Genetic effect of electric pulse-assisted cold ring rolling-quenching and tempering treatment of M50 bearing steel

ZENG Xiaobao; ZHANG Guoliang; CHEN Yu

doi:10.16578/j.issn.1004.2539.2025.08.015

Abstract：[Objective]M50 steel,as a prevailing material for aero-engine bearing rings,typically undergoes cold ring rolling prior to quenching and tempering to achieve ring formation.However,due to the high deformation resistance of M50 at ambient temperature,conventional cold ring rolling processes under large deformation conditions are prone to induce micro-and nano-scale damage,adversely affecting grain refinement and thereby limiting the inheritance of microstructural characteristics during subsequent quenching and tempering,resulting in constrained enhancement of mechanical properties.Thus,a method has been proposed to further enhance the grain refinement of M50 steel under identical cold ring rolling parameters through electro-pulse assistance,thereby improving the microstructural heredity effect during its quenching and tempering process.[Methods]The electric pulse-assisted cold ring rolling-quenching and tempering(EPCRR-QT)process was employed,wherein pulsed electric current was synchronously applied during cold ring rolling to further optimize the microstructure.The evolution behavior of the microstructure during quenching and tempering was systematically analyzed.[Results]The findings indicate that compared with specimens subjected to conventional cold ring rolling followed by quenching and tempering,those processed via EPCRR-QT exhibited a 15.2%refinement in prior austenite grain size.Additionally,reductions are observed in retained austenite content,Mo2C carbide content,and the fraction of low-angle grain boundaries.Correspondingly,Vickers hardness values increase by 4.7%in the quenched state and 4.4%in the tempered state.