Analysis And Research On Wear Resistance And Corrosion Resistance Of Shield Machine Cutter Ring By Shot Peening Strengthen

Shield machine is a tunnel boring machine using shield method.Shield machine has the characteristics of once excavation and laying supporting pipelines,which improves the efficiency and automation of shield construction method.The cutter of shield machine is the main component of rock breaking in the process of tunneling,and the friction and wear are serious in the process of tunneling.At the same time,the cutter of shield machine is also the most vulnerable component in the working process of shield machine.The working conditions of shield tunneling machine are complex.After the tool wear failure,the replacement of the tool wastes time,which reduces the tunneling efficiency and safety.At present,H13 steel is mainly used to manufacture the cutter ring of shield machine.H13 die steel has high toughness,hardenability and cold and thermal fatigue resistance,which is not easy to produce thermal fatigue cracks.However,the hobs of shield machine made of H13 steel also have partial wear,breakage,and wear failures.Therefore,this paper takes H13 steel as the research object,and improves the stress,hardness,wear resistance and corrosion resistance of H13 steel by ultrasonic shot peening and laser shot peening.In this paper,the finite element simulation analysis of rock breaking by hob is carried out by simulation software,and the stress and strain of hob ring during rock breaking are obtained,which provides experimental parameters for friction and wear test of H13 steel after shot peening.According to the principle,formula and equipment parameters of ultrasonic shot peening and laser shot peening,the experimental scheme was formulated.The surface strengthening treatment of H13 steel was carried out by ultrasonic shot peening equipment and laser shot peening equipment.The wear resistance and corrosion resistance of H13 steel after shot peening were analyzed by X-ray stress,microhardness tester,friction and wear tester and electrochemical test workstation.The effects of different shot peening processes and parameters on the wear resistance and corrosion resistance of H13 steel were studied.According to the principle and test scheme of ultrasonic shot peening and laser shot peening,the simulation analysis model is established by using the simulation software and the simulation boundary conditions are set.The simulation analysis of ultrasonic shot peening and laser shot peening is carried out by using the simulation software solver,and the stress and strain results of the two kinds of shot peening H13 steel are calculated.The accuracy of the simulation model was studied by comparing the test and simulation results of ultrasonic shot peening and laser shot peening.It is found that through the simulation analysis of rock breaking by shield cutter,the maximum reaction force of cutter ring subjected to rock is about 243MPa in the process of rock breaking.After a simulation of rock breaking cycle by cutter,the stress of cutter ring is finally stabilized at about 161MPa.With the increase of ultrasonic shot peening amplitude,the hardness and residual compressive stress of H13 steel after ultrasonic shot peening treatment increase,while the friction coefficient,wear volume and corrosion current density of H13 steel decrease.When the ultrasonic amplitude reached the maximum of 40μm,the hardness and residual compressive stress of H13 after ultrasonic shot peening treatment reached the highest,the friction coefficient and wear volume were the lowest,the hardness increased by 18.47%,the residual compressive stress increased by 66.67%,the friction coefficient decreased by 12.69%,the wear volume decreased by 82.02%,and the corrosion current density decreased by 70.94%.With the increase of laser power density,the hardness increment and residual compressive stress increment of H13 steel after laser shot peening treatment first increase and then decrease,while the friction coefficient and wear amount of H13 steel first decrease and increase.When the laser power density is 8.29 GW/cm~2,the hardness of H13 steel increases by 21.45%,the friction coefficient decreases by 12.87%,and the wear volume decreases by 68.77%.When the laser power density is 7.74GW/cm~2,the residual compressive stress of H13 steel increases by152.38%.After strengthening of H13 steel,the corrosion current density did not show a phenomenon that was lower than that of raw materials.According to the simulation analysis of ultrasonic shot peening and laser shot peening,it is found that the residual compressive stress of H13 steel increases with the increase of ultrasonic amplitude.When the ultrasonic amplitude is 40μm,the residual compressive stress reaches the maximum,and the simulation results are in good agreement with the experimental results.With the increase of laser power density,the residual compressive stress of H13 steel increases.When the laser power density is less than 8.29GW/cm~2,the residual compressive stress is in good agreement with the experimental results.When the laser power density is greater than 8.29GW/cm~2,the residual compressive stress has a large error with the experimental results.The results show that through the ultrasonic shot peening strengthening effect and the laser shot peening strengthening effect,it can be found that after the ultrasonic shot peening strengthening of H13 steel,the wear amount and corrosion current density of the material are lower,and the wear resistance and corrosion resistance are better.Moreover,with the increase of ultrasonic shot peening power,the wear resistance and corrosion resistance of H13 steel strengthened by ultrasonic shot peening are enhanced.By comparing the strengthening effects of the two shot peening processes,it is found that when the ultrasonic shot peening amplitude is 40μm,the wear and corrosion resistance of the shield cutter ring material is the best.By comparing the simulation and experimental results,it is found that the difference between the experimental results and the simulation results of H13 steel treated by ultrasonic shot peening is small.The ultrasonic shot peening simulation model can provide data guidance for the ultrasonic shot peening test of H13 steel.