JPH1015671A - Welding method for electron beam welding structure of different material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a method by which a sound electron beam welding is attained without defect of voids due to gas component stagnation, weld crack due to diffusion/hardening of carbon, misalignment or the like due to beam deflection, etc. SOLUTION: In welding two kinds of different materials of electron beam welding structures 1, 2, first, in each groove 7 of the two kinds of different material a build-up weled part 6 is formed by welding filler material having a little gas component overlaid by electron beam welding in a vacuum container; second, after build-up welded part 6 is again given an edge preparation, the grooves are abutted on each other and electron-beam 5 is welded in a vacuum container. Incidentally, one of the two kinds of different materials 1, 2 is 2Cr cast steel, while the other is 9Cr cast steel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for welding a dissimilar electron beam welded structure.

[0002]

2. Description of the Related Art Conventionally, in welding processing of a dissimilar material welding structure such as a turbine casing, it is generally difficult to perform arc welding between dissimilar materials, so that electron beam welding is employed.
As shown in the cross-sectional view, 2Cr cast steel 01 and 9Cr cast steel 0
In No. 2, electron beam welding is performed by directly abutting the groove surfaces, and an electron beam welded portion 03 is formed.

[0003]

However, such as 2Cr cast steel and 9Cr cast steel, oxygen, nitrogen,
Electron beam welding of different materials such as steel containing a large amount of gas components such as hydrogen and steel having a high carbon content, as shown in the figure,
In the electron beam welded part 03 and the surrounding heat affected zone of the base metal, there are cavity defects 04, weld cracks 05 due to diffusion and hardening of carbon,
Further, there is a fear that an out-of-focus defect or the like may occur due to beam deflection due to a potential difference between different materials. Particularly in a large member or a thick member, it is difficult to dissipate gas components, and this tendency is strong.

[0004] The present invention has been proposed in view of the above-mentioned circumstances, and includes a cavity defect due to accumulation of a gas component and diffusion of carbon.
It is an object of the present invention to provide a method for welding a dissimilar electron beam welded structure capable of obtaining a sound electron beam welded portion without welding cracks due to hardening and unsightlyness due to beam deflection.

[0005]

In order to achieve the above object, according to the first aspect of the present invention, when welding two kinds of dissimilar electron beam welding structures, first, two kinds of dissimilar material beveled surfaces are used. In each case, a weld overlay was formed by overlaying a filler material with a low gas component by electron beam welding in a vacuum vessel, and then the weld overlay was re-grooved,
The grooves are butt-butted and electron beam welded in a vacuum vessel.

The invention of claim 2 is characterized in that, in claim 1, one of the two kinds of dissimilar materials is 2Cr cast steel and the other is 9Cr cast steel.

In the method of welding a dissimilar electron beam welded structure according to the present invention, it is possible to prevent a cavity defect which is a problem in the electron beam welding of cast steel, and to weld a dissimilar electron beam such as 2Cr cast steel and 9Cr cast steel. Cracks can be prevented, and unsightly defects based on beam deflection due to the potential difference between different materials can be prevented.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment in which the dissimilar electron beam welding method of the present invention is applied to a thick plate joint of 2Cr cast steel and 9Cr cast steel will be described with reference to the drawings. FIG. 1 shows the method of the present invention in the order of processing steps (I). , (II), (〓).

First, in FIG. 1 (I), an inconel material placing plate plate 3 having a thickness of several mm is placed on a groove surface of a thick 2Cr cast steel 1 and a thick 9Cr cast steel 2 in a vacuum vessel.
Or by continuously supplying an Inconel material filler wire while irradiating an electron beam 5 from an electron gun 4 to perform overlaying, thereby forming an overlay welding portion 6.

Thereafter, as shown in FIG.
A groove finishing process is performed on the overlay welding portions 6 of the cast steels 1 and 9Cr cast steel 2 respectively, and the groove surfaces 7 are abutted with each other, and both are put in a vacuum vessel and subjected to electron beam welding.

Further, as shown in FIG. 1 (A), an electron beam weld 8 is formed.

[0012]

In such a welding method, 2Cr
A bead welded part 6 made of a filler material having a small gas component such as an Inconel material placing plate 3 is applied to the groove face of the cast steel 1 or 9Cr cast steel 2 and then the reworked groove face is butted with electron beam welding. Since the portion 8 is formed, the electron beam welded portion 8 has not only the occurrence of cavity defects due to gas stagnation but also the occurrence of welding cracks due to diffusion and hardening of carbon, and an out-of-focus condition based on beam deflection due to a potential difference. No defects.

In short, according to the first aspect of the present invention, when welding two kinds of dissimilar electron beam welding structures, first, gas components of the two kinds of dissimilar materials are formed by electron beam welding in a vacuum vessel on the two different kinds of beveled surfaces. By forming a weld overlay where a small amount of filler metal is overlaid, and then re-grooving each of the overlay welds, the edges are butt-butted and electron beam welded in a vacuum vessel. The present invention provides a method for welding a dissimilar material electron beam welded structure, which can provide a sound electron beam welded part without a cavity defect due to accumulation of gas components, welding cracks due to diffusion and hardening of carbon, and misalignment due to beam deflection. Is extremely useful in industry.

According to a second aspect of the present invention, in the first aspect, one of the two kinds of dissimilar materials is 2Cr cast steel and the other is 9Cr cast steel.
By using cast steel, cavity defects due to gas component accumulation,
The present invention is extremely useful in industry because it provides a method of welding a dissimilar electron beam welded structure that can provide a sound electron beam welded part without welding cracks due to diffusion and hardening of carbon and unsightlyness due to beam deflection. .

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment in which the present invention is applied to a thick plate joint of 2Cr cast steel and 9Cr cast steel in the order of processing steps.

FIG. 2 is a cross-sectional view of a conventional welded structure of 2Cr cast steel and 9Cr cast steel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 2Cr cast steel 2 9Cr cast steel 3 Inconel material placing plate 4 Electron gun 5 Electron beam 6 Overlay weld 7 Groove face 8 Electron beam weld

Claims (2)

[Claims] When welding two kinds of dissimilar material electron beam welded structures, first, a filler material having a small gas component is laid on each of the two kinds of dissimilar material bevel surfaces by electron beam welding in a vacuum vessel. A dissimilar material electron beam welding structure in which a weld overlay is formed, and then the weld overlay is newly re-grooved, and the gaps are butt-butted and electron beam welded in a vacuum vessel. How to weld things. 2. The method for welding a dissimilar electron beam welded structure according to claim 1, wherein one of the two kinds of dissimilar materials is 2Cr cast steel and the other is 9Cr cast steel.