overload effect because of not distinguishing between the strengthening and reducing effects of environment on the crack closure. The later is a better parameter to describe the overload effect because it can distinguish the environmental effect on the crack closure from the comprehensively environmental effects on both crack closure and crack tip. SEM analysis of the fracture surface shows that the overload plastic strain suffered more erosion in environment than in the air. It is suggested that the reduction of the plasticity-induced crack closure caused by environmental corrosion-erosion is responsible for the reduction of the overload retardation effect.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2003年第6期613-616,共4页
Acta Metallurgica Sinica
基金
国家重点基础研究发展规划项目 G19990650资助
关键词
环境
不锈钢
疲劳裂纹扩展
过载效应
environment, stainless steel, fatigue crack propagation, overload
