Method for controlling class B inclusions of steel rail for high-speed railway

Abstract

The invention relates to the technical field of steel-making, in particular to a method for controlling class B inclusions of a steel rail for high-speed railway. The method is characterized by being started with changing alloy adding variety after converter steel tapping, post-furnace deoxidization system, LF (Ladle Furnace) furnace refining slagging system and VD (Vacuum Degassing) vacuum treatment and by comprising the following steps of: (1) adding SiCaBa powder after converter steel tapping and reducing oxygen content in furnace slag; (2) controlling the addition quantity of a SiCaBa powder desoxidant under the condition guaranteeing total oxygen in steel; (3) adding lime and bauxite and employing a secondary slag practice; and (4) adding a magnesian covering agent for covering tank at the argon blowing point after vacuum breaking of VD furnace. Compared with the prior art, the method provided by the invention has the advantages that the grade of the class B inclusions in liquid steel is reduced below 0.5, steel modification due to unaccepted total aluminum is avoided, and the total aluminum content in steel is lower than the standard by 0.0010%; therefore, the heavy rail tempering rate is improved and huge economic benefit is created for steel and iron enterprises.

Description

technical field [0001] The invention relates to the technical field of steelmaking, in particular to a method for controlling Type B inclusions in steel rails for high-speed railways. Background technique [0002] At present, with the development of passenger-dedicated railways, the demand for high-speed heavy rail steel, especially 350, 380km / h heavy rail steel, has become higher and higher, but the requirements for steel quality have also increased, mainly due to the cleanliness of molten steel. Require. TB / T 3276-2011 "Steel Rails for High-Speed ​​Railways" newly issued by the Ministry of Railways stipulates that the class B inclusions of rails for railways with a speed of 250km / h and above must be ≤ 1.0. [0003] The traditional process is mainly to adopt aluminum-free production process on raw materials, but because the alloy and raw materials contain a certain amount of residual aluminum, and this part of residual aluminum completely enters the molten steel and cannot...

AI Technical Summary

Problems solved by technology

[0003] The traditional process is mainly to adopt aluminum-free production process on raw materials, but because the alloy and raw materials contain a certain amount of residual aluminum, and this part of residual aluminum completely enters the molten steel and cannot be eliminated, forming Al 2 o 3 Inclusions lead to the increase of B-type inclusions (alumina) in heavy rail steel. When the content of B-type inclusions in high-speed heavy rail steel exceeds the upper limit of the standard, it can only be forced to change to other low-demand rail varieties, which affects Normal production plan, and increased production costs