316L不锈钢在模拟人体液内腐蚀疲劳裂纹萌生和扩展过程中应力的作用

EFFECT OF STRESS ON INITIATION AND PROPAGATION OF CORROSION FATIGUE CRACKS FOR TYPE 316L STAINLESS STEEL IN HANK'S PHYSIOLOGICAL SOLUTION

探讨应力在316L不锈钢腐蚀疲劳过程中的作用。应力降低了不锈钢的点蚀电位,促进了腐蚀疲劳裂纹的萌生和扩展。初始疲劳裂纹在点蚀孔中的晶界上萌生,在应力的作用下,裂纹由沿晶变为穿晶扩展,并在断口上产生二次裂纹和疲劳辉纹。

The effect of stress on the initiation and propagation of corrosion fatigue cracks for type 316L stainless steel in Hank's physiological solution was studied. The open circuit potential was not affected by dynamic stress, but the pitting potential decreased with the increase in stress. Pitting corrosion occurred more easily under the effect of stress and the area of higher stress concentration showed higher pit density. Under the coaction of stress and corrosive medium, several corrosion fatigue microcracks might initiated intergranularly at the pit bottom. One of them became the main crack and propagated transgranularly due to stress concentration at the crack tip. The fatigue striation and secondary cracks were observed on the fracture surface.