Microstructure evolution during laser cladding Fe-Cr alloy coatings on ductile cast iron

Abstract

Ductile cast iron illustrates well cast characteristics and abrasive resistance, excellent corrosion resistance and good mechanical properties. Fe-based alloys were always used to repair invalid ductile cast iron components owing to their cheapness in price. But it is difficult to eliminate defects like pores and chilled structure for the remanufacturing of ductile cast iron without preheating and post heat treatment. In this research work, a kind of Fe-based alloy powders were used as the cladding material for the laser cladding process on ductile cast iron, and different cladding procedures had been successfully completed. The microstructure and phase evolution in the partially melted zone (PMZ) and heat affected zone (HAZ) had been investigated. Mechanical properties also had been studied. Scanning electron microscopy (SEM), energy dispersive microanalysis (EDS), X-ray diffraction (XRD) and transmission electron microscope (TEM) were used to determine the microstructure and phase composition of the cladding layers and transition zones. The result revealed that distinct phases were formed during a single pass and multi-layer cladding process. Different kinds of pearlite structures formed in the transition zone during cladding process. Element migration was not apparent near the interface. The wear resistance of the cladding layers was not higher than that of the substrate.