Effect of nitrogen content on stress corrosion cracking and pitting corrosion behavior of AISI 312 weld

A systematic study of the effect of nitrogen addition to the 312 weld on its microstructure and localized corrosion behavior was carried out. Tungsten Inert Gas (TIG) welding of 304L stainless steel with high ferrite containing 312 filler was carried out at a nominal heat input of 0.4 kJ/mm. Nitrogen was introduced in the argon shielding gas and was varied leading to variation from 0.04 to 0.13 wt% N in the welds. Different welds were subjected to potentiodynamic polarization studies in 1N HCl. Slow Strain Rate Testing (SSRT) studies in 1N HCl, at a strain rate of 2.5x10(-6)s(-1), were carried out. As the nitrogen content increased in the weld, passive current density decreased and pitting resistance increased. Stress corrosion cracking (SCC) studies showed that the welds with higher FN (>30) failed in the weld zone, whereas those with lower FN (