Effects of the microstructure and reversed austenite on the hydrogen embrittlement susceptibility of Ni-Cr-Mo-V/Nb high-strength steel

The effects of the microstructure and reversed austenite (RA) on the hydrogen embrittlement (HE) behavior were investigated in NiCrMoV/Nb high-strength steel prepared using three different heat treatments. The quenching and tempering (QT) steel showed a noble HE resistance for the lowest hydrogen diffusion and maximum apparent hydrogen concentration compared to quenching (Q) steel and quenching, lamellarizing, and tempering (QLT) steel. Thermal desorption spectroscopy (TDS) analysis confirmed that RA had an activation energy of 32.5 kJ/mol which indicates a stable trapping site. The QLT steel containing more RA exhibited a higher HE susceptibility, suggesting that RA degrades the HE resistance.