氯化物溶液中不锈钢腐蚀疲劳裂纹初始萌生的过程机理

研究了动应力（往复弯曲疲劳应力）对氯化物溶液中不锈钢点蚀敏感性的促进作用。 在固溶态３１６Ｌ不锈钢表面点蚀孔中产生了明显的非敏化态晶间腐蚀。在点蚀孔内受腐蚀晶界处孕育 产生了初态腐蚀疲劳裂纹，裂纹由沿晶转变为穿晶扩展，形成主裂纹并继续扩展直至材料失稳断裂。阐 述了在动应力和侵蚀性介质联合信息作用下ＣＦ裂纹萌生的过程机理。论述了动应力－环境介质－材料 特性在多种腐蚀类型交互作用中的贡献和相关性。

INITIATION MECHANISM OF CORROSION FATIGUE CRACK FOR STAINLESS STEEL IN CHLORIDE SOLUTION

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