Application of microcrystalline complex modifiers for steel ladle treatment. Part 2. Results of elaboration of a technology for wide range of steels treatment

Abstract

Results of application of microcrystalline complex modifiers (MCM) with alkaline and rare-earth metals at wide range steels ladle treatment. It was shown that substitution of silicocalcium by Si‒Ca‒Ba at deoxidation and modifying of wheel steel ena- bles to increase the metal impact toughness and decrease the wheels rejects. When making ingots of steel 20ГФЛ for railway transport, substitution of ferrocalcium by Si‒Ca‒Ba‒Sr alloy enables to increase the metal impact toughness at test temperature ‒60°С by 64%. The treatment of steel by microcrystalline alloys Si‒Ca‒Ba and Si‒Ca‒Ba‒Sr results in forming oxide-sulfide non-metallic inclusions with more than 2.5 times decreased sizes, as well as decreased general amount of nonmetallic inclusions in the steel. The danger of destruction, for example of a pipe lines, can be sharply decreased in case of metal micro-alloying by rare-earth metals. Forming of cerium and lanthanum hydrides will increase the resistance against hydrogen embrittlement and delamination of carbon and low-alloyed steels, as well as will increase metal corrosion resistance including a bacterial one. Application of MCM with calcium, barium and strontium for pipe steels treatment under comparable conditions enabled to increase calcium recovery by metal by 76.5%. Application of the Si‒Ca‒Ba modifier instead of silicocalcium for treatment of steel S355J2G3N enables to increase the metal impact toughness by 45‒57%. The treatment of metal for large ingots by complex modifiers Si‒Ca‒Ba‒Sr‒REM enables to decrease by 45‒50% the metal chemical non-homogeneity by liquation elements, to decrease contamination of metal by nonmetallic inclusions. Application of Si‒Ca‒Ba modifier results in decreasing consumption of cored wire and cost of the treatment by 38.5% and 11% correspodently. The use of Si‒Ca‒Ba‒Sr alloy results in a decrease of those indicators by 56% and 21% correspondently.