Effects of Warm Working on Microstructural and Shear Deformation Properties of TRIP-Aided Martenitic Steel

Abstract:

The effects of warm working on microstructural, retained austenite characteristics and shear deformation properties of 0.2C–1.5Si–1.5Mn–1.0Cr–0.2Mo TRIP-aided martensitic (TM) steel for applications to automotive frame and forging parts were investigated. When warm working at 550 °C and post cooling at 1 °C/s was conducted to the TM steel, volume fractions of retained austenite and martensite-austenite constituent phase increased and mixture matrix of ultra fine granular bainitic ferrite and fine bainitic ferrite lath was obtained, whereas microstructure of TM steel warm worked at 750 °C exhibited granular bainitic ferrite matrix. These were caused by the dynamic recrystallization and the promotion of bainitic transformation of austenite due to the worm forging at 550 °C with the post cooling rate of 1 °C/s. Maximum shear stress decreased and total shear displacement increased with decreasing working temperature in TM steel. These were caused by the effective strain induced transformation of a large amount of retained austenite and the refined matrix structure.

• Periodical: Materials Science Forum (Volume 879)
• Pages: 2312-2317
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.879.2312
• Online since: November 2016
• Authors: Tomohiko Hojo*, Takuya Kochi, Koh Ichi Sugimoto
• Keywords: Retained Austenite, Shear Deformation Properties, TRIP-Aided Martensitic Steel, Ultra Fine Grain, Warm Working

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