Cuttability Investigation of Coated Carbides

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Abstract
The cutting performance of CVD-Ti(C,N)/Al2O3(Tl), CVD-Ti(C,N)/Al2O3/ TiN(T2) and PVD-TiN(T3) coated inserts was investigated in the dry turning of a low alloy steel. The PVD-TiN single-layer coated insert presented a better cutting performance based on wear and material removal indices than the CVD multilayer coated inserts at low feed rate. At high feed rate, it was the CVD-Ti(C,N)/Al2O3 coated insert that gave the best cutting performance. While excessive nose wear and plastic deformation limited the tool lives of Tl and T2, it was chipping/fracture for T3. Cutting temperature was deduced to have more effect on chip serrations than did degree of work hardening; with PVD-TiN inducing the highest degree of work hardening and lowest cutting temperature. Microstructural evidence also suggested brittle deformation and dissolution/diffusion as the wear mechanisms on T3, and plastic deformation, interfacial, and surface fatigue cracks were the observed phenomena for Tl and T2.