Variation of surface roughness, micro-hardness and friction behaviour during sheet-metal forming

The aim of the research described in this paper is to analyse the evolution of the main surface parameters values and friction coefficient value due to the sheet deformation. Frictional properties of the deep-drawing quality steel sheets were investigated using the strip drawing test under both dry and lubricated conditions. An increase in the plastic deformation of sheets in the range of true strain between 0 to 0.28 caused an increase in the value of amplitude roughness parameters Ra, Rp, Rt, measured along the rolling direction of the sheet metal and perpendicular to this direction. The character of frictional phenomena of the deformed sheets is a complex function of sheet directional topography, formed by pre-straining and strain-hardening phenomena. It was also found that owing to the strain-hardening phenomenon the micro-hardness of the sheet increased with the sheet deformation. However, this relation was near linear.