Research On Stress Corrosion Resistance Of GCr15 Bearing Steel Based On Strengthen Grinding

Recently,China has put forward the"made in China 2025"strategy.In the fields of high-end machine tools,marine engineering equipment,special robots,rail transit and wind power technology,bearings play an indispensable role as key core parts,and their raw material manufacturing and processing level has become one of the"neck"technologies restricting the development of China's industry and manufacturing industry.Aiming at the stress corrosion failure of steel materials for core parts of high-end equipment under severe and complex working conditions,this paper takes GCr15 bearing steel as the research object,focuses on the influence of the coupling effect of mechanical loading and corrosive medium on the stress corrosion failure of GCr15 bearing steel,and comprehensively evaluates the stress corrosion failure behavior of GCr15 Bearing Steel by combining the methods of theoretical analysis,simulation and experimental exploration,The internal mechanism of strengthening grinding technology to improve its stress corrosion resistance was clarified.The main research contents and results are as follows:(1)The dynamic impact collision simulation model of enhanced grinding is established to study the numerical value and distribution of residual compressive stress near the surface of materials under different jet pressures of enhanced grinding.The results show that the residual compressive stress is introduced into the surface of the material after intensive grinding;There is a positive correlation between the residual stress and the residual stress of the sprayed layer,while the residual stress is positively related to the residual stress of the sprayed layer.(2)The finite element simulation model of mechanical electrochemical multi physical field coupling stress corrosion is established,and the influence and action law of stress load on electrochemical corrosion process are analyzed.The results show that the stress load will break the equilibrium state of the original corrosion dissolution reaction,resulting in the decrease of corrosion potential and the increase of corrosion current density;When the stress at the crack exceeds the yield strength of the material and plastic deformation occurs,the corrosion current density increases by 59.19%and the corrosion dissolution reaction rate increases.(3)The strengthening grinding experiments of GCr15 bearing steel samples under different jet pressures were carried out,and the hardness,grain size and microstructure of the processed samples were observed,detected and analyzed.The results show that the hardness,grain refinement and dislocation density are positively correlated with the injection pressure,but the increasing trend gradually slows down.Compared with the raw sample,when the injection pressure reaches 0.8MPa,the surface hardness of the sample material increases by129HVand the grain size decreases by 23.5?m.Dislocation density increased by12.15×10¹⁵m^-2?(4)The stress corrosion experiment was carried out on the samples after intensive grinding,and the stress corrosion behavior of GCr15 bearing steel and the influence law and mechanism of intensive grinding on its stress corrosion performance were analyzed and explored.The results show that the stress corrosion fracture of GCr15 Bearing Steel in neutral chloride solution is intergranular fracture;The stress corrosion sensitivity of the sample without enhanced grinding is 0.28,and the stress corrosion sensitivity of the sample material when the jet pressure of enhanced grinding reaches 0.8MPa is 0.131;Combined with the analysis of the experimental results of enhanced grinding,it can be seen that the residual compressive stress is introduced into the near surface of the material after enhanced grinding,which reduces the occurrence of local stress concentration,inhibits the initiation and expansion of stress corrosion cracks,and alleviates the promoting effect of stress load on the corrosion process.The stress corrosion resistance of GCr15 bearing steel has been comprehensively improved under the synergistic effect of stress strengthening of grinding machinery and microstructure strengthening.