| AVS 66th International Symposium & Exhibition | |
| Applied Surface Science Division | Thursday Sessions |
| Session AS-ThP |
| Session: | Applied Surface Science Poster Session |
| Presenter: | Honglong Che, Dalian University of Technology, China |
| Authors: | H.L. Che, Dalian University of Technology, China M.K. Lei, Dalian University of Technology, China |
| Correspondent: | Click to Email |
Low temperature nitriding of Fe-Cr-Ni austenitic stainless-steel forms a nitrogen supersaturated layer that owns a composite property of wear and corrosion resistance. It is widely used in the industry, and nuclear power plant is a very important application for its stringent performance requirements. To understand the nature of this nitrogen supersaturated layer, a serial systematically composition changed Fe-Cr-Ni austenitic stainless steel in three groups are prepared, nitrided and investigated. It is confirmed that the nitrided layers on all the Fe-Cr-Ni austenitic alloys are consistent of duplex structure of outer γ -Fe N like orderedγ'N and inner γN, althougha featureless continuous layer is observed with light-optical microscopy and a gradual decrease in nitrogen content is measured with EPMA when the alloys with a Cr-content over 12 wt. %. Cell model based on Cr-N and Fe-N interaction that considered the atomic construction of octahedral interstice is built that can explain the composition and structure evolution during the alloy composition change. The Cell Model is also used to calculated the average nearest neighbor nitrogen atoms (ANNNA) around Cr and Fe, which well explained the extended X-ray absorption fine structure (EXAFS) experiment results in both as nitrided and denitrided of 304 and 316 stainless steel. It further confirmed the reasonability of Cell Model and revealed the atomic structure of the γ'N and γN phase.