Durability of deterministic textures produced by maskless electrochemical texturing (MECT) during Skin pass cold rolling

Abstract

Skin pass is a fundamental finishing process to control the sheet roughness in cold metal rolling. The energetic and tribological efficiency of this process can be improved by surface texturing to control the roll surface topography and consequently the final sheet roughness. In this work, deterministic textures were produced on flat segments of skin pass rolls using the maskless electrochemical texturing (MECT) technique. The textures consisted of arrays of circular dimples. After texturing, the specimens were coated either with hard chrome or NiP electroless coatings, aiming to evaluate the ability of electroless NiP coating to protect textures as a potential replacement of the carcinogenic hard chrome coating. The evaluation of the texture durability was carried out via dry reciprocating sliding tests with samples extracted from cold rolling work rolls. The test configuration and conditions were chosen to intensify the wear process in order to evaluate the durability of the textures during skin pass cold rolling. Wear evaluation was also by analyzing changes in roughness parameters. The results indicated that the best tribological performance occurred for the textured surfaces coated with NiP. The average coefficient of friction of the textured surfaces coated with NiP was around 16 % lower than that of the uncoated textures and around 19 % lower than that of textures coated with hard chrome coated. Although the mass loss was negligible in the tests, the analysis of surface topography parameters showed that both hard chrome and electroless NiP coatings acted to decrease the wear of MECT textured surfaces.