Submerged arc welding iron and steel has the following features. The original metal core and the electrode, usually differs sufficiently clean and satisfactory chemical composition. In the process of welding mild steel the most heavily burned and vaporized manganese; weld metal is oxidized to form iron oxide FeO. Therefore, the flux must be well and played havoc with the electrode wire to replenish the manganese content in the bath. But an entirely deoxidized flux, ie, containing no higher oxides of manganese and iron oxides in the welding conditions enter into chemical interaction with the molten metal. most important reactions are the reduction of the oxides of manganese and silicon flux the molten iron, the so-called silicon-and margantsevosstanovitelny process : MnO + FeO = Fe + Mn and SiOa + 2Fe = 2FeO + Si, these reactions enrich the weld metal silicon and manganese, but also the ferrous oxide FeO, for the removal of which is necessary to apply appropriate measures, such as to maintain an acidic nature of the slag, which connects the FeO in silicate, insoluble in the liquid metal. Increasing the manganese content at the expense of fused fluxes are almost never excessive. Increasing the silicon content is sometimes higher than the permissible limits, and you have to take steps to reduce it. Physical properties of the flux is not less important than its chemical composition. The melting point of flux, as a rule, should not exceed 1200 ° C. The viscosity of the flux in the molten state should be negligible. In most cases, better results provide fluxes that provide for short-Research Institute of molten slag. To reduce the viscosity of the flux and to reduce its melting temperature using special additives: natural mineral - fluorspar, the chemical composition is nearly pure calcium fluoride CaF2. However, during welding, it forms harmful gases containing fluorine, and also reduces the stability of the arc. applied fluxes are fused glassy appearance, amorphous particles of poluproznachny, they are called vitreous, or "flux-glass"; bulk density 1,5-1, 8 g/cm3. Sometimes used pumiceous flux, or "flux-pumice", which has a bulk density of 0.6-0.9 g/cm3, and consisting of a finely porous opaque particles. Granulation fluxes ", ie, grain size, in different cases, ranging from 0.5 to 3 mm. Most often used fused fluxes are synthetic silicate, smelted in furnaces have a slightly acidic character and the content of manganese oxide, are vysokomargantsovistym. To distinguish between the flux basis, additives, impurities and pollution. basis of flux are usually double or triple silicate of manganese oxide, calcium oxide, magnesium oxide, aluminum, and so dlS.kachestve additive that reduces the melting point and viscosity, most often used fluor spar. impurities and contaminants from entering into flux with the source materials and fuel, as well as furnace linings, the most important iron oxide, aluminum oxide A12O3, sulfur and phosphorus. All these impurities and pollution are harmful to the flux, and the maximum content is limited specifications. compositions fused flux percentage for automatic arc welding mild steel electrode wire Sv-08 or CB-08A according to GOST 2246-60. fluxes produced by our industry in large quantities and are the most common, and they are vysokomargantsovistym. Bezmargantsovistye fluxes for welding mild steel is not currently used. Get the satisfactory results of welding mild steel under srednemargantsovistymi fluxes is only possible using a special electrode wire with a high content of manganese. Application srednemargantsovistyh flux is very small. One of the best and widely used in our industry is vysokomargantsovisty flux OSC-45, KV developed Liubavskii. This manganese silicate MnOSiO2, to which to reduce the melting temperature and viscosity and to improve the technological properties added in the smelting of calcium fluoride porosity (other incidental impurities and pollution). flux has a high fluidity and low viscosity at the melting temperature steel. Due to the high content of manganese oxide, this flux can be used for welding low-carbon steels of low-carbon standard electrode wire, while the seams of high quality are obtained. Flux OSC-45 is less sensitive than other fused fluxes, deviations in the chemical composition of base metal, welding wire and of the flux, as well as rust, contained on the surface of the base metal, which is practically very valuable. * The disadvantages are the high flux of fluorine that may cause poisoning of workers welding in confined spaces (inside boilers, tanks, etc.) and also decreases the stability of the arc. flux AN-348, developed at the Institute of Electric them. Paton, provides somewhat greater stability of the arc as compared with the flux OSC-45. even higher stability of the arc welding under flux AN-348-A, is also made less harmful gases at work because of low content. CaF2. Fluxes OSC-45 and AN-348 produced the industry in large quantities. Fused fluxes are produced in the following way. Components of flux - manganese ore, silica sand, fluorspar, etc. - mixed in a powdered state in the desired ratio and charged into a melting furnace (electric arc or the Glass-flame). By melting the charge and getting the homogeneity of the liquid product at a temperature of 1400 ° C is admitted into a fine spray granulation tank with running water, which breaks up into individual grains and solidifies in an amorphous glassy form without crystallization. flux then dried, crushed in a mill and passed through two sieves, having, for example, the first 16 holes of 1 cm2, and the second 600 holes of 1 cm2. residue on the second sieve is a finished product; the remainder goes to the first sieve to re-crushing. material passing through the second sieve is in the charge for subsequent batches. chemical composition of the final flux should match the technical specifications can be verified by analysis of samples.
See also:
Automatic Arc Welding
Automatic ADS
Machines with a Constant Feed Rate of Electrode
Flux Equipment
Settings for Automatic Arc Welding
Automatic Submerged Arc Welding Introduction
Fluxes for Automatic Arc Welding
Processed Fluxes
Ceramic Fused Fluxes
Semi-Automatic Arc Welding
Arc Welding with Flux Cored Wire
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