SU1388435A1 - Method and apparatus for modifying high-duty cast iron with vermicular graphite - Google Patents

Abstract

The invention relates to metallurgy and foundry production and can be used to obtain high-strength iron with vermicular graphite operating under thermal shock conditions, for example, chill tooling, engine parts and heat treatment furnaces. The purpose of the invention is to increase the stability of the modification, the quality of the cast iron, the extrusion reliability under conditions of heat-treated with heating up to 350-550 ° C and increase the stability of the modification by more complete dissolution of the modifier and melt homogenization. The method of modifying high-strength iron with vermicular graphite includes the primary modification by graphitizing ligatures, which sit down on the bottom of the ladle before pouring the melt, stand in the ladle, download slag, and secondary modify by mechanical mixtures. In the case of primary modification, homogenizing additives in an amount of 0.2-3.0% by weight of metal are introduced into the melt together with ligatures, and the secondary modification is carried out in a homogenization chamber of the mold with spiroidizing additives mixed with fluorspar. An apparatus for carrying out the method for modifying high-strength iron with vermicular graphite includes a runner bowl, a reaction chamber, an inlet and an outlet stand, runner channels and a stopper. The device additionally contains a homogenization chamber j separated from the reaction chamber by a partition with separate gating channels provided with a movable gate, the height of the homogenization chamber being 2-6 heights of the reaction chamber, and the cross-sectional area of the outlet outlet gating section. 2 sec. f-ly, 1 ill., 2 tab. "(L from 00 00 4:00 ate

Description

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11: 5 The invention relates to metallurgy and casting production and can be used to obtain high-strength cast iron with vermicular grains (operating under conditions of thermal shock, such as chill tooling, engine parts and heat-treating furnaces).

The purpose of the invention is to reduce the stability of the modification, the quality of the pig iron, the operational reliability under heat exchange conditions with heating to 350-550 ° C and increase the stability of the modification by more complete dissolution of the modifier and homogenization of the melt.

The drawing shows the scheme of the proposed device.

The device includes a gating chute 1, an input hundred to 2, a gating channel 3, a reaction chamber 4, a stopper 5, an output hundred to 6, an external gating channels 7, a homogenizing chamber 8, a partition 9, a mobile partition 10. The output hundred k 6 is associated with a mold cavity (not shown). The device is made of molding sands. The partition 9 and the sub- V1t.nush gate 10 are made of fire-resistant materials.

The device works in the following way.

The melt, which underwent primary modification by graphitizing ligatures and homogenized with additives, is poured from the casting ladle (not shown) into the runner bowl 1, from where it passes through the input hundred to 2 and the runner channel 3 to the cavity. pre-placed spheroidizing additives mixed with fluorspar. The melt, the passage above the modifier, dissolves it and, through the outlet gating channels 7 of the partition 9, enters the homogenization chamber 8. The movable shutter 10 is initially set so that its top

the holes coincided with the top of the first

Esanapa 7 partition 9 (as shown in the drawing). In this case, the modified melt enters the homogenization chamber through the upper septum. As the modifier dissolves and the level of the melt melts to the top of the second channel 7, the single shutter 10 is lowered and the upper channel gradually opens, 5

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VA at the same time riTopon, and propelling; - gots modifitspropy ppl; pch into the homogenization chamber. As the modifier modifier dissolves, the mobile shutter is lowered onto another channel, etc. until the completion of the modification process, ensuring that the MBLM layer-by-layer uniform dissolution of the modifier. The number of channels and the distance between them is selected depending on the size of the reaction chamber, the type and fraction of the modifier with the calculation of its complete dissolution. The melt entering the homogenization chamber is bent, averaged over the composition, non-metallic inclusions emerge. After the homogenization chamber is filled, the stopper 5 is taken out and the metal of the output one hundred to six enters the cavity of the mold. The modification process continues until the modifier is completely consumed and the mold is filled.

When the height of the homogenization chamber is less than 2 the height of the reaction chamber, the composition averaging and melt homogenization are insufficient, and as its height increases more than 6 times, the casting properties of cast iron and the stability of its composition and properties are found.

The cross-sectional area of the outlet stack is 0.7-1.0 the cross-sectional area of the discharge runner channel. With such a ratio of cross-sectional areas, which are determined experimentally, optimal conditions are created for homogenizing, mixing, and improving the quality of the iron in the castings. When the ratio is less than 0.7, the modifying effect and the operational durability of castings are reduced, and at a ratio of more than 1.0, the stability of the quality of the modified cast iron and the structure of the cast iron in

A method of modifying high-strength cast iron with vermicular graphite is tested according to a known process and proposed. Apply an eutectic composition cast iron, produced by duplex-pro, essom: coke-gas cupola - induction mixer. The melt in the ladle is modified with ligatures containing REM (FS ZORMZ) and homogenizing additives of quotted silicon carbica, in an amount of 0.2-3% by weight of the metal.

In tab. Table 1 lists the amounts of additives used in primary and secondary modification, the chemical compositions of modified iron, and the characteristics of the stability of the modification of pig iron and its contamination with non-metallic inclusions.

In the implementation of the proposed method, nitrided silicon carbide containing 3.5 wt.% Of nitrogen is used as homogenizing additives.

In tab. Figure 2 shows data on the mechanical and operational properties of cast irons in castings depending on the amount of the homogenizing additive in the ladle and the change in the design parameters of the reaction-homogenizing device for secondary modification with a mixture of spheroidizing magnesium-containing (9.8% magnesium) additives and fluorspar.

As can be seen from the table. 1 and 2, the proposed method for modifying pig iron provides higher stability of the modifying, quality of cast iron and high operational durability under heat exchange conditions than the basic method of modifying high strength iron with vermicular graphite.

The application of the proposed method for obtaining high-strength iron with vermicular graphite ensures an increase in the efficiency of the modification, the qualities of the iron, which makes it possible to reduce the consumption of modifiers and ligatures by 20-45%.

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Claims (2)

1. Method for modifying high-strength iron with vermicular graphite, including primary modification by graphitizing 1-1 ligatures, sitting down on the bottom of the ladle before pouring the melt, holding the ladle, downloading slag, and secondary modifying mixtures that are different in order to increase stability modifying, casting 5, and cast iron and operational reliability in conditions of heat shifts with heating up to 350–550 ° C; during the initial modifying, homogenizing additives are added to the melt ve 0.2-3.0% by weight of metal and the secondary modification is carried out before the mold spheronized additives mixed with fluorspar. 2. A device for modifying high-strength iron with vermicular graphite, containing a runner bowl, a reaction chamber, an inlet and an outlet stand, runner channels and a stopper, characterized in that, in order to improve the quality of cast iron and increase the modifying stability by more fully dissolving the modifier and melt homogenization, it additionally contains a homogenization chamber, separated from the reaction chamber by a partition with outlet gates, provided with a movable gate, with the height g mogenizatsionnoy camera 2-6 is the height of the reaction chamber, and outlet cross-sectional area of the riser - 0.7-1.0 vshusknogo cross sectional area of the sprue. table 2 7O at  five