POSSIBILITY OF REDUCING NITROGEN AND OXYGEN CONTENTS DURING ARGON STIRRING OF HADFIELD STEEL

摘要

Using the resin or sodium-silicate-bonded sand mixtures increases the gas contents in castings owing to the chemical penetration between molten steel and a mould or owing to using of return scrap during the melting process. Argon stirring of Hadfield steel in the ladle with the capacity of 7 t eliminated the critical gases contents in castings, at which gas porosity, micro-shrinkages and needles are observed. The argon stirring conditions observed in these investigations, assured oxygen content below 6 ppm and nitrogen content below 380 ppm in Hadfield castings with the weight of 5.5 t.