JP2011245522A - Structure of welded joint of steel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the structure of the welded joint of steel having higher strength than the strength of the joint which is determined from the material strength of a weld zone, wherein the applicable to job-site execution is possible and there is no need for special welding technique and technical skill, by providing a soft joint which is low in cost and is mitigated in conditions of post heating control, welding heat input and inter-pass temperature, mainly about a welded joint part of ultra-high-strength steel.SOLUTION: The structure 1 of the welded joint includes: first steel 2; second steel 3; the joint weld zone 4; and a first reinforcing member 5 and second reinforcing member 6, for reinforcing the joint weld zone 4. The material strength of weld metal 7 in the joint weld zone 4 is smaller than any material strength of the first steel 2 and the second steel 3, the first reinforcing member 5 is brought into contact with and joined with the surface 4a on one side of the joint weld zone 4 through the weld metal 7, and also the second reinforcing member 6 is joined with the surface 4b of the other side of the joint weld zone 4. The material strength of the first reinforcing member 5, the second reinforcing member 6 and the material strength of the weld metal 7 are smaller than any material strength of the first steel 2 and the second steel 3.

Description

  The present invention relates to a welded joint structure for steel materials.

  In recent years, 800N to 1000N class ultra-high strength materials have come to be used as pillar materials for building structures as the building structures become taller and larger. Although the columnar material made of an ultra-high strength material can reduce the cross-sectional area, there is a problem in securing the performance of the welded joint.

  A welded joint used for a building structure is generally a so-called overmatching joint in which the material strength of a welded portion is higher than the material strength of a base material. However, a very expensive welding material is used to realize an overmatching joint that exceeds the strength of the base material of the column material made of an ultra-high strength material of 800N to 1000N class. In addition, since it is necessary to strictly manage the prognostic heat, application to building structures that require on-site welding is greatly limited. In addition, since the welding heat input and the temperature between welding passes are more severe than those of low-strength welding materials, work efficiency is also reduced.

  On the other hand, soft joints, which are so-called undermatching, where the material strength of the weld is lower than the material strength of the base metal, are lower in cost than the use of high-strength welding materials, and the prognostic heat management and welding input. There is a merit that a joint can be obtained by welding with relaxed conditions such as heat and interpass temperature, and it has been actually used for penstock, for example. It has been conventionally known that a soft joint can obtain a welded joint that exceeds the strength of the base metal depending on the shape condition of the weld.

  According to Non-Patent Document 1, the strength of the soft joint depends on the relative thickness of the soft portion (ratio of the thickness of the soft portion to the plate thickness), and the joint strength increases as the relative thickness decreases. It is disclosed that the tensile strength is exceeded.

Sato, Doi, Toyoda, Size effect on static strength of welded joints including soft layer, Journal of the Japan Welding Society, Vol. 37, No. 11 (1968)

  In order to reduce the relative thickness of the soft part, it is necessary to perform so-called narrow groove welding in which the groove dimension of the welded part is reduced. However, in actual construction of a building structure, it is extremely difficult to strictly secure a narrow groove due to the size of the member and its error.

  Even if a narrow groove can be secured, special welding skills and techniques are required to obtain a sound welded joint with few defects by carrying out the welding, ensuring a stable weld joint with a narrow groove. It is difficult to do.

  The present invention is a joint welded portion that exists between a first steel material, a second steel material, and the first steel material and the second steel material and connects the first steel material and the second steel material in the material axial direction. And a first reinforcing material that reinforces the joint welded portion, and a welded joint structure of a steel material, wherein the material strength of the weld metal in the joint welded portion is any of the first steel material and the second steel material strength The first reinforcing member is bonded to and joined to one surface of the joint weld through the weld metal, and the material strength of the first reinforcing member and the material strength of the weld metal Is a welded joint structure of steel, which is smaller than the material strength of either the first steel material or the second steel material.

In the present invention, it is desirable that both the first steel material and the second steel material are steel pipes, and that the first reinforcing material has an annular outer shape whose inner surface abuts against the outer surface of the joint weld.
In the present invention, it is desirable that the joint weld portion has a groove having a Le shape or a V shape.

  The present invention further includes a second reinforcing material that reinforces the joint welded portion, the second reinforcing material is joined in contact with the other surface of the joint welded portion, and the material strength of the second reinforcing material is increased. It is desirable that it is smaller than the material strength of any of the first steel material and the second steel material.

  According to the present invention, for example, it is possible to provide a soft joint that is low in cost and has a reduced prognostic heat management and welding heat input / interpass temperature conditions, mainly for welded joint portions of ultra-high-strength steel materials. Therefore, it is possible to provide a welded joint structure of a steel material having a strength higher than the joint strength required from the material strength of the welded portion without requiring a special welding technique or skill.

FIG. 1 is an explanatory view showing an example of a welded joint structure of steel materials according to the present invention. FIG. 2A and FIG. 2B are explanatory views showing an example of a welded joint structure of a steel pipe according to the present invention.

The present invention will be described with reference to the accompanying drawings.
FIG. 1 is an explanatory view showing an example of a welded joint structure 1 of a steel material according to the present invention. As shown in FIG. 1, the welded joint structure 1 includes a first steel material 2, a second steel material 3, a joint weld portion 4, a first reinforcing member 5, and a second reinforcing member 6.

[First steel material 2, second steel material 3]
The first steel material 2 and the second steel material 3 are both 800N to 1000N class ultra-high strength materials. As for the 1st steel material 2 and the 2nd steel material 3, all are the steel pipes used as a pillar material of the high-rise and large-scale building structure.

The 1st steel material 2 and the 2nd steel material 3 should just have one surface and the other surface, for example, plate materials, such as a thin plate and a thick plate, a steel pipe, and a shape steel are illustrated.
[Fitting weld 4]
The joint weld 4 exists between the first steel material 2 and the second steel material 3. The joint weld 4 connects the first steel material 2 and the second steel material 3 in the respective material axial directions (vertical direction in FIG. 1).

It is desirable that the joint weld 4 has a groove having the shape of a rectangle as shown in FIG. 1 or a groove having a V shape.
The material strength of the weld metal of the joint weld 4 is desirably smaller than any of the material strengths of the first steel material 2 and the second steel material 3 and is, for example, 600 to 800 N class. Thereby, the cost reduction of a weld metal can be aimed at.

[First reinforcing material 5]
The first reinforcing member 5 is joined to the one surface 4 a of the joint weld 4 through a weld metal 7. As a result, the first reinforcing member 5 reinforces the welded joint portion 4.

The material strength of the first reinforcing material 5 is smaller than the material strength of either the first steel material 2 or the second steel material 3, and is, for example, 600 to 800 N class.
[Second reinforcing material 6]
In the present invention, the second reinforcing material 6 is used as necessary. The second reinforcing member 6 is joined in contact with the other surface 4 b of the joint weld 4. Thereby, the 2nd reinforcement material 6 reinforces the joint welding part 4. FIG.

The material strength of the 2nd reinforcement material 6 is smaller than any material strength of the 1st steel materials 2 and the 2nd steel materials 3, for example, is 600-800N class.
In addition, the code | symbol 8 in FIG. 1 is a backing metal for welding.

The welded joint structure 1 of the present invention is configured as described above.
When the steel material having the welded joint structure 1 is subjected to a tensile force that gradually increases in the axial direction (vertical direction in FIG. 1), the joint welded part 4 that is a soft part is first plasticized.

  At this time, a compressive strain corresponding to the Poisson's ratio is likely to be generated in the thickness direction of the joint weld 4, but the first reinforcing member 5 is joined to one surface 4 a of the joint weld 4 and the other surface 4 b is joined. The second reinforcing material 6 is joined, and the weld joint 4 is constrained by the first reinforcing material 5 and the second reinforcing material 6.

  For this reason, it becomes a triaxial tensile stress state inside the joint welded portion 4, the apparent axial strength of the weld metal of the welded joint portion 4 increases, and is higher than the joint strength obtained from the material strength of the joint welded portion 4. A strong joint is realized.

  The first reinforcing member 5 and the second reinforcing member 6 of the welded joint portion 4 only need to be able to restrain the strain in the plate thickness direction generated in the welded joint portion 4. The steel material 2 and the second steel material 3 may have strengths lower than the base material strength of each of the steel material 2 and the second steel material 3.

  The joining of one surface 4a of the welded joint portion 4 and the first reinforcing member 5 and the joining of the other surface 4b and the second reinforcing member 6 are first performed with respect to the first layer side of the welded joint portion 4 as the second layer. Since the reinforcing material 6 serves as a backing metal as it is, it is not necessary to take special measures to perform bonding.

  On the other hand, the final layer side of the welded joint portion 4 needs to be welded to join the first reinforcing material 5. The strength of the weld metal 7 is the same as that of the first reinforcing material 5. It may be smaller than the material strength (of course, it may be higher than the base material strength, but the construction cost increases). Therefore, the weld metal that joins the first reinforcing member 5 and the second reinforcing member 6 to the front and back surfaces 4a and 4b of the welded joint portion 4 is also low in cost and high in the same manner as the joint welded portion 4 that is a soft joint. It becomes possible to form efficiently.

FIG. 2A and FIG. 2B are explanatory views showing an example of the welded joint structure 1 of the steel pipe 9 according to the present invention.
As shown to Fig.2 (a), with respect to the steel pipe 9 which has the welded joint structure 1 of this invention, an annular reinforcement is used as the 1st reinforcement material 5 and the 2nd reinforcement material 6, and a circumference joint weld part 4, when the first reinforcing material 5 and the second reinforcing material 6 constrain the compressive strain of the Poisson's ratio that is about to occur in the plate thickness direction of the circumferential joint weld 4 described above. Since the circumferential stress generated in the annular first reinforcing member 5 and the second reinforcing member 6 resists the stress in the radial direction of the steel pipe 9 generated, the restraining effect of the peripheral joint weld 4 is applied to the plate joint. The joint strength of the joint welded portion 4 can be further increased.

  Furthermore, as shown in FIG. 2 (b), if the groove shape of the joint welded portion 4 has a shape of V or V, the relative thickness of the soft portion on the weld joint root side is reduced. As a result, the restraining effect is further enhanced, so that it is possible to omit the second reinforcing material 6 on the root side, that is, the back surface side of the joint welded portion 4 (inner surface side in the case of a steel pipe). In this case, if the backing metal 10 is disposed instead of the second reinforcing member 6 to form the first layer of the welded portion, welding can be performed without any problem.

DESCRIPTION OF SYMBOLS 1 Welded joint structure 2 1st steel material 3 2nd steel material 4 Joint welding part 4a One surface 4b The other surface 5 1st reinforcement member 6 2nd reinforcement member 7 Weld metal 8, 10 Backing metal 9 Steel pipe

Claims (4)

A joint weld that exists between the first steel material, the second steel material, and the first steel material and the second steel material and connects the first steel material and the second steel material in a material axial direction. And a welded joint structure of steel comprising a first reinforcing member for reinforcing the joint welded portion,
The material strength of the weld metal of the joint weld is less than the material strength of either the first steel material or the second steel material,
The first reinforcing material is joined and joined to one surface of the joint welded portion via a weld metal, and the material strength of the first reinforcing material and the material strength of the weld metal are: A welded joint structure for steel, which is smaller than the material strength of any of the first steel and the second steel.   The first steel material and the second steel material are both steel pipes, and the first reinforcing material has an annular outer shape whose inner surface abuts against the outer surface of the joint weld. The welded joint structure of steel materials according to claim 1.   The welded joint structure for steel according to claim 1 or 2, wherein the joint welded portion has a groove having a shape of V shape or V shape.   Furthermore, a second reinforcing material for reinforcing the joint welded portion is provided, the second reinforcing material is joined in contact with the other surface of the joint welded portion, and the material strength of the second reinforcing material is increased. The welded joint structure for steel materials according to any one of claims 1 to 3, wherein the material strength is lower than any material strength of the first steel material and the second steel material.

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