Fluxes For Electroslag Welding

Depending on the chemical composition of the fluxes for electroslag welding are the following types:

• high-silicon manganese - AN-348, FC-7, etc.;
• nizkokremnistye Manganese - AN-8, AN-22, FC-21, etc.;
• nizkokremnistye bezmargantsevye - AN-9, AN-25 and others;
• fluoride - ANF-5-14 ANF, ANF-R, etc.

In addition to the requirements for reliable protection of molten metal, the optimum metallurgical and chemical interactions, and provide the necessary mechanical properties of welded joints in flux for electroslag welding process is presented and a number of requirements:

• ensure a stable flow of the electroslag process;
• seal the cavity, and welding slag bath and prevent leakage into the gap between the product and sliders, sliders do not wring;
• provide easy separation of the slag crust on the surface of the weld.

These requirements are most important and provided, above all, an appropriate choice of values ​​of electrical conductivity and viscosity of the flux.

In electroslag welding heat is not an arc, and the slag bath by passing current through it. Therefore, the stability of the process is determined not by the presence of elements with low ionization potential, as in arc welding, and electrical conductivity of flux. The higher (up to a certain level), the electrical conductivity of the liquid flux, the more stable the process of electroslag welding. However, excessively high values ​​of electrical conductivity of flux (eg, ceramic, containing a significant amount of ferro-alloys) reduces heat in the slag bath, which can lead to the formation of fusions.

The graph below shows that the highest electrical conductivity have fluoride fluxes. They provide the best stability of the electroslag welding process, but have limited use (for example, for welding high-alloy austenitic steels) because of the need for low voltage welding, making it difficult to obtain the required penetration edges.

At the same time should be optimal and the viscosity of the molten flux. On the one hand, it should not be too flowable so as not to flow into the gap between the product and moving the slider. On the other hand, the high viscosity of the molten flux and its rapid solidification at low temperatures can occur from squeezing sliders welded edges and undercuts may appear at the surface of the weld and slag inclusions. Therefore, in terms of the requirements necessary to select a flux is not very "short" slag, ie, the viscosity of which varies slowly with decreasing temperature. At the same fluoride fluxes (eg, ANF-P) are the worst because they have a "short" slag (from the rapid increase in viscosity at low temperatures).

Separability of the slag crust depends on the thickness of the oxide film on the surface of the weld metal and, mainly, of the content in the flux of manganese oxides Mn 2 O 3 and MnO. The smaller the number in the flux, the better the separability of the slag crust.

To start the electroslag process can be used flux AN-25. It is electrically conductive, even in the solid state in contrast to many other fluxes designed for electroslag welding. In the absence of flux AN-25 can start with an arc welding process, which stops after filling the flux and its melting and electroslag goes into the process as a result of shunting arc melted conductive flux ("solid" start). Often used "liquid" start when poured molten flux previously.

Welding fluxes are used as special (AN-8, AN-8M, EN-22, etc.) and some of the fluxes for arc welding, electroslag suitable for the process (AN-348A, ANF-1, FC-7, 48 - PF-6, etc.). As with arc welding, the more alloyed steel, the more fluoride CaF 2 and less oxides MnO and SiO 2 must be contained in the flux.

When welding carbon and low alloy steels fluxes AN-8, AN-8M, EN-22, a 48-RP-6 is preferred over flux FC-7 and AN-348-A. Last less suitable for welding with high wire feed speed and welding seams extended. Fluxes AN-22, and 48-RP-6, in addition, a better help to reduce the sulfur content in the weld. When welding carbon steels, and the positive results achieved with the use of flux AN-47 and AN-348-B.

For medium-and high-alloy steels used fluxes 48-RP-6-1 ANF, ANF-7, etc. When welding stainless steels can be applied fluxes marks the 48-RP-6-6 ANF, ANF-7, ANF-8, ANF-14, a heat-resistant steels - Fluxes ANF-7-8 ANF, ANF-R, AN-292, etc. For high-strength alloy steels (20H2M, 25HNZMFA, etc.) can be used flux AN-9.

Electroslag welding and surfacing of cast iron can be performed using flux AN-75, ANF-14. For welding of titanium using flux brands ANT-2 ANT-4, etc., for aluminum - fluxes AN-A301, A302 and AN-al

Consumption of flux for electroslag welding of about 10-20 times less than in arc welding.

Flux	A typical field of application
AN-8	carbon and low alloy steels
АN-22	low-and medium-steel
АN-348-А АN-348-В	carbon low-alloy steel
FC-7	low-carbon and carbon steels
FC-21	heat-resistant pearlitic steel
48-PF-6	different types of steels (low and high, carbon, etc.)
АNF-1	high-alloy steels

See also:
electroslag welding technology
submerged arc welding technology

Welding materials:

welding electrodes welding wire welding flux for arc welding carbon dioxide helium

argon protective gas mixture acetylene propane-butane IAF