Considering that the price of ferro titanium alloy is relatively low and it can improve the performance of steel, titanium is usually added to steel as a microalloying element. However, due to the active nature of titanium, it easily reacts with oxygen and nitrogen in the steel during ladle furnace refining, reducing the effective titanium content in the steel, affecting the absorption rate of titanium, resulting in higher alloy costs and large fluctuations in product performance. How can the existing ferro titanium alloy process be optimized?
Hot metal pretreatment→combined blowing converter→LF refining→(RH vacuum)→double-strand slab continuous casting machine.
First is to accurately adjust the desulfurization model according to the composition of the molten iron during hot metal pretreatment, and ensure that the slag is clean, to prevent "back-sulfurization" in the converter smelting process, and to avoid the use of large argon stirring due to the tight time of the desulfurization process.
The second is to strengthen terminal control in the converter smelting process. The sliding plate is used to block the slag to strictly control the amount of slag and reduce the oxidation in the slag. At the same time, the converter top slag should be modified, and aluminum-based ladle modifier should be added to the surface of the ladle slag for top slag modification to reduce the content of unstable oxides (FeO, MnO) in the slag.
The third is to optimize the production process, strengthen the matching between converter and continuous casting machine, reasonably control the production rhythm, and prevent the converter from throwing steel in advance. Increase the tapping temperature of the converter by 10 to 20°C, strengthen the heat turnover of the ladle, reduce the temperature drop of the ladle, and control the total refining heating time within 10 minutes.
Fourth, white slag is produced quickly during the LF refining process. The white slag cannot be too thin and should maintain a certain viscosity. The structure of the refined slag should be optimized to ensure the submerged arc effect. According to the different metallurgical functions of the refining process, the opening degree of the dust removal valve should be adjusted reasonably to ensure the slight positive pressure atmosphere in the furnace. It is forbidden to add ferro titanium when the temperature is raised. After the desulfurization task of molten steel is completed, ferro titanium should be added at one time. When alloying titanium, it is necessary to comprehensively consider factors such as the titanium content in the ferro titanium alloy, the amount of molten steel, and the thickness of the slag layer. After the alloying is completed according to the upper limit control of the composition, it is strictly forbidden to stir with atmospheric argon or send electricity for a long time to raise the temperature.
The factors that affect the stability of titanium microalloying include: the oxidizing property of molten steel, the oxidizing property of steel slag, the secondary oxidation of molten steel, the content of gas in steel, the timing of adding ferro titanium, and the control of argon gas flow. Through a series of process improvement measures such as steel slag modification, strong deoxidation, rapid white slag generation by LF refining, and reduction of nitrogen content in steel, the titanium loss was reduced by an average of 0.010%, and the titanium-iron alloy absorption rate reached 89%. The absorption rate of titanium alloy is improved. Increasing ω [Ti] by 0.001% can reduce the cost of ferro titanium alloy by RMB 0.06 per ton of billet, which has obvious economic benefits.