Effects of Mo on the Precipitation Behaviors in High-Nitrogen Austenitic Stainless Steels

Feng Shi 1), Yang Qi1, 2) and Chunming Liu 2) 1) School of Science, Northeastern University, Shenyang 110004, China 2) Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110004, China

摘 要：Precipitation behaviors of Fe-18Cr-18Mn-0.63N and Fe-18Cr-18Mn-2Mo-0.69N high-nitrogen austenitic stainless steels during isothermally aging at 850℃ have been investigated by optical microscopy （OM）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and X-ray diffraction （XRD）. The experimental results show that precipitation displays a discontinuous cellular way and the precipitates are identified as Cr2N in Fe-18Cr-18Mn-0.63N steel. The addition of Mo makes precipitation occur not only at the grain boundary but also inside the grain and precipitation also displays discontinuous cellular way. The precipitates at the grain boundary and in the cell are both identified as Cr2N phase and χ phase and the precipitates inside the grain are identified as χ phase in Fe-18Cr-18Mn-2Mo-0.69N steel. The nucleations of χ phase and Cr2N phase at the grain boundary are both governed by the diffusion of Cr atoms. The formation and growth of χ phase inside the grain are induced by the impoverishment of N atoms with increasing aging time.

关键词：