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

V. Valasamudram (Department of Mechanical Engineering, Adhiyamaan College of Engineering, Hosur, India)
S.S. Mohamed Nazirudeen (Department of Metallurgical Engineering, PSG College of Technology, Coimbatore, India)
P. Chandramohan (Department of Mechatronics Engineering, Sri Krishna College of Engineering and Technology, Coimbatore, India)
K.P. Thenmozhi (Department of Metallurgical Engineering, PSG College of Technology, Coimbatore, India)

Anti-Corrosion Methods and Materials

ISSN: 0003-5599

Publication date: 21 March 2008

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.

Keywords

Citation

Valasamudram, V., Mohamed Nazirudeen, S., Chandramohan, P. and Thenmozhi, K. (2008), "Experimental studies of thermo‐mechanical treatment on conventionally melted high nitrogen martensitic stainless steel", Anti-Corrosion Methods and Materials, Vol. 55 No. 2, pp. 73-78. https://doi.org/10.1108/00035590810859449

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Publisher

:

Emerald Group Publishing Limited

Copyright © 2008, Emerald Group Publishing Limited

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