CS263236B1 - Electrode basic coat for welding non- and low-alloyed steels by direct or alternating current - Google Patents

Abstract

The aim of the solution is a suitable basic composition packaging materials of electrodes for welding unalloyed and low alloy steels and direct current at the same time high quality welded indicators metal, productivity and labor economics. Electrode cover while keeping all content decisive components of the hitherto known packaging, especially fluorides, by the addition of readily ionizing components, namely metal powders in the sum of their contents from 1 to 37% by weight, with at least half of them it forms a magnesium, a ferritite, in proportion to it to the sum of the other desoxidation contents The ingredients are 0.3 to 1 in 1 and volboy other pure slag-forming substances allow welding alternating current and direct current.

Description

It is an object of the present invention to provide a basic electrode sheath composition that provides manual arc welding of non-alloy and low-alloy steels by alternating current.

The welding electrode casing intended for welding these steels is generally molded into unalloyed or low-alloy steel wire and therefore has a decisive influence on the welding properties of the electrodes and the properties of the weld metal obtained by melting them. The achievement of their highest level is possible from the existing known packaging with a basic packaging. These containers contain mainly alkaline earth carbonates, such as calcium carbonate, magnesium carbonate. less often barium or strontium, and mixtures thereof, and generally calcium fluoride, the raw materials used usually in the form of minerals, provide not only the basic character of the slag but also the ability to form solid chemical bonds with impurities, e.g. phosphorus and sulfur, a strong refining effect of the basic coatings and the resulting slags arises. At the same time, decomposition of carbonates during welding produces carbon dioxide, intensively protecting the molten droplets of the weld metal from the undesirable effects of the air atmosphere. The reduction of the melting point of the formed alkali metal oxides and the formation of slag of optimum viscosity is ensured primarily by calcium fluoride, usually used in the form of mineral - fluorspar. The presence of calcium fluoride, sometimes additionally enhanced by the addition of other fluorine-containing compounds, such as aluminum, sodium, barium or trisodium hexafluoroaluminate or disodium hexafluorosilicate, etc., allows the formation of gaseous compounds with hydrogen and thus most desirable reduction of its content in the weld metal. In addition, the basic coating comprises, over a wide range, the optional content and form of the deoxidizing components, guaranteeing a low content of oxygen and oxidic inclusions in the weld metal. Such containers may also contain other slag-forming components, such as rutile, kaolin, or metal - to increase yield, iron powder or lower levels of alloying metal powders and their alloys, e.g. of manganese, chromium, nickel or ferro-manganese, ferro-silicon, ferro-chromium, ferro-molybdenum, feroniob, etc.

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A serious disadvantage of electrodes with basic sheaths, which always contain indispensable fluorides in varying amounts, is the reduced or eliminated possibility of their use for alternating current welding. The highly electronegative fluorine anion removes free electrons from the ionized arc, thereby significantly reducing the conductivity of the arc column. As a rule, arc ignition is difficult, and re-ignition, corresponding to the AC frequency, and thus process stability is virtually impossible.

Existing ways of solution consisted in seeking external assistance measures, eg. in the construction of high-voltage open-source welding power sources and hence increased ionisation capability, but with a high accident risk. Another possibility was the installation of high-frequency ionizers, which enrich the arc space with ions. In the field of packaging composition modifications, the fluoride content, which is one of the basic components, has been reduced, thus impairing its functional effects. A more common method was to use electrodes with other, less valuable, packaging.

The invention solves the composition of the electrode sheath, which, while retaining the basic character, can be used primarily for alternating but also direct current welding. The new effect, ie the usability of AC welding electrodes while maintaining all the useful properties of the basic electrodes, was achieved by the addition of easily oxidizable components, namely metal powders with an ionization potential of less than 7.8 V, eg magnesium, aluminum or calcium combined content of 1.0 to 3.0% by weight, the magnesium being at least half of this content and the addition of titanium in the form of ferrotitanium. Ferrotitanium is a constituent of desoxidizing components, which in the package according to the invention must be between 8 and 16% by weight, the ratio of the ferrotitanium content to the sum of the other desoxidizing content being 0.3 to 1 to 1.

The electrode sheath according to the invention must further comprise 22 to 35 wt. alkaline earth carbonates, such as calcium carbonate, magnesium carbonate or barium carbonate alone or in a mixture at any ratio,

283 238, which may be in the form of naturally occurring minerals or in the form of chemical compounds, 18 to 25 95 wt. fluoride such as calcium fluoride in the form of mineral or a chemical compound, optionally aluminum fluoride, barium fluoride, sodium fluoride, trisodium hexafluoroaluminate or disodium haxefluorosilicate alone or in a mixture in any ratio.

In addition, the electrode sheath must contain slag-forming inorganic substances individually or in a mixture without limiting their ratio in the sum of their contents of 9 to 16% by weight, eg natural rutile, kaolin, feldspar, mica, natural or synthetic calcium silicate (wolastonite) or titanium silicate / perowskit /. In order to ensure good compressibility of the packaging material, the packaging material must also contain, individually or in a mixture, plasticizers of an inorganic or organic nature individually or in a mixture in the sum of their contents of 0.5 to 10 95% by weight, for example talc, bentonite, potassium silicate, cellulose derivatives; alginates. To increase the yield of the weld metal, the coating comprises iron powder in a volume of from 10 to 40 wt%.

To modify the chemical composition of the weld metal, the wrapper, individually or in a mixture, may contain alloying additives in a total of 0.5 to 10 95 wt%, e.g. chromium or ferrochromium, nickel, ferromolybdenum, feroniob or ferovanad;

The composition of the packaging material according to the invention has been verified on several electrode portions. For example, a coating of electrodes having the following composition: calcium carbonate 27% by weight, magnesium carbonate 3 95% by weight, calcium fluoride 18% by weight, aluminum fluoride 2% by weight, sodium fluoride 1% by weight, ferrosilicon 6% by weight · , ferromangan 2 95 wt., ferrotitanium 4 95 wt., magnesium 1.5 95 wt., aluminum 0.5 95 wt., natural rutile 3 wt.%, kaolin 5 95 wt., synthetic calcium silicate 2 95 wt. ferro chromium 3 95 wt., ferro molybdenum 1, 5 95 wt., nickel metal 1 95 wt., iron powder 8 95 wt., bentonite 1 wt. and car boxyme tulle cellulose 0.5 $ haot. This coating was pressed to unalloyed wire after kneading with potassium waterglass. The welding properties of the electrodes prepared in this way were verified by AC welding on the welding transformer WT 315 and subsequently on the DC source4.

283 238 direct current - rectifiers WTU 315 * 8 and in both cases proved to be satisfactory results of properties that are influenced by the type of welding current ie mainly ignition and re-ignition of the arc, continuity of electrode burning, bead shape and drawing, appearance, physical properties and removability. slags. Such properties of the weld metal expressed by its chemical composition by weight - C 0.078 & Mn 0.82%, Si 0.51 95,

P 0.022 95, S 0.017 95, Cr 1.35 95, Ni 0.50 95 and Mo 0.58 95 corresponded to the required values.

For electrodes intended for welding of non-alloy steel, the following packaging has been prepared: calcium carbonate / limestone / 26.5 wt., Calcium fluoride / fluorspar / 21.4 95 wt., Trisodium hexafluoroaluminate 2.5 95 wt., Ferro-silicon 4 , 5 95 wt.%, Feromangan 1.8 95 wt.%, Ferrotitanium 5.7 wt.%, Magnesium 1.8 wt.%, Kaolin 5.0 $ wt., Natural rutile 3.9 T wt., Carboxymethylcellulose 0, 6 95 wt.%, Iron powder 26.3 95 wt. Electrodes verified by alternating and direct current welding were pressed from this container, connected with potassium water glass. The welding and performance properties of the electrodes as well as the properties of the weld metal and the weld joint obtained by melting them complied with the requirements. The chemical composition, including gas content, mechanical properties over the entire operating temperature range, integrity and cold crack resistance, were examined, and all results were found to be fully satisfactory. they meet the technical requirements provided by the known electrode sheaths known to date, and the differences in the values obtained by AC and DC welding are irrelevant.

It is evident from the examples that the novel effect of the basic electrode sheath according to the invention lies in the possibility of their use for alternating current welding in general and at achieving comparable complex performance properties of electrodes and weld metal obtained by melting them in direct current welding. electrodes with basic packaging.

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The electrodes with a coating according to the invention can be used for welding products of non-alloy and low-alloy steels, eg structures, vehicle components and transport equipment not subject to special regulations, are intended for metalwork, repairs and the like.

Claims (2)

A basic electrode sheath for welding non-alloy and low alloy steels with alternating and direct current, comprising from 22 to 35% by weight. % alkaline earth carbonates, e.g. calcium carbonate, magnesium carbonate, optionally strontium carbonate, or barium carbonate alone or in a mixture in any proportion, in the form of natural minerals or in the form of chemical compounds, from 18 to 25 wt. % of fluorides, e.g. calcium fluoride in the form of a mineral or chemical compound, optionally aluminum fluoride, barium fluoride, sodium fluoride, trisodium hexafluoride or disodium hexafluorosilicate alone or in a mixture in any ratio, from 9 to 16 wt. alone or in a mixture in any ratio of slag-forming components, e.g. % natural rutile, kaolin, feldspar, mica, natural or synthetic calcium silicate, or natural or synthetic titanium silicate, alone or in a mixture of from 8 to 16 wt. desoxidizing components, e.g. % ferromangan, ferro-silicon and ferrotitanium, from 0.5 to 10 wt. alone or in a mixture in any ratio of plasticizing components of an inorganic or organic nature, e.g. talc, bentonite, potassium silicate or cellulose derivatives or alginates, from 10 to 40 wt. characterized in that the ratio of the ferrotitanium content to the sum of the other desoxidizing components is 0.3 to 1 to 1 and the content is 1.0 to 3.0% by weight. One or more metal elements having an ionization potential of less than 7.8V in the form of powders, e.g. magnesium, calcium, aluminum, the magnesium being at least half of the total content of these components. 2. The basic electrode coating for welding according to claim 1, characterized in that it comprises from 0.5 to 10 wt. alloying additives in the form of metal powders or ferro-alloys individually or in a mixture.