OBSERVATIONS REGARDING STRESS CORROSION PHENOMENA IN AN AUSTENO-FERRITIC STAINLESS STEEL.

The steel investigated is Swedish UHB STAINLESS 44L. The structure is 60% ferrite and 40% austenite. Resistance to stress corrosion cracking was tested in a 40% calcium chloride solution, with and without anodic polarization and in the vapor phase over a solution containing 100 ppm chlorides as NaCl at 225 degree C. Welded and unwelded samples were used. The tensile stress applied was about 450 N/sq mm. No cracking occurred in the base metal. Occasional cracking in welded samples can be avoided if the filler material has the same composition as the base metal and, in the case of multipass welds, the welding is performed in such a way that the first run is exposed to the environment in which stress corrosion resistance is required. This is especially important when using electrodes that solidify as austenite, such as Inconel 82 or 625.