Comprehensive Analysis of Microalloying Element V Improving Hydrogen Embrittlement Resistance of 1300MPa Bolt Steel.

In this study, the effect of vanadium addition (0.14 wt pct) on microstructure and hydrogen embrittlement (HE) susceptibility were investigated in 1300 MPa strength level bolt steel, and hydrogen trapping and diffusion were analyzed by hydrogen permeation and thermal desorption spectroscopy (TDS). The results showed that the addition of 0.14 wt pct V in the bolt steel can significantly improve the HE resistance. The vanadium addition can form a large number of V precipitates. Compared with the V-free bolt steel with the same strength, the vanadium addition steel possessed more significant precipitation strengthening and lower dislocation density, which was the main reason to reduce the HE susceptibility. In addition, the vanadium precipitates can provide a lot of hydrogen traps and refine the grains, resulting in the uniform distribution of hydrogen and the reduction of hydrogen accumulated at local grain boundaries, which was helpful to inhibit the hydrogen induced cracking (HIC). [ABSTRACT FROM AUTHOR]