Structure Formation in High-Nitrogen Steel during Heat Treatment

Abstract:

Steel 06Cr18Mn19Mo2N (P900N + Mo) was chosen to study the phase composition and structural transformations occurring in high-nitrogen nickel-free austenitic steels as a result of heat treatments to which they are exposed during production or operation. The methods of light and electron microscopy, X-ray diffraction and dilatometric analysis were used in the work. The heat treatment scheme included hot plastic deformation, quenching and aging over a wide temperature range. It is shown that after the hot plastic deformation and quenching from 1050-1150 °С, and also after quenching with subsequent aging at 300 and 500 °С, the structure consists of austenite and isostructural matrix of nanoscale nitrides CrN. Thermal aging of steel at 700-750 °C causes the formation of Mo₂N nitrides along the grain boundaries, and at 800 °C the decomposition of austenite is accompanied by a discontinuous reaction γγ_depleted + σ with the formation of the χ-phase at prolonged exposures.

• Periodical: Solid State Phenomena (Volume 284)
• Pages: 447-454
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.284.447
• Online since: October 2018
• Authors: Vera V. Berezovskaya*, Eugeny A. Merkushkin, Yu. A. Raskovalova
• Keywords: Austenite, Discontinues Decomposition, High-Nitrogen Steel, Mo₂N, Nanoscale Nitrides, Polymorphic Transformation, σ and χ-Phase

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