Effect of Micro-cracks in Layer on Performance of CVD Coating Carbide Cutting Tool.

Abstract

Micro-cracks were mechanically induced in the CVD coating layers on a cemented carbide tool . With decreasing mean value of distance between cracks from 200 ƒÊm to 20 ƒÊm, tensile residual stress in the coating decreased from 0.55 GPa to 0.05 GPa, the initiation time of thermal fatigue cracks in face milling became longer, and the chipping resistance in interrupted cutting tripled. It seems that the improvement of tool performance is closely related to the relief of tensile residual stress in the coating.