METHOD OF MICRO-ALLOYING OF STEEL WITH NITROGEN Russian patent published in 2005 - IPC

FIELD: metallurgy; micro-alloying of steel with nitrogen.

SUBSTANCE: proposed method includes melting metal in steel-melting unit, teeming the metal into ladle, deoxidation, drawing sample for check of nitrogen content and tapping. Micro-alloying of steel with nitrogen at specified content of aluminum of 0.005-0.03% is performed at two stages: during tapping of metal and its deoxidation, it is preliminarily saturated with nitrogen due to addition of nitrided ferro-alloy and final correction of chemical composition of metal pertaining to content of nitrogen is performed by blowing the gaseous nitrogen at flow rate determined from the following relationship: τ_N=390.63Q_{n req.}-2272.29Q_{N inter.}where τ_N is time of blowing with nitrogen, min; Q_{N req.} is required content of nitrogen in steel, %; Q_{N inter.} is content of nitrogen in sample before blowing, %; Q_Al is content of aluminum in finished steel, %.

EFFECT: reduction of non-metallic inclusions; possibility of obtaining fine-dispersed structure and required quality of casting.

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