Modifying and Micro-Alloying Effect on Carbon Steels Microstructure

Abstract

Small additives of elements exhibiting high chemical activity with respect to iron and impurities, included in its composition, have a complex effect on the structure and properties of steel. Moreover, as a result of the modifying and refining effect of micro-additives, the amount, dispersion and morphology of nonmetallic inclusions change, and when alloying the matrix, hardenability, uniformity of structure and resistance to brittle fracture of steels change, too. The article presents a metallographic analysis of carbon steel deoxidized by a complex Са – Ва alloy. Deoxidation of steel using the complex Са – Ва alloy allows significant reducing the content of nonmetallic inclusions, modifying residual nonmetallic inclusions into favorable complexes with their uniform distribution in the volume of steel, and significant increasing the mechanical properties of steel. The high surface activity of barium makes it possible to consider barium as a rather effective modifier. The use of barium in alloys leads to grinding of non-metallic inclusions, homogenization of liquid metal, lowering the liquidus temperature, grinding of primary grains of cast steel, and increasing technological ductility.