Microstructure and Properties of HDS65 Wire Surfaced Wear-Resistant Layer for Water Wall of Circulating Fluidized Bed Boiler in Power Plant

A kind of iron-based flux-cored wire（HDS65 welding wire）for wear-resistant surfacing layer of water wall of circulating fluidized bed boiler in a power plant was developed. The single-layer multi-pass surfacing welding test was carried out on 20G steel substrate by CO₂ shielded arc welding, and the weldability of the welding wire and the forming quality, microstructure and high temperature friction and wear behavior of the surfacing layer were studied. The results show that the weldability of HDS65 welding wire was good, and the weld bead was formed well. There were no pores and cracks inside and outside the surfacing layer. The microstructure of surfacing layer was mainly composed of lat martensite, solid solution based on intermetallic compound FeCr and discontinuously distributed fine carbides. The hardness of the surfacing layer was high, in the range of 630–690 HV. Compared with that of YD490 wire surfacing layer, the erosion wear amount of HDS65 wire surfacing layer was lower, the degradation rate was slower, and the erosion wear resistance was better at 350 ℃ and 600 ℃. With the increase of temperature, the erosion wear amount of HDS65 wire surfacing layer increased, indicating that the erosion wear resistance became worse; the friction factor decreased, reaching 0.2–0.3 at 600 ℃, which was much lower than that of 20G steel substrate; the wear volume increased, which was 0.628 mm³ at 600 ℃, only about 1/2 of that of 20G steel substrate.