Enhanced Mechanical Properties of Sintered Iron via Cyclic Induction Heat Treatment

In order to improve the mechanical properties of sintered iron, the cyclic induction heat treatment (CIHT) was applied to produce ultrafine microstructure on surface. The surface microstructure of refined grains and micropores, and the related mechanical properties were investigated. Results indicated that the refined grain (24.60–3.66 μm) and micropore (9.52–1.67 μm) contribute to a substantial improvement in compressive yield strength (177–555 MPa) and surface microhardness (123.0–300.8 HV0.1) of the sintered iron samples. Grain refinement was ascribed to the high nucleation rate and short grain growth time, which is due to rapid processing and a large number of microporous interfaces. Meanwhile, the micropore structure was refined due to grain refinement in resintering process. Thus, the CIHT is considered as a feasible method to improve mechanical properties of iron-based sintered alloys, providing them with more promising applications on key structural parts.