Tribological behavior of superduplex stainless steel against PVD hard coatings on cemented carbide

Superduplex stainless steels (SDSS) are used to manufacture components in the oil and gas extraction industries. Machining of SDSS is difficult due to both built-up edge (BUE) formation on cutting tool surface at relatively low cutting speeds and rapid tool wear at higher cutting speeds caused by high strength and work hardening. Appropriate coating systems on cemented carbide tools (WC-Co) are crucial for adequate process performance, as well as SDSS/coated WC-Co tribological pair characterization. In this work, three types of coatings with chemical composition (at %) Al50Cr50N, Al60Cr40N, and Al50Cr50N/Ti95Si5N were deposited, by physical vapor deposition (PVD), on cemented carbide substrate. After, characterization was performed through X-ray diffraction (XRD), SEM, nanoindentation, tribological tests, and surface roughness. The results showed that SDSS prevailing wear mechanism was adhesion for all coatings investigated. Wear rate and friction coefficient are associated to coating chemical composition; Al50Cr50N/Ti95Si5N coating system presented the lowest interaction with SDSS, resulting in the lower friction coefficient and, consequently, reduced specific wear rate.