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Open AccessFeature PaperArticle

Influence of Hot Forging Parameters on a Low Carbon Continuous Cooling Bainitic Steel Microstructure

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Post-Graduation Program in Mining, Metallurgical and Materials Engineering, Federal University of Rio Grande do Sul, Avenida Bento Gonçalves, 9500, 91509-900 Porto Alegre, Brazil
2
Leibniz-Institut für Werkstofforientierte Technologien, Badgasteiner Street 3, 28359 Bremen, Germany
*
Author to whom correspondence should be addressed.
Metals 2020, 10(5), 601; https://doi.org/10.3390/met10050601
Received: 13 April 2020 / Revised: 1 May 2020 / Accepted: 4 May 2020 / Published: 6 May 2020
Thermomechanical processing of low carbon bainitic steels is used to obtain a bainitic microstructure with good strength and toughness by continuous cooling after forging without the need of further heat treating, hence reducing manufacturing costs. However, hot forging parameters can significantly influence the microstructure in the forged material. A series of heat treating and forging experiments was carried out to analyze the effect of austenitizing time and temperature on the grain growth and the effect of forging temperature on the Prior Austenite Grain Size (PAGS) and continuously cooled microstructure. The forged microstructures were characterized by optical microscopy, microhardness tests, and X-ray diffraction. The results indicate that at 1200 °C austenitizing temperature abnormal grain growth takes place. Forging temperature significantly affects the PAGS and the subsequently formed microstructure. At high forging temperature (1200 °C), an almost fully bainitic microstructure was obtained. As the forging temperature was reduced to 1100 and 1000 °C, the PAGS refined, while the polygonal ferrite faction increased and the amount of retained austenite decreased. Further evaluations showed that a decrease in the forging temperature results in a higher carbon concentration in solution in the retained austenite leading to a stabilization effect. View Full-Text
Keywords: thermomechanical processing; grain growth; forging; retained austenite; bainitic microstructure thermomechanical processing; grain growth; forging; retained austenite; bainitic microstructure
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MDPI and ACS Style

Silveira, A.C.F.; Bevilaqua, W.L.; Dias, V.W.; de Castro, P.J.; Epp, J.; Rocha, A.S. Influence of Hot Forging Parameters on a Low Carbon Continuous Cooling Bainitic Steel Microstructure. Metals 2020, 10, 601.

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