FATIGUE BEHAVIOR OF IRON-BASED SINTERED MATERIAL - A REVIEW

During the last decades, the demand for lower production costs and the reduction of weight resulted in the use of PM iron and PM steel for h ighly stressed fatigue loaded components. The fatigue behaviour of suc h PM materials has been described in numerous papers. However, the stu dies were mostly limited to investigations of the influence of various processing, sintering parameters, and alloying techniques. Relatively few authors applied more basic scientific considerations to understan d the fatigue behaviour of sintered iron based material. Thus, a main objective of this review is to consider the characteristic porous micr ostructure, which may consist of singular isolated pores in a solid st ructure up to an interconnected th reo dimensional porous configuratio n resembling an almost different material. The response of such struct ures to various stages of the fatigue process, starting from the damag ing criteria such as the cyclic plastic strain, to crack initiation an d crack propagation will be presented. Considerations in terms of a fr acture mechanics approach to such porous structures are proposed. Thes e imply the possibility of predicting some fatigue characteristics whi ch may reduce experimental effort. (C) 1997 The Institute of Materials and ASM International.