SURFACE COATED CEMENTED CARBIDE CUTTING TOOL HAVING HARD COATING LAYER EXHIBITING EXCELLENT WEAR RESISTANCE IN HIGH SPEED MACHINING

摘要

The invention provides a coated cutting tool made of cemented carbide in which a hard coating layer has excellent wear resistance in high-speed cutting operation, wherein (a) a crystal orientation hysteresis layer which consists of a carbonitride compound layer and (b) a hard coating layer which consists of a layer of nitride compound and has a well defined crystal orientation and/or degree of crystallinity are formed on the surface of a cemented carbide substrate, preferably on the surface of a tungsten carbide based cemented carbide or titanium carbonitride based cermet by physical vapor deposition, wherein the crystal orientation hysteresis layer is deposited between the surface of a cemented carbide substrate and the hard coating layer. In one specific example, (a1) the carbonitride compound layer has an average thickness of 0.05 to 0.5 mu m and is preferably a Ti-Al carbonitride compound layer expressed by the composition formula as (Ti1-XAlX)(N1-YCY), wherein X ranges from 0.05 to 0.20 and Y ranges from 0.01 to 0.15 by atomic ratio and (b1) the nitride compound layer has an average thickness of 2 to 15 mu m and is preferably a Ti-Al nitride compound layer expressed by the composition formula as (Ti1-ZAlZ)N, wherein Z ranges from 0.45 to 0.65 by atomic ratio. In another specific example, (a2) the carbonitride compound layer has an average thickness of 0.05 to 0.5 mu m and is preferably a Ti-Al carbonitride compound layer expressed by the composition formula as (Ti1-XAlX)(N1-YCY), wherein X ranges from 0.01 to 0.15 and Y ranges from 0.01 to 0.15 by atomic ratio and (b2) the nitride compound layer has an average thickness of 2 to 10 mu m and is preferably a AI-Ti-Si nitride compound layer expressed by the composition formula as (Al1-(A+B)TiASiB)N, wherein A ranges from 0.35 to 0.55 and B ranges from 0.05 to 0.20 by atomic ratio.