Generation and control of tungsten surface dislocations during ultrasonic elliptical vibratory cutting process

At present, tungsten is mainly processed with geometrical accuracy as the target, and the influence law of each process parameter (PP) on tungsten surface dislocations is unclear. This limits the performance of the tungsten divertor in a high-temperature plasma environment. Through ultrasonic elliptical vibration cutting (UEVC) simulation and experiments, the influence of PPs on surface dislocations was revealed. The results show that dislocations are formed in the material by tool shear removal and squeeze, and the generation and distribution of dislocations are closely related to the elliptical trajectory. Meanwhile, tungsten surface dislocations were affected by PPs. Increasing the edge radius (ER), cutting depth and vibration amplitude (VA), and decreasing the clearance angle (CA), rake angle (RA), cutting speed, vibration frequency (VF), and axis ratio (AR) could improve the dislocation density (DD) of the machined surfaces. The larger the contact area in the cutting zone, the greater the cutting volume, the longer the cutting time, the larger the elliptical radius in the cutting depth direction, or the fewer the elliptical vibrations, the more likely it is that dislocations will form. In addition, experiments were conducted at various cutting depths, and it was found that the DD on the tungsten surface increased with the increase in cutting depth, which validated the study's findings. The study provides a technical reference for the generation and control of tungsten surface dislocations during UEVC.