Surface-coated cutting tool in which hard coating layer demonstrates excellent chipping resistance

Abstract

The present invention provides a surface-coated cutting tool in which a hard coating layer demonstrates excellent chipping resistance in high-speed intermittent machining. The surface-coated cutting tool comprises a lower layer composed of a Ti compound layer and an upper layer composed of a columnar crystal Zr-containing alpha-Al2O3 layer which are formed by vapor deposition. A surface layer of the lower layer is composed of a TiCN layer with a layer thickness of more than 500 nm. Oxygen is only exited in a depth region up to 500 nm in a thickness direction of the TiCN layer, and has an average content of 0.5-3 atom%. The horizontal average diameter of Zr-containing alpha-Al2O3 particles right above the lower layer is 0.1-0.3 [mu]m, and the horizontal average diameter of Zr-containing alpha-Al2O3 particles right above the upper layer is 0.5-1.0 [mu]m. For Zr-containing alpha-Al2O3 particles of the whole upper layer, the Zr-containing alpha-Al2O3 particles which a tilt angle formed by the normal of a plane (0001) and a normal of the surface of a tool substrate being 0-10 degrees account for 45 area%, and in the area where the film thickness from an interface to the upper layer is less than 1 [mu]m, the orientation of the plane (0001) is less than 10%, and the orientation of (02-21) is more than 30%.

Description

technical field [0001] The present invention relates to a hard coating that exhibits excellent adhesion strength even when cutting various steels or cast irons under interrupted cutting conditions in which high speed and intermittent / impact loads act on the cutting edge. A surface-coated cutting tool that exhibits excellent chipping resistance and exhibits excellent cutting performance over a long period of time (hereinafter referred to as a coated tool). Background technique [0002] In the past, it is known that the surface of a substrate generally composed of tungsten carbide (hereinafter referred to as WC)-based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN)-based cermet (hereinafter these are collectively referred to as a tool substrate) is known. A coated tool formed by forming a hard coating layer composed of the following (a) and (b): [0003] (a) The lower layer is a Ti compound layer, which consists of Ti carbide (hereinafter represent...

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Problems solved by technology

[0011] In recent years, the performance of cutting devices has been significantly improved. On the one hand, there is a strong demand for cutting labor and energy saving, and even cost reduction. With this, the cutting process tends to be faster and a high load is applied to the cutting edge. However, The current situation is as follows: in the above-mentioned conventional coated tools, it is not a problem to use them for continuous cutting or interrupted cutting under normal conditions such as steel or cast iron, but especially when they are accompanied by high heat generation and intermittent impact When used under the condition of high-speed interrupted cutting where a high-speed load acts on the cutting edge, the lower layer composed of the Ti compound layer constituting the hard coating layer and the Al containing Zr 2 o 3 The adhesive strength of the upper layer composed of layers is insufficient, and abnormal damage such as peeling and chipping between the upper layer and the lower layer occurs, so the service life is reached in a short period of time

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