Surface remanufacturing of ductile cast iron by laser cladding Ni-Cu alloy coatings

Abstract

Ductile cast iron is hard to be remanufactured without preheating and post heat treatment owing to the complicated phase evolution and a great tendency to form chilled structure during cladding process. Ni-Cu alloy shows great ability to obstruct the diffusion of carbon in the transition zone during the welding of cast iron due to the low solubility of carbon in nickel alloy. In the present study, different kinds of simulated grooves were devised to estimate the remanufacturing process of ductile cast iron by laser cladding. Ni-Cu alloy were used as the filling material. The microstructure and phase evolution in the transition zone were illustrated and mechanical properties have also been studied. Scanning electron microscopy (SEM), energy dispersive microanalysis (EDS), X-ray diffraction (XRD) and transmission electron microscope (TEM) were used to identify the microstructure and phase types of the claddings and transition regions. The result illustrated that various microstructures were formed during laser remanufacturing. Circular groove and cross cladding procedure were conductive to reduce residual stress. Microhardness decreased obviously after multi thermal cycles. The specimen shows ultimate strength of 502 MPa no less than that of the substrate.