Laboratory Evaluation of New Low Alloy Gear Steels

The bending fatigue, charpy impact, impact fatigue, and metallurgical properties of carburized 8620, EX 10, EX 15, and 1524 steel gears were evaluated to determine if equivalent hardenability is a criterian sufficient to merit the substitution of 8620 with EX 10 and EX 15 for gearing applications. Tests run on actual gear teeth using a unique test fixture show that the impact requirements of each application must be considered. Sufficient samples should be tested to insure that neither the substitute steel nor the heat treatment have reduced the performance under impact loading.