Microstructural evolution of novel continuously cooled carbide free bainitic steel during sliding wear

Abstract

In this present work, the dry sliding wear behavior of novel continuously cooled ultrafine carbide free bainitic (CFB) steel has been studied against EN31 steel using a pin-on-disc tribometer. The effects of changing the load on wear rate, the topography of the worn surface and microstructure near the worn surface have been studied. It was found that this novel CFB steel has excellent wear resistance properties, as could be seen from the calculated specific wear rates (mm3 × m-1 × N-1). Such a property might have been due to very good work hardening behaviour originating because of the evolution and accumulation of lattice defects like the generation of high dislocation density as well as due to the transformation of meta-stable retained austenite into martensite under deformation. Wear samples were characterized by many techniques which include scanning electron and atomic force microscopy, profilometer, X-ray diffraction (XRD) and micro-hardness measurements. Calculations of the XRD profiles showed an increase in dislocation density up to 127%. Around 33% increase in hardness on the worn surface of samples for 50 N normal load were measured. It could also be observed that the wear mechanism has been changed as well from lower to higher load conditions.