National University of Science and Technology “MISiS”, Novotroitsk affiliate (Novotroitsk, Russia):

A. N. Shapovalov, Cand. Eng., Associate Prof., Head of the Metallurgical Technologies and Equipment Dept., e-mail: alshapo@misis.ru

NPP Technologiya Ltd. (Chelyabinsk, Russia):
V. A. Golubtsov, Cand. Eng., Chief Specialist in Steel
I. V. Bakin, Head of Innovation, Modernization and Technical Development Dept.
I. V. Ryabchikov, Dr. Eng., Professor, Scientific Сonsultant

The results of testing complex microcrystalline modifi ers (CMM) containing calcium, barium, strontium, rare-earth metals (REM) in the processing of steel for 17G1S-U tubes in order to reduce its contamination by non-metallic inclusions (NMI), including corrosion-active ones are presented. It was established that during the processing of steel by experimental modifi ers, a decrease in both the maximum NMI index and the average level of contamination for the main types of NMI is provided. The most signifi cant decrease in NMI is observed for brittle silicates, which is a positive fact, since this type of inclusions has an acute-angled shape and is a stress concentrator. The increase in metal quality indicators for NMI was observed as the chemical composition of the experimental modifiers became more complicated. The use of experimental modifiers allowed to reduce metal contamination with corrosive active NMI. The test rolled product, which is purest by NMI of this type, was obtained during the processing of metal with INSTEEL® 5.1 and INSTEEL®9.4 modifiers. In addition, the use of experimental modifiers provided complex oxysulfides of calcium, cerium, lanthanum with a low oxygen content, which increases the corrosion resistance of steel. As a result of the experiments, the potential, higher efficiency of the CMM of INSTEEL® series for reducing the contamination of steel by NMI of all types was shown, unattainable with the traditional technology of out-of-furnace steel treatment using silicocalcium.

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