A newly designed hot-stamping steel alloyed by chromium(Cr)and manganese(Mn)without boron(B)addition was developed for automobile mass reduction.The experimental results showed the Cr-Mn alloyed steel could be quenched to full martensite microstructure when the cooling rate was higher than 14 ℃/s.Yield strength,tensile strength and elongation of the experimental hot stamping part reached 1 180 MPa,1 645 MPa and 8.4%,respectively.The experimental hot stamping part possessed higher tensile strength and elongation,compared with conventional hot-stamping steel of 22MnB5.Furthermore,excellent processing flexibility would be obtained in this novel hot-stamping steel because of its lower critical cooling rate and phase transformation temperature.The design of the composition and investigations of microstructure,mechanical properties and hot-stamping processing were also studied.
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