Fatigue behavior of a high density powder metallurgy steel

Rotating bending fatigue tests were carried out on a high density Fe-2%Ni b ased powder metallurgy steel at 50 Hz frequency and at room temperature. Th e material was subjected to high cycle fatigue to evaluate endurance/fatigu e limit and its influence on heat treatment/microstructure. The fractured f atigue surfaces were examined using scanning electron microscope to study t he mechanism/s associated with crack propagation. Optical microscopy was ca rried out to characterize the microstructures resulting from different heat treatments. The microstructure was observed to have an influence on endura nce/fatigue limit. As-sintered material exhibited the lowest endurance/fati gue limit when compared with the material in the hardened and tempered cond ition. Electron microscopy studies demonstrated the mechanism/s of crack li nking and/or interconnection of pores characterizing the crack propagation. It has been observed that, by carefully designing the heat treatment the h igh density powder metallurgy steel can be beneficially used in fatigue loa ded components. (C) 2000 Elsevier Science Ltd. All rights reserved.