Selective unidirectional median crack propagation in glass achieved by mechanical scribing

This work reports a selective median crack propagation phenomenon in glass, leading to a novel glass cutting process. We found that by scribing a glass sample to the extent of plastic deformation with a deformation depth of 100–400 nm, followed by inducing an initial crack, a subsurface crack with a depth of ~ 10 μm was propagated backward along the centerline of the scribed region with a speed of 1 μm/s order. The crack depth and propagation speed were increased by increasing the scribing load. We conclude that the propagation direction was determined by the effect of the shear stress caused by a scribing tip sliding motion.