Improvement in the life of cast equipment for heat-treatment furnaces

Abstract

1. Introduction of up to 0.08% (by calculation) of yttrium-cerium group REE and up to 0.4% of vanadium and niobium nitrides provides marked dendrite refinement in steel 4Kh18N24S2L structure, its physical homogeneity is improved, and there is uniform distribution of primary carbide precipitates throughout a grain. 2. Addition of vanadium and niobium nitrides to steel 4Kh18N24S2L leads to a marked improvement in heat resistance, and addition of REE leads to improved scaling resistance and resistance to intercrystalline corrosion. 3. With the combined introduction of up to 0.08% REE and up to 0.4% of nitrides the time to failure in long-term strength tests is increased by a factor of three, oxidation rate at 900°C is reduced by 16%, and an increase in steel 4Kh18N24S2L thermal stability by a factor of three provides a 20–40% increase in the life of cast equipment for heat-treatment furnaces. 4. Combined modification and strengthening by REE and nitrides with a reduction in carbon and silicon content makes it possible to reduce the nickel content of steel 4Kh18N24S2L from 24 to 18% for heat-treatment furnace equipment, and to obtain a saving of 150 rubles/ton of casting.