Method for producing high-alloy low-phosphorous steel used for boiler tube by adopting electric-arc furnace

Abstract

The invention provides a method for producing high-alloy low-phosphorous steel used for a boiler tube by adopting an electric-arc furnace. The method comprises the steps of electric-arc furnace smelting, LF (low frequency) refining, VD (vacuum degassing) vacuum treating and continuous casting, wherein the electric-arc furnace smelting step comprises the followings steps of: heating furnace chargeby adding fresh lime and ferric oxide into an electric-arc furnace with furnace charge together; when the furnace charge is smelted by 30-40%, adding the fresh lime in batch, adopting high-slag-quantity operation, and controlling basicity of slag to be 3.5-5.0 and FeO content to be 25-35%; rapidly discharging dephosphorized slag when the furnace charge is completely smelted and a temperature of afurnace hearth is 1520-1550 DEG C; adding the fresh lime in batch to strengthen dephosphorization, making high-basicity slag, controlling the basicity of the slag to be 5.0-6.0, and simultaneously controlling the FeO content to be 30-40%; and when the temperature of the furnace hearth is more than 1580 DEG C, adding the fresh lime in batch, automatically flowing the slag, and carrying out molten steel decarburization. According to the method disclosed by the invention, steel with a low phosphorus content, used for the boiler tube, can be produced.

Description

technical field [0001] The invention relates to an electric arc furnace smelting method, in particular to a method for producing high-alloy low-phosphorus steel for boiler tubes by using an electric arc furnace. Background technique [0002] At present, power plant boilers have developed from 200MW and 300MW subcritical units to 600MW and 1000MW super (super) critical units. The 12Cr1MoVG and 15CrMoG high-pressure boiler tubes commonly used in subcritical units have been adopted by ASME / ASTM standards for higher steel grades. Alloy high-pressure boiler tubes P22, P91, etc. instead. With the increase in the construction of super (super) critical thermal power units in recent years, the demand for high-alloy high-pressure boiler tubes in ASME / ASTM standards has increased sharply in the manufacture of power plant boilers and in the installation of power plants. It is getting higher and higher, and the phosphorus content in molten steel is required to be less than 0.008%. [0...

AI Technical Summary

Problems solved by technology

[0010] In order to solve the problem of high phosphorus content in boiler steel in the prior art, the present invention provides a method for producing high-alloy low-phosphorus steel for boilers using an electric arc furnace. The method includes electric arc furnace smelting, LF refining, VD vacuum treatment and Continuous casting, the electric arc furnace smelting includes the following steps: adding fresh lime and iron oxide together with the charge into the electric arc furnace, and heating the charge; when the charge is melted by 30-40%, adding fresh lime in batches, and operating with a large amount of slag , and the slag basicity is controlled at 3.5-5.0, and the FeO content is controlled at 25-35%; when the charge is completely melted and the temperature of the molten pool reaches 1520-1550°C, the dephosphorization slag is quickly discharged; fresh lime is added in batches to strengthen dephosphorization, To produce high-basic slag, the basicity of the slag is controlled at 5.0-6.0, and the content of FeO is controlled at 30-40%; when the temperature of the molten pool reaches 1580°C or higher, fresh lime is added in batches, the slag is automatically flowed, and the molten steel is detached at the same time carbon