Micro-blasting effect on fracture resistance of PVD-AlTiN coated cemented carbide cutting tools

The dry micro-blasting effects on the fracture resistance of PVD-AlTiN coated cemented carbide cutting tools were studied. The AlTiN coatings with the composition of (Al0.60Ti0.40)N were deposited using cathodic arc evaporation method. The two types of coatings, which had a compressive residual stress of 0.1 GPa (Low-σ) and 2.6 GPa (High-σ), were prepared. The coated samples were subjected to the dry micro-blasting treatment by Al2O3 grains at pressures of 0.11 MPa, 0.14 MPa, and 0.17 MPa. A milling test using AISI 4140 (42CrMo4) steel as the workpiece material was carried out for evaluating the fracture resistance of the prepared samples. The tool life cutting distance of Low-σ sample micro-blasted at 0.14 MPa and 0.17 MPa was 2.9 m and 7.2 m, respectively, largely extended as compared to that of as-deposited Low-σ sample, 1.0 m. On the other hand, the tool life of High-σ sample micro-blasted at 0.14 MPa was 8.6 m, almost same with that of as-deposited High-σ one, 8.8 m. Those results indicate that the dry micro-blasting effect on the fracture resistance is larger for the Low-σ coating than for the High-σ one.