Effects of Heat Treatment Parameters on the Microstructure and Properties of Bainitic Steel

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 trans...

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Bibliographic Details
Published in:Journal of materials engineering and performance 2019-11, Vol.28 (11), p.7171-7180
Main Authors: Adamczyk-Cieślak, Bogusława, Koralnik, Milena, Kuziak, Roman, Smaczny, Michał, Zygmunt, Tomasz, Mizera, Jarosław
Format: Article
Language:English
Subjects:
AUSTENITE
BAINITE
Characterization and Evaluation of Materials
Chemistry and Materials Science
Corrosion and Coatings
Engineering Design
HARDNESS
HEAT TREATMENTS
MATERIALS SCIENCE
MICROSTRUCTURE
Quality Control
Reliability
Safety and Risk
SCANNING ELECTRON MICROSCOPY
STEELS
THIN FILMS
Tribology
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Summary: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.
ISSN:1059-9495
1544-1024
DOI:10.1007/s11665-019-04452-x