Adhesion transfer in sliding a steel ball against an aluminum alloy

High-temperature sliding experiments have been carried out to study both direct and back adhesion transfer between Al-Mg alloy metal and the ball bearing steel sample. It was shown that a transfer layer consisting of aluminum alloy formed on the trailing hemisphere of the steel ball. The amount of transferred metal increased with the test temperature from 25 to 200 degrees C. The periodical back transfer from the steel ball to the aluminum alloy disk was observed at the test temperature 100 degrees C. The wear groove bottom was characterized by the presence of large aluminum alloys transfer layer bulges, transfer layer film and plastically deformed subsurface layer. It was found that aluminum alloy transfer layer might accumulate on the trailing hemisphere of the ball and then could stick back to the wear groove surface of the disk. Such an adhesion transfer mechanism may be effective for metal transfer during friction sir welding by not threaded pins or pins fully covered by the transfer metal film.