Electric heating – Metal heating – Nonatmospheric environment at hot spot
Patent
1982-02-18
1984-03-20
Reynolds, B. A.
Electric heating
Metal heating
Nonatmospheric environment at hot spot
B23K 2500
Patent
active
044383134
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to the art of welding and is specifically concerned with a method for electroslag welding of metals by a large-section electrode.
DESCRIPTION OF THE PRIOR ART
There has been proposed a method for electroslag welding of copper blanks (U.S. Pat. No. 3,885,121), comprising the steps of establishing and overheating a slag bath by a nonconsumable electrode, removing the nonconsumable electrode from the overheated slag bath and replacing it by a consumable electrode, fusing the latter electrode by the heat of the slag bath and filling with the molten metal the inlet metal mould and the gap between the edges being weld-joined, and subsequently removing the inlet shrinkhead.
The changeover from the process of establishing and overheating the slag bath by the nonconsumable electrode to the process of welding proper by the consumable electrode, inherent in this method, is a prolonged intermediate step which brings about a considerable loss of the heat accumulated in the slag bath and, as a result, a lack of fusion at the beginning of the weld. Also, overheating the slag bath causes it to boil, which upsets the stability of the process.
This method necessitates the step of cutting and appropriate equipment to remove the inlet shrinkhead from the weld joint.
Known in the art is also a method for electroslag welding by a large-section electrode (Safonnikov A.N. Svarka metallov plastinchatymi elektrodami (Metal welding by plate electrodes). Kiev, "Tekhnika", 1966, pp. 57-58), comprising the steps of establishing a slag bath by a consumable electrode, filling by the molten metal the inlet metal mould and the gap between the edges being weld-joined, and subsequently removing the inlet shrinkhead. In this method, the rate of electrode fusion in establishing the slag bath, fusing the electrode and the edges being weld-joined, and filling by the molten metal the inlet metal mould and the gap between the edges, remains constant on condition that the electrical parameters of the welding process are unchanged.
This method fails, however, to ensure a proper fusion of the edges being weld-joined at the bottom of the weld, which leads to an increased electrical resistance of the welded contact. For a proper fusion of the edges at the bottom of the weld and a low electrical resistance weld to be attained, a long time must be spent for heating the slag bath to the working temperatures; in welding, e.g., aluminium, the time is as long as 3-5 min.
The term "working temperatures" is intended to denote the temperature range at which a stable electroslag process and a sound weld are attained.
Extended inlet metal moulds dictated by this prior art method to bring the slag bath to the working temperatures result in a considerable over-expenditure of the electrode metal.
After a weld joint has been made by the prior art method, the inlet shrinkhead is removed by mechanical, arc, etc. cutting.
SUMMARY OF THE INVENTION
The principal object of the invention is to provide a method for electroslag welding of metals by a large-section electrode, which ensures a higher quality of the weld, improved mechanical properties of the weld joint as a whole, a low electrical resistance of the welded contacts, and simplified removal of an inlet shrinkhead by reducing the duration of heating to working temperatures and by forming a brittle interlayer between the inlet shrinkhead and the weld.
This object is attained by a method of electroslag welding of metals by a large-section electrode, comprising the steps of establishing a slag bath, fusing an electrode and the edges being weld-joined, filling with the metal being fused the inlet metal mould and the gap between the edges, and subsequently removing the inlet shrinkhead. According to the invention, the electrode is in establishing the slag bath and filling the inlet metal mould, fused at a rate lower than the rate of its fusion in filling the gap between the edges being weld-joined at constant electrical parameters of the electroslag welding, and
REFERENCES:
patent: 3885121 (1975-05-01), Dudko et al.
Safonnikov, A. N., Svarka Metallov Plastinchatymi Elektrodami (Metal Welding by Plate Electrodes). Kiev, "Tekhnika", 1966, pp. 57-58.
Antonov Anatoly V.
Safonnikov Anatoly N.
Akademii Nauk Ukrainsko
Institut Elektrosvarki Imeni E.O. Patona
Reynolds B. A.
Sigda Catherine M.
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