Four-point bending fatigue behaviour of an iron-based laser sintered material

New material processing methods such as laser sintering of metal powder necessitates new knowledge and characterization of the material to support its implementation in technical applications. Fatigue behaviour of a laser sintered FeNiCu-alloy was studied with emphasis on crack path, initiation and propagation. Fatigue crack growth was investigated by surface replication in four-point bending fatigue tests. The fatigue behaviour was controlled by the complex layered structure. Pores on or under the surface were preferable places for crack initiation. Crack linkage and deflection occurred due to crack tip interaction with microstructure and sinter layers where microcracks initiated at pores adjacent to the advancing crack tip. Crack growth rate and stress intensity factor were calculated from surface replicas and showed an oscillating behaviour.