Effect of the Chemical Composition and Microstructure of the Substrate on Properties of CVD-coated Cemented Carbide Tools

Abstract

The strength and cutting performance of the cemented carbide tools coated with titanium carbide(called TiC) by CVD process were studied in relation to the amount of βtWC-TiC-TaC solid solution) and the grain size of substrate carbides. It was found that the strength of coated alloys having the same amount of βt and the same thickness of coated layer was improved with increasing grain size of carbides. The result of milling test for 2μmTiC-coated alloy showed that the resistance to fracture of cutting edge was improved and the resistance to flank wear was decreased with decreasing the amount of βt and increasing grain size of carbides. It was suggested that CVD-coated cemented carbide tool showing a long life time could be obtained, when the amount of βt and the grain size of carbides of substrate are controlled appropriately.