A method for controlling the nodule of continuous casting nozzle of titanium-containing if steel

Abstract

The invention discloses a method for controlling nodulation in the continuous casting nozzle of titanium-containing IF steel. The technological process includes: molten iron pretreatment desulfurization → converter top-bottom compound blowing → RH vacuum treatment → continuous casting. In converter top-bottom compound blowing, the carbon mass fraction of molten steel at the end of converter blowing is 0.03%-0.04%, and the temperature is ≥1680°C. When RH arrives at the station, the carbon mass fraction of molten steel is 0.025%-0.035%, the free oxygen mass fraction is 0.045%-0.085%, and the molten steel temperature is 1620-1640°C. After RH decarburization, the mass fraction of free oxygen in molten steel is 0.02%-0.04%. At the end of decarburization, Al grains and metal manganese are added first, and the molten steel is circulated in the vacuum chamber for 4-7 times. After the mass fraction of free oxygen in the molten steel is ≤0.0003%, FeTi alloy is added. After all the alloying is completed, the molten steel circulates 9-11 times in the vacuum chamber. The MO index of ladle top slag after RH deoxidation alloying is controlled at 0.02‑0.04. Through the implementation of this method, the Ti‑Al‑O composite inclusions and Al 2 o 3 The nozzle nodulation problem caused by inclusions, the number of continuous casting furnaces for a single nozzle is increased from 2-3 furnaces to 6-8 furnaces, which can reduce production costs and improve product quality.

Description

technical field [0001] The invention belongs to the field of iron and steel metallurgy, and in particular relates to a method for controlling nozzle nodulation of titanium-containing IF steel continuous casting. Background technique [0002] IF steel, due to the low content of C and N, adding a certain amount of Ti and Nb, the C and N atoms in the steel are fixed into carbides and nitrides, so that there are no interstitial atoms in the steel, also known as interstitial atomic steel. IF steel has the characteristics of low yield strength and yield ratio, high elongation, high plastic strain ratio, high work hardening index, and excellent deep drawing performance. The main components of titanium-containing IF steel are: C≤0.005%, N≤0.003%, Al: 0.03%-0.05%, Ti: 0.01%-0.1%. During the steelmaking and continuous casting process of titanium-containing IF steel, a large amount of Al is produced in molten steel due to the deoxidation and alloying operation. 2 o 3 Inclusions and...

AI Technical Summary

Problems solved by technology

Therefore, in the production of titanium-containing IF steel, in Al 2 o 3 Under the joint action of inclusions and Ti-Al-O composite inclusions, submerged nozzles are prone to nodules