CASTING OF PIPE STEEL ON A SINGLE-STRAND CASTER SLAB CASTER

Abstract

It is preferable to cast pipe steel on a slab caster with a vertical section, which allows to produce castings with less metal contamination by non-metallic inclusions. The paper considers casting of pipe steel on a single-strand slab caster of curvilinear type with a base radius of 11 m, a vertical section of 2.7 m, with soft compression of the billet. The productivity of the machine significantly depends on the cross-sectional dimensions of the castings and other factors. The paper studies the influence of slab cross-sectional dimensions and parameters of the temperature-rate mode of pipe steel casting on the productivity of a single-strand CCM. For this purpose the array of production data of pipe steel casting of strength class K60 from 105 melts was investigated. In the majority of cases – 89 melts (85% (relative)) were cast billets with cross-sectional dimensions of 350×2600 mm, the rest of the metal had a cross-section of 250×(2250, 2600) mm. The main difference between slabs was in the thickness of billets: 250 and 350 mm. In the work it is established that the hourly productivity of a single-strand slab caster of curvilinear type with a vertical section when casting tubular steel of strength class K60 into slabs of 350×2600 mm cross-section is on average equal to 291.8 t/h. This is 1.2 times higher than when casting slabs of 250×(2250, 2600) mm – 245.8 t/h. As a result of correlation-regression analysis of the data set of 89 melts when casting slabs with the cross-section of 350×2600 mm, statistically significant dependences of the speed of pulling the billets out of the mold and the hourly productivity of the CCM on the superheating of the metal in the intermediate ladle above the liquidus temperature were established. In order to obtain hourly productivity of CCM not less than 290 t/h it is necessary to have average superheating of metal in the intermediate ladle above the liquidsus temperature not more than 28 °С.