Evaluation of Vitreous and Devitrifying Enamels as Hot Forming Lubricants for Aluminum AA5083 Alloy

Abstract

The adhesion of aluminum to tool surfaces during the hot forming of sheet aluminum alloys presents challenging tribological problems. Graphite and boron nitride are commonly used as aluminum adhesion mitigating solid lubricants for hot forming processes, but lubricant breakdown in high-stress areas, such as corners and bends, remains an issue compromising the quality of the formed parts as well as the tool life. Low-melting temperature enamels may provide an affordable and easy to apply alternative. In this study, vitreous (amorphous glass) and devitrifying (two phase crystalline glass) layers were deposited on the surface of sheet aluminum samples with a sedimentation technique. Enamel lubrication was effective in preventing aluminum transfer to the steel counterface. Hence, the prospect exists for the use of these enamels as aluminum workpiece lubricants in hot forming operations.