Development of the vibrocasting alumina-spinel ladle nozzles technology for vacuum casting of steel

Abstract

The effect of grain size composition of the coarse-grained part of batch on the properties of alumina-spinel vibrocasting mass (moisture, flowability during vibration) and on the properties of unburned and fired at 1580 °C vibrocasting samples from it has been studied. The optimal grain size composition of the coarse-grained part of the vibrocasting alumina-spinel mass, its moisture content and flowability during vibration, ensuring the achievement of the highest properties of products from it (open porosity 14.3 %, apparent density 3.33 g/cm3, cold crushing strength 365 N/mm2) were established.
 Taking into account the obtained research results, in JSC “URIR named after A. S. Berezhnoy”, experimental ladle nozzles of alumina-spinel composition with high properties (chemical composition, wt. %: Al2O3 — 96.0 %, MgO — 1.5 %, SiO2 — 0.6 %; open porosity 14.0—14.5 %; apparent density 3.32—3.35 g/cm3; cold crushing strength 320—360 N/mm2) were manufactured by the vibration casting method.
 Industrial tests of these ladle nozzles carried out in service at one of the metallurgical enterprises of Ukraine during vacuum casting of steel from tundish found that, they provide continuous casting of steel from 240 to 450 tons at a temperature of 1580—1650 °C and are characterized by high corrosion resistance (they have insignificant wear of the steel-pouring channel, which does not exceed ~ 3—5 mm).
 The petrographic studies of a ladle nozzle sample after service established that, due to the contact of molten steel with refractory, a strip up to ~ 0.2 mm wide from spinel forms in it, which restrains the penetration of molten metal through pores and microcracks into the ladle nozzle structure and prevents its wear, thereby increasing its corrosion resistance.
 As a result of the carried out research, at JSC “URIR named after A. S. Berezhnoy”, a technology of vibrocasting alumina-spinel ladle nozzles for vacuum casting of steel from tundish, which is not inferior to the best world analogues in terms of properties, has been developed.
 The use of high-quality ladle nozzles in vacuum casting of steel from tundish will ensure the production of large-size castings from high-quality steel with increased operational characteristics, which will lead to a longer service life of steel structures and metal parts of machines and mechanisms for consumers in various industries.