Study On The Reinforcement Process Of The Surface Shotblast Of Carburized Gear Steel

Shotblast reinforcement is the most commonly used surface strengthening method for gears,which can not only improve the fatigue resistance and wear resistance of gears,but also maintain good toughness in gear core.In this paper,the effects of the projectile diameter and shot peening intensity on the surface microstructure,residual austenite,residual stress,microhardness and surface topography of carburizing 20Cr2Ni4 A and carburizing 9310 steel,on friction,wear and erosion performance of carburizing 20Cr2Ni4 A steel and on friction and wear performance at different temperatures of carburizing 9310 steel were systematically investigated.Besides,the effects of projectile diameter and velocity on the residual stress field and surface roughness of 9310 steel surface were studied by ABAQUS finite element analysis software.After shot peening process,under other conditions the same circumstances,with the increase of the projectile diameter,the sample surface martensite structure content of carburizing 20Cr2Ni4 A and carburizing 9310 steel specimens increased obviously,and the full width at half maximum of X-ray diffraction on the surface of the specimens increased as well;the transformation of residual austenite to martensite of the specimen surface increased and the affected distance of residual austenite deepened;the residual stress on the sample surface increased and the residual stress distribution deepened.With the increase of the shot peening intensity,the residual austenite content of the specimen surface was gradually reduced,and the induced depth for transformation of residual austenite to martensite increased;the residual stress of the specimen surface obviously imcreased,the residual stress distribution obviously deepened and the distance of the maximum residual stress increased as well;the microhardness of the specimen surface improved,but the surface roughness increased obviously at the same time.For carburizing 20Cr2Ni4 A steel,in the friction and wear test,when the other conditions are the same,with the increase of projectile diameter or the shot peening intensity,the friction coefficient of specimens basically remained the same,and the wear rate significantly reduced;the wear mechanism for specimens with unshot peening process and shot peening process(1)was mainly abrasive wear,abrasive wear accompanied by adhesive wear for specimen withshot peening process(2)and mainly adhesive wear for specimens with shot peening process(3)and(4).In the erosion test,under the erosion of 30 ° erosion,the shot peening process had little effect on the erosion performance and the main failure mechanism was the small angle plough cut erosion;under the erosion of 90 ° erosion,the shot peening process incrased erosion resistance and the the main failure mechanism was high angle pit type erosion.For carburizing 9310 steel,under the same conditions in the room temperature friction and wear test,with the increase of the projectile diameter,the friction coefficient of the specimens increased but the wear rate obviously reduced.With the increase of the shot peening intensity,the friction coefficient was almost a constant,and the wear rate of the sample gradually reduced.The wear mechanism for specimens with unshot peening process and shot peening process(1)was mainly abrasive wear,abrasive wear accompanied by adhesive wear for specimen with shot peening process(2)and mainly adhesive wear for specimens with shot peening process(3),(4)and(5).The friction coefficient of the samples was not affected by various temperatures during high temperature friction wear test.At 100? and200?,the shot peening process improved the wear resistance of specimens,but the improvement effect disappeared at 300? and the wear loss decreased due to the oxidation of grinding crack surface oxidation;at 100?,wear mechanism was priorly abrasive wear,mainly adhesion wear at 200?,and mainly adhesion wear at 300?.Based on the analysis of surface microstructure,surface pressure stress field and wear resistance of carburized 20Cr2Ni4 A steel and carburized 9310 steel injection pellets,it can be known that the shot blasting process(4)can be used as the best shot blasting scheme for cementing 20Cr2Ni4 A steel.The shotblast process(4)and the process(5)can be used as the shotblast scheme for the carburizing 9310 steel.Through the study of the finite element simulation of 9310 steel shot peening,that with the increase of projectile size or shot peening,surface residual compressive stress,the residual compressive stress and its deep layer and the depth of the residual compressive stress increases,but the surface roughness is increased significantly.