Speed effect on the material behavior in high-speed scratching of BK7 glass

Abstract

Scratch tests are often performed at a speed that is significantly lower than the real application like machining and grinding. However, brittle materials like BK7 behave very differently under high-speed conditions due to the more promising temperature and stain rate effects Therefore, it is important to study its material behavior under high-speed condition. In this study, single scratch tests and consecutive scratch tests were performed on BK7 under scratch speeds of 1, 5 and 20 m/s, which were much higher than the traditional scratch tests. The surface morphology as well as the subsurface cracks of the scratch grooves was inspected under AFM and FIB-SEM. The thermal effect that caused the changes in ductile-brittle transition (DBT) and scratch morphology was simulated and explained by a thermal-stress coupled finite element analysis. Finally, the changes in material removal behavior as well as the crack initiation mechanism due to speed effect was revealed.