Electric heating – Metal heating – Nonatmospheric environment at hot spot
Patent
1983-02-15
1986-03-11
Albritton, C. L.
Electric heating
Metal heating
Nonatmospheric environment at hot spot
219 73, B23K 2500
Patent
active
045756066
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to electroslag welding with a consumable electrode and to a flux utilized in this method. The invention may be utilized in welding ingots of practically any thickness and made preferably from metals possessing high thermal conductivity, such as aluminum, copper etc.
2. Description of the Prior Art
Known in the art is a method of electroslag welding with a plate electrode (A. N. Safonnikov, "Svarka metallov plastinchatym elektrodom", K., Tekhnika, 1966, pp. 57-61).
The welding process is carried out as follows. Parts to be welded are mounted with a required gap. Then a forming device is assembled. A plate electrode mounted within an electrode holder is introduced into the gap space. A flux is charged so that the lower end of the electrode is immersed thereinto. The process of welding is initiated at a low feed speed of the plate electrode by means of short-time switchings. At the initial moment, there occurs melting of the electrical conductive flux serving as a fluxing agent for a main welding flux. As a slag pool is being formed, the flux designed for welding the parts is added in small portions. After the slag pool is formed, a stable electroslag process is established. The feed speed of the electrode is gradually increased and adjusted in accordance with a calculated speed. Prior to the termination of the welding process, due to the limited heat removal, at the edges of the parts being welded there is observed a considerable heating of edges in the upper portion of the weld butt, thereby resulting in a nonuniform penetration into the edges being welded, and in some cases even at incomplete penetrations, especially in the starting point of the weld.
The experiments have demonstrated that for the purpose of practicing the above method it is most expedient to utilize fluxes based on calcium fluoride. The main feature of these fluxes consists in that they form practically neutral slags. In the course of welding with the use of such fluxes the reliable protection of the weld pool is ensured and interaction between slag and metal is eliminated. Besides calcium fluoride, said fluxes further comprise various oxides. For instance, known in the art is a flux containing the following ingredients, percent by weight:
______________________________________ CaF.sub.2
65 to 75
CaO 18 to 30
SiO.sub.2
2
______________________________________
However, the flux utilized in the above described method passesses inadequate activity to an oxide film, which results in the appearance of incomplete fusion in the welded joints even in the case where the penetration into the edges is sufficient.
SUMMARY OF THE INVENTION
The object of the invention is the provision of a method of electroslag welding and a flux providing for an increase in the quality of welded joints when welding parts having large cross-section by way of controlling the speed of electrode fusion in course of welding.
The object set forth in attained by a method of electroslag welding, wherein parts to be welded are mounted with a required gap, a forming device is assembled, an electrode is introduced into the gap between the parts to be welded, the gap is filled with a flux, a slag pool is set with subsequent melting of the electrode and the edges being welded, according to the invention, in the process of welding the zone of electrode melting is cooled.
The above method provides for a uniform and sufficient fusion of the welded edges when welding metals possessing high thermal conductivity. The effect is achieved due to an increase in the energy per unit length, resulting from a decrease in the melting rate of the electrode. The melting rate of the electrode is reduced by means of cooling the zone of electrode melting.
The zone of electrode melting is recommended to be cooled by means of application to the electrode substances decomposing with heat absorption.
The above modification of the method makes it possible to maintain a constant volume of the slag pool.
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REFERENCES:
patent: 3296412 (1967-01-01), Waite et al.
patent: 3627592 (1971-12-01), Schmidt et al.
patent: 3660629 (1972-05-01), Nakai et al.
patent: 3869592 (1975-03-01), Paton et al.
patent: 4086463 (1978-04-01), Omori et al.
patent: 4368371 (1983-01-01), Dilthey et al.
A. N. Safonnikov, "Svarka metallov plastinchatym elektrodom", K. Technika, 1966, pp. 57-61.
Antonov Anatoly V.
Safonnikov Anatoly N.
Albritton C. L.
Sigda Catherine M.
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