Investigation on sulfide stress cracking behavior of high-strength low-alloy steel for oil country tubular goods based on intercritical quenching and V alloying

To meet the service requirements of high-strength low-alloy steel for oil country tubular goods (OCTG) in H 2 S-containing environments, the effects of intercritical quenching and Vanadium (V) alloying on sulfide stress cracking (SSC) were investigated. Both intercritical quenching and V alloying improved SSC resistance, with V-alloyed ferrite/martensite dual-phase steel showing the highest. Despite comparable yield strengths, differences in SSC resistance indicated that microstructural characteristics governed SSC resistance. Compared with the fully martensitic counterpart, ferrite/martensite dual-phase steel displayed lower dislocation density, Σ3 grain boundary length, and residual stress, improving SSC resistance. Moreover, V alloying promoted nanoscale VC precipitates. Thermal desorption spectroscopy (TDS) revealed higher hydrogen desorption content from high temperature peak, indicating that VC precipitates may act as more effective irreversible hydrogen traps. Crystallographic and crack trace analyses showed that V alloying promoted SSC crack deflection along tortuous ferrite/martensite interfaces rather than continuous propagation along {001} cleavage planes, enhancing crack propagation resistance.