Damage Mechanisms of Material in Single-Cone Scratching

Abstract

The scratching test has been a key method to characterize the basic mechanics of material in vast scenarios. Although attentions have been paid to this field for decades, a comprehensive analytical framework, which includes material flow, fracture initiation, and crack propagation, is still missing. The wide application of scratching test and the accurate description of material behaviors in friction is thus limited. To address the problem, an analytical frame model was established in this study. The strain distribution and pileup ratio in the symmetry section of the front ridge was calculated. Furthermore, the ductile fracture law was also included to predict the mechanism and the initiation location of fracture in the scratching process. The predictive results were further validated by scanning electron microscope (SEM) observations of the scratched grooves. The effects of cone angle and material properties on the damage mechanisms of material in the scratching process were studied. It was revealed that the damage mechanism changes from shear failure to tensile failure, and further to plastic deformation with the increase of cone angle and the ratio of yielding stress to Young’s modulus. Finally, a map of the damage mechanism of material in the scratching process was obtained by utilizing the developed model. The presented works are meaningful to the understanding of material behavior in ploughing and helpful in predicting and controlling the surface quality of those parts subject to different machining and forming processes.