Modelling of friction for high temperature extrusion of aluminium alloys

During high-temperature ball-on-disc tests of aluminium against steel, hot aluminium deformsand wear track evolves. The individual contributions of ploughing and shearing to theapparent friction and the contact pressure are unknown. The aim of this chapter was todevelop a model capable of determining these parameters. It was found that during high-temperature ball-on-disc tests, the ploughing friction accounted for only about 1% of theapparent friction, although the ploughing friction coefficient increased with increasing wearlap, while the shear friction played a dominant role in determining the apparent frictionmeasured. The mean contact pressure decreased significantly as the test proceeded. This chapter is reproduced from the article published in Tribology International, vol. 42,pp. 15-22, Jan 2009.