Study On The Cutting Performance Of Multicomponent Coated Hss Tools--Wear Rule And Failure Mechanism Under Dry Drilling

As an effective approach to improve performances of cutting tools, the technologies of coated tools have been rapidly developed and broadly applied. The multicomponent CrAlTiN coatings was deposited by close field unbalance magnetron sputtering ion plate physical vapor deposition (PVD) technique. The coatings characteristics and cutting performances of coated tools were studied.During determination of the coatings characteristics, the coatings surfaces and across-sections were observed using scanning electron microscope (SEM) and transmission electron microscope (TEM). Results show that the multicomponent CrAlTiN coatings matching with high-speed steel (HSS) substrate is much more ideal and the coatings microstructure is even and compact, by X-ray Diffraction (XRD) analysis, it is also found that the coatings has gradient phases structure and composition along the thickness , as well as high thermal stability. By experimentations of indentation, scratch and Pin-on-Disc, the coatings have many advantages including higher hardness and toughness, excellent anti-friction and wear performance and stronger adhesion with the substrate.A large number of cutting tests were carried out with the multicomponent CrAlTiN coated HSS twist drills to 45#, 30CrMnSiA and D406A steel with different strength and hardness. The cutting performance and wear characteristics were analyzed. Results show that the cutting performance of M2 HSS drills with multicomponent CrAlTiN coatings is obviously improved that compared with TiN and uncoated drills, the drills life is prolonged. The initial wear stage of the coated drills is relatively shortened, and the normal wear stage is obviously extended. Through observing the wear regions of drills by SEM, results show that the failure of drills is mainly due to crack and flake of the coatings that results from the plastic deformation of the drills substrate in the chisel regions, wear form is mechanical and adhesive in major cutting edges, and in outer corner regions, the wear failure exhibits mechanical and adhesive at lower speed & thermal oxidation and plastic deformation at higher speed.In a word, the multicomponent CrAlTiN coatings can obviously improve the performance of HSS cutting tools and could be widely used in manufacturing.