Subsurface damage evaluation in the single abrasive scratching of BK7 glass by considering coupling effect of strain rate and temperature

BK7 glass has been extensively used in astronomical observation systems, laser fusion devices and precision optical measuring instruments. In order to improve the surface integrity during the high-speed grinding of BK7 glass, the underlying science in the single abrasive scratching of BK7 glass has been theoretically and experimentally explored. It is found that in the abrasive-workpiece contact zone the coupling effect of the strain rate and temperature plays an important role in affecting the material properties, the radius of the plastic deformation zone, the distribution of the elastic stress and the length of the median which in turn affect the subsurface damage in the single abrasive scratching process. The model for predicting the depth of subsurface damage by considering the coupling effect of the strain rate and temperature in the single abrasive scratching of BK7 glass has been theoretically developed and experimentally validated. It is also noted from experimental analysis that with an increase of the strain rate and temperature caused by the high scratching speed at the same cutting depth the radius of plastic deformation zone decreases, and the initiation and propagation of the median crack, lateral crack and radial crack are suppressed, which facilitate for shortening the crack length, reducing the brittle fracture, improving the surface integrity and decreasing the subsurface damage.