Coated cemented carbide cutting tool member and process for producing the same

Abstract

The present invention relates to a coated cemented carbide cutting tool member, which includes: a substrate and a hard coating layer deposited on the substrate, wherein the hard coating layer has an average thickness of 3 to 25 μm and includes: (1) at least one layer having an average thickness of 0.1 to 5 μm and including a granular Ti compound selected from the group including TiC, TiN, TiCN, Ti2O3, TiCO, TiNO, TiCNO and mixtures thereof; (2) a TiCN layer having an average thickness is 2 to 15 μm and including a longitudinal growth crystal structure; and (3) an Al2O3 layer having an average thickness of 0.5 to 8 μm; wherein the TiCN layer includes a growth direction and a compositional gradient of carbon and nitrogen along the growth direction. The invention also relates to a process for producing a coated carbide member, which includes depositing a TiCN layer with a reactive gas, the layer having a lower portion and an upper portion; and, during the depositing, changing a concentration in the reactive gas of at least one selected from the group including CH3CN, CH4, N2, and mixtures thereof; wherein the depositing of the lower portion is carried out at a deposition temperature of 850-950° C., and the depositing of the upper portion is carried out at a deposition temperature of 960-1040° C. The invention also provides a coated carbide member produced by the above-noted process. By use of the present invention, a coated carbide member is provided that resists chipping of cutting edge over long periods of time even when used for high speed, high feed, and thick depth-of-cut interrupted cutting operations of steels and cast irons.

Dependencies are inferred from the claim text.