A novel tailoring strategy for simultaneously enhancing the creep strength and hydrogen embrittlement resistance of ferritic heat-resistant steels

For engineering applications of 9%Cr ferritic heat-resistant steels, it remains a critical challenge to achieve concurrent improvements in creep strength and hydrogen embrittlement (HE) resistance. Herein, a novel process involving high-temperature normalizing, austenite-field deformation, and tempering (NADT) was designed to increase the prior austenite grain (PAG) size, refine martensitic laths, and promote the dispersed precipitation of M23C6 carbides and Cu-rich particles (CRPs) via dislocation-assisted nucleation. These precipitation features could synergistically enhance the creep strength through boundary pinning and dislocation stabilization, while also acting as irreversible hydrogen traps to effectively retard hydrogen diffusion. As a result, the creep strain of the steel at 650 °C/180 MPa for 3000 h was reduced from 16.5% to 9.2%, and the HE susceptibility decreased from 34.5% to 13.6%. This work provides an effective microstructural tailoring strategy to overcome the long-standing trade-off between creep strength and HE resistance of 9%Cr ferritic heat-resistant steels.