| 摘要 |
PROBLEM TO BE SOLVED: To provide a cutting tool made of a surface coated high-speed tool steel having improved tool life. SOLUTION: The cutting tool made of the surface coated high-speed tool steel is formed by vapor-depositing a hard coating layer composed of an upper layer and a lower layer made of (Cr, Al, Si) N on the surface of a substrate of high-speed tool steel, wherein the upper layer has an average layer thickness of 0.5 to 1.5μm and the lower layer has an average layer thickness of 2 to 6μm respectively, the upper layer has an alternately laminated structure of a thin layer A and a thin layer B having one layer average layer thickness of 5 to 20 nm (nanometer) respectively, the thin layer A is formed of (Cr, Al, Si) N layer satisfying a specified composition formula: [Cr<SB>1-(A+B)</SB>Al<SB>A</SB>Si<SB>B</SB>] N, and the thin layer B is formed of (Cr, Al, Si) N layer satisfying a specified composition formula: [Cr<SB>1-(C+D)</SB>Al<SB>C</SB>Si<SB>D</SB>] N, the lower layer has a single phase structure, and is formed of (Cr, Al, Si) N layer satisfying a specified composition formula: [Cr<SB>1-(E+F)</SB>Al<SB>E</SB>Si<SB>F</SB>] N. COPYRIGHT: (C)2007,JPO&INPIT
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