Research On Shot Peening Strengthening Mechanism And Tribological And Contact Fatigue Performance Of New Type Steel For Shaft

With the development trend of high power and light weight of high-speed and heavy-duty vehicles,it is bound to make the working conditions of the drive shaft worse,and its wear and fatigue failures will increase.The study of new steel for shafts is imminent.25CrNi2MoV steel is a new type of high-speed heavy-duty shaft steel.It is of great engineering significance to improve its comprehensive performance and servi ce life by surface strengthening technology.However,the research on shot peening strengthening of the material has not been reported yet.In this paper,by shot peening strengthening of25CrNi2MoV steel,the effects of shot peening process parameters on its surface properties,friction and wear properties and contact fatigue properties were systematically studied,and the shot peening mechanism was clarified.The main research contents are as follows:?1?The effect of shot peening on the surface properties of 25CrNi2MoV steel was studied.The results show that shot peening can produce a severe plastic deformation strengthened layer with a certain thickness on the surface of the material.Shot peening can improve the surface roughness and surface microhardness of the material,refine the grain size of the surface layer of the material and increase the surface residual compressive stress of the material.When the shot peening pressure,coverage and projectile diameter are 0.6MPa-300%-0.8 mm and 0.2 MPa-300%-0.4 mm,respectively,the maximum surface hardness and residual compressive stress,the minimum surface roughness can be obtained.?2?The finite element simulation of shot peening on 25CrNi2MoV steel was studied by ABAQUS software.The results show that when the shot peening speed increases,the residual compressive stress on the surface of the material increases in sequence,and the maximum residual compressive stress on the subsurface increases first and then decreases.When the projectile diameter increases,the residual compressive stress on the surface of the material increases first and then decreases,and the maximum residual compressive stress on the subsurface increases in sequence When the coverage increases,the residual stress of the surface layer of the material does not change significantly.The errors between the simulated values and the experimental values of the surface residual compressive stress are between10.5%and 14.0%,which indicates that the shot peening finite element model has high accuracy.?3?The effect of shot peening on the friction and wear properties of 25CrNi2MoV steel was studied.The results show that under the shot peening process parameters?0.6MPa-300%-0.8 mm?with maximum surface hardness and residual compressive stress,the material obtains the best sliding and fretting wear resistance,and its sliding and fretting wear volume are reduced by 36.1%and 33.4%,respectively.After shot peening,the fretting wear mechanism of the material changes from adhesive wear to abrasive wear.?4?The effect of shot peening on the contact fatigue properties of 25CrNi2MoV steel was studied.The results show that with the increase of shot peening intensity,the contact fatigue life of the material increases first and then decreases.When the shot peening intensity is 0.423 mm A,the material obtains the maximum contact fatigue life and its specified life(L₁₀),median life(L₅₀)and characteristic life(L_63.2)are 4.24,3.47 and 3.34 times the corresponding life of the original sample,respectively.The main contact fatigue failure modes of the original sample are fatigue spalling and delamination.The main failure modes of the shot peened samples are pitting and fatigue spalling.