SU1395682A1 - Method of out-of-furnace processing of steel in production of billets by continuous casting - Google Patents

Abstract

The invention relates to methods for secondary treatment of steel in the preparation of blanks by continuous casting. The purpose of the invention is to increase the absorption of titanium, the quality of the slab surface and the cold resistance of sheet steel in the hot rolled state. The method includes preliminary deoxidation with aluminum (0.4-0.5 kg / t), modifying with titanium (0.2-0.3 kg / t, boron microalloying (O, 65-0, 75 -kg / t 10% FeB) and final microalloying with a titanium-containing powder tape with a flow rate of 0.4-0.6 kg / t, covered with 0.015-0.030 kg / t of flux i. Wick ppata in the mold caster, and provides for the coating of the surface of the steel in the mold 0.18-0.25 kg / t of amorphous graphite, and the optimal ratio of input elements (HA + Ti) / 10B is 1.0-2.0. . The number of slab sweeps is reduced to 10–25%, the absorption of titanium is up to 60%, the work of steel destruction in the hot-rolled state when testing hot-rolled sheets at C is 46-49 J. 1 hp f-ly, 1 tab. (L () JV Oi OQ to

Description

The invention relates to metallurgy and can be used in the preparation of steel continuous cast slabs and hot rolled sheets of them.

The purpose of the invention is to increase the absorption of titanium, the quality of slabs and the cold resistance of sheet steel in the hot-rolled state.

Complex slitting, modification and microalloying in accordance with ITAI + Ti

relations with attitude;: -, are equal

1 UD

1.0-2.0, increases the cold resistance of steel, since aluminum, increased the steel forms brittle oxides, which with the introduction of titanium are modified by it and become more plastic and less dangerous stress concentrators. At optimum content, titanium also forms microdispersed carbonitrides, evenly distributed in the steel volume, which increase the mechanical properties and impact toughness. Boron, when performed, is in solid solution and has a positive effect on the properties of the steel. If this ratio is less than 1.0, then oxides and boron nitrides are formed in the grain boundaries because of excess boron, if it is greater than 2.0, then titanium is in excess and in the grain boundaries it forms carbonitrides that are within the grain boundaries and embrittle them and steel in general, which reduces the mechanical properties and cold resistance of hot rolled metal.

Separate input of titanium eliminates the growth of teeming glasses with titanium oxides and thus improves the quality of slabs, as well as enhances its absorption.

The invention is illustrated by examples, the results of which are shown in the table.

Steel is smelted in open-hearth furnaces with a capacity of 140 tons. Pre-deoxidation, modification and microalloying are carried out in a steel casting ladle: aluminum, titanium and boron (10% FeB), respectively. The casting is carried out on a vertical matine of continuous casting of blanks (SL :) in a slice section of 150x1000-1200 mm. The metal mirror in the mold is covered with amorphous graphite - with a consumption of 0.18-0.25 kg / t of steel. The final microalloying is carried out in the mold of the caster with titanium-containing powder tape (wire) containing a fluxing additive (fluorspar).

Spread onto a sheet 10-18 mm thick. Testing of hot-rolled sheets for specific bending was carried out according to the fourth, section GOST 5521-76 on samples with a sharp notch (g - 0.25 mm) at a temperature of minus 20 ° C.

The proposed method makes it possible to prevent breaks in the continuous casting of steel, to increase the absorption of titanium, to improve the quality of slabs and the cold resistance of steel in the hot-rolled state.

I

Claims (2)

1. The method of after-treatment processing of steel in the preparation of blanks by continuous casting, including the input of aluminum, titanium, and boron blanks into the casting cradle after filling with 1/2 to 1/3 of its height and coating the steel surface in the crystallizer with amorphous graphite with a consumption of 0.18 -0.25 kg / t of steel, which is made with the fact that, in order to assimilate titanium, the quality of slabs and cold resistance of sheet steel in the hot-rolled state, titanium is planted in two portions mi: the first in the amount of 0.2-0.3 kg / t together with boron is introduced into the steel the ladle after the addition of aluminum, the second portion of titanium is introduced into the mold in the form of a pororl of titanium in the amount of 0.40, 6 kg / ton with the addition of flux in the amount of 0.015-0.030 kg / ton of steel, upon receipt of the ratio in the finished steel (K1 + Tr) / 10 V, equal to 1.0-2.0. 2. The method according to claim, characterized by the fact that titanium powder and dDYuca are injected with the help of a ribbon of wire. Paw 1Trototilv.