Effect of N content in duplex stainless steel

Gomez de Salazar JM et al. investigated the effect of different N2 content in the protective gas on the properties of duplex stainless steel. The results show that with the increase of N2 partial pressure PN2 in the mixed gas, the mass fraction of nitrogen ω (N) in the weld begins to increase rapidly, and then the change is little. The ferritic phase content φ (α) in the weld decreases linearly with the increase of ω (N), but the influence of φ (α) on tensile strength and elongation is just opposite to that of ω (N). With the same ferritic phase content φ (α), the tensile strength and elongation of the base metal are higher than that of the weld. This is due to differences in microstructure. The impact toughness of the joint can be improved with the increase of N content in the duplex stainless steel weld metal, which is due to the increase of γ phase content in the weld metal and the reduction of Cr2N precipitation.