310奥氏体不锈钢应力腐蚀的透射电镜原位观察

IN SITU TEM OBSERVATION OF SCC IN 310 STAINLESS STEEL

用自制的恒位移加载台，在透射电镜中原位观察３１０奥氏体不锈钢在纯水中局部溶解前后裂尖位错组态的变化以及微裂纹的形核和扩展．结果表明，３１０奥氏体不锈钢在室温纯水中局部阳极溶解能促进位错发射、增殖和运动，在低应力下，纳米级微裂纹在无位错区中连续或不连续形核，由于介质的作用，纳米级微裂纹并不钝化成空洞或缺口，而是解理扩展．

The in situ TEM observations of dislocation emission, motion and the initiation of nanocrack in 310 stainless steel in water were carried out. Using a special constant deflection device,the dislocation configuration change ahead of a loaded crack tip before and after anodic dissolution in the the deionized water and the initiation, propagation of nanometre scale stress corrosion cracks have been oberved. The results showed that SCC in thin foil specimen of 310 stainless steel can occur in water.The localized anodic dissolution of 310 stainless steel in water at room temperature facilitated dislocation emission, multipication and motion. A nanocrack initated in the DFZ or at the blunted crack tip in corrosion solution after dislocations emission, multiplication and motion reached critical condition. Because of the influence of the corrosion solution, the nanocrack propagates and forms a cleavage microcrack during stress corrosion instead of blunting into a void as it does during a tension test without solution.