The Role of Adhesive Forces and Mechanical Interaction on Material Transfer in Hot Forming of Aluminium

In this work, the mechanisms resulting in transfer of aluminium on hot forming tools have been analysed by means of two separate laboratory tests. The influence of chemical affinity in aluminium adhesion has been studied in contact tests, measuring the force used in pulling at low velocity an aluminium ball pressed against a tool surface. The role of mechanical interaction has been investigated through ball-on-disc sliding tests at high temperature, using tool steel discs with different surface finish against an aluminium counterpart. These tests have been used for the evaluation of different strategies in adhesive wear reduction, including different tool steels and surface modification, and to study the effect of surface finish on the material transfer mechanisms observed.