Superior hydrogen embrittlement resistance of 1.9 GPa-grade precipitation hardening stainless steel achieved by multi-phase precipitation engineering

Overcoming the inherent high susceptibility of hydrogen embrittlement (HE) remains an enduring objective in the development of precipitation hardening stainless steels. This study demonstrates how multi-phase precipitation engineering synergistically enhances hydrogen resistance in duplex-aged Ferrium S53 steel through coupled experiments and simulations. TDS analysis identifies three distinct hydrogen desorption peaks corresponding to trapping at martensitic substructures, austenite interfaces, and nanoprecipitates, with the secondary-aged condition showing enhanced trapping capacity. Microstructural engineering through optimized aging generates high-density M₂C/α'_Cr nanoprecipitates and stabilized austenite, shifting hydrogen desorption peaks to higher altitudes and reducing mobile hydrogen populations. Fracture analysis demonstrates the competing roles of plasticity-mediated and decohesion mechanisms, with their relative dominance evidenced by hybrid fracture features combining intergranular cracking with localized plasticity markers. First-principles calculations reveal Mo-modified carbides exhibit reduced vacancy formation barriers while increased hydrogen binding energy. The coordinated microstructure design achieves superior embrittlement resistance through: (i) TDS-verified hydrogen capture at engineered reversible traps, (ii) dislocation pinning that impedes hydrogen transport, and (iii) suppression of critical hydrogen accumulation at vulnerable interfaces. These findings establish a microstructure-property framework for developing hydrogen-resistant alloys via precipitation engineering.