FI60820B - ANVAENDNING AV EN KOPPARLEGERING FOER STRAENGGJUTKOKILLER - Google Patents

Description

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Patent and Registration Office .. , . . ,. ,. ,. . . _. , (44) Date of issue and date of issue. - oi 1 p Ai

Patent · och registerstyrelsen v ’AmOktn utiagd och uti.ikrift« n pubikend ‘01 (32) (33) (31) Pyy «l« ty atuolkay * -B.jird priority 06.08.76

Federal Republic of Germany-Förbundsrepubliken

Tyskland (DE) P 26 35 ^ 3.8 (71) Kabel- und Metallwerke Gutehoffnungshiitte Aktiengesellschaft,

Vahrenwalder Strasse 271> 3000 Hannover, Federal Republic of Germany Förbundsrepubliken Tyskland (DE) (72) Hans Joachim Wallbaum, Osnabruck, Horst Gravemann, Osnabruck,

Federal Republic of Germany-Förbundsrepubliken Tyskland (DE) (7 ^) Oy Kolster Ab (5M Use of copper alloy for continuous casting molds -Användning av en kopparlegering för stränggjutkokiller

The invention relates to the use of a copper alloy containing 1.5-4% of iron and up to 0.04% of phosphorus, the remainder of copper and ordinary impurities.

As a material for the production of continuous casting molds for the continuous casting of high-melting metals such as steel, copper has long been used, which, due to its high thermal conductivity, is able to conduct heat away from the melt very quickly. The wall thickness of the molds was chosen to be large enough to withstand the expected mechanical stresses.

In order to increase the heat strength, it has been proposed to make continuous casting molds from an alloy with at least 85% copper and at least one other alloying element influencing the separation hardening. Up to 3% of chromium, silicon, silver, and beryllium are proposed as alloying elements. Also, the continuous casting molds made from this raw material were not yet completely satisfactory, because the alloy components silicon and beryllium in particular strongly reduce the thermal conductivity. (Austrian patent OE-PS 234 930).

2,60820 Therefore, in order to improve the thermal conductivity, a copper raw material with 0.05-0.08% chromium and 0.005-0.04% phosphorus and the rest copper has become known for continuous scale lock coils.

2

Cold working has a brugell hardness of 120 kp / mm and a thermal conductivity of at least 80% of the thermal conductivity of pure copper. The temperature of the loss of strength is above 350 ° C (German Announcement publication DT-AS 2 318 662).

None of these solutions has yet been completely satisfactory as a raw material for continuous casting molds.

Thus, the invention comprises the use of a copper alloy with 1.5-4.0% iron, up to 0.04% deoxidizing agent, e.g. phosphorus, the rest copper and common impurities, in the cured state as a raw material for continuous casting molds, in particular for the casting of high melting metals .

Boron, lithium, calcium, magnesium, phosphorus, etc. are used as deoxidizers for copper.

Preferably, the raw material contains 2.0-2.5% iron and 0.05-0.25% zirconium and 0.005-0.02% forsor.

In particular, the addition of zirconium precludes the use of this copper alloy for continuous casting molds.

The raw material is characterized by particularly advantageous mechanical and physical properties. Its thermal conductivity is more than 70% of the thermal conductivity of pure copper. The values of heat strength, thermoplasticity and softening temperature are likewise in a very advantageous range for continuous casting molds. Brinell hardness, as a measure of wear strength, achieves values greater than 120. Another essential requirement for continuous casting molds is high corrosion resistance to the cooling water met by the disclosed copper alloy.

Although U.S. Patent 2,137,281 discloses a copper alloy with 0.1-5% iron and 0.1-3% zirconium, this raw material is used only for resistors that must have high hardness and high electrical conductivity. Therefore, this raw material is proposed as a material for the manufacture of electrodes for electric resistance welding. No conclusions can be drawn from this U.S. patent about the behavior of the copper alloy in the area important to this invention.

3,60820

The invention is further illustrated by the following exemplary embodiment.

The copper alloy with 2.5% iron, 0.15% zirconium and 0.01% phosphorus, the rest of the copper and ordinary impurities, was first cast into a block with a diameter of 420 mm and extruded at about 950 ° C into a tube, having an outer diameter of 220 mm and then hardened. The tube was then cold formed in several drawing steps by about 50%, reducing the outer diameter to 150 names. The tube was then annealed at 475 ° C for 1.5 hours and cooled.

This was followed by final processing into tube packages.

After this treatment, the finished continuous casting molds had the following material characteristics: thermal conductivity 70% of the thermal conductivity of pure copper softening temperature 600 ° C hardness HB 2.5 / 62.5 145 N, 2 tensile fracture] new 420 / mm elongation at break 15%

Even after a longer period of use, no defects in the molds to date, such as shrinkage of the package and the formation of hot cracks in the area of the bath surface, were found in the continuous casting mill. Similarly, the incidence of wear at the lower end of the mold was clearly lower.

A copper alloy containing 2.35% iron, 0.10% zirconium and 0.03% phosphorus was cast into a rolling stock preform which was hot rolled at 950 ° C with a 60% reduction in cross section and rapidly cooled thereafter. The sheet was then surface machined and cold-machined 45% in several rolling steps. The plate was then annealed at 500 ° C for 1 hour and slowly cooled in an oven. After annealing, the plate was further cold worked by Vals yielding 38% and annealed for 10 hours at 450 ° C.

This was followed by pre-processing into mold plates. The plates had the following substance identification values:

Thermal conductivity 73% IACS

softening temperature 55 ° C

hardness HB 2.5 / 62.5 125 N, 2 tensile fracture] new 392 / mm elongation at break 18% heat strength at 300 ° C 321 ^ / mm ^

Fracture at 300 ° C 63%.

* 60820 The mold made of these sheets had, after 450 filling times, excellent dimensional stability in the empty space of the mold forming the filament due to the high thermal strength of the raw material.

Up to now, up to 1.5% of copper was found in cocaine materials.