Effect of Surfacing Current on Microstructure and Properties of Fe-Cr-W-Nb Flux Cored Wire Surfaced Cladding Layer

A Fe-Cr-W-Nb flux cored wire was designed, and the cladding layer was prepared on the surface of Q235 steel matrix by submerged arc surfacing technology under different surfacing currents (350, 400, 450, 500 A). The effects of surfacing current on the microstructure, microhardness and high temperature wear resistance of the cladding layer were studied. The results show that the cladding layers prepared under different surfacing currents were mainly composed of Fe-Cr solid solution, M₂₃C₆, NbC and a small amount of M₇C₃ and Fe₃W₃C. With the increase of surfacing current, the shape of NbC hard phase particles gradually became regular. When the surfacing current was 450 A, the shape of hard phase particles of the cladding layer was the most regular with consistent size and uniform distribution, and the cladding layer formed a good metallurgical bond with the steel matrix. When the surfacing current was too large (500 A), the hard phase particles were connected to each other to form an irregular shape, the size was obviously increased and the distribution was uneven. With the increase of the surfacing current, the microhardness of the cladding layer first increased and then decreased, and the wear mass loss first decreased and then increased. When the surfacing current was 450 A, the microhardness was the largest, the wear mass loss was the smallest, showing the best wear resistance, and the wear mechanism was oxidative wear.