304L不锈钢在高温高压水中的腐蚀疲劳裂纹扩展行为

摘要

基于直流电压降方法(direct current potential drop,DCPD)测量得到了304L不锈钢在325℃空气和含氧超纯水中的疲劳裂纹扩展速率;采用FORD-ANDRESEN模型、Bechtel Bettis模型和PSI模型进行结果分析比较;用扫描电镜观察了断口形貌.结果表明:低频低载荷下,腐蚀对疲劳的加速作用高达1 000倍,高频高载荷下则只有1.5倍;FORD-ANDRESEN模型对于解释腐蚀疲劳机理和预测腐蚀疲劳裂纹扩展速率更加合理与准确,BechtelBettis模型和PSI模型可以对试验结果进行比较,但无法给出各种因素对裂纹扩展的影响;疲劳断口形貌观察到明显的疲劳辉纹,疲劳破坏形式为穿晶断裂.%The fatigue crack growth rate of 304L SS was measured at 325 ℃ in air and oxygenous ultrapure water based on direct current potential drop (DCPD) method.Results were predicted and analyzed with FORD-ANDRESEN model,Bechtel Bettis model and PSI model.The fatigue fracture surface was observed by scanning electron microscopy (SEM).The results showed that the fatigue crack growth rate was accelerated as high as 1 000x at lower frequency & lower load;while only 1.5x at higher frequency & high load.FORD-ANDRESEN model was more proper and accurate for explaining the mechanism of corrosion fatigue and predicting the corrosion fatigue crack growth rate.Bechtel Bettis model and PSI model could estimate and compare the experimental results,but could give explanation of the effects of various parameters on crack growth.The fatigue fracture surfaces revealed obvious fatigue striations,and fatigue failure was transgranular attack.