FI82893B - ANVAENDNING AV EN UTSKILJNINGSHAERDBAR SOM RAOVARA FOER STRAONGGJUTNINGSKOKILLER. - Google Patents

Description

1 8289ο

Use of precipitation-curable copper alloy as a raw material for continuous castings

The invention relates to the use of a copper alloy containing 0.2 to 1.2% of nickel, 0.04 to 0.25% of phosphorus and the remaining copper and impurities due to the manufacturing conditions.

Copper (mainly type SF-Cu) has long been used as a raw material in the production of continuous casting molds for use in the ingot casting of high melting metals such as steel 10, which due to its high thermal conductivity can conduct heat away from the melt very quickly. The wall thickness of the molds is chosen so large that it sufficiently satisfies the desired mechanical requirements.

In order to increase the heat resistance, it has been proposed that continuous casting molds be made of an alloy containing at least 85% copper and at least one other alloying component-20 which affects the precipitation hardening. Up to 3% of chromium, silicon, silver and beryllium are reported as alloying components. The continuous casting molds made from this raw material were also not entirely satisfactory because the alloying components silicon and beryllium in particular greatly reduced the conductivity (AT-25 Patent Publication 234,930).

None of these solutions as raw materials for continuous casting molds were yet fully satisfactory.

The invention comprises the use of a copper alloy containing 0.2 to 1.2% nickel, 0.04 to 0.25% phosphorus and the remaining copper and impurities due to the manufacturing conditions as a raw material for continuous casting molds.

Preferably the nickel content is 0.3 to 0.5% and the phosphorus content is 0.06 to 0.1%, the ratio of nickel to phosphorus being 3.5 to 7: 1, preferably 5: 1.

35 The raw material is characterized by particularly advantageous mechanical and physical properties. The alloy has a thermal conductivity of about 80% of the value of pure copper.

2 82893 The values of thermal strength, tensile strength and thermoplasticity are also in a very advantageous range for continuous casting molds. The Brinell hardness used as a measure of wear resistance reached values above 100. An essential additional requirement for continuous casting molds is the high corrosion resistance provided by the copper / nickel / phosphorus alloy.

U.S. Pat. No. 2,155,405 discloses a copper alloy containing 0.25 to 3% nickel, 0.05 to 0.6% phosphorus and the remainder copper. This alloy, which is intended as an electrical conductor, has an electrical conductivity of 67% (IACS) and is said to have good tensile strength.

The physical properties desired of continuous casting molds are not limited to conductivity and tensile strength, but are also properties that are not inferred from U.S. Patent 2,155,405.

Since the temperature of the melt in contact with the mold wall in the case of steel is above 1,300 to 20 ° C (the melting point of copper and copper alloys is about 1,100 ° C), good thermal conductivity is of course also involved. However, since the wall of the molds can withstand temperatures up to 450 ° C, the heat resistance is of great importance, i.e. the sharp deterioration in strength must be transferred to a temperature range above the operating temperature of the molds. Thus, the alloy ring used according to the invention has a semi-hard temperature (recrystallization temperature) of about 575 ° C.

Another important property of the raw materials for continuous casting molds 30 is thermoplasticity, which is determined by elongation at break. The high elongation at break combined with the high thermal strength results in a raw material for continuous casting molds which shows only slight wear and has no tendency to crack under thermal stresses in the region of the casting surface 35. The final measure of non-shrinkage is still the elongation behavior at higher temperatures.

i 3 82893

Since continuous casting molds are usually cooled from the outside with water, good corrosion resistance is also required from the raw material of the molds.

The invention is further clarified by the following use-5 example.

A copper alloy containing 0.43% nickel, 0.0801% phosphorus and the remaining copper and impurities due to manufacturing conditions was formed into a tube after extrusion by casting. The dissolution annealing of the tube 10 was then performed for one hour at 700 ° C. After solution annealing, the second sample was cold worked again by 10%, and the second sample by 20%. Both samples were then tempered at 450 ° C for 8 hours.

A comparison of the technical values shown in Tables A, B and C shows unequivocally that the alloy according to the invention is in all respects superior to the reference raw material hitherto used almost exclusively for molds, SF copper.

Compared to the reference raw material, copper / chromium / zirconium, some properties have to be considered inferior, but the alloy according to the invention is more cost-effective than copper / chromium / zirconium alloy because the dissolution annealing temperature is clearly lower than copper / chromium / zirconium. for this reason, the risk of the formation of coarse grains and the formation of wreckage is avoided. In addition, the components of the alloy according to the invention are substantially less expensive.

Of course, the invention is not limited to use by way of example, but the alloy according to the invention can also be used for all kinds of molds which can be used to produce metal molds in a semi-continuous or completely uninterrupted manner, e.g. raw molds, ingots of all kinds, casting wheels, roll covers, etc.

4 82893

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Claims (4)

7 82893 A precipitation hardenable copper alloy containing 0.3 to 0.5% nickel, 0.06 to 0.1% phosphorus and the remainder copper and impurities due to the manufacturing conditions, wherein the ratio of nickel to phosphorus is 3.5 to 7. : 1, preferably 5: 1, use as a raw material for continuous casting molds. Process for the production of continuous casting molds from a copper alloy according to Claim 10, characterized in that the alloy is hardened by hot-forming, cold-formed by at least 10% and then annealed for 1 to 8 hours at a temperature of 350 to 500 ° C. Process according to Claim 2, characterized in that, after the hot working, the solution annealing is carried out at a temperature of 650 to 750 ° C. Process according to Claim 3, characterized in that the alloy is cold-formed by at least 10% after annealing at a temperature of 350 to 500 ° C. β 82893