Synergistic improvement of wear and corrosion resistance in secondary-hardened martensitic steel via cyclic quenching process

Under harsh service conditions, secondary hardening ultra-high-strength martensitic steel often suffers from mutually aggravated wear and corrosion damage, while conventional heat treatments struggle to achieve synergistic improvement of both properties. In this work, the cyclic quenching (CQ) treatment (five cycles of rapid heating to 900 °C, short-time holding, and quenching) is proposed to simultaneously enhance the wear and corrosion resistance through microstructure reconstruction. After the treatment, the width of martensitic laths was refined from ∼400 nm to ∼90 nm, accompanied by a high density of dislocations and the precipitation of dispersed nano-sized carbides. During wear sliding, the synergistic effect of grain refinement and high-density dislocations substantially converted the wear mechanism from severe plastic ploughing and delamination to mild elastic deformation and micro-oxidation lubrication. Consequently, the average coefficient of friction decreased from 0.757 to 0.530, and the wear rate was reduced by approximately 46.3%. In corrosive environments, the high density of high-angle grain boundaries introduced by CQ serves as fast nucleation sites and preferential ion-transport channels for the passive film, driving the transformation of the passive film from a loose structure dominated by Fe 3 O 4 , Ni(OH) 2 and AlCl 3 to a compact structure dominated by Fe 2 O 3 , NiO, MoO 3 and Al 2 O 3 . As a result, the polarization resistance is increased by more than three times, and the maximum pitting depth was reduced by 50%. This study demonstrates how the CQ treatment can be used to break the trade-off between wear resistance and corrosion resistance in martensitic steels through the synergistic effects of defect engineering and microstructural refinement.