Study on strain rate and heat effect on the removal mechanism of SiC during nano-scratching process by molecular dynamics simulation

To study the influence of strain rate and heat effect on the removal behavior of SiC, the dislocation nucleation/propagation, amorphization and abrasive wear behavior are analyzed in detail according to the mechanical response and temperature distribution in the machining region at different strain rate. The strain rate effect and the thermal softening effect directly affect the material removal amount and form of the subsurface damage. The study found that when the cutting speed reaches 50 m/s, the maximum material removal amount can be obtained. When the cutting speed reaches 150 m/s, the depth of the damaged layer reaches over 6 times of the residual processing depth. There is a large difference in the influence of the strain rate effect caused by the change in velocity on different types of dislocations. The stress component, scratch hardness, and hydrostatic pressure in the machining direction are continuously reduced as the cutting speed increases, and the thermal softening effect caused by the cutting heat is the main factor leading to this phenomenon. Abrasive wear behavior is the result of the coupling action of impact effect and grinding heat. When the cutting speed is 50 m/s, the minimum wear loss can be obtained.