Effects of Heat Treatment Parameters on the Microstructure and Properties of Bainitic Steel
- Warsaw University of Technology, Faculty of Materials Science and Engineering (Poland)
- Stanisław Staszic Institute for Ferrous Metallurgy (Poland)
- ArcelorMittal Poland S.A. (Poland)
The results obtained in the present study demonstrate the effects of various types of heat treatment processes on the microstructure and hardness of new trip-assisted carbide-free bainitic steel. The steel was subjected to three variants of heat treatment processing with an isothermal bainitic transformation temperature in a range from 350 to 480 °C. Changes of temperature and time of isothermal holding caused changes in the values of retained austenite (RA) volume fraction and carbon content. Reduction in the isothermal holding temperature resulted in the increased concentration of carbon in austenite. Also, the investigations of the microstructure showed that size and morphology of the austenite evolved during heat treatment. The SEM observations revealed that the steel subjected to heat treatment is composed of the carbide-free bainite with ferrite plates and a high volume fraction of retained austenite in the form of thin layers or islands. With the lower isothermal holding temperature and the higher degree of bainitic transformation, the more the RA morphology changed from island to layer type. The application of the lowest isothermal temperature resulted in a significant refinement of the microstructure components: the bainitic ferrite plates and the RA layers. Also, the mechanical properties obtained from the tensile testing and hardness measurements were correlated to the microstructure of the investigated steel after different isothermal holdings.
- OSTI ID:
- 22970315
- Journal Information:
- Journal of Materials Engineering and Performance, Vol. 28, Issue 11; Other Information: Copyright (c) 2019 ASM International; Country of input: International Atomic Energy Agency (IAEA); ISSN 1059-9495
- Country of Publication:
- United States
- Language:
- English
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