Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D7/00—Casting ingots, e.g. from ferrous metals
  • B22D7/02—Casting compound ingots of two or more different metals in the molten state, i.e. integrally cast

Definitions

• the present invention relates to the art of metallurgy, and is particularly concerned with methods of producing multi-layer metal ingots.
• Each portion of metal following the first is supplied after the preceding crystallized layer has formed a hard crust of metal contacting the liquid slag layer disposed above it.
• This method provides for using the slag as a means of protecting the poured-in layer (portion) of metal from oxidation and for cooling the metal. This is achieved by using a liquid slag ata temperature which is substantially lower than the melting temperature of the poured-in metal layer.
• the pouring of metal of subsequent layers onto the hard surface of preceding layer covered with cooling slag fails to ensure a high quality of. fusion of the layers along the entire surface of the built-up ingot. Poorest quality of fusion of layers,including interlayers of hard slag inclusions, are characteristic of peripheral areas of the ingot contacting the casting mold side walls.
• Yet another object of the present invention is its economy and efficiency.
• the crystallization of metal of each poured-in layer under the heated slag layer ensures an upwardly directed crystallization of metal of each layer and of the ingot as a whole.
• the maintaining of an interlayer ofliquid metal having a thickness of 0.02 to 0.20 of the layer thickness on the surface of the previously poured in layer covered with heated slag ensures a high quality of fusion of metal of the this layer with the subsequently poured in metal along the entire surface of the ingot.
• the degree of crystallization of the metal layer at the moment of pouring-in the subsequent layer (crystallization of 0.80 to 0.98 of its thickness) which ensures maintaining the interlayer of liquid metal, allows the formation of a fine-grained structure of ingot metal. An insignificant intermixing of adjacent layers takes place which is permissible for metals of a variety of compositions.
• liquid slag temperature it is preferable to maintain the liquid slag temperature by 50 to 300 C higher than the melting temperature of metal layer contacting it.
• This temperature range will ensure the most economical and efficient heating of the metalnecessary for upwardly directed crystallization of ingot layers.
• Such pouring of metal will ensure its distribution over the more cooled, as compared with the central zone, periphery of the ingot which contacts the side walls of the casting mold; enhance the quality of fusion of the layers, and finally, improve the side surface of the ingot.
• the casting mold wall temperature higher than the temperature, comprising 0.3 of the melting temperature of the used slag in the zone of its contact with the heated slag.
• This feature will enhance the degree of upwardly directed crystallization of metal, and also'improve the quality of ingot side surface.
• the slag can be heated during the period of crystallization of the ingotlayer using electric current passed between nonconsumable electrodes immersed therein.
• This feature will ensure a high degree of efficiency of slag preheating and its uniform heating thoughout.
• a liquid metal can be poured having a chemical composition other than the metal of the previously pouredin layer.
• Liquid slag is poured into a casting mold installed on a cooled stool.
• the slag is heated with electric current passed between nonconsumable electrodes immersed therein.
• a first portion of metal is poured through a layer of liquid slag into the mold in order to form the first layer of the ingot.
• the volume of the portion is selected taking into account the layer thickness should be 0.01 to 0.5 of the ingot width (mold bottom portion).
• the nonconsumable electrodes are immersed into the slag which covers the layer of poured metal and the slag is heated in the area of its contact with the poured metal layer by current passing between the nonconsumable electrodes.
• the temperature of the liquid slag is maintained in the region of 50 to 300 C higher than the temperature of metal contacting it.
• the thermal conditions of heating are maintained along the entire surface of contact of slag with the poured metal during the course of the entire period of crystallization of metal of the this layer.
• the temperature of its walls in the area of contact with the slag is maintained higher than the temperature constituting 0.3 of the temperature of melting of the slag used.
• the thickness of the separate layers of ingot is variable within 0.01 to 0.5 of the width of the ingot.
• the metal for the second portion is supplied in a form of a split stream directed onto the surface of the preceding layer contacting the mold side walls at a distance less than 0.25 of the ingot width at the level of this layer.
• the slag which covers the metal is heated to a temperature exceeding the melting temperature of the metal of second layer by 50 to 300 C.
• the second layer of the ingot is crystallized under the layer of slag heated to this temperature until an interlayer of liquid metal is formed on its surface ofa thickness of0.02 to 0.2 of the second layer thickness.
• a next portion is poured, the metal of which can possess a chemical composition differing from that of the metal of preceding layer.
• the method of producing multi-layer metal ingots described is most advantageous for casting ingots having layers of metals having diverse chemical composition, also, for casting large-size high-quality ingots with layers of metals having identical chemical composition.
• the pilot tests perfonned on a six-ton multi-layer ingot have shown that the ingot metal possessed an uniform fine-grained structure with distinct separation of layers, and exhibited high quality fusion of the layers.
• the sheet metal obtained after rolling the ingot possessed good mechanical properties.
• a method of producing multi-layer metal ingots comprising the steps of (a) establishing a heated liquid slag bath in a casting mold; (b) pouring a portion of metal therein which forms a first layer of the ingot; (c) crystallizing said first layer of the ingot under said heated liquid slag contacting it, the temperature of which slag being maintained higher than the metal melting temperature of said layer; (d) pouring a further portion of metal to form a second layer of the ingot, which portion is poured onto a liquid surface of metal on the preceding layer which has substantially crystallized under the liquid slag, said liquid surface of metal forming an interlayer and having a thickness equal to 0.02 to 0.2 of the layer thickness; and (e) repeating steps (b) through (d) to build up a predetermined number of layers.
• portions of liquid metal are selected such as the ratio of the ingot layer thickness to its width is within 0.01 to 0.5.
• portions of liquid metal following the first portion are supplied in the form of a split stream directed onto the liquid surface of preceding layer contacting the side walls of the casting mold at a distance from side walls of less than 0.25 of ingot width.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Continuous Casting (AREA)
• Dental Prosthetics (AREA)

Applications Claiming Priority (3)

Publications (1)

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Family Applications (1)

Country Status (8)

Cited By (6)

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Citations (2)

• 1972
  • 1972-06-06 AT AT485272A patent/AT330380B/de active
  • 1972-06-12 FR FR7221081A patent/FR2141833B1/fr not_active Expired
  • 1972-06-15 IT IT50930/72A patent/IT965832B/it active
  • 1972-06-15 US US00263096A patent/US3807485A/en not_active Expired - Lifetime
  • 1972-06-15 SE SE7207919A patent/SE384640B/xx unknown
  • 1972-06-15 DE DE19722229299 patent/DE2229299A1/de active Pending
  • 1972-06-15 DD DD163727A patent/DD98462A1/xx unknown
  • 1972-06-16 GB GB2836572A patent/GB1375067A/en not_active Expired

Patent Citations (2)

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