JPH10314976A - Welded joint - Google Patents

Abstract

(57) [Summary] The present invention reduces the material strength that greatly affects the fatigue and corrosion of welded joints, reduces the stress concentration at the welding root and toe where cracks are relatively easy to enter, and , By increasing the residual stress. In a joint of a structure manufactured by welding, a welding route portion and a toe portion of a welded portion after welding are further welded using a welding rod made of a material that causes martensitic transformation, and the welding route portion is formed. And, by forming the shape of the toe portion into a smooth shape, stress concentration at the welding root portion and the toe portion of the welded joint is reduced, and the residual stress is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for reducing the stress of a joint by using a welding rod made of a material which causes a martensitic transformation in the shape of a welding root portion and a toe after welding. It is intended to reduce the concentration, improve the strength of the welded portion of the welded joint produced by the above-mentioned welding, and improve the reliability.

[0002]

2. Description of the Related Art Conventional welding joints are disclosed in
As disclosed in Japanese Patent No. 70583, a method of maintaining and improving the strength of a welded joint by controlling a welding method has been generally used. However, little attention has been paid to a technique for maintaining and improving the strength of the welded joint by changing the joint shape itself. Also,
In JP-A-5-296257, the strength of a welded joint is improved by focusing on the shape of the joint and creating a shape in which stress concentration is unlikely to occur. However, no attention is paid to the material and residual stress of the portion.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to reduce the stress concentration at the welding root and toe of a welded joint in a joint of a structure manufactured by welding, and
Attempts to reduce residual stress.

[0004]

In order to solve the above-mentioned problems, a welding route portion and a toe portion of a welded portion after welding are further welded by using a welding rod made of a material which causes martensitic transformation. By forming the shape of the root portion and the toe portion into a smooth shape, stress concentration at the welding root portion and the toe portion of the welded joint is reduced, and the residual stress is reduced.

[0005]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a cross-sectional view of an electron beam welded joint structure as an example of a cross-sectional view of a joint structure formed by welding with one welding pass in the thickness direction according to the present invention. The flange 3 and the web 4 of the T-shaped weld joint are joined by electron beam welding 1. In this state, as shown in the conventional welded joint structure by electron beam welding in FIG. 2, the flange 3 and the web 4 of the T-shaped welded joint are vertically joined, and the joint is also at a right angle. Since the stress concentration occurs, the fatigue strength of the welded joint decreases.

Therefore, after the completion of electron beam welding, as shown in FIG. 1, a welding rod made of a material that causes martensitic transformation is used to form a joint portion of a T-type welded joint with an angle at which stress concentration is likely to occur. In order to form the joint shape, the weld overlay is smoothly overlapped to form the shape of the welding root portion and the toe portion of the T-shaped welded joint on a smooth curve. Thus, stress concentration at the welding root portion and the toe portion of the T-shaped welded joint can be reduced, and the residual stress can be reduced. That is, the fatigue strength of the welded joint can be improved.

When the T-type welded joint and the toe after the completion of electron beam welding are welded using a welding rod made of a material that causes martensitic transformation, the shape of the joint is as shown in FIG. , A smooth curve is formed by the mass 201 of the welding pass. Although the stress concentration is considerably reduced even in this state, as shown in FIG. 4, in order to form a joint shape in which there is no place such as a straight line where stress concentration easily occurs and an angle by the straight line, As shown in FIG. 4, by smoothing the shape of the welded portion 202 and the toe of the welded joint by surface processing, for example, grinder processing, stress concentration at the welding root portion and the toe of the welded joint is reduced. In addition, since a welding rod made of a material that causes martensitic transformation is used, residual stress can be reduced, and as a result, fatigue strength can be improved by a synergistic effect of the two.

Before joining the T-shaped welded joint by the electron beam welding 1 of FIG. 2, the martensitic transformation as shown in FIG. Using a welding rod made of the material to be raised, in order to form a joint shape in which an angle formed by a straight line where stress concentration is likely to occur due to electron beam welding 1 and a straight line cannot be formed, the weld overlay is smoothly overlapped in advance, and FIG. By performing the electron beam welding 101 as shown in the figure, the shapes of the welding route portion and the toe portion of the T-type welded joint by the electron beam welding are formed smoothly, so that the welding route of the T-type welded joint by the electron beam welding is achieved. The stress concentration at the portion and the toe portion can be reduced, and the strength can be improved.

Further, after the welding 2 of the T-type welded joint and the toe of the T-shaped welded joint by the electron beam welding 1 is completed with the material causing the martensitic transformation, a straight line where stress concentration is likely to occur and an angle formed by the straight line are not formed. In order to make the joint shape as simple as possible, the shape of the welding root portion and the toe portion of the T-shaped welding joint is smoothed in advance by grinder processing, and then the electron beam 1 is applied. There is also a manufacturing method capable of reducing stress concentration at the toe and improving strength.

FIG. 7 shows that a T-type welded joint is formed by using two flanges 301 and one web 4 to form an electron beam weld 102 and a martensite-based weld 2 using the present invention.
It is sectional drawing at the time of manufacturing using. Conventionally, as shown in FIG. 8, after the end of electron beam welding, straight and straight angles are formed at the welded end, and that portion often causes a problem in strength. This flange 301 and two webs 4
Is welded by electron beam welding 102, and as shown in FIG. 7, the attachment portion is made smooth using a filler metal 2 of a martensitic material, thereby alleviating the stress concentration of the T-shaped joint. In addition, the residual stress can be reduced and the fatigue strength can be improved.

[0012]

According to the present invention, the welding route and the toe of the welded portion after welding are further welded using a welding rod made of a material that causes martensitic transformation, and the shapes of the welding route and the toe are formed. By forming a smooth shape, the stress concentration at the welding root and toe of the welded joint can be reduced, and the residual stress can be reduced. Furthermore, the fatigue strength of the welded joint of the welded joint And the reliability of the welded joint can be increased.

[Brief description of the drawings]

FIG. 1 is a sectional view of a welded joint structure according to the present invention.

FIG. 2 is a cross-sectional view of a welded joint structure manufactured by a conventional welding pass.

FIG. 3 is a cross-sectional view of an electron beam welded joint structure.

FIG. 4 is a sectional view of an electron beam welding joint structure.

FIG. 5 is a cross-sectional view of a welded joint structure formed by overlay welding.

FIG. 6 is a sectional view of a welded joint structure manufactured by electron beam welding.

FIG. 7 is a sectional view of a T-shaped welded joint structure.

FIG. 8 is a sectional view of a conventional T-shaped welded joint structure.

[Explanation of symbols]

1, 101, 102 ... electron beam welded part, 2, 202 ...
Welds, 203 ... Welds for smoothing the shape after attaching two flanges with a large cross-sectional area, 3,301,3
02: flange, 4: web.

Claims (1)

[Claims] In a joint of a structure manufactured by welding, a welding route portion and a toe portion of a welded portion after welding are further welded using a welding rod made of a material that causes martensitic transformation, A welded joint characterized by reducing the stress concentration at the welding root portion and the toe end of the welded joint and reducing the residual stress by forming the shape of the portion and the toe portion into a smooth shape.