Microstructure and Mechanical Properties of 9CrNB Steel after Heat Treatment

Abstract:

This paper deals with the analysis of microstructure in the conditions after austenitising at high temperatures (1150 °C, 1180 °C a 1210 °C/45 min) for 9CrNB steel, and with the analysis of microstructure in the conditions after subsequent tempering at temperatures 740 °C, 770 °C, 800 °C/1 hr. After austenitising the microstructure was formed of lath martensite with secondary carbides. The average size of initial austenitic grains ranged from 144 μm (1150 °C) to 163 μm (1210 °C). Increasing the austenitising temperature led to insignificant improvement in strength properties, while the plasticity of the steel decreased. Microstructure in tempered conditions was formed from tempered martensite. This martensite had lath morphology, with inhomogeneus distribution of precipitates. Higher austenitising temperature and increased tempering temperature led to spheroidal and growth of secondary particles. The tempering effect on strength and plastic properties of steel are also described.

• Periodical: Materials Science Forum (Volume 891)
• Pages: 167-170
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.891.167
• Online since: March 2017
• Authors: Pavel Bekeč*, Ľudovít Parilák, Pavol Beraxa, Milan Mojžiš, Lucia Domovcová, Martin Fujda
• Keywords: 9CrNB Steel, Grain Growth, Heat Treatment, Microstructure

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