Production and further application of cored wire with ferroniobium filling for steel alloying at steelmaking shop of PAO NLMK

Abstract

Taking into account market status of ferroniobium filled cored wires as well as necessity to decrease metal products cost in PAO NLMK, a production technology of cored wire with ferroniobium filling developed. For the wire shell manufacturing a steel cold-rolled band was used, having thickness of 0.4 mm, width of 59.2 mm made of domestic production 08Ю grade steel. The tensile strength was from 26 till 37 kg/mm 2 , specific elongation >30 %. A sample was taken from every bundle to check the wire shell lock closing tightness and to determine the coefficient of its filling by the powder-filler. To decrease the risk of the wire first layers deformation while coiling into bundle and the wire rupture during uncoiling in BOF shops, the bundle internal diameter was increased from 560 mm till 730 mm. The cored wire bundles packing was made by a polyester band. The test of pilot cored wire with ferroniobium filling was done at steel ladle treatment areas according to existing technology instructions. For the pilot wire application parameters analysis the indices of heats array were selected, for which other niobium- containing materials were not used. For comparison the heats indices were selected of similar assortment groups, for which only wires of outside manufactures were used (lump ferroniobium was not used). Based on pilot wire test results it was noted, that at production of low-silicon assortment the average pilot wire consumption on 0,001 % [Nb] growth was equal to 3.27 kg, regular wire consumption 3.19 kg. At production of 08Ю steel of low-silicon low-sulphur assortment, low-alloyed assortment with mass suphur portion less 0.002%, the wire consumption for 0.001 % [Nb] growth was 7.5 kg at test heats and at comparative — 7.6 kg.