Effect of vanadium content on hydrogen embrittlement of 1400 MPa grade high strength bolt steels

Abstract

In this work, the hydrogen embrittlement (HE) characteristics of 1400 MPa bolt steels with three different vanadium contents of 0, 0.17 wt% and 0.34 wt% were evaluated. The characteristics of the microstructure and dislocation density of the experimental steels were analyzed, and their effects on HE were also discussed. The results showed that with increasing V content, the HE resistance of the experimental steels was improved, and the experimental steel with the highest V content possessed the best HE resistance. The V-precipitates of steels with V contents of 0.17 wt% and 0.34 wt% were reversible hydrogen traps, and the inhibitory effect of V-precipitates on hydrogen-dislocation interactions improved HE resistance. In addition, a lower dislocation density and finer martensitic structure were also beneficial for hindering hydrogen-induced cracking (HIC).