Effects of Cr3C2 addition on microstructure and corrosion properties of Cr3C2/15–5PH composite coatings on 12Cr13 by laser cladding

Abstract

The application of laser cladding technology to prepare iron-based composite coatings has significant advantages in improving the surface properties of 12Cr13 stainless steel. 15–5PH composite coatings reinforced with CrC particles of different contents (0–25 wt%) were prepared on the 12Cr13 surface by the coaxial powder feeding laser cladding system. The microstructure, phase composition, element distribution, corrosion resistance and corrosion mechanism of the composite coatings were analyzed and studied by optical microscope, scanning electron microscope, X-ray energy dispersive spectrometer, X-ray diffractometer and electrochemical workstation. The results indicated that the CrC/15–5PH composite coatings exhibited good macroscopic morphology and dilution rate under appropriate laser cladding process parameters. The addition of CrC particles changed the main phase from -Fe to -Fe and formed new carbide phases (MC and CrC). The CrC/15–5PH composite coatings exhibited a typical microstructure with rapid solidification characteristics, and the addition of CrC significantly changed the grain size. The distribution of Fe, Ni, and Cr elements in the composite coatings was uniform, and the relative content of Cr elements increased and remained at high level. The 15-5PH composite coating with 15 wt% CrC exhibited a lower corrosion current density and higher impedance modulus values. The surface of this composite coating had no obvious corrosion pits, and the passive film effectively retarded the further corrosion by the Cl- ions on the surface during the electrochemical corrosion process. By preparing a 15–5PH composite coating with 15 wt% CrC on the surface of 12Cr13, the corrosion resistance of the surface can be effectively improved.