Influence of surface finish on fatigue cracking behavior of reactor pressure vessel steel in high temperature water

摘要

The low cycle fatigue behavior of a low-alloy reactor pressure vessel (RPV) steel was investigated in high temperature water. Main attention was paid to the effects of surface finish of specimens on fatigue cracking behavior. It was found that the influence of surface finish on fatigue resistance of the steel was strain-rate dependent in high temperature water. Pretty obvious degradation of fatigue resistance appeared at fast strain rate with rougher surface finish. At slow strain rate, surface circumferential scratches promoted crack initiation and propagation. The fracture surface showed relatively flat and slight crack-arrest features. At fast strain rate, surface scratches also promoted crack initiation, but seemed not to dominate crack propagation. The fracture surface showed typical terraced and fan-like features. The above fatigue cracking behavior can be rationalized by a strain-rate dependent environmentally assisted cracking process of low-alloy RPV steel in high temperature water.