Semiconductor laser cladding of an Fe-based alloy on nodular cast iron

Abstract

Coatings on the surface of nodular cast iron were prepared using a continuous wave semiconductor laser as a function of laser power. The cross-sections were etched by aqua regia to reveal the microstructure, and then the surfaces were examined by optical microscopy (OM) and scanning electron microscopy (SEM). The phase composition was analyzed by X-ray diffraction (XRD), and the hardness was measured using a Vickers hardness tester. The wear behaviors were examined using a microscopic wear test machine. The results revealed that the microstructure of the coatings was mainly composed of martensite and austenite. As the laser power increased, a wider columnar dendrite zone and an equiaxed dendrite zone can be observed, and the proportion of martensite decreased and retained austenite increased. The hardness first increased and then decreased with the increasing laser power. Solidification cracking was detected at higher laser power. All the worn surfaces at different laser powers exhibited typical adhesive wear, and the coatings with more martensite had better wear resistance.