Study On The Grinding Performance Of 12Cr2Ni4A Carburized Steel Under CNTs Lubricating Medium

12Cr2Ni4A steel is a high-quality alloy structural steel,this material has high strength,good toughness,good hardenability,after carburizing and quenching its surface hardness and wear resistance are very good,in actual production,because the steel has good hardenability,after carburizing-primary quenching-high temperature tempering-secondary quenching-low temperature tempering,the material's heart strength and plasticity,toughness can be a good match,and Therefore,it is widely used in important parts with high load,large cross-sectional area and good toughness,such as for manufacturing various gears and shafts.Because of its susceptibility to thermal damage during the grinding process,it affects the surface quality of the workpiece.Therefore,it is necessary to use grinding fluid for cooling and lubrication to improve the grinding efficiency and surface quality of the workpiece after grinding.Some additives are added to the conventional grinding coolant to improve the grinding quality,but it will bring pollution to the environment.Since nanoparticles have very good heat transfer and antifriction and friction reduction properties,most importantly,they are not harmful to the environment.In this paper,a nano-fluid casting grinding method is proposed for the experimental grinding study of12Cr2Ni4 A carburized steel to analyze the effects of grinding force,specific grinding energy,surface roughness,microhardness,residual stress,and sub-surface thermal damage.(1)A two-step method was used to prepare carbon nanotubes(CNTs)and deionized water to produce nanofluids as grinding fluids.Chemical and physical methods were used to improve the dispersion and suspension stability of nanoparticles in the base fluid.The dispersion of carbon nanotubes(CNTs)in the base fluid was improved by using a nonionic dispersant polyvinylpyrrolidone(PVP),and finally the nanofluid was prepared by uniformly dispersing the CNTs in the base fluid using an ultrasonic vibrator.(2)The grinding test was conducted on 12Cr2Ni4 A carburized steel by using the nanofluid casting grinding method,and the grinding force during the grinding process was measured by using a three-way piezoelectric crystal force measuring instrument in comparison with the normal dry type and the conventional casting type.The highest reduction was 25.9%,and the highest reduction in grinding energy was39.9%.(3)The effect law of grinding parameters on surface roughness,microhardness and residual stress was investigated and the results were analyzed.It was found that when the grinding speed vs=30m/s,the values of surface roughness of three different cooling and lubrication methods were the smallest,among which the surface roughness of nano-fluid casting type performed the best and the surface quality after grinding of nano-fluid casting type was significantly improved;the surface quality of workpiece after grinding of conventional casting type and normal temperature The microhardness of the workpiece surface after dry grinding showed different degrees of heat-affected layer;the surface residual stresses on the workpiece surface after nanofluid casting type grinding performed better than those of conventional casting type grinding,and the surface residual tensile stresses were formed on the workpiece surface due to high temperature in ambient temperature dry grinding.(4)The surface morphology after grinding was analyzed under different grinding parameters,and the grinding burns on the subsurface after grinding were analyzed and found that quenching burns and tempering burns occurred to different degrees on the subsurface in conventional cast grinding and ambient dry grinding.