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Experimental studies of thermo‐mechanical treatment on conventionally melted high nitrogen martensitic stainless steel

Experimental studies of thermo‐mechanical treatment on conventionally melted high nitrogen... Purpose – The main purpose of this paper is to produce high‐nitrogen martensitic stainless steels (HNMSS) using a conventional induction furnace with better mechanical properties and to improve the properties by thermo‐mechanical treatment (TMT). Design/methodology/approach – Production of two types of HNMSS alloys with Chromium – 8.22 and 15.84 wt% was carried out using a conventional melting furnace. The theoretical nitrogen solubility of the produced alloys was calculated and compared with the actual nitrogen solubility of the alloys. The produced alloys were subjected to TMT, characterized by hardness measurement, tensile testing micro examinations in the as cast, hardened, TMT treated and TMT hardened and tempered conditions. Findings – The actual nitrogen solubility achieved in the HNMSS specimens was in agreement with the calculated theoretical nitrogen solubility using thermodynamic relationships. Thermo‐mechanically treated specimens exhibited the break‐up and refinement of the original coarse cast structure by repeated recrystallization as fine grain size in the austenitic condition and reduced proportion of residual deformed δ ferrite. Thermo‐mechanically treated, hardened and tempered specimens showed higher hardness up to 525 VHN, with strength and toughness. Research limitations/limitations – In the conventional melting process, purging nitrogen into the melt and increasing the percentage of nitrogen is the primary limitation and retaining the same into the solution during thermo‐mechanical treatment is the secondary limitation. Originality/value – Work on melting of nitrogenated steels using controlled atmospheric conditions with special equipment was carried out earlier. This practice cannot be adopted on a commercial basis, where mass production is the prime requirement. Therefore, the uniqueness of this paper lies in communicating the melting practice of HNMSS using a conventional induction furnace followed by the optimum TMT. This takes the production and TMT of HNMSS into the commercial casting industry for mass production. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Anti-Corrosion Methods and Materials Emerald Publishing

Experimental studies of thermo‐mechanical treatment on conventionally melted high nitrogen martensitic stainless steel

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Publisher
Emerald Publishing
Copyright
Copyright © 2008 Emerald Group Publishing Limited. All rights reserved.
ISSN
0003-5599
DOI
10.1108/00035590810859449
Publisher site
See Article on Publisher Site

Abstract

Purpose – The main purpose of this paper is to produce high‐nitrogen martensitic stainless steels (HNMSS) using a conventional induction furnace with better mechanical properties and to improve the properties by thermo‐mechanical treatment (TMT). Design/methodology/approach – Production of two types of HNMSS alloys with Chromium – 8.22 and 15.84 wt% was carried out using a conventional melting furnace. The theoretical nitrogen solubility of the produced alloys was calculated and compared with the actual nitrogen solubility of the alloys. The produced alloys were subjected to TMT, characterized by hardness measurement, tensile testing micro examinations in the as cast, hardened, TMT treated and TMT hardened and tempered conditions. Findings – The actual nitrogen solubility achieved in the HNMSS specimens was in agreement with the calculated theoretical nitrogen solubility using thermodynamic relationships. Thermo‐mechanically treated specimens exhibited the break‐up and refinement of the original coarse cast structure by repeated recrystallization as fine grain size in the austenitic condition and reduced proportion of residual deformed δ ferrite. Thermo‐mechanically treated, hardened and tempered specimens showed higher hardness up to 525 VHN, with strength and toughness. Research limitations/limitations – In the conventional melting process, purging nitrogen into the melt and increasing the percentage of nitrogen is the primary limitation and retaining the same into the solution during thermo‐mechanical treatment is the secondary limitation. Originality/value – Work on melting of nitrogenated steels using controlled atmospheric conditions with special equipment was carried out earlier. This practice cannot be adopted on a commercial basis, where mass production is the prime requirement. Therefore, the uniqueness of this paper lies in communicating the melting practice of HNMSS using a conventional induction furnace followed by the optimum TMT. This takes the production and TMT of HNMSS into the commercial casting industry for mass production.

Journal

Anti-Corrosion Methods and MaterialsEmerald Publishing

Published: Mar 21, 2008

Keywords: Nitrogen; Solubility; Stainless steel; Thermo dynamics; Melting

References