SCC of sensitized 304SS in high temperature water with anionic impurities contamination

摘要: This paper describes some results selected from a larger program which was aimed at understanding the stress corrosion cracking initiation of 304 stainless steel in high temperature deaerated/hydrogenated water. With large number statically loaded samples it became apparent that challenge to initiate SCC on tested However, only small minority samples, were thermally sensitized underwent SCC. The presented here shows findings investigation these and indicates synergism between sensitization, ionic impurities and/or superficial defects as well aggravating factor cold work. In fact, none non materials (within time scale tests), while three sample extensive crack morphology fractured predominantly intergranular with transgranular regions. Transmission electron microscope (TEM) containing tips prepared by focused ion beam (FIB). analysis revealed contain dual layer oxide (outer magnetite inner Cr rich oxide) metallic Ni enrichment ahead tip. Furthermore, finger-like features protruding several hundreds nanometres along slip planes intersecting found. It also noted oxidation deformation bands developed asymmetrically advancing further into grain most favourable crystallographic orientation. is likely be caused dominating one consequent generation strain gradient across boundary. therefore postulated propagation might associated formation inside material.