INITIATION MECHANISM OF CORROSION FATIGUE CRACK FOR STAINLESS STEEL IN CHLORIDE SOLUTION
氯化物溶液中不锈钢腐蚀疲劳裂纹初始萌生的过程机理

The acceleration effect of dynamic cyclic stress on the susceptibility to pitting corrosion for stainless steel 316L in chloride solution was investigated. In the pits on surface of solution treated stainless steel appeared obviously the nonsensitive intergranular corrosion. At the corroded grainboundaries in pits the corrosion fatigue cracks were initiated. The CF cracks propagated and transformed from intergranular to transgranular, forming principal crack and propagating continuously until failure of the material. The transformation course and its effect mechanism from pitting corrosion to CF failure under cyclic stress were investigated. The interaction of multiple corrosion types for stainless steel was proposed and confirmed by the experiment. Under given condition some different corrosion types initiated and progagated one after another or simultaneously, and one corrosion type was accelerated or transformed to another corrosion type. The environmental conditions and material characteristic f