Microstructures and properties of low-chromium high corrosion-resistant TiC–VC reinforced Fe-based laser cladding layer

Abstract

Effects of 3.0wt.%Cr and/or 0.25wt.%CeO2 on microstructures and properties of TiC–VC reinforced Fe-based cladding layer were investigated by using X-ray diffractometry (XRD), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS). Passive films formed on cladding layers surface were investigated by using X-ray photoelectron spectroscopy (XPS) and Mott–Schottky analysis. Results showed that phases of cladding layers were α-Fe, γ-Fe, TiC, VC and TiVC2. There were no obvious effects of adding 3.0wt.%Cr and/or 0.25wt.%CeO2 on cladding layers phases. The microstructure of the cladding layer with 3.0wt.%Cr and 0.25wt.%CeO2 was lath martensite and retained austenite. Microhardness of the cladding layer with 0.25wt.%CeO2 decreased slightly. Microhardness and corrosion resistance of the cladding layer with 3.0wt.%Cr and 0.25wt.%CeO2 both increased, the corrosion resistance increased 7.33 times while the EIS Nyquist spectrum transformed into a capacitive arc. The passive film formed on the cladding layer without Cr and CeO2 was Fe3O4 which displayed p type semiconductivity. The passive film formed on the cladding layer with 3.0wt.%Cr and 0.25wt.%CeO2 was composed of Fe(OH)3 and Cr(OH)3, which displayed n and p type semiconductivity respectively.