RU2355781C2 - Flux cored electrode with filler silicocalcium with rare-earth metals for out-furnace steel treatment - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to ferrous metallurgy, particularly to out-furnace treatment of metallurgical melts by powder reactant. Flux cored electrode consists of steel shell and filler, consisting mechanical mixture of milled powdery silicocalcium of grades CK-20 or CK-30 and rare-earth metals (REM) in the form of powder or granules at following content of components in filler, wt %: silicocalcium of grades CK-20 or CK-30 40-98, REM 2-60. Block coefficient of flux cored electrode is 0.5-0.75.

EFFECT: increasing of metals corrosion resistance, content reduction of corrosion-active nonmetallics, increasing of recovery grade and calcium efficiency.

3 cl

Description

The invention relates to ferrous metallurgy, and in particular to out-of-furnace treatment of metallurgical melts with powder reagents. The patented invention will find application in the production of a new promising flux-cored wire with a filler of silicocalcium with rare earth metals (REM), which is intended to increase the corrosion resistance of steel.

Flux cored wire with silicocalcium filler is widely used for out-of-furnace treatment of steel and cast iron. Silicon-calcium treatment of steel is one of the mandatory requirements of a number of standards of the USA, Great Britain and the countries of the European Union, due to the complex effect of calcium on improving the properties of steel.

Silicocalcium (GOST 4762-71) is an active complex deoxidizer, steel degasser, and an effective desulfurizer, which ensures a high amount of deoxidation and ensures the minimum amount and optimal shape of non-metallic inclusions, improves the strength properties of rolled products, forgings, and castings.

Known wire for out-of-furnace steel processing, consisting of a metal sheath and a powder filler containing calcium and silicon. The calcium content is 15-30 wt.% (Publication "Metal and casting of Ukraine", 2000, No. 1-2, p.17-20). The introduction of calcium into molten steel in an alloy with silicon reduces the elasticity of dissociation of calcium vapor, and the vapor of the latter has time to react in the depth of the melt. This achieves a certain degree of deep passivation of calcium, and the processing process proceeds calmly, without bubbling and emissions, which allows to increase the degree of use of calcium. However, this wire has a number of significant drawbacks. At the indicated content, calcium and silicon form a chemically unstable compound CaSi ₂ . Moreover, with a calcium content of 25-30%, the melting point of such a compound is relatively low (about 1000 ° C), which leads to increased waste, a low degree of absorption of calcium and an increased consumption of wire.

Known flux-cored wire for out-of-furnace treatment of metallurgical melts, the closest in composition and technical nature and selected as a prototype of the patented invention (RF patent No. 2289631, C21C 7/00).

The filler wire is a mechanical mixture of silicon and calcium, which is in the filler both in the form of an alloy with silicon, and in pure form. The filler wire additionally contains aluminum, carbon, phosphorus and iron.

For the production of wire, silicocalcium grades SK15 ... SK30 are mainly used. The use of a patented wire makes it possible to increase the degree of use of calcium, reduce dust and gas production, reduce the cost of manufacturing wire, the cost of processing and consumption of wire.

The disadvantage of this wire is the low corrosion resistance of pipe steels treated with SK15 ... SK30, in particular the high content of corrosive non-metallic inclusions.

The present invention solves the problem of developing a new calcium-containing wire for out-of-furnace treatment, increasing the operational properties of steel, in particular corrosion resistance.

The solution to this problem is achieved as follows.

In a flux-cored wire similar to that described in RF patent No. 2289631, consisting of a steel sheath and a filler containing a mechanical mixture of ground powder alloy SK20 or SK30 and an additional component, according to the invention, rare-earth metals in the form of powder or granules are used as an additional component of the flux-cored wire filler .

The invention provides that the content of the filler components is, wt.%, Respectively:

ground powder alloy SK 20 or SK 30 98-40 Rare Earth Metals (REM) 2-60

According to the present invention, the content of the filler and the steel shell is, wt.%, Respectively 51-75 and 25-49, and the fill factor of the cored wire is 0.5-0.75.

The technical result of the patented invention is as follows.

It is known that silicocalcium is an active complex deoxidizer, a good steel degasser, and an effective desulfurizer. With a high degree of deoxidation, silicocalcium provides a minimum amount and optimal shape of non-metallic inclusions, improves the strength properties of rolled products, forgings and castings.

In the process of developing the present invention, studies have been conducted that have confirmed the increased effectiveness of the integrated use of filler to increase the corrosion resistance of steel by modifying non-metallic inclusions containing sulfur. The patented invention is based on the effect of mutual enhancement of the action of calcium and rare earth metals (REM). The studies conducted allowed us to determine the composition and optimal content of rare-earth metals. In the patented flux-cored wire formulation, the following REM combination is implemented: Ce (cerium), La (lanthanum), Pr (praseodymium), Nd (neodymium). Moreover, the ratio of components is 50, 25, 12.5 and 12.5%, respectively. It should be noted that it is possible to use another combination of rare-earth metals.

As a result of using a new (in composition and weight ratios) combination of flux-cored wire filler components, the following is achieved:

- increase the indicators of corrosion resistance of the metal;

- reduction of the content of corrosive non-metallic inclusions in steel;

- an increased degree of assimilation and the effectiveness of the use of calcium, as well as a more complete globularization of non-metallic inclusions.

The manufacture of a new cored wire with a filler of silicocalcium and rare earth metals is carried out in the traditional way using standard metallurgical equipment.

The metal strip is profiled into a trough-like sheath. A well-mixed mechanical mixture of fillers is loaded into the hopper.

From the hopper, the mechanical mixture of fillers in metered portions is fed into a trough-like metal shell, which is uniformly filled with a mixture of fillers. Then, using the roller stands, they compress the shell and form a lock. The finished wire is wound around a reel and delivered to the steel processing department.

The applicant experimentally tested the patented flux-cored wire with silicocalcium filler and various weight options for the content of rare-earth metals in the filler.

The obtained results confirm that the patented ratios of the components of the flux-cored wire filler (mechanical mixture of ground powder alloy SK 20 or SK 30 and REM) provide increased corrosion resistance and can reduce the content of corrosive non-metallic inclusions.

The analysis of scientific, technical, patent and abstract information confirms the originality of the composition and the novelty of the patented wire.

High technical and economic efficiency of the experimental use of the developed flux-cored wire, its undoubted technological and operational advantages in comparison with the well-known flux-cored wires of a similar purpose confirm the promise and commercial significance of this development.

Claims (3)

1. A flux-cored wire with a filler for out-of-furnace treatment of steel, consisting of a steel sheath and a filler containing a mechanical mixture of ground powdered silicocalcium grades SK-20 or SK-30 and an additional component, characterized in that rare-earth metals (REM) are used as an additional component of the filler ) in the form of powder or granules with the following content of components in the filler, wt.%:
Silicocalcium grades SK-20 or SK-30 40-98 REM 2-60 2. The flux cored wire according to claim 1, characterized in that the content of the filler and the steel sheath is, respectively, 51-75 and 25-49, wt.%. 3. The cored wire according to claim 1, characterized in that the fill factor of the cored wire is 0.5-0.75.