Smelting process for producing low-carbon ultralow-phosphorus steel in converter

Abstract

The invention discloses a smelting process for producing low-carbon ultralow-phosphorus steel in a converter. The smelting process comprises the following steps of: dephosphorizing molten iron desulfurized once by utilizing two times of slagging blowing process, namely, an early stage and a later, or three times of slagging blowing process, namely, an early stage, a middle stage and the later stage, or multiple times of slagging blowing process, wherein the content of phosphorus of the molten iron is 0.11-0.13%; utilizing silicon iron slag regulation, pouring the slag into a slag basin until the slag basin is full each time and controlling process temperature; pouring slag when oxygen blowing is carried out by 40-45%, wherein the target temperature of an early stage is 1,350-1,400 DEG C; and controlling the temperature between 1530 DEG C and 1550 DEG C when a sublance is used for blowing oxygen for 80%, and pouring the slag, so that the low-carbon ultralow-phosphorus steel with terminal phosphorus content being within 0.005% is obtained, wherein the terminal target temperature is 1560-1580 DEG C. The smelting process for producing the low-carbon ultralow-phosphorus steel in the converter, disclosed by the invention, can carry out multiple times of slagging on the molten iron desulfurized once in the converter and has the advantages of being small in molten iron physical heat loss, high in yield and efficiency, low in alloy consumption and cost, and energy-saving.

Description

technical field [0001] The invention relates to a smelting process for low-carbon and ultra-low-phosphorus steel, in particular to a smelting process for producing low-carbon and ultra-low-phosphorus steel by double-slag or multiple-slag methods in a converter. Background technique [0002] The smelting of ultra-low phosphorus steel is generally realized by the process of refining outside the furnace. For alloy steel, high carbon steel and special steel, the patents of publication numbers CN 101319261A, CN 101328529A and CN 101319262A adopt the process of refining outside the furnace for initial dephosphorization and deepening dephosphorization, and the phosphorus content can be controlled within 0.003%. But before refining, it is required that the phosphorus content of converter steel should be below 0.02%. Obviously, these methods need to add an extra-furnace refining process after converter steelmaking to reduce the phosphorus content, and add a specific dephosphorizatio...

AI Technical Summary

Problems solved by technology

[0005] For some special-purpose low-carbon steel and alloy steel grades, such as 9Ni steel for LNG, customers usually require that the phosphorus content is less than 0.005% (ultra-low). From the current existing technology, it is necessary to make the P in molten steel ultra-low Level, it is difficult to use converter steelmaking, and it needs to adopt processes such as molten iron pretreatment and out-of-furnace refining, resulting in increased processes, increased equipment costs, and higher final product costs