Microstructure and mechanical properties of (Fe, Cr)⁷C³-Fe/Hadfield steel composites

In this work, (Fe, Cr)⁷C³-Fe/Hadfield steel composites were fabricated through in situ synthesis with infiltration casting and subsequent heat treatment. The microstructure, microhardness, impact toughness, and wear resistance of (Fe, Cr)⁷C³-Fe/Hadfield steel composites were studied through scanning electron microscopy, X-ray diffraction, microhardness testing, impact testing, and wear testing. The results show that austenite and (Fe, Cr)⁷C³ carbides are predominant phases in the reinforcing bar of the composites. The (Fe, Cr)⁷C³ particulates have an important role in improving the mechanical properties of the composite. The best wear resistance of the composites was 1.6 times higher than that of Hadfield steel under a 5-N load. The wear resistance mechanism was not only due to the higher hardness of the (Fe, Cr)⁷C³-Fe bundle but also to the excellent work hardening ability of the Hadfield steel matrix. The fracture mechanism was in the ductile-brittle fracture mode. The good fracture toughness of the (Fe, Cr)⁷C³-Fe/Hadfield steel composite is mainly due to the presence of microcracks in the interface and the high toughness of the Hadfield steel matrix.