Microstructural evolution and wear behavior of Fe-Cr-Ni-Mo-B cladding alloys deposited by flux-cored arc welding (FCAW)

The surface quality of laminar cooling rolls directly affects the final quality of steel strips produced in continuous casting and hot rolling lines. In this study, Fe-Cr-Ni-Mo-B wear-resistant cladding layers with different Cr and B contents were fabricated by flux-cored arc welding (FCAW). The effects of alloy composition on microstructural evolution, carbide and boride morphology, and wear behavior of the cladding layers were systematically investigated, with particular emphasis on the relationship between microstructural characteristics and wear resistance. Increasing the B content from 0.3 wt% to 0.6 wt% promoted the formation of borides and transformed eutectic M₂B from coarse discrete particles into a fine and relatively continuous network structure. Meanwhile, microstructural refinement was observed, and the microhardness increased from 747.7 HV 0.3 to 810.7 HV 0.3 . With increasing nominal Cr content from 15 wt% to 19 wt% at approximately 0.6 wt% B, the eutectic hard phases progressively coarsened, accompanied by a morphological transition from a fine interconnected network to coarse skeletal and plate-like structures. The retained austenite fraction also increased, while the microhardness decreased to 697.1 HV 0.3 . Among the investigated cladding layers, Fe-15Cr-0.6B-2Ni-2Mo exhibited the best wear resistance, which was associated with its fine and relatively continuous eutectic borides and martensitic matrix. The results indicate that wear resistance is governed not only by the fraction of hard phases but also by their morphology, distribution, and interaction with the supporting matrix. After undergoing high-temperature wear at 600 °C, more pronounced subsurface damage and surface oxidation were observed, demonstrating a significant influence of elevated temperature on the wear behavior. These findings provide guidance for the composition and microstructure design of FCAW Fe-based wear-resistant cladding layers for laminar cooling roll applications.