Microstructure and Mechanical Properties of Austempered Ultrahigh Carbon Steel 1.4%C

Abstract:

An ultrahigh carbon steel alloy containing 1.4 wt pct carbon (UHCS-1.4C) was studied. The steel was processed into ultrafine grain and fully spheroidized microstructure through a controlled rolling and controlled-cooling divorced eutectoid transformation, and was then given austempering treatment to form bainite. The mechanical properties of the heat-treated steel were evaluated by tension tests at room temperature. After austenitized at 850 °C and then austempered at 300 - 350 °C, the microstructure was ultrafine upper bainite, retained austenite, and unsolvable cementite. It was shown that the ultimate tensile strengths of UHCS-1.4C ranged from 1420 to 1830 MPa, elongations to failure from 6 to 14%; the ultimate tensile strength increases with decreasing austempering temperature, while the tensile ductility decreases. The fracture surface of bainitic UHCS-1.4C consists mainly of dimples and voids, which reveal a ductile fracture. The present results indicate that ultrahigh carbon steel can be easily processed to achieve bainitic microstructures and unique properties.

• Periodical: Materials Science Forum (Volume 682)
• Pages: 97-101
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.682.97
• Online since: March 2011
• Authors: Zhan Ling Zhang, Ke Ke Zhang, Yun Yue, Ning Ma, Zhi Wei Xu
• Keywords: Austempering Treatment, Ultrafine Grained, Ultrahigh Carbon Steel

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