JPS6326267A - One side butt welding method for metallic material - Google Patents

Abstract

PURPOSE:To improve the accuracy of detection in ultrasonic flaw detection by bringing an infusible wear plate into close contact with the back of a welding bevel, and forming the weld bead of succeeding layers after the solidification of weld bead of a first layer by holding the back in flush state. CONSTITUTION:The welding bevel 2 of one side butted state is formed in a base metal, and a heat resisting wear plate 7 is brought into close contact with the back of the bevel 2 and inside face is made blocked state. Welding bead 3a of the first layer is formed in the bevel 2. In such case, the wear plate 7 is held to prevent the leakage of molten metal from the bevel 2 and to prevent the sagging of a part of composition of the base metal 1 easily deformable by welding heat. After solidifying the welding bead 3a of the first layer by natural cooling, etc., the wear plate 7 is removed from the back. Then, welding beads of a second layer and a third layer are formed successively in superposed state, and a welding joint is constituted. Thereby, a hollow part due to projecting part is not occurred, and accordingly, the generation of unnecessary ultrasonic echo can be prevented.

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to a method for one-sided butt welding of metal materials, and particularly to a welded joint that is subject to an ultrasonic flaw detection test, to prevent the occurrence of protruding parts of back waves. This invention relates to a welding method that suppresses the welding process.

"Prior Art" Generally, when connecting carbon steel pipes, stainless steel pipes, etc. using welded joints, as shown in Fig. 3 (A), a welded opening is placed on the base material l, which is the pipe wall, with one side butted. Ahead 2
, and multiple layers of weld beads 3a to 3 are formed in the weld groove 2.
3n in a superimposed state to form the welded joint 4,
Work is being carried out to finish the surface of the welded joint 4 into a smooth state as shown in FIG. 3(B). When forming the first layer weld bead 3a, a part of the weld metal or base metal l is melted on the back surface (inner surface in the case of a pipe) of the weld joint 4 constructed by such one-sided butt welding method. When the patient becomes deaf, a protrusion phenomenon, the so-called Uranami, is formed on the back surface.

In addition, for piping used in important parts of nuclear power plants, fire pits, lands, chemical plants, etc., we conduct ultrasonic flaw detection tests on the welded joints 4 to check the integrity of the welded joints. has been confirmed.

"Problems to be Solved by the Invention" However, as shown in FIG. 3(B), on the back side of the welded joint 4 formed by the one-sided butt welding method, there is a protrusion in which a part of the molten metal slightly hangs down. (i.e., Uranami) 5 is formed, and this protrusion 5 and the base material l
A recessed portion 6, which is a so-called discontinuous portion, is formed at the boundary between the inner surface and the inner surface.

Therefore, as shown by the chain line U in Fig. 3(B), when ultrasonic waves are sent, they are reflected as echoes at the recess 6, and even if cracks occur in the weld heat affected zone, etc., the echoes will not be transmitted. A problem arises in that they interfere with each other and reduce the detection sensitivity of defective parts.

The present invention aims to solve the problems of the prior art, and aims to reduce the occurrence of depressions in welded joints, eliminate the generation of unnecessary ultrasonic echoes, and improve the detection accuracy of ultrasonic flaw detection. It is intended to improve.

"Means for Solving the Problems" The one-side butt welding method for metal materials of the present invention involves closely contacting the back side of the one-side butt part in the welding groove with a receiving plate that is non-fusible to the weld metal. There is a step of forming an initial layer of weld beads in the weld groove of the receiving plate portion, and then forming weld beads of the next layer and subsequent layers after the initial layer of weld beads is solidified.

When the backing plate is brought into close contact with the back side of the welding groove and the back side is held flush, and the weld metal, etc. is about to protrude from the back side of the welding groove due to the first layer of welding. Secondly, it prevents the molten metal from dripping to the back surface and maintains a flush state. It also prevents the molten metal from melting and integrating with the receiving plate, so as not to affect the welded joint.

Next, after the weld bead in the first layer has solidified, weld beads in the next layer and below are formed to form a welded joint, and the receiving plate At the appropriate time, it is removed and separated from the welded joint.

"Example" Hereinafter, an example of the method for one-sided butt welding of metal materials according to the present invention will be described based on FIGS. 1 and 2.

In one embodiment, a piping (pipe) is the base material 1, and a welding joint 4 is constructed by superimposing a plurality of weld beads 3a to 3n on the welding groove 2. Therefore, the welding groove 2 The back surface of the one-sided butt portion in 2 is the inner surface.

[Closure of the back side of the weld groove] Then, prior to starting the forming work of the weld joint 4, the first
As shown in Figure (A), a welding groove 2 is formed in the base metal l in a state where one side butts, and a heat-resistant receiving plate 7 is brought into close contact with the back surface of the welding groove 2. ,
Keep the inside closed. This receiving plate 7 is made of a material that is non-fusible to the weld metal, that is, a material with a high melting temperature that does not soften significantly at the melting temperature of the weld metal, and as shown in FIG. When the material l is a tube, for example, a ring-shaped material made of a suitable ceramic material and having a plurality of slits 8 formed on the inner circumference is used, and the ring-shaped receiving plate 7 is inserted into the tube. Insert and keep in close contact.

[Formation of initial layer weld bead] As shown in FIG.
a to prevent the molten metal accompanying the formation of the weld bead 3a from leaking downward from the welding groove 2, and to prevent a part of the structure of the base metal l, which is easily deformed by welding heat, from hanging downward. Hold it like this.

[Removal of backing plate: The first layer of weld bead 3a is solidified by natural cooling or the like. In the case of a tube, a shrinkage effect occurs due to cooling, so that a compressive stress is applied to the ring-shaped receiving plate 7 shown in FIG. 2', leading to a fractured state. And the first
As shown in Figure (C), the broken receiving plate 7 is removed from the back side of the welding groove 2. In this case, slit 8
is something that promotes the cracking of the receiving plate 7, and is set together with the shape and dimensions of each part.

[Overlapping formation of weld beads] After solidifying the first layer of weld beads 3a, as shown in FIG. 1(D), weld beads are sequentially formed in the second and third layers in an overlapping state to form the weld joint 4. do.

[Surface finish] FIG. 1(E) after the final weld bead 3n is formed.

As shown in FIG. 2, the base material 1 is made into a flat state by grinding to match the surface of the base material 1.

If the welded joint 4 is configured through such a process, when the first layer weld bead 3a is formed, the receiving plate 7 is brought into close contact with the back surface of the weld groove 2, and the back surface is held flush. Therefore, the occurrence of the phenomenon in which molten metal etc. protrudes from the welding groove 2 to the back surface is effectively prevented, and a part of the weld metal or the constituent metal of the base metal 1 does not hang down and protrude to the back surface. Therefore, the depression 6 shown in FIG. 3 described in the prior art is not formed.

Therefore, when performing an ultrasonic flaw detection test on the welded joint 4, it is possible to suppress the generation of unnecessary echoes and improve the detection accuracy of defective parts during ultrasonic flaw detection.

[Other embodiments] Note that the present invention includes the following embodiments.

(?) Applicable to plate-shaped base materials other than piping.

(b) The surface of the receiving plate that contacts the base material is mainly made of a heat-resistant material.

(C) Instead of a ring shape, the receiving temporary is made into a plate shape or an arc shape.

(d) Pressing the receiving plate against the back surface of the base material using a resilient member such as a spring.

(e) Omit the temporary receiving slit.

(f) To be attached to the back surface of the base material as a receiving plate with a structure made by pasting a heat-resistant material on adhesive tape.

(g) The receiving plate should be removed from the back surface of the base metal at any time after the initial layer weld bead has solidified.

"Effects of the Invention" As explained above, according to the method for one-sided butt welding of metal materials according to the present invention, ■ a receiving plate is arranged on the back side of the one-side butt part in the weld groove to create a closed state. Therefore, it is possible to prevent molten metal and the like from protruding onto the back surface of the base material during the formation of the first layer weld bead.

(2) By solidifying the weld bead in the first layer, it is possible to prevent the weld bead from sagging toward the back surface due to the formation of a subsequent weld bead, so it is possible to easily close the weld groove with the receiving plate.

■The back side of the welded joint is kept flush to prevent the formation of depressions, which prevents the generation of unnecessary echoes during ultrasonic flaw detection tests and improves work accuracy and efficiency during ultrasonic flaw detection tests. can be increased.

■Applicable to welded joints of pipes and other shapes, with a wide range of applications and high practicality.

It has the following effects.

[Brief explanation of drawings]

FIGS. 1(A) to E) are explanatory views of the process order in an embodiment of the one-sided butt welding method for metal materials according to the present invention, and FIG. 2 is a view taken along the line nn in FIG. 1(B). Figure, 3rd
Figure (A) (I3) is an explanatory diagram of the process order in a conventional example of the welding method. l...Base metal, 2...Welding groove, 3a~
3n welding bead, 4... welding joint, 5...
...protrusion, 6 ... recess, 7 ... receiving plate, 8 ... slit. Applicant Ishikawajima Harima Heavy Industries Co., Ltd. Figure 1 Figure 2 Figure 8 b

Claims (1)

[Claims] A receiving plate that does not melt the weld metal is brought into close contact with the back side of the one-side butt part of the welding groove,
Forming an initial layer of weld bead in the weld groove of the receiving plate part,
1. A method for one-sided butt welding of metal materials, characterized in that after the weld bead of the first layer is solidified, weld beads of the next layer and subsequent layers are formed.