FR2501556A1 - PROCESS FOR OBTAINING CONTINUOUS, TUBULAR, STRAIGHT OR CURVED CASTING SHELLS, WITH PARALLEL OR CONICAL INTERIOR CONTOURS, COPPER ALLOY FOR RECEIVING - Google Patents

Abstract

A.PROCESS FOR OBTAINING CONTINUOUS CASTING SHELLS. B. CHARACTERIZED IN THAT A COPPER ALLOY TUBE IS USED SUITABLE TO UNDERSTAND ANYTHING WITH: FORMING AT THE SOLUTION ANNURING TEMPERATURE - ANNING AT 400600C FOR AT LEAST 15 MINUTES - AND EXPLOSION FORMING. C. THE INVENTION RELATES TO THE MANUFACTURE OF SHELLS FOR CONTINUOUS CASTING.

Description

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  The invention relates to a method for ob-

  retention of continuous tubular casting shells, curves, the walls of the shell which form the inner empty space being formed by an explosive material to the geometrical measurements of a matrix. DEAS 2533528 discloses a process for forming the walls of continuous casting shells, wherein the walls of the shell forming the hollow volume are subjected to a force forming these walls and released by an explosive material, and thus the walls are formed to the geometric dimensions of a matrix. The advantage of the process, known, is that the shells formed according to this process, constituted by copper or a copper alloy, exhibit

  surface properties and particular dimensional accuracy

  especially good with regard to the hollow form. Here, the annealing may be subjected to a starting material having a Rockwell B hardness 40 so as to obtain a material of a hardness

Rockwell B between 50 and 75.

  The disadvantage of this method is that, by explosive forming, only a small reduction in wall thickness can be obtained, which means that it is also not possible to perform low cold forming

  global. This results in a relative overall resistance

  of the shell section, and thus moderate form stability. To this is added another drawback which consists in the fact that, in common copper alloys, the deformation obtained by cold forming is reversible already at

  3500C, which considerably limits the lifespan of shellfish

  subject to significant solicitations. This process allows

  possible to achieve higher resistances by

  use of higher alloyed copper alloys. Those present

  However, the disadvantage of inadequate thermal conductivity

  and a tendency to cracks in the area

bath surface.

  The object of the invention is to propose a method which makes it possible to manufacture shells of any shape or size, for example tubular shells with very thick walls, of imortant dimensions, for continuous casting workshops, which have, in addition to solidity very high, a softening temperature and a thermal resistance

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  The choice of the appropriate components of the alloy allows for high and very high thermal conductivities or a defined firing rate in the

  case of shells for me.gPnetic agitatior.

  For this purpose, the invention proposes a method characterized in that, as a starting material, or using a tube made of a copper alloy capable of undergoing annealing firstly, this tube first undergoes solution annealing. at a temperature specific to the alloy, that is to say that the forming of the tube is carried out at the dissolution annealing temperature, that the tube having undergone this dissolution annealing is subjected during at least 15 minutes at an annealing at a temperature of

  400 to 6000C, and then the forming is carried out by explo-

  if we. In the case of curved tubular shells, a folding operation is furthermore interposed between the setting annealing

solution and annealing by quenching.

  The shells obtained according to this process already have a strength much higher than that of the shells obtained by known methods. This is because, as a material for the shell, a copper alloy capable of annealing is used. Increasing resistance

  is obtained in the case of these materials, by annealing at 400-

  6000C, by quenching effect by structural hardening. The improved properties of the shell result in a longer service life, which provides higher dimensional stability with respect to thermal stresses, particularly at higher temperatures.

  high temperatures, and higher resistance to abrasion.

sion, which reduces wear.

  It is still possible to increase the

  With the process according to the invention, the softened tube is cold-formed, mechanically, by conventional methods. This is preferably achieved by introducing a mandrel into the tubular shell, - in the case of curved tubes, a mandrel of corresponding curvature - and that the shell in common with the mandrel, is subjected to impression by a matrix. The degree of cold forming can be here, depending on the desired final strength, between 2 and 30%. Because of the very high strength values obtained after annealing, it is also advantageous to establish the final geometric dimensions of the

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  tubular shell, already during calibration after annealing

  dissolution. It is thus possible to eliminate deformities

  appearing during an anneal, using a step of

  plosion and get an optimal end product.

  The choice of copper alloys suitable for

  Annealing, which can be used, depends on the specific

  to which a given type of shell is subjected. For the most common applications, a copper alloy with 0.3-1.2% chromium is used with particular advantage.

  0.05-0.2% zirconium. This material ensures the shell

  the high thermal conductivity required. Compared with the standard materials used up to now, such as copper SF, copper-silver-phosphorus alloys, the shells produced from the copper-chromium-zirconium material capable of annealing, according to the method of the invention , present

  a much higher resistance to temperature and

  brasion. They have practically no deformation

  in use and have a very long life.

  The invention will be better understood with the aid of the example below, describing the manufacture of a shell

copper-chromium-zirconium.

  From a copper alloy with 0.7% chromium and 0.18% zirconium, the remainder being copper and the usual impurities, a rod is first cast, then by spinning at 103 ° C., it is prepared a tube. The tube obtained by spinning is quenched with water. From this tube, tube pieces are separated, bent on a bending machine, and a circular section die is introduced into the recess of the tube pieces. On the outside of the tubular parts, an explosive charge is uniformly distributed and ignited. Then, the matrix is removed from the tubular piece and subjected to annealing at 4750C for 4 hours. In the tubular part removed from the annealing furnace,

  slightly deformed, one introduces after cooling

  trice, whose section corresponds exactly to that of the flange to be formed. It must be ensured here that the slightly curved matrix is introduced into the curved tubular piece so that the direction of the curvature of the tubular piece and the direction

  of the curvature of the matrix are oriented in the same direction

  tion. As described above, the explosive forming is performed again, and the tubular shell is

  thus cold formed to the desired measurements.

  The following properties of the finished shell thus obtained were measured: thermal conductivity 87% - softening temperature (1% fall in RT resistance after 1 hour of annealing.) 52500 - hardness HB 2.5 / 62.5 145 - tensile strength 442N / mm2 - elongation of rupture 26% thermal resistance at 2000C 380N / mm2 - heat resistance at 3500C 318N / mm2 The casting shells manufactured according to the above process still retain, after 450 casting fillers, a dimensional stability sufficient at the surface of the bath and present at the base of the island, only weak

wear phenomena.

  The finishing of a conical square shell in the same copper-chromium-zirconium material, presenting even higher resistance properties, will be better

  understood using the example below.

  First a round tube is spun to

  9500C-, then it is formed by stretching to the desired square shape.

  The square tube is subjected for 45 minutes to a solution annealing at 9900C. After cooling, the tubular pieces are calibrated by means of a mandrel and a matrix, with simultaneous reduction of the wall thickness to 15% of the final dimension and subjected to annealing for 6 hours at 4500C. The final calibration is then carried out by

  explosion forming as described above.

  The following characteristics were found on the finished shells: - thermal conductivity: 84% - softening temperature 5100C hardness HB 2.5 / 62.5 159 - tensile strength 521 N / mm - elongation of rupture 21%

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  For an intermediate shaped shell of this type, the wear resistance of the base

  shell is significantly improved.

  In the case of shells requiring a particularly high thermal conductivity, for example due to a poor quality of the cooling water, it is advantageous to manufacture shells from a copper alloy containing 0.05-0, 3% zirconium, according to

  the process of the invention. Thanks to an international cold forcing

  appropriate mechanical mediation, resistance can be achieved

  tensile strength of about 350N / mm2 with thermal conductivities

  more than 93%. The softening temperature of these materials is above 550 ° C. For special cases where a magnetic stirring process is provided in the vicinity of the shell, it is desirable to have a shell material having such a low electrical conductivity. as possible, so as not to weaken the field. As for a material of this type, the thermal conductivity is reduced in the

  same proportions as electrical conductivity, temperatures

  very high wall thicknesses may appear. In order to ensure freedom of deformation, the shell material must have a suitable high thermal resistance. To meet these requirements, annealing materials such as copper-nickel-phosphorus with 0.6 to 1.5% nickel, 0.1 to 0.3% phosphorus and copper-copper are used. cobalt-beryllium with 1 to 2.5% cobalt or 1 to 2.5% nickel or 0.5 to 1.5% nickel + 0.5 to 1.5% cobalt and

  always 0.3 to 0.6% of beryllium, and still copper-nickel-

  silicon with 0.2 to 1.1% silicon and 1.2 to 3.5% nickel.

  According to the process of the invention, for example, a curved rectangular tubular shell having an internal size of x220 mm and a wall thickness of 14 mm made of a copper-cobalt-beryllium alloy with 2 , 2% cobalt and 0.54% beryllium. A square tube is first produced by spinning and then subjected to solution annealing for 45 minutes at 93 ° C. The desired curvature is obtained on a bending machine. Then, a tubular piece is calibrated on a mandrel by explosion forming as described above. After that, the shell is annealed for 5 hours at 4800C. Then, the annealing deformation is removed by forming with a mandrel, by explosion, and thus the shell undergoes a post-calibration. On this tubular shell, the following characteristics were determined: - thermal conductivity 54% - softening temperature 505 C - hardness HB 2.5 / 62.5 235 - tensile strength 805N / mm2 - elongation of rupture 17% - resistance thermal at 200 C 735N / mm - thermal resistance at 350 C 629N / mm When implementing a so-called stirring shell, due to the weakening of the field, we obtain a stirring action significantly greater than that obtained with the known shells. Dimensional stability

  so is good again after more than 100 casting loads.

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Claims (4)

  1- Process for obtaining shells   continuous tubular, curved casting, the walls of the shell-   which form the inner void space being formed by an explosive material to the geometrical measurements of a matrix, characterized in that, as a starting material, a tube made of a copper alloy capable of undergoing annealing, is used.   tube first undergoes solution annealing at a temperature of   re proper to the alloy, that is to say that the forming of the tube is carried out at the temperature of the solution annealing, the tube having undergone this solution annealing is subjected for at least 15 minutes at an annealing at a temperature of 400 to 6000C, and then the formation is carried out by explosion.   2- Process according to claim 1,   characterized in that between the solution annealing and quench annealing operations, the tube undergoes cold forming.   3- Method according to one of the claims   1 or 2, characterized in that a mandrel is introduced into the tubular shell and that the shell in common with the   mandrel, undergoes the impression of a matrix.   4- Process according to any one of   Claims 1 to 3, characterized in that one uses a   copper alloy with 0.3% to 1.2% chromium and 0.05 to 0.2% of zirconium.