Abstract
The fatigue strength of the sintered and super rapid induction heated and quenched (SRIQ) compact made of the 0.6 mass% Mo - 0.2 mass% Mn prealloyed steel powder has been investigated. As the effective case depth in the SRIQ material decreased, fatigue strength increased, and reached to 400 MPa equivalent to two times of the carburized material in the case of 1 mm of the effective case depth. Moreover, fatigue strength of 500 MPa was obtained by double SRIQ treatment, in which specimens was quenched to the center region in the first SRIQ, and to 1 mm of the effective case depth in the subsequent treatment. The improvement in the fatigue strength can be considered to result from not only the high compressive residual stress but also the fine prior austenite grain.
