Investigating the influence of titanium on wear characteristics of P/M hot extruded alloy steels

Abstract

Powder metallurgy (P/M) processes is one of the fastest growing manufacturing fields. P/M process has outspread its applications in almost all the engineering fields like aerospace, automotive, manufacturing industries. P/M steels are most promising candidate materials for producing small components with high strength, but their wear resistances characteristics are mainly influenced by its alloy composition as well as the sintering conditions. The present work investigates the dry sliding wear characteristics of P/M hot extruded alloy steels with the addition of Titanium (Ti) in the Fe-1W-1C (base alloy). As these elemental alloy compositions find in numerous of applications as cutters, tools, bearing roller, fasteners, etc. The pin-on-disc tribometer was used to explore the wear characteristics at 2 m s−1 (constant speed) for a distance of 3600 m in ambient temperature. The extruded steel pins with a diameter of 6 mm were used for wear test against EN 38 steel disc as per ASTM G99 standard at 30, 50 and 70 N loads. The as-sintered microstructure exhibits the ferritic-pearlite structure. Alongside the microstructures of hot extruded alloy steels reveals the alternate lamellas as well as Widmanstatten ferrite, pearlite and bainite. The study assimilated that the addition of Titanium (4%) exhibited greater wear resistance due to the WTiC (secondary phase) embedded in the matrix of the Fe-W-C. The wear debris has been characterized by x-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The wear debris analysis confirms the presence of WTiC, TiC and the iron oxides in major amounts and small traces of Fe, WC. The delamination wear was observed as the common wear mechanism during lower loads, whereas the oxidative wear was predominant at higher loads.