Tribological evaluation of aluminum and magnesium sheet forming at high temperatures

The tribological mechanisms during interaction of aluminum and magnesium sheets with ferrous metal tools at high temperature are very complex and involve friction, wear, transfer of material, and deformation simultaneously. The tribological behaviour of both AA5083 aluminum and AZ31B magnesium alloy sheets sliding against tool steel were found to impact the quality of components manufactured with elevated temperature metal forming processes such as Quick Plastic Forming (QPF) and Superplastic Forming (SPF), or warm forming. The adhesion of aluminum to forming tools is of concern since it directly influences the quality of the formed part, while the choice of the tooling material and its surface influence tool cost, required maintenance, and durability. A flat-on-flat test method has been developed which allows measurement of wear and friction coefficients as well as determination of the onset of adhesion. The test allows the screening of tool surface material coatings and lubricants during interaction of aluminum or magnesium with tool surfaces at high temperature.