RU2537415C1 - Alloying briquette for steel deoxidation - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: briquette is obtained by pressing of aluminium scrap, iron and nickel turnings at the following ratio of components, wt %: aluminium scrap 0.5-2, nickel turnings 2-7.5, iron turnings - the rest. The briquette can be made as cylinder or truncated cone, with the following ratio of the height, the bottom base and top base - 10:8:3. Briquette weight is 12 to 18 kg.

EFFECT: invention allows to improve the efficiency of deoxidizing effect and alloying of melted steel due to increase of mastering factor and more uniform distribution of components in the melt, lower the cost price of the briquette due to simplicity of fabrication and use of metal scrap.

2 cl, 1 tbl

Description

The invention relates to the field of metallurgy and can be used for deoxidation and alloying of liquid steel.

Deoxidation of liquid steel is known during its out-of-furnace treatment with aluminum alloy (SU 1025731, published on 06/30/1983).

The disadvantage of this process is that the addition of aluminum in the form of ingots for the purpose of deoxidation of liquid metal is accompanied by a large uncontrolled burning of aluminum during its interaction with slag oxides and atmospheric oxygen and, accordingly, wide variations in its content in the finished steel, and uneven distribution of aluminum in the melt.

The closest in technical essence and the achieved result to the invention is a briquette for steel deoxidation obtained by pressing aluminum scrap and particles of an alloy based on iron in the following ratio of components, wt.%: Aluminum scrap - 25-32, particles of an alloy based on iron - 68 -75 (RU 2259405, published October 27, 2004).

The use of a briquette of this composition allows to reduce the cost of briquette due to the simplicity of production and disposal of aluminum and iron-containing waste, to improve the quality of steel by increasing the proportion of aluminum interacting with steel, its absorption coefficient and uniform distribution in the volume of liquid steel. The absorption coefficient of aluminum when using such briquettes was 61%.

The disadvantages of this invention is the following. The high content of aluminum in the briquette leads to its surfacing on the surface of the melt and the oxidation of aluminum with the transition to slag. The briquette of this invention does not contain alloying components and does not improve the quality of steel. The shape of the briquette does not take into account its surface, which is in contact with atmospheric oxygen, which leads to large losses of aluminum.

The technical result is aimed at obtaining a briquette that provides effective deoxidation and alloying of steel, reducing the cost of finished products and simplifying the introduction of additives in liquid steel, necessary to obtain a metal of a given composition.

Features of the invention consist in the fact that the alloying briquette for the deoxidation of steel is made of secondary aluminum, iron and nickel.

It differs in that it contains aluminum scrap, iron shavings and an alloying nickel additive in the following ratio of components, wt.%:

Aluminum scrap - 0.5-2

Nickel shavings - 2-7.5

The rest is Iron Chips.

The briquette may be in the form of a cylinder or a truncated cone, in which the height, lower base and upper base have a ratio of 10: 8: 3.

Aluminum deoxidizes steel, binding oxygen, passes into oxide and forms slag. The content of aluminum scrap in the briquette depends on the amount of oxygen in the steel and is in the range of 0.5-2% of the total weight of the briquette.

A decrease in the aluminum content of less than 0.5 wt.% In the briquette inhibits the diffusion processes associated with the dissolution of the metal and slows down the process of steel deoxidation. In this case, undesirable carburization of steel and deterioration of its mechanical properties occur. An increase in the aluminum content above 2 wt.% In the briquette is undesirable, since this violates the requirements of GOST for the composition of the steel and its wear resistance deteriorates.

Nickel is an alloying component. It lowers the cold-brittleness threshold of steel and, consequently, increases its viscosity reserve.

Nickel contributes to the grinding of ferrite and perlite grains in steel, which significantly increases the viscosity of steel, increases the stability of austenite, reduces the critical hardening rate and increases hardenability, and also increases the corrosion resistance of steel.

A nickel content of less than 2 wt.% Will be insufficient to give the steel the necessary properties. The increase in nickel content above 7.5 wt.% Requires special alloying conditions in order to obtain high alloy steels.

Iron chips are the main component of the briquette, allowing related elements to be evenly distributed in the melt bath with high digestibility.

The briquette may be in the form of a cylinder or a truncated cone, in which the height, lower base and upper base have a ratio of 10: 8: 3. Such dimensions provide immersion of the cone with the bottom base up. Moreover, the surface of the cone is maximally in the melt, which contributes to the rapid assimilation of the deoxidizer and alloying components with minimal fumes.

The mass of the briquette is 12-18 kg. Going beyond 18 kg will not provide sufficient briquette strength. A weight of less than 12 kg is not economically viable, which is associated with the manufacture, transportation and loading of small briquettes into the bathtub.

An example of the implementation of the proposed briquette for deoxidation of steel.

Steel carbon chips of grade 16A were crushed (with parallel sorting from foreign inclusions: pieces of metal, garbage, etc.) into a fine fraction 14A, coil size 5-30 mm, then fed to the press with the final pressing force on the rod of the master cylinder 630 tons with obtaining briquettes with a diameter of 170 mm, a height of 100-150 mm. The mass of briquettes was 12-18 kg.

Tests of the proposed briquettes were carried out to determine the efficiency of deoxidation of the intermediate steel produced from chipboard in a steel pouring ladle. The number of briquettes to be melted in the ladle was determined based on the production of 0.05 wt.% Aluminum in steel after deoxidation.

Table 1 The results of the study of briquettes of various compositions Experience Number Briquette Options Parameter Values Assimilation coefficient of aluminum one Scrap aluminum content 1.3 wt.% 73% Nickel content 5.2 wt.% Briquette weight 16.6 kg The ratio of height, lower and upper bases of a truncated cone 10: 8: 3 2 Scrap aluminum content 0.6 wt.% 75% Nickel content 2.3 wt.% Briquette weight 16.5 kg The ratio of height, lower and upper bases of a truncated cone 10: 8: 3 3 Scrap aluminum content 2.1 wt.% 69% Nickel content 7.4 wt.% Briquette weight 15.5 kg The ratio of height, lower and upper bases of a truncated cone 10: 8: 3

Under identical conditions with the prototype (metal temperature 1590 ° C, carbon concentration 0.05 wt.%), The assimilation coefficient of aluminum when using the proposed briquettes was 69-75% (table 1). Also, unlike the prototype, the proposed briquette has alloying properties.

Claims (2)

1. Alloying briquette for the deoxidation of steel, made of secondary aluminum, iron and nickel, characterized in that it contains the mentioned components in the form of aluminum scrap, iron shavings and nickel shavings in the following ratio, wt.%: Aluminum scrap 0.5-2 , nickel chips 2-7.5, iron chips - the rest, and the mass of the briquette is 12-18 kg. 2. The briquette according to claim 1, characterized in that it has the shape of a cylinder or a truncated cone, in which the height, lower base and upper base have a ratio of 10: 8: 3.