SU725788A1 - Method of continuous casting of aluminium alloy ingots - Google Patents

Description

The invention relates to metallurgy and is intended to produce ingots from cast and deformable aluminum alloys. A method for continuous casting ingots is known, which includes the introduction of aluminum bars containing modifiers 1 into the melt. A disadvantage of the known method for continuous casting ingots is that the melt is contaminated with oxides from the surface of the rod. Oxide-insoluble inclusions in the alloy are entrained by the melt stream and enter the ingot, causing defects in the form of discontinuities in the semifinished products. In order to eliminate this drawback, a layer of liquid flux with a thickness equal to 0.4 to 1.0 of the thickness of the melt layer is induced above the melt layer and with a melting point 5-35 ° C higher than the melting point of the rod, which is continuously introduced into the melt through a layer of liquid flux with a speed selected from the relation: V. where h is the total height of the layers of the melt and flux, mm; d is the diameter of the rod; mm; 1.5 - dimensional coefficient, mm / sec. The temperature range of 5-35 ° C is selected from the condition that the casting temperature of most aluminum wrought alloys is 700 ° C, and the melting point of aluminum alloy alloys is 665 ° C. The melting point of the flux should be below the casting temperature of the alloy. When a solid rod is passed through a layer of liquid flux, the flux solidifies as a crust on the surface of the rod. Heating is up to the melting temperature, the rod together with the flux crust melts in the aluminum alloy layer, and the flux melts somewhat later than the rod, due to its higher melting temperature and lower heat capacity than that of the rod material. The melting of the rod can occur both in the flux layer and in the aluminum melt layer. The melting rod is mixed with the aluminum melt.

and the liquid flux, the density of which (1.5 g / cm) of Menbshe aluminum molten density (2.35 g / cm) floats up, carries along particles of oxide film. Liquid flush freezer wets alumina particles than liquid aluminum. The surface tension at the boundary of the flustaz is 80-150 erg / cm and EOO erg / cm, respectively.

A higher melting point for the flux than for an aluminum bar prevents premature separation of the flux from noBepJiHOCTH elite solid bar; the rod should melt first and flow out from under the crust of the flux frozen on it, or, in extreme cases, the melting of the flux and the rod should occur simultaneously. At the specified ratio of the heights of the layer of the liquid flux and the liquid alloy, a crust of flux with a thickness of about 15-40 / o from the diameter of the rod is formed on the rod. This amount of frozen flux is sufficient to reliably float the particles of oxide a lumini. This also contributes to the correct choice of the ratio between the feed rate of the rod, its diameter and the total height of the layer of liquid flux and alloy. When a bar is fed, it does not have time to freeze the required thickness of the flux layer, and the bar itself may not melt. With a slow feed, the rod will melt in the layer of liquid flux, which does not cause undesirable effects.

Example. Testing of the proposed method was carried out on a deformable aluminum alloy D 16. A layer of liquid flux 80 mm high was induced above a layer of melts with a height of 100 mm. The melt temperature is 700 ° C, the melting point of the flux based on NaCl, KCl, NasAlFe salts is 670 ° C. In the melt D 16, through a layer of liquid flux, a rod with a diameter of 8 mm from the alloy AI-2, Ti was introduced. The bar entry speed was V 1.5 (1004-80): 8 33.75 mm / s.

On the rod, a crust of flux thickness of 1-3 mm thickened. The selected bar input mode led to a uniform distribution of titanium throughout the entire flow of the melt and reliable separation of oxide captives from it.

The table shows the results of testing the proposed method for casting ingots from alloy D16, depending on the mode of bar insertion into the melt.

The study of technological samples from the ingot showed that the alloy contamination decreased by 4 times (from 0.08 to 0.02), and the number of defects in semi-finished sheet products was reduced by 1.8 times. Marriage of semi-finished products from the above defects decreased by 22.4 / o.

If it is necessary to introduce such an amount of modifier into the alloy, which is associated with an increase in the bar insertion rate above the limiting one, then 2.3 ... bars should be simultaneously introduced, correspondingly reducing the insertion rate as many times as compared to a single bar.

690

100

50

100

670,100

670,100

80 100

56 32.5

0.5

0.01

0.6 0.03 0.4 0.02 33.75 19

0.6 0.08

Claims (1)

Claims. The method of continuous casting of ingots from aluminum alloys, including the input of an aluminum bar containing modifiers into the melt, characterized in that, in order to improve the quality of the ingots, a layer of liquid flux with a thickness of 0.4-1.0 thick is applied over the melt layer , and with a melting point above the melting point of the rod, which is continuously introduced into the melt through a layer of liquid flux at a rate selected from the relationship: V, where h is the total height of the melt layers and flux, mm; d is the diameter of the rod, mm; 1.5 - dimensional coefficient, mm / sec. Sources of information taken into account in the examination 1. US patent number 3605075, cl. 75-135,1969