INFLUENCE OF SUBSTRATE SURFACE ROUGHNESS ON PUSH-OFF STRENGTH FOR FRICTION SURFACING OF LOW CARBON STEEL WITH AA6061-T6 ALUMINIUM ALLOY

Abstract

Surface roughness plays an essential role in friction surfacing deposition as a smooth substrate surface polishes both consumable and substrate tools, resulting in a lack of deposition. Hence, an attempt is made to investigate the effect of substrate surface roughness while friction surfacing of AA6061-T6 coating on CR01 low carbon steel and its performance is compared through push-off strength. It is revealed that with an increase in substrate surface roughness, more rubbing action occurs between consumable tool and substrate, which results in higher heat generation and reduction in deposition thickness. The grain refinement is observed at the coating region due to dynamic recrystallisation, which results in fine grain microstructure. The substrate with Ra roughness values 1.5-2.5, 5.5-6.5 and 7.5-8.5 µm showed 26, 32 and 45 MPa push-off strength, respectively. Hence, it is inferred that the push-off strength increases substantially with an increase in the substrate surface roughness.