Influence On The Microstructure And Properties Of GCr15Steel By Electropulsing

Bearing is an important support component in mechanical equipment. With applicationenvironment complicating, Bearing’s performance and life have been required more andmore severely. As rolling bearing manufacturing steel, GCr15steel seriously affected thelife of bearing, so increment of bearing life depends on the performance of GCr15steel.Since electropulsing has been regarded as a new technology to evidently influence materialmicrostructure and performance in recent years, it has caused more and more attention bypeople. In this paper, the studies focus on the influence of microstructure and mechanicalproperties for GCr15bearing steel by electropulsing.The research found that different electropulsing parameters and cooling conditionshave different effects on the microstructure and mechanical properties of GCr15steel. Asthe pulse current density or the duration of action increased, microstructure of GCr15steeltransforms from pearlite to martensite and mechanical properties also improve. However,with the pulse current continuously increasing, excessive heat leads to microstructurecoarsening and grain growth, therefore it’s mechanical properties decrease. Although themartensite for GCr15steel in the water-cooled condition is finer and smaller than in theoil-cooled condition, the mechanical properties in water-cooled condition is poorer than inoil-cooled condition due to the fast water cold speed forming micro-cracks. Compared withconventional heat treatment, the tensile strength and elongation increased to3%and31.3%respectively by electropulsing treatment of optimized parameters. And wear resistance alsois correspondingly improved.For GCr15steel of different initial state, the degrees of martensite refinement isdifferent, but also the carbide particles are in the different forms of precipitating in thematrix. These lead the mechanical properties of the different initial state to have differenceby electropulsing. The results show that, the finer and more diffused carbide particles of pre-treatment are, the better mechanical properties are.Meanwhile different post-treatment after electropulsing also makes microstructure andperformance change. As the effect of the secondary electropulsing treatment of smallparameters is similar to tempering treatment, it can replace tempering treatment. For GCr15steel electropulsing surface treatment, it is found that due to organic combination of hardand soft phase the wear resistance is better than traditional heat treatment. However,different electrode shape has not same influence on GCr15steel wear resistance. Forrectangular electrode, the tip treatment zone is emerged of stress concentration and tensilestress, and the strengthening effect in different directions is also different. Therefore thewear resistance after rectangular electrode treatment is poorer than spherical electrodetreatment. This laid a foundation for the further research about GCr15steel’s engineeringapplication after electropulsing treatment.