Precipitation and strengthening behavior of massive δ-ferrite in dissimilar stainless steels during massive phase transformation

The purpose of this study is to discuss the microstructural evolution and mechanical property of the weld metal in the dissimilar stainless steels during the gas tungsten arc welding (GTAW) process. The massive precipitates and austenite phases were observed in the weld metal during the dissimilar stainless steels welding process. The XRD analyses showed that the δ-ferrite had the highest diffraction intensity all the phases in weld metals during the GTAW process. The amounts of δ-ferrite in the stainless steels weld metal also maintained a higher value after dissimilar welding. The massive δ-ferrite was identified to be a Cr-rich and Ni-depleted phase by mapping and WDS analysis, which indicated that Cr element was a stabilizer of the massive δ-ferrite in the weld metal stainless steels during dissimilar welding. The precipitation of the massive δ-ferrite was obvious to promote hardness values in the dissimilar stainless steels weld metals.