Exploring the microstructure and wear-resistance of Fe-Cr-C-W arc cladding coatings by laser remelting

Abstract

In this study, Fe-Cr-C-W cladding coatings were fabricated by arc cladding (AC) and subsequently post-treated through laser remelting (LR). The microstructure was characterized using optical metallography (OM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The wear resistance was assessed using microhardness tests and a ring-disc tribometer under loads of 300, 400, and 500 N at room temperature (RT) and 200 °C. The impact of LR on the microstructure and wear resistance of the Fe-Cr-C-W cladding coatings was investigated. The results indicate that the two fused cladding coatings predominantly consist of martensite, M₇C₃ and M₂₃C₆ phases. LR refined the grains of the cladding coating, reducing the average dendrite size from 6.34 μm to 4.63 μm, decreasing porosity, and increasing microhardness by 16 % to 858 HV_0.5. At elevated temperatures (200 °C), the average coefficient of friction (COF) for LR-treated coating decreases to 0.115 under a load of 500 N, attributed to the formation of oxide layer and the generation of tempered martensite. At RT, the primary wear mechanism was abrasive wear. At elevated temperatures, adhesive wear intensified and was accompanied by oxidative wear. Furthermore, the LR-treated coating demonstrated a more stable COF and a lower wear rate at 200 °C/500 N, enhancing its suitability for high-temperature and high-load applications. The unique synergy between tempered martensite and oxide film in the Fe-Cr-C-W cladding coatings at 200 °C significantly reduced the COF to 0.115.