DE2228280C3 - Method for electroslag casting of ingots - Google Patents

Description

of a furnace, and the weight of each melt is less than the weight of the ingot.

When filling the block form with steel, the electrodes are moved upwards, in each case a current in a range of 10 to 20 thousand amperes is maintained across the electrodes.

After 4 to 5 hours (the time it takes to obtain the next melt in the electric arc furnace is required), is in the block form over the slag on the liquid surface of the previous one Portion that has solidified by more than half, the second metal portion weighing about 10 t is poured. Servings of this size are taken 19 to 20 times until the prescribed blood pressure is reached of 190 t poured in repeatedly.

Between the individual pouring processes, an electrical operating state is established in the block form maintained, which ensures the liquid state of the metal on the block mold walls. this will by arranging the electrodes on the block mold walls, by increasing their number and supported by rotating the block shape about its longitudinal axis through an angle of 30 to 120 ". After the last metal portion has been poured in, the electricity supplied to the slag bath becomes electrical Performance gradually decreased, with the electrodes ensuring the metal bath solidification without forming a shrinkage cavity to the block mold axis be moved.

The method described here for electroslag pouring of blocks is particularly suitable

for the production of large, high-quality forging blocks weighing over 40 t and up to 200 to 300 t, as it is particularly suitable for the construction of rotors of turbines with a power over one million megawatts are required.

ίο The high quality of what is obtained after this procedure Large ingot is not only made by electroslag treatment of the steel in the ingot shape and achieved by its directional solidification, but also by the fact that this block consists of a

•• 3 steel of an electric arc furnace can be produced, d. H. from a (according to the content of sulfur, Oxygen and non-metallic inclusions) purer steel than Siemens-Martin steel, from which large forging blocks are currently

be poured in this way. The metal can before pouring in the block form subjected to treatment by synthetic slags and with inert gases be blown through.

In a kinematic reversal of the described

»5 the electrode holder can also move around the The longitudinal axis of the block form can be reversibly rotated, the latter remaining immobile.

Claims (2)

more than half of the metal of the preceding claims: portion is solidified, that these portions amount to 5 to 25 percent by weight of the block weight, that the 1. Method of electroslag casting of electrodes when casting on the perimeter of the block mold on blocks by adding 5 in portions and after pouring the last metal-liquid metal into a mold in which previously eir. portion in the block shape to the central part of the Slag bath is generated and preferably attached to the horizontal metal bath surface of the block by means of electrodes non-consumable electrodes. supplied stream is heated, thereby the block shape is advantageously characterized with the fact that each of the first io casting blocks rotated around their longitudinal axis by a portion of the subsequent portion of liquid metal angle that is 30 to 120 ^: on the surface of the liquid Metal that is passed through the inventive dimensioning of the casting preceding portion as soon as portions and their addition in dependence more than half of the metal from the previous solidification process and the different portion has solidified. that these portions 5 to 15 borrowed arrangement of the electrodes in the course of 25 percent by weight, the block weight, casting process and at the end of the casting process that the electrodes when pouring on the block mold is arranged in the block head into the formation of a circumference and after pouring the last - Uniform structure ensured, with th metal portion in the block shape at the zen a rotation of the block shape alternately in the central part of the horizontal metal bath surface 20 one and the other direction are approximated by an angle of the block. from 30 to 120 ^: a more uniform temperature 2. The method according to claim 1, thereby achieved distribution along the circumference of the mold indicates that the block shape becomes with that in it. to be cast block around its longitudinal axis The invention is now based on an execution an angle is reversibly rotated, the 30 to 25 example, which allows the production of large forging 120 is. blocks concerns, explained in more detail. In the production of large forging blocks e.g. of 190t weight is a water-cooled one Block form of about 2500 mm diameter and 30 5000 mm height used, which is on a water- The invention relates to a method for refrigerated saucer is set up on which Electro-slag pouring of blocks through portions - previously a steel start-up washer is placed, wise supply of liquid metal in one whose chemical composition is that of the Mold in which a slag bath is previously created and which comes as close as possible to the casting blocks. In the by means of electrodes, preferably not melted off- 35 block form, for example, six Graphitelek- the electrodes, supplied current is heated. trod to touch their lower ends with From the applicant's DT-AS 12 80 506, one of the approach discs is introduced. The diameter Method of casting metal blocks in which each electrode is 200 to 400 mm. The number the metal after the liner slag casting process in the electrodes is expediently divisible by three the ingot mold is cast, known that it is chosen as a result and by eiu «.» "Three-phase alternating current is characterized by the fact that slag is fed before the source is poured. liquid metal by means of current-carrying electrodes The electrodes are evenly placed around the circumference by virtue of their electrical resistance directly to the block shape cross-section at intervals of approximately melted in the mold and the metal was deposited 100 to 300 mm from the block mold walls. the solidification heated by the same electrode 45 assigns. In the block form is a slag that or is fed in. For casting blocks, which has a high refinability, or a The length is 2 to 3 times larger than its diameter, a mixture of the generic constituents of such a species is, it is proposed there that the liquid metal is poured into slag. Each pair of electrodes is pour two, three or more operations, where- voltage of the order of 50 to 90 volts at after each pouring an electric 50 from a three-phase transformer or from slag feed or heating of the three single-phase transformers and the cast block part follows to melt even with large slag. This forms in the Block length a structure without axial errors. Block shape a layer of liquid slag - that keep. Slag bath - and the electroslag begins The invention is based on the object of a 55 process of heating this bath. In processes for electro-electrophoretic casting of blocks, the block shape can also be poured into a specially melted slag that is liquid by adding liquid metal in portions. Then it is stated in a mold that in blocks of any block shape the first steel portion of 10 t weight dimensions is poured into the block head, which was previously melted in an arc steel wall-free structure, 60 melting furnace . Here, if _e is due to insufficient capacity of the melting furnace in the block form a metal layer of about the batches for the individual portions in succession 250 mm thickness (0.1 of the block diameter)
that need to be melted. Each subset following the first serving This is done in a process that initially applies the liquid metal to the liquid surface mentioned type achieved according to the invention in that 65 of the previous portion passed if more than Each portion following the first portion has solidified half of it. These portions are sigen metal on the surface of the liquid metal carry from 5 to 25 percent by weight of the block the previous serving is directed as soon as weight. They make successive melts