REINFORCING-BAR HOT-ROLLED STEEL AND METHOD OF STEEL MELTING FOR ITS PRODUCTION Russian patent published in 2001 - IPC

FIELD: metallurgy, applicable in production of welded hot-rolled reinforcing bars of A500S class for reinforced-concrete structures. SUBSTANCE: reinforcing-bar hot-rolled steel contains the following ratio of components, wt.%: carbon, 0.16-0.24; manganese, 0.60-0.95; silicon, 0.50-0.90; vanadium, 0.12-0.20; chromium, not more 0.20; nickel, not more, 0.15; copper, not more 0.10; the balance, iron. Steel ultimate strength-yield point ratio is 1.25-1.40. Method of steel production includes production of intermediate product from naturally alloyed vanadium iron; steel melting in steel-melting unit; pouring of steel melt into ladle and its deoxidation and alloying with ferroalloys. In this case, steel is melted from solid steel scrap and liquid intermediate product containing the following ratio of components, wt.%: carbon, 3.2-3.7; manganese, 0.03-0.1; silicon, 0.03-0.1; vanadium, 0,03-0.1; chromium, 0.03-0.1; phosphorus, not more 0.05; sulfur, not more 0.05; the balance, iron; with provision of 14-58 wt.% of vanadium in steel and the rest of vanadium is introduced into ladle in the form of silicovanadium. Steel deoxidation and alloying in ladle are performed with simultaneous blowing-through with nitrogen. The claimed method provides production of well welding hot-rolled steel with yield point of at least 500 N/sq.mm, ultimate strength of at least 600 N/sq.mm, elongation δ₅ at least 14% with reduction cost due to reduced quantity of manganese and simplified production process. EFFECT: production of well welding hot-rolled steel. 3 cl, 3 tbl, 10 ex