Tribological behaviour of ultra-thin stainless steel in micro deep drawing with graphene nanosheets

In this study, the micro deep drawing (MDD) experiments of an austenitic stainless steel with 40 μm in thickness were conducted using the lubricants containing different mass fractions of graphene nanosheets (GNS) in ethanol. Prior to the MDD tests, the lubricants with GNS concentrations of 5, 10, and 15 mg/ml were synthesised by mixing different amounts of GNS with pure ethanol, and then sprayed uniformly on the blank surface. The friction-reduction mechanisms of the GNS in the MDD were discussed by analysing the profile and surface roughness of the microcups. The results indicated that the GNS could reduce the friction and improve the surface quality of the micro products during the MDD process. In particular, the lubricant with 10 mg/ml GNS enabled the lowest drawing force, wrinkling, and surface roughness of the drawn microcup. These findings contribute to a better understanding of the friction-reduction mechanisms of using GNS in the MDD of materials.