SU923738A1 - Method of refining alloy in casting mould - Google Patents

Description

The invention relates to foundry and can be applied in the production of steel and iron castings.

Known technical solutions aimed at cleaning the metal in the process of pouring it into the mold.

On the path of movement of the metal in the form, a filter rod is installed, consisting of 13 several disks made of natural mica, or provide for the installation of a molybdenum screen in the sprue system (P.

The mentioned solutions help to clean the metal from large inclusions, mainly of slag origin, due to purely mechanical filtration. At the same time, non-metallic inclusions (deoxidation products) remain in the metal, their removal is extremely insignificant.

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In addition, the use of natural mica and molybdenum as a material for the screen is limited: in the first case, the temperature. a swarm of melt, in the second - the presence of iron in the alloy, which promotes the dissolution of molybdenum.

The closest in technical essence to the proposed is

¹⁰ method of cleaning metal, which involves covering the molybdenum mesh with a refractory material consisting of adund (80%) and silicate (20%). Metal smelting and refining

¹⁵ carried out according to the adopted technology. The filter mesh (screen) is installed in the. gating system on the path of movement of the metal in the form. The presence of the coating on the grid allows you to apply it when casting iron-based alloys. However, in this case, the removal of inclusions occurs mainly due to mechanical filtration and

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the size of removable inclusions is governed by the size of the cells on the screen [2]

The disadvantage of this method is the impossibility of removing small inclusions formed in the metal during the refining melting period, i.e. metal cleaning is achieved to a small extent. In addition, the known method does not solve the problem of removing inclusions of different origin, formed on the basis of either acidic oxides or basic oxides, i.e. there is no selective cleaning of the metal.

The purpose of the invention is to improve the quality of metal alloys due to the reduction in them of non-metallic inclusions.

This chain is achieved by

> (then in the method of refining an alloy in a casting form, mainly iron-based, including deoxidation of the alloy, installing a mesh filter made of acidic oxides and alloy casting in the casting system of the casting system, an additional filter based mesh is additionally installed in the gating system basic oxides.

Moreover, as the material for the mesh filter of acidic oxides using silicon dioxide.

In addition, as the material for the mesh filter of the basic oxides, use calcium oxide or magnesium oxide.

The method is as follows.

In the gating system of the form, two screens are installed, one of which is covered with a material based on 5ΐ0 ^. and the second is based on MDO, CaO.

The metal intended for pouring is melted according to the adopted technology, deoxidizing it depending on the chemical composition of the melt by one or another component (titanium, aluminum, silicon-containing deoxidizers, etc.). The deoxidizing products (remaining in the melt) are inclusions of various nature (based on acidic or basic oxides) and size. For example, when chromic acid and chromium-nickel-manganese steels are deoxidized only with silicon, large inclusions containing silicon oxide are formed in the metal. If calcium is present in calcium detectors, calcium compounds are included in nonmetallic inclusions. The resulting metal times40

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molded according to the adopted technology in a mold with screens installed in it.

In addition to metal purification due to purely mechanical filtration, additional selective refining occurs due to the interaction of substances of different nature. For example, screen material based on basic oxides and non-metallic inclusions of acid oxides or vice versa.

The role of physicochemical processes in metal filtration is different and depends on the basic material of the filter. The influence of their (physicochemical processes) is also associated with the specific chemical composition of the inclusions, the temperature regime of the fill. Taking into account these factors allows you to choose the right filtering mesh material depending on the presence of certain inclusions in the metal, depending on the technology of the metal melting

Example. For the experiment, steel 1X18H9 is taken. The metal is deoxidized in the ladle with silicon and then with aluminum.

For the manufacture of prototypes, three forms are prepared, in the gating system of which two filter grids are installed on the basis of acidic and basic oxides in the following variants.

Option ’Mesh Filter I Sour + Sour

 TT Main + main

III sour + basic

at a distance of 100 mm from each other.

An acidic mesh filter is obtained by impregnating a KS-11-LA silica fabric with a 1.6x 1.6 cell with a 10% solution of polymethylsiloxane resin (PMS) in acetone (the mesh material has an acidic character — 5ΐ0 ^).

The main draw filter prepared by impregnating the same tissue suspension% PMS resin 10 + acetone 55 + powder (filler) of fused magnesite (MgO or CaO) 35Posle provisional 3 ^_ hour air drying the impregnated mesh filters their rolled for 0, 5 h at 300 ° C. The sour metal is poured into three forms with grids of the indicated variants.

The results of cleaning

metal from non-metallic inclusions are given in the table.

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Option Average score for inclusions Oxides | Sulphides | Silicates | Globulin | Carbonitrides Source metal 0.85 0.6 1 L5 1.05 4.9 I • 0.70 0.6 1.2 0.9 4.9 eleven 0.70 0.5 0.8 0.8 4.8 III 0.65 0.50 0.8 0.75 4.8

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As follows from the table, the best cleaning of the metal occurs during the installation of grids for option III, i.e. when installing an acidic and basic filter that provides the best physico-chemical ’melt cleaning conditions from inclusions of different nature.

Feasibility or other efficiency is the best cleaning of the metal by the proposed method as compared with the prototype, and compared with other cleaning options. The purest metal (from non-metallic inclusions) has the best mechanical, technological (ductility, weldability, etc.) and operational properties.

The advantage of the proposed method is that when using a physicochemical mechanism for cleaning metal from inclusions, it is possible to conduct metal smelting, creating deacidification products of one given nature in it, for example, smelting chromium nickel-manganese steel with deoxidation only with silicon-containing components, and filtering it when pouring into form only through the main filters.

In other words, the process of smelting metal and its casting is considered in the complex of smelting-casting. At the same time, the costs in the process of smelting metal can be reduced due to

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predetermined deoxidation mode, reduced deoxidation period with additional cleaning (selective cleaning) when pouring metal into the mold.

Claims (3)

Claim 1. A method of refining an alloy in a casting form, mainly iron-based, including the deoxidation of the alloy, installing a mesh filter from a material based on acidic oxides in the gating system of the casting mold, and pouring the alloy into qualities, in the gating system, an additional second filter grid based on basic oxides is installed. 2. The method according to p. ^ Characterized in that as the material for the mesh filter of acidic oxides using silicon dioxide. 3. The way pop. ^ characterized in that as a material for. basic oxide filter meshes use calcium oxide or magnesium oxide.