Ultra-low aluminum steel and smelting method thereof

Abstract

The invention belongs to the technical field of ferrous metallurgy and particularly relates to ultra-low aluminum steel and a smelting method thereof. The smelting method provided by the invention adopts a production route with the steps of deep removal of S and P by molten iron pretreatment, decarbonization by a converter, deoxidization and alloying of silicon manganese during tapping, deslagging by argon blowing, deep removal of O, S and P by ladle refining, micro-alloying of Ti, Ni, Mo, V and other elements, RH (Ruhstahl-Hausen) vacuum circulation degassing, soft argon blowing and full-protection casting; the prepared ultra-low aluminum steel has low content of harmful elements, particularly has low content of O and Al, can prevent the inclusion of brittle aluminum oxide and realize high impact-resistant and fatigue-resistant performances of the steel, and is suitable for application fields with relatively high requirements for fatigue and impact performances, such as high-speed track traffic and the like.

Description

technical field [0001] The invention belongs to the technical field of iron and steel metallurgy, and in particular relates to an ultra-low aluminum steel and a smelting method thereof. Background technique [0002] Inclusions in steel, especially brittle inclusions, are the key factors that reduce the fatigue life and impact resistance of steel, and have become obstacles to the high-end application of steel materials; for most steel types, brittle inclusions in steel are mostly hard and not Deformed Al 2 o 3 , (Mg / Mn)O·Al 2 o 3 And TiN (CN), for the removal of inclusions and deformation control, the existing technology starts from the two main technical routes of improving the purity of steel and adding calcium to the inclusions to treat denaturation, and minimizes the amount of aluminum oxide and nitride However, the research on alumina-based inclusions in the prior art revolves around how to control the target composition of inclusions, that is, to promote the remova...

AI Technical Summary

Problems solved by technology

[0002]Inclusions in steel, especially brittle inclusions, are the key factors that reduce the fatigue life and impact resistance of steel, and have become an obstacle that limits the high-end application of steel materials; for large In most steel types, the brittle inclusions in the steel are mostly hard and non-deformable Al2O3, (Mg / Mn)O·Al2 sub>O3 and TiN (CN), for the removal of inclusions and deformation control, the existing technology starts from the two main technical routes of improving the purity of steel and adding calcium to the inclusions to treat denaturation. The harm of alumina-based and nitride-based inclusions is reduced to the greatest extent; however, the research on alumina-based inclusions in the prior art revolves around how to control the target composition of inclusions, that is, to promote the formation of alumina and other oxides in steel. The melting point of the composite compound removes or changes the brittleness and makes it plastic. Obviously, if the alumina inclusions are to be fundamentally eliminated, the formation conditions of the alumina inclusions should be fully controlled, that is, how to control the dissolved aluminum and dissolved oxygen in the steel. amount, and control the formation conditions of brittle alumina to the greatest extent. For this technical route, the existing technology has carried out a lot of research and design on how to reduce the oxygen content in steel, that is, deoxidation technology. Recent research shows that in After the oxygen content in the steel is reduced to several to tens of ppm (10-6), the control of the dissolved aluminum content in the steel is the key factor to change or eliminate the formation of alumina and its hazards. However, since aluminum is the deoxidation factor of most steel types at present, aluminum is also considered to be one of the elements with the strongest deoxidation ability; therefore, in limiting the formation of alumina series inclusions, research on the control of aluminum content in steel Less, for the development of steel types, for steel types with extremely high requirements for fatigue resistance and impact resistance, such as key components of high-speed railways, it is necessary to develop pure steel with low or ultra-low aluminum content, from the two levels of dissolved aluminum content and dissolved oxygen content. To control the formation conditions of alumina-based inclusions, it is necessary to develop a method for controlling ultra-low aluminum content steel and its inclusions.