Flux-Cored Wire for the Surfacing of Parts Subject to Wear

Flux-cored wire of Fe–C–Si–Mn–Cr–Ni–Mo composition (type A in the International Institute of Welding classification) is developed for the surfacing of abrasively worn parts. In the laboratory, multiple surface layers are applied to plate samples, with preliminary heating to 350°C and subsequent (after surfacing) slow cooling. An ASAW-1250 welding tool with the new wire is used for surfacing: six layers are applied to a 09Г2С steel plate. Instead of amorphous carbon, the wire consists of dust containing carbon and fluorine, with the following composition: 21–46% Al2O3, 18–27% F, 8–15% Na2O, 0.4–6.0% K₂O, 0.7–2.3% CaO, 0.5–2.5% SiO2, 2.1–3.3% Fe₂O₃, 12.5–30.2% Ctot, 0.07–0.90% MnO, 0.06–0.90% MgO, 0.09–0.19% S, and 0.10–0.18% P. The filler is a powder: PZhV1 iron powder (State Standard GOST 9849–86); FS75 ferrosilicon powder (State Standard GOST 1415–93); FKh900A high-carbon ferrochrome powder (State Standard GOST 4757–91); FMn78(A) carbon ferromanganese powder (State Standard GOST 4755–91); PNK-1L5 nickel powder (State Standard GOST 9722–97); FMo60 ferromolybdenum powder (State Standard GOST 4759–91); FV50U0.6 ferrovanadium powder (State Standard GOST 27130–94); PK-1U cobalt powder (State Standard GOST 9721–79); and PVN tungsten powder (Technical Specifications TU 48-19-72–92). Analysis of the applied layer shows that, within the ranges studied, carbon, chromium, molybdenum, nickel, manganese and, to a small extent, vanadium both increase the surface hardness and slow sample wear. Increasing the tungsten concentration somewhat increases the surface hardness but decreases the wear resistance. The low ductility of the matrix prevents the retention of tungsten carbides at the surface and so, rather than uniform surface wear, what is observed is crumbling of strong carbide particles from the matrix, with the formation of cracks that facilitate additional wear. The introduction of cobalt in the batch does not markedly affect the hardness and surface wear: the matrix obtained is more ductile but less hard. With no hard carbide particles in the matrix, the introduction of cobalt is deleterious. Multifactorial correlation analysis yields dependences of the hardness and wear resistance of the applied layer on the content of elements in the Fe‒C–Si–Mn–Cr–Mo–Ni–V–Co flux-cored wire.