Abstract
High cycle fatigue properties of Metal Injection Molded (MIM) cold work tool steel and wrought steel (JIS SKD11) were investigated via ultrasonic fatigue test. The wrought steel specimens were tempered at 423 K for 1 hour. On the other hand, the MIM steel specimens were tempered at various temperatures in order to evaluate effect of tempering temperature on fatigue property. The ultrasonic fatigue tests were performed in the fatigue life range of N=103-108. Fatigue strength of the MIM steel specimens was equivalent to that of the wrought steel specimens. Fatigue strength of the MIM specimens declined with increasing tempering temperature. The results of microstructure observation showed that the diameter and shape of carbide of the MIM specimens were more uniform than those of the wrought steel specimens.
