Hardening the hard-alloy edge tool used for cutting the tough-to-machine titanium alloys and chromium–nickel steels with multilayered nanostructured coatings

Complex investigations into physicomechanical properties and adhesion strength in the coating–carbide cutting insert system of monolayered coatings (Ti–Al–N) and multilayered coatings (Ti–Al–N/Cr–N, Ti–Al–N/Zr–N/Cr–N) are performed. The advantage of using the latter, which is associated with the passage from the adhesion mechanism of coating destruction to the cohesion mechanism with an increase in parameters H3/E2 and H/E that characterize the material resistance to plastic and elastic deformation, respectively, is shown. The introduction of chromium into the composition of Ti–Al–N coatings decreases the friction coefficient (from 0.52 to 0.45) and decreases the probability of adhesion interaction with the treated material. Comparative operational tests of carbide cutting inserts (CCIs) with coatings under study in the course of continuous cutting steel #12Kh18N10T# showed that the largest wear resistance is characteristic of Ti–Al–N/Zr–N/Cr–N coatings. Wear tests of CCIs made of VK6NST and TT10K8B alloys with Ti?Al–N/Zr–N/Cr–N coatings in the course of longitudinal turning steel 12Kh18N10T and VT20 alloy evidence an increase in their resistance up to a factor of 3.0–3.5 both at low and high cutting rates. These coatings provide an increase in resistance of cutting tool and in milling operations of VT20 titanium alloy at a cutting velocity up to 40 m/min.