Abstract
The manufacture and performance of case-carburized gears were investigated from the result of roller tests which simulated gear tooth contact. First, the rolling-sliding contact surface of various processing case-carburized steels was observed by using a scanning electron microscopy (SEM). Secondly, the relation between surface hardness and surface failure was studied. On the rolling-sliding contact surface of the tempered steel, the subzero treated and tempered steel, the tempered and shot peened steel, and, the subzero treated, tempered and shot peened steel, the following results are obtained: (1) In the case of low load condition, cracks and micropits occur between grinding grooves. (2) Under a heavy load, the grinding grooves disappear completely, then, cracks, micropits, small pits, pits and spalls occur. (3) Even though the case-carburized surface is hardened by subzero treatment and shot peening, the wear and surface fatigue are not improved.
