Content of Total Oxygen in Liquid Steel as a Criterion of Estimating Nonmetallic Inclusions in Pipe Steels

—A statistical analysis is performed to determine the total oxygen content in pipe steel samples at the stage of continuous casting on a continuous casting machine (CCM) of the casting-and-rolling complex (CRC) at AO VMP. The microstructure of rolled steel samples is studied, and the chemical composition of nonmetallic inclusions is determined by electron-probe microanalysis. A laboratory analysis of samples of liquid steel and hot-rolled CRC steel is performed by the inert gas fusion method. The dependences between the time of metal residence in a ladle, the magnesium content in nonmetallic inclusions, and the average number of nonmetallic inclusions in rolled steel and the total oxygen content in liquid steel at the stage of continuous casting are built.