Effect of Annealing on Properties of the TiN & TiAlN Coatings Deposited on Powder Metallurgy High Speed Steel ( S790 )

Abstract

To improve the mechanical properties of the physical vapor deposition (PVD) coatings deposited on fine-blanking tools and increase the tool life, TiN and TiAlN coatings were deposited on the powder metallurgy high speed steel S790 substrates by Multi-arc ion plating, and then annealed at the temperature of 500°C for one hour in vacuum enviroment. The phase variation, residual stress, morphology, surface microhardness and adhesion strength of coatings were respectively analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), Vickers hardness tester and automatic scratch tester. The preferred orientations in the coatings are not changed after annealing, indicating no disparities in the crystal structure of the coatings. The residual stress of coatings released a little after annealing, however the adhesion strength between the coatings and substrates increased obviously, which indicated that the properties of the TiN and TiAlN coatings deposited on S790 steel were improved.