Microstructure, wear and electrochemical behaviors of laser cladding Fe-based coatings with various molybdenum contents

Abstract

Fe-based alloy coatings with different Mo contents were fabricated on 45 steel substrates by laser cladding. X-ray diffractometer (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) were used to analyze the phase composition and microstructural evolution of the coatings. The effects of Mo addition on the wear and electrochemical behaviors of the coatings were analyzed by ball-on-disc wear tester and electrochemical workstation. The results showed that the addition of Mo could help refine grains and promote the transition of dendrites to equiaxed grains. With the increase of Mo content, the hard phases changed from Fe2B to Mo2FeB2. Mo and Cr tended to aggregate in the intercrystalline regions in the form of hard phases. When the Mo content was 4.8 wt%, the hardness increased by 3.6 times compared with that of the substrate. The wear resistance of the coatings increased with the Mo addition. Mo played the role of fine grain strengthening and solid solution strengthening, which was beneficial for the improvement of the hardness and wear resistance. Polarization curves and electrochemical impedance spectroscopy test results revealed that the addition of Mo could improve the corrosion resistance of Fe-based coating.