TUNGSTEN RECOVERY FROM OXIDE DURING FLUX CORD WIRE SURFACING

Abstract

Influence of introduction of tungsten powder and tungsten concentrate into surfacing flux-cored wire on structure, structural components microhardness, hardness and wear of the surfacing layer has been studied. Flux cored tungsten-containing wires of H- and E-types according to the IIW classification were manufactured for surfacing in laboratory. Powders of silicon KR-1 (GOST 2169 – 69), manganese MR-0 (GOST 6008 – 82), chromium PKhA-1M (industrial standard TU 14-1-1474 – 75), vanadium VEL-1 (industrial standard TU 48-0533 – 71), nickel PNK-1l5 (GOST 9722 – 97), aluminum PAP-1 (GOST 5494 – 95), tungsten PVT (industrial standard TU 48-19-72 – 92) and iron powder PZhV-1 (GOST 9849 – 86) were used as fillers. In some wires tungsten concentrate KSh-4 (GOST 213 – 83) produced by “AIR” mining company” JSC was used instead of tungsten powder. Gas cleaning dust of aluminum production of the following chemical composition: 21.00 – 43.27 % Al2O3; 18 – 27 % F; 8 – 13 % Na2O; 0.4 – 6.0 % K2O; 0.7 – 2.1 % CaO; 0.50 – 2.48 % SiO2; 2.1 – 2.3 % Fe2O3; 12.5 – 28.2 % Cgen; 0.03 – – 0.90 % MnO %; 0.04 – 0.90 % MgO; 0.09 – 0.46 % S; 0.10 – – 0.18 % P (by weight) was used as a carbon-containing reducing agent. Wire with diameter of 5mm manufactured at laboratory installation ASAW 1250 tractor was used for surfacing. Surfacing modes were: Is = 400 – 450 A; Ud = 32 ÷ 36 V; Vs = 24 ÷ 30 m/h. Surfacing was performed under a layer of AN-26S flux and flux made of silicomanganese slag; number of deposited layers – 5. Chemical composition of deposited metal was determined, metallographic analysis of deposited layer was carried out: size of the former austenite grain, size of martensite needles, degree of contamination by nonmetallic inclusions were stated and wear tests were carried out, hardness and microhardness were measured. The possibility in principal of using tungsten concentrate instead of tungsten powder in studied flux cored wires is shown, degree of tungsten extraction was calculated. For H-type fluxcored wire, introduction of tungsten concentrate instead of tungsten powder into the charge of wire does not increase contamination of deposited layers with nonmetallic inclusions and reduces size of the primary austenite grain. Use of tungsten concentrate in E-type flux-cored wire manufacturing helps to reduce size of the primary austenite grain and size of martensite needles, increasing microhardness of martensite in structure of deposited layer. Introduction of tungsten concentrate instead of tungsten powder into the composition of the charge of H-type wire provides a significant increase in hardness and wear resistance of deposited layer.