Effect of vanadium on hydrogen embrittlement susceptibility of high-strength hot-stamped steel

Abstract

Based on the chemical composition of traditional hot-stamped steel (e.g., 22MnB5 and 30MnB5), Nb and V microalloying elements are added into 30MnB5 steel to meet the requirements of ultra-high strength, excellent ductility and potent resistance to hydrogen embrittlement (HE) at the same time. The influence of hot-stamped steel on HE was studied by conducting a hydrogen permeation method and pre-charged hydrogen slow strain rate test. Meanwhile, the experimental steel microstructures and corresponding fracture surfaces are observed and analyzed to characterize HE behavior. The results show that a finer microstructure, a lower apparent diffusion coefficient of hydrogen and a smaller percentage of strength and plasticity reduction are obtained due to the addition of the vanadium element into hot-stamped steel. Compared to the V free experimental steel, the steel with 0.14 wt.% V has a large number of dispersive precipitates and more grain boundary areas, which makes hydrogen atoms dispersedly distribute.