环境对AISI321不锈钢疲劳裂纹扩展过载效应的影响  

EFFECTS OF ENVIRONMENT ON THE OVERLOAD BEHAVIOR OF FATIGUE CRACK PROPAGATION FOR AISI 321 STAINLESS STEEL

作　　者：关辉[1] 李劲[2] 魏学军[1] 韩恩厚[1] 柯伟[1] 

机构地区：[1]中国科学院金属研究所金属腐蚀与防护国家重点实验室,沈阳110016 [2]复旦大学材料科学系,上海200433

出　　处：《金属学报》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

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.

关 键 词：环境 不锈钢 疲劳裂纹扩展 过载效应 

分 类 号：TG142.71[一般工业技术—材料科学与工程] TG111.7[金属学及工艺—金属材料]