Paul Wycliffe

Galling in aluminum alloys and Duralcan aluminum matrix composites

Abstract Galling behaviour of DuralcanTM aluminum matrix composites (metal matrix composites (MMCs): 20 vol.% SiC in an Al-Si alloy matrix) is compared with that of unreinforced 6061 aluminum alloy and cast iron. Counterface materials were 52100 bearing steel and cart iron with test conditions consisting of cylinders of the ferrous materials sliding on plates of the aluminum based materials, in reciprocating motion without lubrication. The onset of galling was studied in a stepped load test. Neither the 52100 steel sliding on cast iron, nor the cast iron sliding on the MMC exhibited galling through the range of loads tested. Instead they exhibited uniform, rectangular wear tracks consistent with truncation of surface asperities and increasing conformity of the surfaces as wear progressed. The unreinforced 6061 alloy, exhibited galling at low loads with protrusions forming on the hard steel slider that caused abrasion of the aluminum alloy. Thus conformity of contact decreased as wear progressed. Galling is discussed in relation to contact geometry and wear mechanism maps.