University of Oulu

Järvenpää, A.; Jaskari, M.; Juuti, T.; Karjalainen, P. Demonstrating the Effect of Precipitation on the Mechanical Stability of Fine-Grained Austenite in Reversion-Treated 301LN Stainless Steel. Metals 2017, 7, 344.

Demonstrating the effect of precipitation on the mechanical stability of fine-grained austenite in reversion-treated 301LN stainless steel

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Author: Järvenpää, Antti1; Jaskari, Matias1; Juuti, Timo2;
Organizations: 1Kerttu Saalasti Institute, Future Manufacturing Technology Group, University of Oulu
2Centre for Advanced Steels Research, Materials and Production Engineering Unit, University of Oulu
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 8.1 MB)
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Language: English
Published: Multidisciplinary Digital Publishing Institute, 2017
Publish Date: 2017-10-30


According to recent investigations, a huge difference exists in the mechanical stability of austenite between the grain-refined structure states obtained in reversion annealing at 800–700 °C or at 900 °C, in a 301LN type austenitic stainless steel. Precipitation of chromium nitride occurring at these lower temperatures has been argued to be the factor reducing the stability. To prove this argument, a fine-grained, very stable austenitic structure was created at 900 °C in 1 s, and subsequently annealed at lower temperatures between 850 and 750 °C, up to 1000 s. It was found that the subsequent annealing at 750 and 800 °C resulted in prominent gradual decrease of the mechanical stability under tensile straining, detectable after 10 s annealing duration and continued until 1000 s. Only minimal grain growth occurred, which decreased the stability very marginally. The degree of the stability drop followed the predicted kinetics of the Cr2N precipitation with regards as its dependence on annealing duration and temperature. Further, the tensile yield strength of the fine-grained structure increased slightly due to the annealing. The presence of nano-sized Cr2N particles was verified after 1000 s holding at 750 °C. These observations and predictions yield firm evidence for the imperative contribution of precipitation to the highly reduced mechanical stability of grain-refined austenite in this steel.

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Series: Metals
ISSN: 2075-4701
ISSN-E: 2075-4701
ISSN-L: 2075-4701
Volume: 7
Issue: 9
Article number: 344
DOI: 10.3390/met7090344
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
Funding: Antti Järvenpää acknowledges with gratitude the funding from Technology Industries of Finland Centennial Foundation Fund for the Association of Finnish Steel and Metal Producers and the Interreg Nord 2014–2020 program, as well as the continuous support from Outokumpu Stainless Oy.
Copyright information: © 2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (