Experimental investigation on the nanomechanical properties of lubricated and non-lubricated AISI 1018 mild steel using nanoindentation technique.

In this study, AISI 1018 Mild/Low Carbon Steel is used as a metal substrate for investigating the nanoindentation effects at room temperature in the dry and lubricated regimes. The Oliver-Pharr technique is employed to estimate the unloading data of nanoindentation according to the Power law and the peak load (P_max) is increased from 0-10000 µN for all the nanoindentation experiments. The Coconut oil and different concentrations of Graphene-Coconut oil nanofluids are used to lubricate the metal substrate and their mechanical properties such as hardness, Young modulus, residual indentation depth, and contributions of elastic as well as plastic parts to total nanoindentation deformation are observed. The mechanism of the change in surface deformation rate of nanofluid lubricated metal substrate is also demonstrated through their indentation hardness AFM micrographs. The results exhibit that the lubrication of metal substrate by 0.1 wt% of Graphene-Coconut oil nanofluid significantly reduces the permanent plastic surface deformations. [ABSTRACT FROM AUTHOR]