Effect of nitrogen on solidification mode and microstructure of 316L stainless steel

Three kinds of welding wires with different ni-trogen contents were used for TIG welding of 316L austenitic stainless steel.The solidification mode of the welds and the pre-cipitation behavior of austenite and ferrite were contrastively ana-lyzed,and the effect of nitrogen on solidification mode and mi-crostructure of the weld metal was investigated.The results show that the weld with nitrogen content of 0.018% solidifies as pri-mary ferrite mode and vermicular or skeletal ferrite remains on the dendritic axis.With the increase of nitrogen content to 0.088% and 0.16%,the weld solidifies as primary austenite mode and ferrite occurs as small particles between primary aus-tenite dendrites;the ferrite number (FN) decreases and the re-markably coarse austenite is also found.