Pitting Corrosion Resistance of Nitrogen-Added Type 304 Stainless Steel Weld Metal with Different Heat Inputs

The influence of heat input on the pitting corrosion resistance and microstructural changes of type 304 (UNS⁽¹⁾ S30400) stainless steel (SS) weld metals containing different amounts of nitrogen was evaluated. The results indicated that the pitting corrosion resistance decreased slightly as the heat input was increased and this deleterious effect of heat input was offset by the increase in the nitrogen level. Pitting attack was found to occur at the austenite/delta ferrite interfaces and at the austenite phase boundaries. As the heat input was increased the nitrogen content in the weld metal decreased. A marginal increase in the ferrite number (FN) was observed as the heat input was increased, owing to the reduction in nitrogen level.