Effects of substrates and PVD-coated layers on flank notch wear of carbide tool in stainless steel cutting

In many cases of stainless steel cutting operations with carbide tools, a tool life strongly depends on flank notch wear of depth-of-cut rather than average flank wear of main cutting edge. To improve a tool life in this case, therefore, the flank notch wear must be depressed to generate. In this study, the notch wear of coated carbides in turning and milling operations of austenite-based stainless steel was investigated in relation to mainly substrates corresponding to M20, K20 or Z20 and PVD-coated. layers such as TiN, Ti(C,N) and (Ti,Al)N layers. The results obtained are as follows: (1) In turning operation, Z20 substrate with super microparticle size of WC for PVD-coated grades was more excellent in flank notch wear resistance than M20 and K20 substrates and (Ti,Al)N layer was much more superior in it than TiN or Ti(C,N) layer by PVD and also multi-layers by CVD. Therefore, the combination of Z20 substrate and (Ti,Al)N layer by PVD showed the smallest flank notch wear for stainless steel turning. (2) In milling operation, the combination of Z20 and (Ti,Al)N or Ti(C,N) layer by PVD showed the longest tool life due to the remarkable decrease of the flank notch wear. The above results were discussed with some properties of substrates and coated layers.