Single tooth bending fatigue tests were carried out using spur gears of 1.5Cr-0.2Mo sintered steel having a density of 7.55 g/cm3 and the effects of surface rolled or shot peening (WPC) on bending fatigue strength were examined. P/M gears were case-carburized. The bending fatigue durability of this P/M gears not surface densified is equal to that of case-carburized wrought alloyed steel gears of SCM415. The bending fatigue limit of the P/M gear was much improved by WPC. The impact strength of P/M gear tooth was investigated using an impact testing machine for gears. The mean value of peak impact damage torque of the surface rolled P/M gears almost matches that of wrought steel gears of SCM415. Both test results indicate the feasibility of this high density Cr-Mo P/M gears to replace case-carburized wrought steel gears made of typical Cr-Mo alloyed steel.
