Electric heating – Metal heating – By arc
Reexamination Certificate
1999-09-08
2001-01-30
Shaw, Clifford C. (Department: 1725)
Electric heating
Metal heating
By arc
Reexamination Certificate
active
06180919
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to the field of welding, more particularly, to a method of making welded joints for products of maraging steels, and can find application in manufacturing various components in the rocket and aircraft industry and other engineering branches.
BACKGROUND OF THE INVENTION
A method for welding high-strength alloys, comprising welding an insert between the pieces jointed, is known in the art (SU Inventor's Certificate No. 336111, B 23 K 9/02, 1972).
However, in this case the insert is made of a material having a less strength than that of the material of the welded pieces, resulting in the reduced strength of the welded joint as a whole.
Most closely approaching the present invention is a method for making a welded joint, comprising the steps of resistance welding a thin metal backing of the same metal as that of a filling wire to an edge of one of pieces welded, fitting up a joint, and welding at a constant current of opposite polarity (JP Application No.
58-9779
, B 23 K 9/23, published in 1983).
The method permits obtaining high-quality joints in products made of heat-resistant stainless steels and carbon steels. However, there exist a number of structures of maraging steels that could not be welded by the prior art method without cracks.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an improvement in quality of a welded joint for components made of maraging steels.
A method in accordance with the invention provides a welded joint free of the shrinkage and cold cracks when welding pieces of maraging steels.
The object of the invention is achieved in a method of making a welded joint, comprising the steps of resistance spot welding an intermediate element to an edge of one of pieces welded, fitting up the welded pieces and welding, wherein the intermediate element is made of the same metal as that of the welded pieces and covered with a layer of chromium, said fitting up of the pieces is made by tacking using a manual argon-arc welding with a nonconsumable electrode on a kept weld backing of the same metal as that of the pieces, the argon-arc welding is accomplished at a nonrotatable position of the pieces by two runs of a nonconsumable electrode at transverse oscillations of the electrode relative to the weld at a frequency of 60-80 oscillations per minute, a first run being made at a reduced welding current comprising 30-70% of a rated current. When welding ring joints, a second run is made in two half-turns of downhill welding with overlapping of the beginning and the end of the weld.
The method procedure can be studied with reference to welding a pipeline to a stator body and a generator body of a liquid-propellant rocket engine as an example. The welded components are made of a maraging steel.
REFERENCES:
patent: 3288981 (1966-11-01), Mabry et al.
patent: 58-009779 (1983-01-01), None
patent: 336111 (1972-09-01), None
Derkach Gennady Grigorievich
Loginov Anatoly Lukich
Masljukov Oleg Andreevich
Pestova Margarita Borisovna
Semenov Viktor Nikonorovich
Christie Parker & Hale LLP
Otkrytoe Aktsionernoe Obschestvo "Nauchno-Proizvodstvennoe Obied
Shaw Clifford C.
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