The effects of phosphorus and sulfur on susceptibility to weld hot cracking in austenitic stainless steels

Five heats of Type 308 austenitic stainless steel were custom designed and melted with equal combined phosphorus and sulfur (P+S) levels of 0.032 wt-%, representing very low S and high P, very low P and high S, and equal amounts of each at both median and very low levels. The effect of individual P and S levels on weld hot cracking behavior was studied using the Subscale Varestraint test. Phosphorus and sulfur partitioning and observed effects on cracking were studied using optical and scanning electron microscopy and microprobe. Results showed that P is more potent in exacerbating cracking susceptibility in the fusion zone, and S is more potent in exacerbating cracking in the heat-affected zone, with low contents of both residual elements being more effective for avoiding HAZ cracking than a small amount of ferrite.