Diode laser cladding of Fe-based alloy on ductile cast iron and related interfacial behavior

In this research, repairing of V-grooves on ductile cast iron substrates has been successfully completed with diode laser cladding technique using Fe-base self-fluxing alloy powder as the cladding material. The repaired samples are free of any defects such as pores and cracks with appropriate process parameters and the V-groove bevel. The bonding interface behavior at different power levels and the effect of the V-groove bevel on the cracking sensitivity of the coatings have been investigated. Optical microscopy, scanning electron microscopy, energy dispersive microanalysis and X-ray diffraction were used to characterize the cladded layers and bonding interfaces. Microhardness of the repaired samples was evaluated after cladding. The results revealed that good bonding interface with discontinuous fusion zone can be achieved at a lower laser power. The cracking sensitivity of the cladded layer is closely related to the V-groove bevel and the V-groove with larger bevel can be repaired with no cracks and pores. The cladded layers consist of austenite and martensite while some carbides such as Cr7C3, Fe7C3 and Fe3C are formed in the bonding interface. Microhardness is rather homogeneous throughout the cladded layers and much higher than that of the substrate.