On the behavior of nitrogen in a low-Ni high-Mn super duplex stainless steel

The present work describes an investigation on a new series of low-Ni high-Mn super duplex stainless steels (DSSs) 25Cr–2Ni–3Mo–10Mn–xN with nitrogen concentrations varying in the range between 0.37 and 0.50 wt.%. It was observed that these alloys have a ferrite–austenite structure. Under the same heat-treatment conditions, the austenite shows a marked upward tendency with an increase in N content. Nitrogen delays the precipitation of σ phase. The increase in nitrogen enhances the yield strength (YS), ultimate tensile strength (UTS) and ductility as well as the pitting corrosion potential of the materials. The pitting corrosion occurs in the austenite phases in the case of low N content (0.37 wt.%), but in the case of high N content (0.50 wt.%) it happens in the ferrite phases.