Surface Martensite Strengthening of Ultra-fine Porous Iron

The surface martensite strengthening of ultra-fine isotropic porous iron has been performed via carburization and quenching treatment at 950 °C for 30 min. This paper is devoted to investigating the evolution of microstructure and related mechanical behavior of porous iron after carburization treatment. Results indicate that an effective carburization thickness (300 µm) contributes to a substantial improvement in compressive ductility (62%) and surface hardness (219 HV0.025) of carburized porous iron. Further, the quenching treatment after carburization produces the porous iron with an ultra-fine martensite microstructure on surface layer that makes porous iron attain the highest yield strength (256 MPa) and energy absorption capacity (85 KJ kg−1). The major contribution of this present work is a demonstration that an improvement in mechanical properties of ultra-fine porous iron can be achieved through the carburization and quenching treatment to control the phase structure on surface. Thus, the surface martensite strengthening is considered as a feasible method to prepare more valuable porous iron based alloys, and to provide them with more promising applications on key structural parts.