SURFACE COATED CUTTING TOOL WHOSE HARD COATING LAYER EXERTS EXCELLENT CHIPPING RESISTANCE IN HIGH-SPEED INTERMITTENT CUTTING WORK

摘要

PROBLEM TO BE SOLVED: To provide a surface coating cutting tool whose hard coating layer exerts excellent chipping resistance in high-speed intermittent cutting work of stainless steel or the like.SOLUTION: A surface coating cutting tool includes a base element surface coated with a hard coating layer formed of a (TiAl)(CN) layer deposited by a chemical vapor deposition method using a reaction gas containing Al(CH)as a component. An average Al content ratio, X, and an average C content ratio, Y(where X, Yare atomic ratios) in the layer satisfy respective predetermined content ratios. Crystal grains constituting the layer include ones having a cubic structure. In a frequency distribution of measured inclination angles of the normal line of a plane (100) of the crystal grains with respect to a normal line direction of the base element surface, a frequency ratio of the inclination angles within a range of 0 to 12 degrees in the whole inclination angle frequency distribution is 45% or more. It is observed in a structure from a surface side, that each of the crystal grains having the cubic structure has a polygonal shape having angles not less than 90 degrees in a plane vertical to the layer thickness direction, and that a facet formed of an equivalent crystal plane represented as the plane (100) accounts for an area ratio of 50% or more on the above-mentioned plane.