High temperature wear and friction behaviour of nitrided, PVD-duplex and CVD coated tool steel against 6082 Al alloy

• Published in: Wear Vol. 271; no. 9; pp. 2089 - 2099
• Main Author: Pellizzari, M.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 29.07.2011; Elsevier
• Subjects: Aluminium; Aluminum; Aluminum base alloys; Applied sciences; Chemical vapor deposition; Contact; CVD; Duplex-PVD; Exact sciences and technology; Fracture mechanics (crack, fatigue, damage...); Friction; Friction, wear, lubrication; Fundamental areas of phenomenology (including applications); Hot wear; Machine components; Mechanical engineering. Machine design; Nitriding; Physics; Roughness; Solid mechanics; Structural and continuum mechanics; Surface finishing; Ultrasonic testing; Wear; CVD; Friction; Duplex-PVD; Hot wear; Roughness; Nitriding; Aluminium; Chemical stability; Chromium nitride; High temperature; Tool steel; Surface finishing; Duplex process; Physical vapor deposition; Duplex stainless steel; Aluminium base alloys; Experimental study; Adhesion; Chemical vapor deposition; Contact surface; Surface treatment; Surface hardness; Wear; Nitriding steel; Tribology
• ISSN: 0043-1648; 1873-2577
• DOI: 10.1016/j.wear.2011.01.067

► Hot sliding of surface engineered tool steel against 6082 Al alloy. ► Extended damage for base and nitrided steel, localized damage for coated systems. ► Duplex-PVD and CVD coatings delay the transition to unstable frictional contact. ► Mirror polishing extends the stable frictional contact regime. ► PVD and CVD coatings show lower Al transfer than nitrided and base steel. The hot tribological contact between a surface engineered hot work tool steel and 6082 Al alloy was evaluated by means of a block on disc test configuration, under conformal contact. The steel was nitrided, duplex-PVD (CrN, TiAlN, TiCN) and CVD coated (TiC + TiN), following the typical processing conditions used for extrusion dies. Furthermore, different degrees of surface finishing were considered. The contact was characterized in terms of damage mechanism, friction behaviour and tendency towards Al pick up by the die material. The surface engineered steel showed better properties than base material in view of the higher load bearing capacity. This was particularly beneficial for duplex-PVD samples, combining high surface hardness with good stability against chemical dissolution by hot aluminium. The double layered CVD coating also showed excellent properties in view of the high interfacial adhesion, which was a limiting factor for duplex coatings. A lower resistance was highlighted by the compound layer in nitrided samples, due to the higher affinity of Fe to Al. This resulted in a heavy pick up and the formation of big hard particles on the die surface, very detrimental for the surface finishing of the extrudate. In coated samples, the friction diagrams evidenced a delayed transition towards an unstable contact regime, which could be associated to a lower tendency towards the formation of build up layer of aluminium. The positive influence of a better surface finishing was demonstrated, as well.