Improving hydrogen embrittlement resistance of high-strength martensitic steel via Cr–V–Ti co-alloying

Multi-element microalloying is an effective strategy for mitigating hydrogen embrittlement (HE) in high-strength steels. In this study, the hydrogen-trapping behavior and HE resistance of a Cr–V–Ti microalloyed high-strength martensitic steel (MP steel) containing multiple precipitates were investigated in comparison with a reference steel (Base steel). Transmission electron microscopy showed that Cr–V–Ti co-alloying promoted the formation of finer and denser precipitates, reducing the average precipitate size from 103.7 ± 31.2 nm in the Base steel to 47.17 ± 30.79 nm in the MP steel. Slow strain rate tensile testing showed that the elongation-loss-based HE index decreased from 72.2% in the reference steel to 38.6% in the MP steel, while the strength-loss-based HE index decreased from 26.8% to 14.0%. After hydrogen charging followed by holding at room temperature for 6 h, thermal desorption analysis showed that the MP steel retained 0.96 ppm hydrogen, compared with 0.39 ppm in the Base steel, indicating a stronger deep hydrogen-trapping capability. High-resolution transmission electron microscopy further revealed semi-coherent precipitate/matrix interfaces containing misfit dislocations and pronounced local strain fields, which provided effective deep hydrogen-trapping sites. These results demonstrate that Cr–V–Ti co-alloying promotes the formation of finer and denser carbide precipitates, enhances deep hydrogen trapping, and thereby improves the HE resistance of high-strength martensitic steel.