Research On Corrosion Resistance Behavior Of GCr15 Bearing Steel Processed By Enhanced Grinding

GCr15 bearing steel is one of the most commonly used industrial steel at present,and it is the main material used in all kinds of equipment basic parts.In this paper,GCr15 bearing steel was taken as the research object,and the corrosion resistance behavior of GCr15 bearing steel before and after intensive grinding was studied through the microstructure changes of GCr15 bearing steel before and after intensive grinding.Firstly,based on the impact theory of strengthening grinding,the effect of strengthening grinding on the surface microstructure of GCr15 bearing steel was analyzed.According to the relevant literature,the corrosion behavior of GCr15 bearing steel was simulated by using cellular automata,and the corrosion evolution process of GCr15 bearing steel with different grain sizes was obtained.The samples with different strengthening grinding time were obtained by using the single variable method The microstructure and properties of the samples were observed and analyzed;the corrosion resistance of the samples before and after intensive grinding was tested,and the corrosion resistance process was studied through the microstructure and properties before and after corrosion.The main conclusions are as follows(1)When GCr15 bearing steel is processed by strengthening grinding,the steel ball and grinding powder impact on its surface at high speed,causing plastic deformation on the surface of the material and producing plastic strengthening layer,which makes dislocation density increase and grain size decrease,thus making the material more corrosion-resistant.(2)The corrosion resistance process of GCr15 bearing steel was simulated by cellular automata.It was found that the depth of corrosion pit expanded rapidly in the corrosion resistance process,while the width expanded rapidly in the early stage,and slowly in the middle and late stage.The speed of metal dissolved basically remained unchanged,and the dissolved cells showed a linear growth.By changing the parameter D value of metal materials,different grain sizes were established It is found that the smaller the D value is,the finer the grain of the metal material is and the better the corrosion resistance is.(3)With the increase of grinding time,the thickness of plastic deformation layer increases from 50 ?m to 115 ?m,the dislocation density increases from 0.2×1015m-2(3min)to 3.7×1015m-2(15min),and the grain size decreases from 23.2 ?m(3min)to 3.7 ?m(15min).The martensite becomes finer and shorter,mixed with austenite and carbide,and has no obvious difference The average value of surface roughness increases by 0.03?0.15;the surface hardness increases by 85%?100%,and the hardness decreases with the increase of distance from the machined surface until it is the same as that of the substrate.(4)It can be seen from the electrochemical corrosion test that with the processing time,the self-corrosion potential of each sample is within the range of 590mv?630mv,and the self-corrosion current is within 338.51?380.43 m A/cm2.After the intensive grinding,the corrosion rate of each sample decreases,and the corrosion rate of sample D is the lowest when the processing time is 9min,and the corrosion rate decreases by 11.02%.The increase of dislocation density and grain refinement make the surface plastic deformation layer more compact,and the corrosion reaction occurs when the corrosion liquid is not easy to enter the grain boundary gap;martensite becomes smaller and shorter and mixed with carbide,which makes the corrosion reaction difficult to proceed smoothly;the increase of silicon and chromium content helps GCr15 bearing steel to form passivation film to prevent the corrosion reaction.(5)From the immersion corrosion test,it can be seen that with the processing time,the corrosion pit area formed on the surface of each sample is far less than that of the unprocessed sample;the content of silicon and chromium;the corrosion rate after 7 days of immersion is reduced from 18.8 mg / cm2·d to the lowest 11.1 mg / cm2·D.The results show that the enhanced grinding can make GCr15 bearing steel more resistant to immersion corrosion,and the effect is the best when it is processed for 9min.(6)From the friction corrosion test,it can be seen that with the processing time,the friction coefficient and wear amount of each sample begin to decrease,and the corrosion rate decreases from the highest 116.2mg/cm2 to the lowest 12.1mg/cm2;there is no obvious corrosion pit on the surface,the width of wear mark on metallography becomes narrow;silicon and chromium increase.The results show that the friction and corrosion resistance of GCr15 bearing steel after strengthened grinding is obvious.