Microstructural Evolution and Quenching Properties of 22MnB5 Steel for Hot Stamping during Resistance Heating

Abstract:

Austenitic continuous heating transformation dynamics, microstructural evolution and quenching properties of 22MnB5 steel during resistance heating were investigated. Steel sheets with thickness of 1.6 mm were heated to various temperatures (800~1200 °C) either by resistance heating at two heating rates of 100 and 300 °C/s or furnace heating. The increment of superheat degree was parabolic relationship with increasing heating rate. Samples heated above Ac₃ of respective heating rates exhibited a full martensite microstructure and a hardness of above 490 HV. Austenitic coarsening rate of resistance heating samples was much lower than those by furnace heating. Austenite grain size by resistance heating was smaller than 38 μm while these by furnace heating reached 74 μm at 1200 °C. Samples heated by resistance heating at 300 °C/s had a good performance of 1800 MPa tensile strength and 5.6 % elongation, and product of strength and elongation reaches 10080 MPa%. The good combination of tensile strength and elongation by resistance heating might result from the finer austenite grain size and smaller martensite plate.

• Periodical: Advanced Materials Research (Volume 849)
• Pages: 75-80
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.849.75
• Online since: November 2013
• Authors: Cai Na Sun*, Heng Hua Zhang
• Keywords: 22MnB5 Steel, Hot Stamping, Microstructure Evolution, Quenching Properties, Resistance Heating

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