Stress Corrosion Studies on Some Stainless Steels in Elevated Temperature Aqueous Environments Available to Purchase

Stress corrosion cracking (SCC) of alloys used in electric power generation equipment, particularly boiler and heat exchanger tubing, is a major factor in reliability, and research continues to develop SCC information for both existing and new alloys. The present study concerns stainless steels with ferritic, martensitic, duplex and austenitic structures. The SCC of the alloys was investigated as a function of heat treatment in a series of environments related to steam supply systems in electric power stations. The ferritic stainless steels were a 12% Cr Type 405, Ti-stabilized 18 Cr-2 Mo, and E-Brite 26 Cr-1 Mo. The high chromium ferritics are susceptible to 885°F embrittlement. At the lower temperatures of the potential applications for which the present work was undertaken, i.e., 600°F, the 885°F embrittlement phenomenon is of unknown potential importance. Therefore, this metallurgical condition was investigated for the two high Cr ferritic alloys. The duplex material was Sandvik 3RE60 which could also embrittle similar to the ferritics; therefore, the 885°F treatment was applied to this material. In austenitic steels, one concern for the corrosion properties remains the 'sensitized' condition which was therefore also included in the present studies. Type 304 stainless steel was used as the reference austenitic and Type 410 as the reference martensitic.