SU1294545A1 - Electrode coating composition - Google Patents

Abstract

The invention relates to the field of welding, in particular, to the compositions of electrode coatings for welding in various spatial positions of economically insulated corrosion resistant steels. The aim of the invention is to increase the corrosion resistance of the weld metal and the productivity of welding by increasing the depth of penetration. The arc melting capacity during electrode welding increases as a result of the introduction of magnesium fluoride and manganese chloride in the coating composition. Resistance to corrosion cracking of the weld metal is achieved by introducing chromium into the coating. Dp providing the ability to conduct welding in a vertical position and at the non-rotary joints of pipes in the gas-packing system of the coating includes the following e components: marble, fluorspar, titanium dioxide, soda, coal tar pitch. Ferrosilicon and mica are introduced into the coating to improve the plasticity of the coating under the conditions of the crimping of the electrodes. 2 tab. (Ls

Description

112945

The invention relates to the field of welding, in particular, to compositions of electrode coatings for welding in various spatial positions of eco-alloyed corrosion-resistant 5 steels.

The aim of the invention was to increase the corrosion resistance of the weld metal and welding performance over

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by increasing the depth of burning.

Magnesium fluoride and manganese chloride impart to the electrode coating the property of increasing the melting ability and the achievement of v welds with the required resistance to stress corrosion cracking. It can be assumed that the joint management of these components favorably affects the electrophysical properties of the arc gap (which drastically increases the specific pressure of the arc column), which allows increasing the depth of penetration. At the same time, a balanced content of chromium in the coating causes the ratio of basic structural metals similar to the base metal to form. composition of yur x (austenite and ferrite), which achieves increased resistance to stress corrosion cracking.

At the same time, an increase in the penetration depth for a given composition of the electrode coating occurs at lower values of heat input, which also positively manifests itself in maintaining ductility at the heat-affected welded joint due to reduced heat input, reduced y-S conversion, and reduced growth of the ferritic grain. In addition, increasing the penetration depth significantly improves the performance of the manual welding process, as it significantly reduces the need for cutting welded

edges.

I

Known components (such as marble, fluorspar, titanium dioxide, soda, coal tar pitch) are contained in the coating to create the necessary gas and slag phases, as well as to enable the welding to be carried out in a vertical position and at the non-rotating pipe joints.

Ferrosilicon and mica are contained in the coating to improve the forming ability of slag and to achieve higher

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of the plasticity of the coating on the conditions of the electrodes. The boundaries of these components are widely known from the practice of manufacturing electrodes. Like these components, chromium is also a known ingredient and is introduced into the coating to improve the overall corrosion resistance of the welded joint. However, its content in the composition of the coating is somewhat modified due to its optimal influence on the structure of the weld metal and, as a result, its properties. The composition of the electrode coating is presented in Table. one.

To quantify the effect on the properties of the seams filled with coated electrodes of this composition, a series of batches are subjected to testing, 13 of which the concentration of magnesium fluoride and manganese chloride is systematically changed from 1 to 12 and 7%, and the content of the remaining ingredients is prescribed either in known limits

or with some changes. I

In all cases, the indicated electrode coatings are applied to the rods (0– 3-4 mm) of the most common ecoo-alloyed wire, EV-06X21N7BT (EP-500); the weight ratio of the coating is prescribed to 0.4; preparation of the formulation and pressure testing of the coating is carried out according to the usual technology; as a binder using ordinary sodium glass; the coating components are ordinary (standard) powdered electrode materials. Welding is performed on the same modes with constant heat input.

Samples are sheet plates of 200 150 10 mm in size from steel grades KO-3 and EP-53. The tendency of the weld metal and corrosion cracking is judged by the results of standard tests - in a 42% solution of magnesium chloride. The depth of penetration is assessed metallographically. The resistance of welds against intercrystalline corrosion is revealed by tests in copper sulphate solution (AM method). The processability of the coatings is determined on the basis of a conventional 3-point scale.

Presented in table. 2 the results of the experiments showed that rdzde.chns with- an introduction to the comp. pg-

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magnesium fluoride and manganese chloride does not introduce noticeable changes in the increase in the melting capacity; the joint administration of 3% magnesium fluoride and 2% manganese chloride has a similar effect. In case of their joint content, respectively, equal to 5 and 3%, the depth of penetration is increased by 40-50%; moreover, a further increase in the concentration of magnesium fluoride to 10% and manganese chloride to 5% contributes to an increase in the depth of penetration by 80-140%, i.e. increases the melting capacity of the electrodes by about 1.5 times. Further increase in magnesium fluoride and manganese chloride, respectively, over 10 and 5% adversely affects the properties of the coating, as it leads to a decrease in the depth of penetration.

The introduction of chromium into the coating below 5% and above 8% does not allow achieving stable resistance of welds to corrosion cracking and the connection with the formation of a weld metal of the microstructure with a consistent ratio between the main components (austenite and ferrite).

On this basis, the boundaries of the content of magnesium fluoride, manganese chloride, and chromium in the coating should be recognized as 5–10%, 3–5%, and 5–8%, respectively; Coatings with 2-4% ferrosilicon and 0.5-1.0% mica have the best technological properties.

The composition of the electrode coating allows an increase of 40-140%

weld penetration T1 to achieve the required resistance of welds against corrosion cracking (including resistance to intercrystalline corrosion 1). At the same time, this coating is characterized by simplicity in production, does not contain scarce components, and makes it possible to conduct welding in a vertical position and at non-rotary joints of pipes.

Claims (1)

Invention Formula The composition of the electrode coating for welding in different spatial. positions of economically alloyed corrosion-resistant steels, containing marble, magnesium carbonate, fluorspar, chromium, titanium dioxide, coal tar pitch, soda, and with the fact that, in order to increase the corrosion resistance of the weld metal and welding performance by increasing the depth of penetration, the composition additionally contains magnesium fluoride, manganese chloride, ferrosilicon, and mica in the following ratio, wt.%: Magnesium fluoride5-10 Manganese Chloride 3-5 Ferrosilicon2-4 Mica 0.5-1 Soda0.3-0.9 Coal tar 2-6 Magnesium carbonate 3-7 Titanium dioxide4-8 Chrome 5-8 Fluorspar 25-30 MarbleEverything Else I Table 1 No fly Satisfactory table 2 Inclined Continuation of table 2