High Temperature Oxidation Resistance and Mechanical Properties of Uncoated Ultrahigh-Strength Steel 22MnB5

Abstract

High temperature oxidation resistance, flow stress curves and forming limit diagram (FLD) of the uncoated hot stamping steel sheet 22MnB5 were investigated in this paper. Compared with the specimens heated at 850 and 950 °C, the specimens austenizied at 900 °C have better surface quality, but oxidation layer without exfoliated still exists. In the temperature range of 500–900 °C with the strain rates of 0.45, 0.10 and 0.015 s⁻¹, the isothermal flow stress of 22MnB5 with austenite microstructure satisfied the classical Inoue Katsuro constitutive equation: $\sigma = K\varepsilon^{n} \dot{\varepsilon }^{m}$. The least squares curve fitting results show that constitutive equation satisfied $\sigma = K{ \exp }(\beta /T)\varepsilon^{{n(T, \dot{\varepsilon } )}} \dot{\varepsilon }^{m(T)}$ during the nono-isothermal deformation. Based on the parameters obtained by tensile tests, the bulging processing was simulated and analyzed using ABAQUS software. The results of simulation date and tests date about failure mode and FLD of specimen are consistent, so the creditability and rationality of simulation method are verified.

F2012-H02-007