Effect of nitrogen addition on the stress corrosion cracking behavior of 904 L stainless steel welds in 288 degrees C deaerated water

This paper concerns with the effect of nitrogen addition to 904 L stainless steel (SS) welds on their stress corrosion cracking (SCC) behavior in high temperature (288 degrees C) and high pressure (1050 psi) water of high oxygen content (100 ppb) and high conductivity (2.5 mu S/cm). For this study, 316 L SS base plate TIG welded with 904 L SS filler wire and with nitrogen contents of 0.027, 0.058 and 0.095 wt.% were used. Flat pin-loaded tensile specimens were fabricated from transverse welds, with the weld in the gauge length. Slow strain rate tests (SSRT) were carried out at a strain rate of 2.2 x 10(-6) s(-1). The study shows that the samples, when tested in air, failed at the weld fusion zone for 0.027 and 0.058 wt.% N and at the base metal for 0.095 wt.% N. In the environment, the samples failed in the base metal except the one with least nitrogen content (0.027 wt.%). With nitrogen addition, as the failure location shifted to the base alloy, the weld seemed to acquire SCC resistance and became even more resistant than the base alloy. (c) 200