JP3817669B2 - Method of welding structural members and welded joints - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for welding structural members and thick plate structural members in the field of construction and civil engineering, and a welded joint.
[0002]
[Prior art]
Conventionally, when joining structural members, bolt joining and welding joining are performed. In particular, welding is frequently used because it has a minimum number of members and has advantages such as rapid construction and cost competitiveness. However, there is a problem in welding joining that the toughness of a weld heat affected zone (hereinafter referred to as HAZ) is reduced. In particular, it becomes a big problem at a site where high stress is expected when an external force acts on a building, for example, a welded joint between a through diaphragm and a column material.
[0003]
Conventionally, when a diaphragm and a column material are welded at a factory, for example, complete penetration welding is performed with a groove angle of about 30 to 45 degrees on a column side steel plate. At this time, the welded part and its peripheral part are constituted by a high strength weld metal, HAZ or the like. Usually, HAZ often has reduced strength and toughness with respect to the base material (steel material).
[0004]
Therefore, if stress concentration occurs in the vicinity of the weld and a ductile crack occurs from the vicinity of the weld, the property of the ductile crack is almost perpendicular to the stress direction (in this case, the thickness direction), and the strength and toughness. It propagates through a small area.
[0005]
In particular, at the column-diaphragm junction, bending stress is applied in addition to tensile stress. The stress maximum point is generated at a position farther than the diaphragm due to the restraint effect due to the surplus diaphragm and weld metal. For example, in a welded joint having a rhombic groove, the HAZ is generated almost parallel to the groove surface. Or the possibility that the crack propagated along the melting line was high.
[0006]
FIG. 10 is an explanatory view of a modified bead corresponding to the decorative welding shown in the “Cold Forming Square Steel Pipe Design and Construction Manual” (published by Nippon Building Center).
In FIG. 10, 11 is a pillar material, 13 is a backing metal, 20 is a through diaphragm, 30 is a weld metal, and 31 is a decorative weld metal.
As described in the above manual, “When a correction bead is placed in order to correct the shape of the welded toe part after welding, it is usually ...” The main purpose is to modify the shape.
[0007]
FIG. 11 is a perspective view for explaining a welding joining method using a steel material excellent in arrestability disclosed in Japanese Patent Laid-Open No. 2000-158127. In FIG. 11, 11 and 12 are square steel pipes, 20 is a through diaphragm, 21 is a steel material excellent in arrestability, and 2 is an H-shaped steel. As a method for preventing brittle fracture, the weld line is set at an angle of 20 ° or more with respect to the direction of stress, and the propagation of brittle cracks is cut off and stopped by a steel material having excellent arrestability.
[0008]
[Problems to be solved by the invention]
However, the prior art has the following problems. That is, in FIG. 10, if makeup welding corresponding to the surplus portion is inadvertently performed, the base material is cured, and the material may be deteriorated. In other words, since this phenomenon occurs regardless of the strength of the steel sheet, no matter what high-quality, high-strength material is used, the welded part is preceded by breakage, resulting in performance as a high-quality, high-strength material. Could not be fully demonstrated.
[0009]
In addition, even when rolling steel, the material is refined by devising the heat cycle and plastic working without increasing the additive elements, and high strength is achieved. The refined structure is returned to the particle size before the temperature-controlled rolling, and the toughness of the base material is greatly reduced.
[0010]
In addition, in the part welded with the groove, the factor governed by the detail near the weld, that is, the crack propagates along the HAZ and melt line generated almost parallel to the groove surface. A sufficient effect could not be expected only with the material improvement effect.
[0011]
As shown in FIG. 11, the technique in Japanese Patent Laid-Open No. 2000-158127 is a technique in which the weld line is inclined with respect to the stress direction for the purpose of reducing the weld area near the stress concentration area. Since it is geometrically impossible to use this prior art to weld members whose material axis directions do not match, the material axes of each other are orthogonal or other than 0 degrees, as in the case of column and diaphragm welding. However, it could not be used for welding a portion having an angle of. Furthermore, cutting each joint portion at an angle has caused a significant increase in cost due to an extreme decrease in the yield of the steel material and difficult welding.
[0012]
In addition, as a common problem of the welded part, when the high strength part made of the weld metal does not have sufficient surplus or strength, there is a possibility that the crack generated from the vicinity of the softened HAZ usually occurs from the welded metal part. .
The present invention solves the above problems, minimizes the toughness reduction of the base metal, propagates cracks generated in the vicinity of the welded portion in the base material, and propagates cracks in the base material. It is an object of the present invention to provide a welding method and a weld joint for a structural member that can be controlled.
[0013]
[Means for Solving the Problems]
(1) The present invention is a welding method in which a structural member having a groove is welded to at least one member, and the member material having the groove from an open tip on the surface side of the member having the groove. It has the process of sticking a heat-transfer tape to the range of the distance of 5 mm or more in an axial direction, and the process of butt-welding the said groove part by abutting the edge parts which should be welded.
[0014]
(2) In the member having the groove of the above (1), the present invention provides a weld bead (hereinafter referred to as the most distant position) from the surface-side open tip and the surface-side open tip of the member having the groove. The distance from the toe of the first weld bead is 3 mm or more, and the first weld bead is stacked on the heat transfer tape.
[0015]
(3) According to the present invention, in the member having the groove of (1) or (2), a weld bead (lap welded on the first weld bead from the toe of the first weld bead ( Hereinafter, the distance to the toe of the second weld bead is set to 15 mm or less.
[0016]
(4) The present invention is a welded joint portion of a structural member having a groove on at least one member, and from the open tip on the surface side of the member having the groove, the material axis direction of the member having the groove The heat transfer tape is applied to a range of a distance of 5 mm or more, the ends to be welded are butted against each other, and the groove portion is butt welded, so that the welding heat is substantially parallel to the surface of the member having the groove. It has an influence part.
[0017]
Further, (5) the present invention is the member having the groove of (4), wherein the front end of the first weld bead is located farthest from the open end on the surface side and the open end on the surface side. And the first weld bead is stacked on the heat transfer tape.
[0018]
(6) According to the second aspect of the present invention, in the member having the groove of (4) or (5), the second welded from the toe of the first weld bead onto the first weld bead. The distance to the toe of the weld bead is 15 mm or less.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1
FIG. 1 is a cross-sectional view for explaining the structural member welding method according to Embodiment 1 of the present invention step by step. (A) has shown the state which stuck the heat-transfer tape before welding, (b) has shown the state which complete | finished the welding process.
In FIG. 1, 11 is a member having a groove processing (for example, a square steel pipe flange), 13 is a backing metal, 20 is a mating member (for example, a diaphragm) to be butt welded, 30 is a weld metal, and 31 is a heat transfer tape. A weld metal that has a thermal effect on the member 11, 40 is a weld heat affected zone 1 (HAZ1), 41 is a weld heat affected zone 2 (HAZ2), 42 is a melt wire, and 60 is a heat transfer tape.
[0020]
Fig.1 (a) is a figure which shows the state which abutted the surface to be welded of the members 11 and 20 which should be welded, and affixed the heat-transfer tape 60 before welding. In this figure, the heat transfer tape 60 is affixed in the direction of the material axis of the member having the groove so as to cover a position a predetermined distance L away from the open tip on the surface side of the member having the groove.
FIG. 1B shows a diagram in which the welding process for constructing the weld metals 30 and 31 is completed. Here, at least a part of the weld metal 31 having a thermal effect via the heat transfer tape is placed on the heat transfer tape. A HAZ 140 is generated along the groove surface 110, and a HAZ 2 41 substantially parallel to the surface of the member 11 is generated around the lower portion of the heat transfer tape 60, which is a distance L from the K point. ing. Therefore, when a force such as out-of-plane bending is applied to the welded portion with respect to this structural member, cracks are generated in the region where the HAZ 2 is generated and in the vicinity of the member surface of the melt line 42. Note that all and part of the weld metal 31 and the heat transfer tape 60 may be removed after the HAZ2 is generated.
[0021]
This crack propagates immediately after penetrating HAZ2 41 in the plate thickness direction to the part (sound part of the base material) that is not affected by the welding heat of the member 11 having the groove, and depends on the characteristics of the base material. The crack is controlled.
Here, the application position of the heat transfer tape 60 is recognized as long as it is a distance of 5 mm or more from the K point. However, since the cost is high, it is desirable to be about 3 times the plate thickness or less.
If the heat transfer tape 60 is capable of transferring heat to the base material of the member 11 having the groove and generating the HAZ2 41 around the lower part up to the sticking tip position, the heat transfer tape 60 itself Any material may be used. For example, a heat-resistant tape (ultra-thin glass fiber tape or the like), a heat-resistant steel plate, a ceramic plate, or the like can be used as appropriate.
In addition, the same effect can be recognized when the heat transfer tape 60 is applied even after the weld metal 30 is applied. Further, a part of the weld metal 31 may be applied after the heat transfer tape 60 is pasted, and then the weld metal 30 may be applied.
[0022]
Here, in order to prevent a weld bead having a toe at a position farthest from the open tip on the surface side of the member having a groove from being formed as a single bead, the weld bead that is lap welded immediately above the weld bead The distance B between the toes is controlled to be 15 mm or less. If this distance is 8 mm or less, the effect is further enhanced.
In order to easily obtain the reheating effect by welding, a weld bead having a toe at the position farthest from the open tip on the surface side in a member having a groove, and a weld bead that is laminated and welded immediately above the weld bead are applied. It is desirable not to leave too much time interval. Preferably, the latter weld bead is applied while the temperature of the former weld bead is 50 ° C. or higher.
[0023]
The feature of the first embodiment is that the heat transfer tape 60 is applied before the welding process applied to the groove portion, and when the heat transfer tape 60 is applied, the surface side of the member having the groove The distance L from the open tip can be determined with high accuracy, and the sticking can be performed reliably. Further, the state of HAZ2 41 generated by the weld metal 31 and the heat transfer tape 60 is an extremely important factor for controlling cracks generated by stress applied to the welded portion, and these are set with high accuracy. It has a big meaning.
[0024]
Embodiment 2
The feature of the second embodiment is that, in the first embodiment, the weld bead 31 is applied only to a position retracted from the covering range L by the heat transfer tape 60.
This is because the heat conduction by the heat transfer tape 60 can generate the HAZ 241 over almost the entire periphery of the heat transfer tape 60 even when a part of the heat transfer tape 60 has heat input by welding. However, since the HAZ 241 needs to be reliably generated even when L is the minimum, the toe position of the weld metal 31 needs to be 3 mm or more from the open tip K point.
[0025]
FIG. 2 is an explanatory diagram when attention is paid to the cross-sectional shape of the weld bead in the method for welding structural members of the present invention. 311 is the first weld bead of the weld bead 31, 312 is the second weld bead, 313 is the third weld bead, K is the open end on the surface side, and A is from the K point to the toe of the first bead. The distance, B, is the distance between the toe of the first weld bead and the toe of the second weld bead.
Moreover, FIG. 3 is explanatory drawing when paying attention to the welding heat influence part in the welding method of the structural member of this invention. Reference numeral 40 denotes a welding heat affected zone 1 (HAZ1) along the groove surface, and 41 denotes a weld heat affected zone 2 (HAZ2) substantially parallel to the member surface.
2 and 3 are indicated according to FIG.
[0026]
Embodiment 3
In order to confirm the effect of the present invention, the following experiment 1 was conducted.
Assuming that the crack initiation point is the weld bead toe at the position farthest from the open tip on the surface side in the member having a groove, the surface of the test piece is sampled to be -1 mm from the member surface. A surface notch (2 mmV notch, indicated by point C in FIG. 4) is made in the Charpy impact test piece 50. FIG. 4 shows the state, and FIG. 5 is an explanatory view showing the notch position C of the Charpy test piece 50. The notches were provided at positions where the distance a from the open tip (point K) on the surface side of the member having a groove was 2 mm, 5 mm, 10 mm, and 15 mm. Here, the distance a is a distance from the weld joint portion toward the outside in the material axis direction of the member having a groove.
[0027]
The Charpy impact test results at 0 ° C. are shown in FIG. 6 and FIG.
In FIG. 6, the horizontal axis represents the distance a from the point K, and the vertical axis represents the absorbed energy at the fracture surface transition temperature of each weld.
FIG. 6 shows that the toughness is increased when the distance a from the point K is 5 mm or more. The distance a is preferably about 3 times or less the thickness of the member from the viewpoint of welding cost.
[0028]
FIG. 7 shows the absorbed energy at the fracture surface transition temperature, with the horizontal axis indicating the distance B from the toe of the first weld bead to the toe of the second weld bead that is lap welded onto the first weld bead. The ratio (toughness reduction rate) when the maximum value is 1 is taken on the vertical axis.
From FIG. 7, it was clarified that when the distance B between the toes is 15 mm or less, the absorbed energy can be 90% or more of the maximum value, and the toughness is not lowered. Further, it has been found that the effect becomes large when the distance B is 8 mm or less.
[0029]
Furthermore, in the welding between the column material and the diaphragm at the column beam joint, the stress maximum point is usually farther than the diaphragm (for example, about 3 t) due to the height of the weld bead and the restraint effect of the diaphragm. However, it has been found that the presence of the weld bead of the present invention improves the toughness of the welded portion and can further enhance the safety against cracking from the vicinity of the open tip. This effect can be similarly expected even in the case of a roll column or a press column in which the column material is cold worked at the corners.
Furthermore, if the weld bead surface is finished smoothly, higher safety can be obtained.
[0030]
In the second weld bead that is lap welded on the first weld bead that is farthest from the open tip on the surface side of the member having a groove, the weld heat affected zone has a reheat effect by welding. In order to obtain, it is desirable to apply immediately after welding of the first weld bead.
Preferably, the second weld bead is welded while the temperature of the first weld bead is 50 ° C. or higher.
[0031]
Embodiment 4
Furthermore, in order to confirm the effect of the present invention, the following experiment 2 was performed.
The application position of the heat transfer tape 60 is set to a minimum distance 5 mm of L, and the distance d from the open end (point K) on the surface side of the member having a groove from the toe end of the first weld bead 311 is 2 mm, 3 mm. A specimen with a thickness of 5 mm was produced. A schematic view of this cross section is shown in FIG.
In the same manner as in the third embodiment, a Charpy impact test piece having a surface notch (2 mmV notch) was taken from this test body so that the surface of the test piece was positioned at -1 mm from the member surface. At this time, the notch position corresponds to the distance d.
The test results are shown in FIG. In FIG. 9, the toughness reduction rate converted to an impact test value of 1 when d is 5 mm is shown on the vertical axis and d on the horizontal axis.
As a result, it was found that the toughness value increased rapidly when d was 2 to 3 mm or more.
[0032]
Embodiment 5
A test body was manufactured using a member having a groove as a square steel pipe and another structural member butt welded thereto as a diaphragm, and the same test as in the third embodiment was performed.
As a result, the same effect as in the case of Embodiment 3 was confirmed. The same effect was confirmed when the member having a groove was a circular steel pipe, a welded assembly four-sided box, and a beam flange.
In addition, a full-scale specimen was manufactured in the same manner using a high-strength steel for construction as the material of the square steel pipe, and the same test was performed. As a result, it was confirmed that high toughness was obtained even in the welded portion.
[0033]
【The invention's effect】
The present invention can obtain the following effects.
1) The welding heat affected zone 2 (HAZ2) substantially parallel to the surface of the member having a groove can be controlled and generated.
2) By 1), it is possible to avoid the propagation of a weld heat affected zone 1 (HAZ1) generated substantially parallel to the groove or a crack along the melt line.
3) Surface cracks generated in the welded portion can be propagated in the base material, and the strength reduction of the joint can be minimized.
4) Therefore, since the behavior based on the mechanical properties of the base material is exhibited even after the occurrence of a crack, it is possible to prevent damage to the welded structural member.
5) The welded joint that sufficiently exhibits the performance of the high-quality and high-strength steel sheet can more reliably prevent the strength of the joint from being lowered and breakage, and provide a more reliable welded structure. .
[Brief description of the drawings]
FIG. 1 is a cross-sectional view for explaining a structural member welding method according to Embodiment 1 of the present invention step by step.
FIG. 2 is a cross-sectional explanatory view of a welded joint in the method for welding structural members of the present invention.
FIG. 3 is a cross-sectional explanatory view of a weld joint in the method for welding structural members of the present invention.
4 is a schematic diagram showing a sampling position of a Charpy test piece based on Embodiment 3. FIG.
FIG. 5 is an explanatory view showing notch positions of a Charpy test piece.
FIG. 6 is a chart showing the relationship between distance a and absorbed energy in Embodiment 3 of the present invention.
FIG. 7 is a chart showing the relationship between distance B and absorbed energy in Embodiment 3 of the present invention.
FIG. 8 is a schematic diagram showing a sampling position of a Charpy test piece in Embodiment 4 of the present invention.
FIG. 9 is a chart showing the relationship between distance d and toughness reduction rate in Embodiment 4 of the present invention.
FIG. 10 is a cross-sectional explanatory view illustrating decorative welding in a conventional welding technique.
FIG. 11 is an explanatory diagram for explaining a conventional welding method for building structural members.
[Explanation of symbols]
11: a member having a groove, 110: a groove, 13: a backing metal, 20: a mating member to be butt welded, 30: a weld metal, 31: a weld metal having a thermal effect via a heat transfer tape, 311: First weld bead, 312: Second weld bead, 313: Third weld bead, 40: Weld heat affected zone 1 (HAZ1), 41: Weld heat affected zone 2 (HAZ2), 42: Melting line, 50 : Charpy test piece, 60: Heat transfer tape, K: Open tip on the surface side of a member having a groove, a: Distance from K point to notch position, A: From K point to first weld bead toe Distance, B: Distance between the toe of the first weld bead and the toe of the second weld bead, L: Distance from the K point to the end of the heat transfer tape, C: Notch position.

Claims (6)

A welding method for welding and joining a structural member having a groove in at least one member,
Applying the heat transfer tape from the open tip on the surface side of the member having the groove to a range of a distance of 5 mm or more in the material axis direction of the member having the groove;
And a step of butt welding the groove portions by butting the ends to be welded to each other. In the member having the groove,
The distance between the open tip on the surface side and the toe end of the first weld bead farthest from the open tip on the surface side is 3 mm or more, and the first weld bead is the heat transfer tape. The method for welding a structural member according to claim 1, wherein the method is welded on top. In the member having the groove,
The distance from the toe of the first weld bead to the toe of the second weld bead that is lap welded onto the first weld bead is 15 mm or less. 2. A method for welding structural members according to 2. A welded joint of a structural member having a groove in at least one member,
A heat transfer tape is applied from the open tip on the surface side of the member having the groove to a range of a distance of 5 mm or more in the material axis direction of the member having the groove, and the ends to be welded are butted together. A welded joint portion of a structural member having a welding heat affected zone substantially parallel to the surface of the member having the groove by butt welding the tip portion. In the member having the groove,
The distance between the open tip on the surface side and the toe end of the first weld bead farthest from the open tip on the surface side is 3 mm or more, and the first weld bead is the heat transfer tape. The welded joint portion of the structural member according to claim 4, wherein the weld joint portion is formed on the top. In the member having the groove,
The distance from the toe of the first weld bead to the toe of the second weld bead lap-welded on the first weld bead is 15 mm or less. A welded joint portion of the structural member according to claim 5.

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