Strengthening and toughening mechanism and synergistic effect of 1Cr17Ni2 martensitic stainless steel processed by warm forging stretching

1Cr17Ni2 martensitic stainless steel is widely used in aerospace and high-performance engineering fields due to its excellent strength and corrosion resistance, but the inherent strength-toughness trade-off remains a critical challenge restricting its reliability under extreme conditions. To address this issue, this study systematically investigates the effect of warm forging stretching (WFS) combined with quenching-tempering (QT) on the microstructure evolution and strength-toughness synergy of 1Cr17Ni2 steel. The results demonstrate that WFS processing induces significant grain refinement (average grain area reduced by 75.2% from 8.94 μm 2 to 2.22 μm 2 at 90% deformation), spheroidization and precipitation of M 23 C 6 nanocarbides, and formation of α-fiber texture. These microstructural optimizations synergistically enhance the mechanical properties: compared with QT specimens, the tensile strength of WFS-treated steels increases by 159–201 MPa (reaching 1.19 GPa at 90% deformation), while maintaining uniform elongation above 14%. Notably, the WFS-80% specimen exhibits exceptional strength-toughness balance, with a yield strength of 0.957 GPa, tensile strength of 1.15 GPa, elongation of 15.25%, and impact absorption energy of ∼100 J at −60°C. The strengthening mechanism is dominated by grain boundary strengthening, dislocation strengthening, and precipitation strengthening, while the toughening effect originates from grain refinement-induced crack deflection, texture-controlled fracture path restriction, and delamination cracking-induced stress relief. This study provides a novel thermomechanical processing strategy to overcome the strength-toughness inversion in martensitic stainless steels, offering significant potential for the development of high-performance structural materials in harsh environments.