Fabrication of Ultra High Nitrogen Austenitic Stainless Steel by NH3 Solution Nitriding
SCIE
SCOPUS
- Title
- Fabrication of Ultra High Nitrogen Austenitic Stainless Steel by NH3 Solution Nitriding
- Authors
- Park, WI; Jung, SM; Sasaki, Y
- Date Issued
- 2010-01
- Publisher
- IRON STEEL INST JAPAN KEIDANREN KAIKAN
- Abstract
- Nitrogen addition to stainless steels is very effective for improving mechanical properties and corrosion resistance. N-2 solution nitriding is one of the possible methods to produce high nitrogen stainless steel. However, the nitriding rate by N-2 gas is significantly small and also the attainable nitrogen contents in Fe-Cr alloys is less than 1 mass% in general. NH3 nitriding is an attractive alternative since NH3-H-2 gas mixtures have high corresponding nitrogen potential than that of pure N-2 gas. In the present study, aiming for the enhancement of the nitriding rate and the increase of nitrogen contents more than 1 mass%, NH3 and N-2 solution nitriding of Fe-Cr alloys under various conditions has been carried out and their behaviors of nitrogen absorption in Fe-Cr alloys are investigated. It is found that the suppression of the pre-decomposition of NH3 before it reaches the sample is critical for the effective NH3 nitriding. Compared with the N contents after 1 h nitriding, NH3 nitriding is found to be about 5 times faster than that of N-2 (0.1 MPa) nitriding under the present experimental conditions. In addition the N contents more than 1 mass% were easily achieved by NH3 nitriding. By using devised NH3 gas injection system to minimize the pre-decomposition of NH3 gas, austenitic Fe-23.5Cr alloys with more than 3 mass% of nitrogen (ultra high nitrogen stainless steel) that had never been achieved by solution nitriding was successfully produced.
- Keywords
- high nitrogen stainless steel; nickel-free austenitic stainless steel; nitrogen-alloying; NH3 solid solution nitriding; ABSORPTION
- URI
- https://oasis.postech.ac.kr/handle/2014.oak/25179
- DOI
- 10.2355/isijinternational.50.1546
- ISSN
- 0915-1559
- Article Type
- Article
- Citation
- ISIJ INTERNATIONAL, vol. 50, no. 11, page. 1546 - 1551, 2010-01
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