JP2023162133A - Method for suppressing fatigue crack initiation of weld zone and method for manufacturing weld joint - Google Patents

Method for suppressing fatigue crack initiation of weld zone and method for manufacturing weld joint Download PDF

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JP2023162133A
JP2023162133A JP2023067776A JP2023067776A JP2023162133A JP 2023162133 A JP2023162133 A JP 2023162133A JP 2023067776 A JP2023067776 A JP 2023067776A JP 2023067776 A JP2023067776 A JP 2023067776A JP 2023162133 A JP2023162133 A JP 2023162133A
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lane
weld
suppressing
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impact
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芳史 高木
Yoshifumi Takagi
隆洋 ▲崎▼本
Tahahiro Sakimoto
恒久 半田
Tsunehisa Handa
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JFE Steel Corp
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Abstract

To provide a method for suppressing fatigue crack initiation of a weld zone to improve fatigue strength of a thick material, by processing struck marks corresponding to two lanes in which no fatigue crack occurs, and a method for manufacturing a weld joint that is executed using the method.SOLUTION: In a method for suppressing fatigue crack initiation of a weld zone, a base material part near a weld toe is struck continuously along weld bead to form a first lane that is a belt-like struck mark and further the outside of the base material part is struck to form a second lane that is a belt-like struck mark. Further, it is preferable that when a distance between the weld toe and the struck mark that is the first lane is defined as L1 and a distance between the struck mark that is the first lane and the struck mark that is the second lane is defined as L2, a relational expression of 0.0 mm<L1≤1.0 mm, 0.0 mm≤L2≤2.0 mm is satisfied.SELECTED DRAWING: Figure 1

Description

本発明は、溶接部の疲労亀裂発生抑制方法および溶接継手の製造方法に関する。特に、母材部にハンマーピーニングによる打撃処理を２レーン実施して、大きな圧縮残留応力を付与し、例えば、洋上風力分野のモノパイルにおける溶接部の疲労亀裂の発生を抑制し、疲労強度を向上させる方法に関する。さらに、その方法を用いて施工される溶接継手の製造方法に関する。 The present invention relates to a method for suppressing the occurrence of fatigue cracks in welded parts and a method for manufacturing welded joints. In particular, two lanes of hammer peening are applied to the base metal to impart large compressive residual stress, thereby suppressing the occurrence of fatigue cracks in welds in monopiles used in the offshore wind field, and improving fatigue strength. Regarding the method. Furthermore, the present invention relates to a method for manufacturing a welded joint constructed using the method.

近年、洋上風力分野では建造コスト低減のため、モノパイル形式が検討されている。また、発電コストを下げ、発電効率を高めるために発電機サイズが大型化し、それを支えるモノパイルも大型化している。このモノパイルに使用する鋼板の板厚は、例えば、３０～１００ｍｍの範囲である。しかしながら、モノパイルを運搬する敷設船の積載量に制限があるため、モノパイルへの高強度材適用による減厚化の需要が高まっている。高強度材適用により、現行の設計応力より高応力設計が可能になるが、その場合モノパイルの突合せ円周溶接部の疲労強度低下が懸念される。 In recent years, monopile type wind turbines have been considered in the field of offshore wind power in order to reduce construction costs. Furthermore, in order to lower power generation costs and increase power generation efficiency, generators are becoming larger, and the monopiles that support them are also becoming larger. The thickness of the steel plate used for this monopile is, for example, in the range of 30 to 100 mm. However, because there is a limit to the loading capacity of the laying vessels that transport monopiles, there is a growing demand for thinning monopiles by applying high-strength materials. The application of high-strength materials will enable a design with a higher stress than the current design stress, but in this case there is a concern that the fatigue strength of the butt circumferential weld of the monopile will decrease.

溶接部の疲労強度向上技術として、特許文献１には、母材部を打撃するハンマーピーニング方法が開示されている。この特許文献１に記載のハンマーピーニング方法は、打撃痕の最大深さが０．２ｍｍ以上としている。しかしながら、特許文献１の方法では、打撃痕の幅が狭く、打撃痕の深さが深くなるほど打撃痕形成による応力集中のため、打撃痕により疲労亀裂が発生しうるという問題があった。 As a technique for improving the fatigue strength of welded parts, Patent Document 1 discloses a hammer peening method in which a base metal part is hit. In the hammer peening method described in Patent Document 1, the maximum depth of the impact marks is 0.2 mm or more. However, the method of Patent Document 1 has a problem in that the narrower the width of the impact mark and the deeper the depth of the impact mark, the more stress is concentrated due to the formation of the impact mark, which may cause fatigue cracks to occur due to the impact mark.

特許第５９５５７５２号公報Patent No. 5955752

従来の母材の打撃ハンマーピーニング方法は、対象とする溶接継手の板厚の増加とともに打撃痕の深さを際限なく深くすることができるため、打撃痕から疲労亀裂が発生する可能性がある。そこで、疲労亀裂を発生させずに疲労強度を向上させる打撃痕の施工方法を模索した。 In the conventional method of impact hammer peening of base metals, the depth of the impact marks can be made infinitely deeper as the plate thickness of the target welded joint increases, so there is a possibility that fatigue cracks will occur from the impact marks. Therefore, we searched for a method to create impact marks that would improve fatigue strength without causing fatigue cracks.

本発明は、従来の技術の問題点を解消し、疲労亀裂を発生させない打撃痕を２レーン分処理することで、厚肉材の疲労強度を向上させる方法およびその方法を用いて施工される溶接継手の製造方法を提供することを目的とする。 The present invention solves the problems of conventional technology and improves the fatigue strength of thick-walled materials by treating two lanes of impact marks that do not cause fatigue cracks, and the welding performed using the method. The purpose of this invention is to provide a method for manufacturing a joint.

本発明者らは、前述の目的を達成するため、鋭意検討した。厚肉材の突合せ溶接継手から試験片を採取し、ハンマーピーニング処理により１レーン分の母材打撃を処理した試験片と２レーン分処理した試験片を用いた疲労試験を実施した。それらの疲労試験結果を比較することにより、２レーン分処理した場合の母材打撃ハンマーピーニングにより疲労強度が向上することを新たに知見した。 The present inventors have made extensive studies to achieve the above-mentioned objective. Test pieces were taken from butt-welded joints of thick-walled materials, and a fatigue test was conducted using a test piece that had been subjected to one lane of base metal impact by hammer peening treatment and a test piece that had been treated for two lanes. By comparing these fatigue test results, we newly found that fatigue strength is improved by base metal impact hammer peening when two lanes are processed.

本発明は、かかる知見に基づき、さらに検討を加えて完成されたものであって、本発明の要旨は、次のとおりである。
〔１〕溶接部の疲労亀裂発生を抑制する方法であって、前記溶接部の溶接ビードに沿って連続的に溶接止端部近傍の母材部を打撃して帯状の打撃痕である第１のレーンを形成し、さらにその外側を打撃して帯状の打撃痕である第２のレーンを形成することを特徴とする溶接部の疲労亀裂発生抑制方法。
〔２〕前記〔１〕において、前記溶接止端部と前記第１のレーンの打撃痕との距離をＬ１とし、前記第１のレーンの打撃痕と前記第２のレーンの打撃痕との距離をＬ２としたときに、０．０ｍｍ＜Ｌ１≦１．０ｍｍ、０．０ｍｍ≦Ｌ２≦２．０ｍｍであることを特徴とする溶接部の疲労亀裂発生抑制方法。
〔３〕前記〔１〕または〔２〕において、前記打撃痕の最大深さ（ＤP）と幅（ＷP）の積（ＤP×ＷP）が３．０～５．０ｍｍ2であることを特徴とする溶接部の疲労亀裂発生抑制方法。
〔４〕前記〔１〕または〔２〕において、前記溶接部の母材部が板厚３０ｍｍ以上の突合せ溶接継手であることを特徴とする溶接部の疲労亀裂発生抑制方法。
〔５〕前記〔３〕において、前記溶接部の母材部が板厚３０ｍｍ以上の突合せ溶接継手であることを特徴とする溶接部の疲労亀裂発生抑制方法。
〔６〕前記〔１〕または〔２〕に記載の溶接部の疲労亀裂発生抑制方法を用いて施工されることを特徴とする溶接継手の製造方法。
〔７〕前記〔３〕に記載の溶接部の疲労亀裂発生抑制方法を用いて施工されることを特徴とする溶接継手の製造方法。
〔８〕前記〔４〕に記載の溶接部の疲労亀裂発生抑制方法を用いて施工されることを特徴とする溶接継手の製造方法。
〔９〕前記〔５〕に記載の溶接部の疲労亀裂発生抑制方法を用いて施工されることを特徴とする溶接継手の製造方法。 The present invention was completed based on such knowledge and further studies, and the gist of the present invention is as follows.
[1] A first method for suppressing the occurrence of fatigue cracks in a weld, in which the base metal near the weld toe is continuously struck along the weld bead of the weld to form a band-shaped impact mark. 1. A method for suppressing the occurrence of fatigue cracks in a welded joint, the method comprising: forming a lane, and then striking the outside of the lane to form a second lane, which is a band-shaped impact mark.
[2] In [1] above, the distance between the weld toe and the impact mark on the first lane is L1, and the distance between the impact mark on the first lane and the impact mark on the second lane. A method for suppressing the occurrence of fatigue cracks in a weld, characterized in that, where L2 is 0.0 mm<L1≦1.0 mm, and 0.0 mm≦L2≦2.0 mm.
[3] In [1] or [2] above, the product (D P ×W P ) of the maximum depth (D P ) and width (W P ) of the impact mark is 3.0 to 5.0 mm 2 A method for suppressing the occurrence of fatigue cracks in welded parts.
[4] The method for suppressing the occurrence of fatigue cracks in a welded part according to [1] or [2], wherein the base metal part of the welded part is a butt welded joint with a plate thickness of 30 mm or more.
[5] The method for suppressing the occurrence of fatigue cracks in a weld according to [3] above, wherein the base metal portion of the weld is a butt welded joint with a plate thickness of 30 mm or more.
[6] A method for producing a welded joint, characterized in that it is constructed using the method for suppressing the occurrence of fatigue cracks in a welded joint according to [1] or [2] above.
[7] A method for manufacturing a welded joint, characterized in that it is constructed using the method for suppressing the occurrence of fatigue cracks in a welded joint according to [3] above.
[8] A method for manufacturing a welded joint, characterized in that it is constructed using the method for suppressing the occurrence of fatigue cracks in a welded joint according to [4] above.
[9] A method for producing a welded joint, characterized in that it is constructed using the method for suppressing the occurrence of fatigue cracks in a welded joint according to [5] above.

本発明の２レーン分の母材打撃によれば、１レーン分の母材打撃よりも厚肉材の疲労強度向上が達成でき、産業上格段の効果を奏する。 According to the base material striking for two lanes of the present invention, it is possible to achieve an improvement in the fatigue strength of thick-walled materials compared to the base material striking for one lane, resulting in a significant industrial effect.

本発明に係る２レーンのハンマーピーニング処理方法を示す模式図である。FIG. 2 is a schematic diagram showing a two-lane hammer peening treatment method according to the present invention. 本発明に係るハンマーピーニング処理に用いるチッパーの先端部分の一例で、Ｘ、Ｙ、Ｚ方向を説明する斜視図である。FIG. 2 is a perspective view illustrating the X, Y, and Z directions of an example of the tip portion of the chipper used in the hammer peening process according to the present invention. 本発明に係るハンマーピーニング処理に用いるチッパーの先端部分の一例で、（ａ）はＸＺ断面、（ｂ）はＹＺ断面の形状を説明する模式図である。1A is an example of a tip portion of a chipper used in the hammer peening process according to the present invention, and FIG. ４点曲げ疲労試験方法を説明する模式図である。FIG. 2 is a schematic diagram illustrating a four-point bending fatigue test method.

本発明は、溶接止端部近傍の母材部を２レーン分連続してチッパーで打撃し、溶接止端部に圧縮残留応力を導入して１レーン分の打撃よりも溶接継手の疲労強度を向上させる方法である。 In the present invention, the base metal near the weld toe is continuously hit by a chipper for two lanes, and compressive residual stress is introduced into the weld toe, thereby increasing the fatigue strength of the welded joint more than hitting for one lane. This is a way to improve.

以下、本発明の実施態様について、説明する。 Embodiments of the present invention will be described below.

［２レーン打撃］
前述したように、本発明は、溶接継手の疲労強度を向上させるために、２レーン分の打撃痕を形成して、溶接止端部近傍に圧縮残留応力を導入するものである。具体的には、溶接部の溶接ビードに沿って連続的に溶接止端部近傍の母材部を打撃して帯状の打撃痕である第１のレーンを形成し、さらにその外側を打撃して帯状の打撃痕である第２のレーンを形成するものである。ここで、溶接止端部と第１のレーンの打撃痕との距離をＬ１とし、第１のレーンの打撃痕と第２のレーンの打撃痕との距離をＬ２としたときに、０．０ｍｍ＜Ｌ１≦１．０ｍｍ、０．０ｍｍ≦Ｌ２≦２．０ｍｍとすることが好ましい。また、打撃痕の最大深さ（ＤP）と幅（ＷP）の積（ＤP×ＷP）が３．０～５．０ｍｍ2であることが好ましい。 [2 lane batting]
As described above, in order to improve the fatigue strength of a welded joint, the present invention forms impact marks for two lanes and introduces compressive residual stress near the weld toe. Specifically, the base metal near the weld toe is continuously struck along the weld bead of the weld to form a first lane, which is a belt-shaped strike mark, and the outside of the first lane is further struck. This forms a second lane, which is a band-shaped impact trace. Here, when the distance between the weld toe and the impact marks on the first lane is L1, and the distance between the impact marks on the first lane and the impact marks on the second lane is L2, 0.0 mm It is preferable that <L1≦1.0 mm and 0.0 mm≦L2≦2.0 mm. Further, it is preferable that the product (D P ×W P ) of the maximum depth (D P ) and width (W P ) of the impact mark is 3.0 to 5.0 mm 2 .

なお、圧縮残留応力は、ＡＳＴＭ Ｅ８３７規格（穿孔法）に基づいて測定される。この穿孔法による残留応力測定とは、試験体に穴を開けて、応力が解放される前後の変形量を評価することで残留応力を求める計測手法である。 Note that the compressive residual stress is measured based on the ASTM E837 standard (perforation method). Residual stress measurement using the drilling method is a measurement method for determining residual stress by drilling a hole in a test specimen and evaluating the amount of deformation before and after the stress is released.

ここで、残留応力としては、－４００～－２００ＭＰａが疲労亀裂の発生を抑制するには好ましい範囲である。 Here, the preferable range of residual stress is -400 to -200 MPa to suppress the occurrence of fatigue cracks.

以下に、図１に基づいて説明する。 This will be explained below based on FIG.

まず、溶接止端部３と第１レーンの打撃痕４との距離（Ｌ１）が０．０ｍｍより大で１．０ｍｍ以下であることが好ましい。すなわち、母材（以下、「母材部」ともいう。）１を突合せ溶接して形成した溶接継手の溶接金属２と母材１との境界である溶接止端部３から打撃ピンであるチッパーの先端部で母材１と接する位置までの距離（Ｌ１）が１．０ｍｍ以下であることが好ましい。距離（Ｌ１）が１．０ｍｍを超えると、第１レーンの打撃痕４が溶接止端部３から離れてしまい、溶接止端部３近傍の圧縮残留応力が導入され難くなり、溶接継手の疲労強度向上とはならないからである。また、チッパーの打撃は、溶接止端部３に当たらないようにするために、距離（Ｌ１）は、０．０ｍｍより大きいことが好ましいことから、距離（Ｌ１）は、０．０ｍｍ＜Ｌ１≦１．０ｍｍとすることが好ましい。 First, it is preferable that the distance (L1) between the weld toe 3 and the impact trace 4 of the first lane is greater than 0.0 mm and less than 1.0 mm. That is, a chipper, which is a striking pin, is connected to a weld toe 3 which is a boundary between a weld metal 2 of a weld joint formed by butt welding base metals (hereinafter also referred to as "base metal parts") 1 and base metals 1. It is preferable that the distance (L1) from the tip of the base material 1 to the position in contact with the base material 1 is 1.0 mm or less. If the distance (L1) exceeds 1.0 mm, the impact mark 4 of the first lane will be separated from the weld toe 3, making it difficult to introduce compressive residual stress near the weld toe 3, and causing fatigue of the weld joint. This is because the strength will not be improved. In addition, in order to prevent the chipper from hitting the weld toe 3, the distance (L1) is preferably larger than 0.0 mm, so the distance (L1) is 0.0 mm<L1≦ It is preferable to set it to 1.0 mm.

なお、ハンマーピーニング処理を手動で行う場合には、事前にマーカーを罫書いておくことが好ましい。 In addition, when performing the hammer peening process manually, it is preferable to write a marker in advance.

次に、第１レーンの打撃痕４の外側を打撃して帯状の第２レーンの打撃痕５を形成する。このときの第１レーンの打撃痕４と第２レーンの打撃痕５との距離（Ｌ２）は、０．０～２．０ｍｍであるのが好ましい。距離（Ｌ２）の場合は、第１レーンの打撃痕４に当たっても構わないので、０．０ｍｍ以上であれば良い。また２．０ｍｍを超えると、第２レーンの打撃痕５が溶接止端部３から離れてしまい、溶接止端部３近傍の圧縮残留応力が導入され難くなり、溶接継手の疲労強度向上とはならないからである。 Next, the outside of the impact trace 4 of the first lane is struck to form a band-shaped impact trace 5 of the second lane. At this time, the distance (L2) between the impact marks 4 on the first lane and the impact marks 5 on the second lane is preferably 0.0 to 2.0 mm. In the case of the distance (L2), it does not matter if it hits the impact trace 4 on the first lane, so it is sufficient if it is 0.0 mm or more. Moreover, if it exceeds 2.0 mm, the impact marks 5 of the second lane will be separated from the weld toe 3, making it difficult to introduce compressive residual stress near the weld toe 3, which will not improve the fatigue strength of the welded joint. This is because it will not happen.

次に、打撃痕４および打撃痕５のどちらも、それぞれの打撃痕の深さ方向断面積である打撃痕の最大深さ（ＤP）と打撃痕の幅（ＷP）との積（ＤP×ＷP）が３．０～５．０ｍｍ2であることが好ましい。打撃痕の最大深さ（ＤP）と幅（ＷP）との積（ＤP×ＷP）が３．０ｍｍ2未満では、十分な圧縮残留応力の付与ができないからであり、５．０ｍｍ2を超えると、圧痕箇所から疲労亀裂が発生するからである。より好ましくは、その積（ＤP×ＷP）が３．０～４．０ｍｍ2である。 Next, for both impact marks 4 and 5, the product ( D P ×W P ) is preferably 3.0 to 5.0 mm 2 . This is because if the product (D P ×W P ) of the maximum depth (D P ) and width (W P ) of the impact mark is less than 3.0 mm 2 , sufficient compressive residual stress cannot be applied; This is because if it exceeds 2 , fatigue cracks will occur from the indentation locations. More preferably, the product (D P ×W P ) is 3.0 to 4.0 mm 2 .

［溶接継手の製造方法、溶接方法］
次に、本発明の溶接継手の製造方法、溶接方法について具体例を挙げて説明する。 [Manufacturing method and welding method for welded joints]
Next, the manufacturing method and welding method of the welded joint of the present invention will be explained by giving specific examples.

母材１となる鋼板の鋼種としては、例えば、ＳＭ４９０が挙げられ、引張強度は４００ＭＰａ～６００ＭＰａの範囲が好ましい。 Examples of the steel type of the steel plate serving as the base material 1 include SM490, and the tensile strength is preferably in the range of 400 MPa to 600 MPa.

板厚は、本発明の目的であるモノパイル用に適した厚鋼板が対象であり、具体的には、３０ｍｍ以上が好ましい。より好ましくは、５０～１００ｍｍである。 The plate thickness is preferably a thick steel plate suitable for monopile use, which is the object of the present invention, and specifically, 30 mm or more is preferable. More preferably, it is 50 to 100 mm.

その母材を、入熱０．６～１．０ｋＪ／ｍｍの溶接条件で、炭酸ガスを用いたガスシールドアーク溶接により両面多層溶接し、突合せ溶接継手を作製する。 The base metal is welded in multiple layers on both sides by gas-shielded arc welding using carbon dioxide under welding conditions of a heat input of 0.6 to 1.0 kJ/mm to produce a butt-welded joint.

［ハンマーピーニング処理方法］
得られた突合せ溶接継手を、ハンマーピーニング処理方法により溶接止端部近傍の母材部１に圧縮残留応力を付与する。 [Hammer peening treatment method]
The obtained butt welded joint is subjected to a hammer peening treatment method to impart compressive residual stress to the base metal portion 1 near the weld toe.

上述の溶接継手を形成した後、図１に示すように、溶接止端部３近傍の母材部１を打撃（ピーニング）して、帯状の第１レーンの打撃痕４を形成し、その外側に帯状の第２レーンの打撃痕５を形成する。その範囲は、前述したように、溶接止端部３と第１レーンの打撃痕４との距離（Ｌ１）が０．０ｍｍより大きく１．０ｍｍ以下であり、第１レーンの打撃痕４と第２レーンの打撃痕５との距離（Ｌ２）は、０．０～２．０ｍｍであるのが好ましい。また、それぞれの打撃痕の最大深さ（ＤP）と幅（ＷP）の積（ＤP×ＷP）が３．０～５．０ｍｍ2の範囲とすることが好ましい。この範囲を外れると、圧縮残留応力の導入範囲が小さく、溶接止端部３からの疲労亀裂発生防止効果を発揮することができない。ここで、残留応力は、－４００～－２００ＭＰａの範囲となるように処理を行う。 After forming the above-mentioned welded joint, as shown in FIG. 1, the base material 1 near the weld toe 3 is hit (peened) to form a band-shaped first lane of impact marks 4, and the outside thereof is A band-shaped second lane impact mark 5 is formed on the second lane. As described above, the range is such that the distance (L1) between the weld toe 3 and the impact mark 4 of the first lane is greater than 0.0 mm and 1.0 mm or less, and the distance (L1) between the weld toe 3 and the impact mark 4 of the first lane is The distance (L2) between the two lanes of impact marks 5 is preferably 0.0 to 2.0 mm. Further, it is preferable that the product (D P ×W P ) of the maximum depth (D P ) and width (W P ) of each impact mark is in the range of 3.0 to 5.0 mm 2 . Outside this range, the introduction range of compressive residual stress is small, and the effect of preventing fatigue cracks from the weld toe 3 cannot be exhibited. Here, the treatment is performed so that the residual stress is in the range of -400 to -200 MPa.

［チッパー］
打撃ツールであるチッパーは、４角柱の下端部を半円弧状に湾曲した曲面を呈するものを使用し、その円弧状の曲面で前述の打撃痕の領域を打撃することが好ましい。チッパーの先端部分の形状は、球形、矩形状、あるいはそれに準じた形状のものを用いても構わない。また、その先端部分の厚さ（幅）は、１．０～１０．０ｍｍの範囲が好ましい。 [Chipper]
It is preferable to use a chipper, which is a hitting tool, having a curved surface in which the lower end of a square prism is curved into a semi-circular arc, and to hit the area of the impact marks with the arc-shaped curved surface. The shape of the tip portion of the chipper may be spherical, rectangular, or similar. Further, the thickness (width) of the tip portion is preferably in the range of 1.0 to 10.0 mm.

チッパーの先端形状の一例を図２および図３に示す。図２は、Ｘ方向が打撃の進行方向と直角な方向（溶接線方向に直角な方向）、Ｙ方向が打撃の進行方向（溶接線方向に平行な方向）と定義した場合のＸ方向、Ｙ方向およびＺ方向を説明する斜視図である。図３（ａ）は、チッパーの先端部が、チッパー進行方向（Ｙ方向）に対して直角となる断面（ＸＺ断面）の図であり、図３（ｂ）は、チッパー進行方向（Ｙ方向）に対して平行となる断面（ＹＺ断面）の図である。ここに示すチッパーの一例では、ＸＺ断面の先端部の厚さ（幅）がａ（ｍｍ）の長さで、曲率半径がｒ（ｍｍ）の円弧状の外周部を有しており、かつＹＺ断面の先端部は、長さｂ（ｍｍ）の蒲鉾形状を有している。上記のＸＺ断面の長さａおよびＹＺ断面の長さｂは、ともに１．０～１０．０ｍｍの範囲が好ましい。さらに、５．０～９．５ｍｍの範囲がより好ましい。また、上記の曲率半径ｒは、１．０～１０．０ｍｍが好ましい。１．０ｍｍ未満の場合、溶接止端部に応力集中が発生し易い変形が形成されやすく、１０．０ｍｍ超の場合、打撃の際のチッパーと溶接止端部との接触面積が大きくなり過ぎ、溶接止端部に十分な圧縮残留応力を導入することが難しくなるからである。 An example of the tip shape of the chipper is shown in FIGS. 2 and 3. Figure 2 shows the X direction, Y It is a perspective view explaining direction and Z direction. FIG. 3(a) is a cross-sectional view (XZ cross-section) in which the tip of the chipper is perpendicular to the chipper traveling direction (Y direction), and FIG. 3(b) is a diagram of the chipper traveling direction (Y direction). It is a figure of the cross section (YZ cross section) parallel to . In the example of the chipper shown here, the thickness (width) of the tip in the XZ cross section is a (mm) long, and the chipper has an arcuate outer circumference with a radius of curvature r (mm), and the YZ The tip of the cross section has a semicylindrical shape with a length b (mm). The length a of the XZ cross section and the length b of the YZ cross section are both preferably in the range of 1.0 to 10.0 mm. Furthermore, the range of 5.0 to 9.5 mm is more preferable. Further, the radius of curvature r is preferably 1.0 to 10.0 mm. If it is less than 1.0 mm, deformation that tends to cause stress concentration at the weld toe is likely to occur, and if it exceeds 10.0 mm, the contact area between the chipper and the weld toe during impact becomes too large. This is because it becomes difficult to introduce sufficient compressive residual stress into the weld toe.

このチッパーは、打撃装置と接続しており、この打撃装置は、空気圧または高周波電流や超音波などにより駆動させるものであり、例えば、前述の半円柱形の先端を空気圧で作動させて前述した領域を打撃する方法が好ましい。ここで、打撃頻度（周波数）としては、１００Ｈｚ以下の低周波数とするのが好ましい。 This chipper is connected to a striking device, and this striking device is driven by air pressure, high frequency current, ultrasonic waves, etc. For example, the above-mentioned semi-cylindrical tip is actuated by air pressure to cover the above-mentioned area. A method of hitting is preferred. Here, the striking frequency (frequency) is preferably a low frequency of 100 Hz or less.

また、打撃痕の最大深さ（ＤP）と幅（ＷP）の積（ＤP×ＷP）が３．０～５．０ｍｍ2の範囲となるように制御することが好ましい。 Further, it is preferable to control so that the product (D P ×W P ) of the maximum depth (D P ) and width (W P ) of the impact mark is in the range of 3.0 to 5.0 mm 2 .

さらに、チッパーの打撃方向の傾き角度（θ）は、母材表面に対して８０～１００°程度であれば許容されるが、ほぼ垂直の９０°とすることが好ましい。 Further, the inclination angle (θ) of the chipper in the striking direction is permissible if it is about 80 to 100° with respect to the base material surface, but it is preferably 90°, which is approximately perpendicular.

供試材は、ＳＭ４９０Ｂを用いた。板厚は、５０ｍｍとした。その供試材を以下の溶接条件（入熱０．８ｋＪ／ｍｍ）でガスシールドアーク溶接により両面溶接し、突合せ溶接継手を作製した。溶接継手の特性としては、ヤング率Ｅおよびポアソン比ｖを測定した。その突合せ溶接継手から試験片を採取し、１レーン分のハンマーピーニングを処理したものと２レーン分のハンマーピーニングを処理したものを作製した。それぞれの試験片に対して４点曲げ疲労試験を実施した。 SM490B was used as the sample material. The plate thickness was 50 mm. The test materials were welded on both sides by gas-shielded arc welding under the following welding conditions (heat input: 0.8 kJ/mm) to produce butt-welded joints. As for the properties of the welded joint, Young's modulus E and Poisson's ratio v were measured. Test pieces were taken from the butt welded joints, and two test pieces were prepared: one treated with hammer peening for one lane and one treated with hammer peening for two lanes. A four-point bending fatigue test was conducted on each test piece.

［ガスシールドアーク溶接の溶接条件］
・シールドガス：ＣＯ2
・溶接入熱：０．８ｋＪ／ｍｍ、溶接電流：３１０Ａ、溶接電圧：４０Ｖ
・溶接速度：２９．５ｃｍ／ｍｉｎ
・溶接ワイヤ組成：Ｃ：０．０７ｗｔ％、Ｓｉ：０．３７ｗｔ％、Ｍｎ：１．１１ｗｔ％、Ｐ：０．０１３ｗｔ％、Ｓ：０．００９ｗｔ％、Ｍｏ：０．３７ｗｔ％
・溶接ワイヤ径：１．２ｍｍ [Welding conditions for gas shielded arc welding]
・Shield gas: CO 2
・Welding heat input: 0.8kJ/mm, welding current: 310A, welding voltage: 40V
・Welding speed: 29.5cm/min
・Welding wire composition: C: 0.07wt%, Si: 0.37wt%, Mn: 1.11wt%, P: 0.013wt%, S: 0.009wt%, Mo: 0.37wt%
・Welding wire diameter: 1.2mm

［ヤング率、ポアソン比の測定方法］
ヤング率、ポアソン比は、ＡＳＴＭ Ｅ８Ｍ「金属材料の引張試験方法」に準拠して測定した。 [Method of measuring Young's modulus and Poisson's ratio]
Young's modulus and Poisson's ratio were measured in accordance with ASTM E8M "Tensile Test Method for Metallic Materials."

［４点曲げ疲労試験］
４点曲げ疲労試験方法は、図４に示すような疲労試験装置１０を用いて、疲労試験片１１に応力を繰り返し作用させて４点（疲労試験片１１の上側に２つの上側支点１２と下側に２つの下側支点１３）の曲げによる疲労試験を実施した。すなわち、疲労試験装置１０の上方から衝撃を加えて疲労試験片１１が破断するまでの載荷回数（ｃｙｃｌｅｓ）を求めた。なお、公称応力範囲（ＭＰａ）とは、最大応力と最小応力の差分のことである。 [4-point bending fatigue test]
The four-point bending fatigue test method uses a fatigue testing apparatus 10 as shown in FIG. A fatigue test was carried out by bending the two lower supports 13) on the sides. That is, the number of loading cycles (cycles) until the fatigue test piece 11 breaks when an impact is applied from above the fatigue test apparatus 10 is determined. Note that the nominal stress range (MPa) is the difference between the maximum stress and the minimum stress.

それらの測定結果、試験結果を表１に示す。 Table 1 shows the measurement results and test results.

Figure 2023162133000002
Figure 2023162133000002

Ｎｏ．１～２は、比較例として１レーン分のハンマーピーニング処理した場合の試験結果であり、Ｎｏ．３～６は、本発明の２レーン分のハンマーピーニング処理した場合の試験結果である。ハンマーピーニングを２レーン分処理した場合の試験結果は、ハンマーピーニングを１レーン分処理した場合の試験結果と比較して疲労寿命が２倍以上（疲労設計曲線の１等級分向上）となった。 No. 1 and 2 are test results when one lane was subjected to hammer peening treatment as a comparative example, and No. 3 to 6 are test results when two lanes of the present invention were subjected to hammer peening treatment. The test results when two lanes of hammer peening were applied showed that the fatigue life was more than double (improved by one class on the fatigue design curve) compared to the test results when one lane of hammer peening was applied.

一方で、最大深さと幅の積が６．０ｍｍ2となる母材打撃による従来手法のＮｏ．７では、打撃痕から疲労亀裂が発生した。 On the other hand, the conventional method No. 1 using base material impact has a maximum depth and width product of 6.0 mm 2 . In No. 7, fatigue cracks occurred from impact marks.

さらに、Ｎｏ．８は、打撃痕の深さと幅の積が小さい比較例である。 Furthermore, No. No. 8 is a comparative example in which the product of the depth and width of the impact mark is small.

Ｎｏ．９は、打撃痕の深さと幅の積が６．０ｍｍ2と大きい例であるが、２レーン分の打撃処理を行うことで、圧縮残留応力が付与され、若干疲労強度が向上した。 No. No. 9 is an example in which the product of the depth and width of the impact marks is as large as 6.0 mm 2 , but by performing the impact treatment for two lanes, compressive residual stress was applied, and the fatigue strength was slightly improved.

以上のように、本発明は、溶接ビードに沿って２レーン分の打撃痕を形成することにより、打撃痕からの疲労亀裂は発生せず、１レーン分の打撃痕による疲労強度向上よりも大きな疲労強度向上効果を発揮した。 As described above, in the present invention, by forming impact marks for two lanes along the weld bead, fatigue cracks do not occur from the impact marks, and the fatigue strength is improved more than by impact marks for one lane. It demonstrated the effect of improving fatigue strength.

１ 母材（母材部）
２ 溶接金属
３ 溶接止端部
４ 第１レーンの打撃痕
５ 第２レーンの打撃痕
１０ 疲労試験装置
１１ 疲労試験片
１２ 上側支点
１３ 下側支点
１４ 負荷治具
１５ 受け治具
Ｌ１ 溶接止端部と第１レーン打撃痕との距離
Ｌ２ 第１レーン打撃痕と第２レーン打撃痕との距離 1 Base material (base metal part)
2 Weld metal 3 Weld toe 4 Impact marks on the first lane 5 Impact marks on the second lane 10 Fatigue test device 11 Fatigue test piece 12 Upper fulcrum 13 Lower fulcrum 14 Loading jig 15 Receiving jig L1 Weld toe Distance L2 between the first lane impact mark and the first lane impact mark Distance between the first lane impact mark and the second lane impact mark

Claims (9)

溶接部の疲労亀裂発生を抑制する方法であって、前記溶接部の溶接ビードに沿って連続的に溶接止端部近傍の母材部を打撃して帯状の打撃痕である第１のレーンを形成し、さらにその外側を打撃して帯状の打撃痕である第２のレーンを形成することを特徴とする溶接部の疲労亀裂発生抑制方法。 A method for suppressing the occurrence of fatigue cracks in a weld, the method comprising: continuously striking the base metal near the weld toe along the weld bead of the weld to create a first lane, which is a belt-shaped strike mark; A method for suppressing the occurrence of fatigue cracks in a welded part, the method comprising: forming a weld, and then striking the outer side of the lane to form a second lane, which is a band-shaped impact mark. 前記溶接止端部と前記第１のレーンの打撃痕との距離をＬ１とし、前記第１のレーンの打撃痕と前記第２のレーンの打撃痕との距離をＬ２としたときに、０．０ｍｍ＜Ｌ１≦１．０ｍｍ、０．０ｍｍ≦Ｌ２≦２．０ｍｍであることを特徴とする請求項１に記載の溶接部の疲労亀裂発生抑制方法。 When the distance between the weld toe and the impact mark of the first lane is L1, and the distance between the impact mark of the first lane and the impact mark of the second lane is L2, 0. 2. The method for suppressing fatigue crack generation in a welded joint according to claim 1, wherein 0 mm<L1≦1.0 mm and 0.0 mm≦L2≦2.0 mm. 前記打撃痕の最大深さ（ＤP）と幅（ＷP）の積（ＤP×ＷP）が３．０～５．０ｍｍ2であることを特徴とする請求項１または２に記載の溶接部の疲労亀裂発生抑制方法。 3. The impact mark according to claim 1 or 2, wherein the product (D P ×W P ) of the maximum depth (D P ) and width (W P ) of the impact mark is 3.0 to 5.0 mm 2 . Method for suppressing fatigue crack occurrence in welded parts. 前記溶接部の母材部が板厚３０ｍｍ以上の突合せ溶接継手であることを特徴とする請求項１または２に記載の溶接部の疲労亀裂発生抑制方法。 3. The method for suppressing the occurrence of fatigue cracks in a welded part according to claim 1, wherein the base metal part of the welded part is a butt welded joint having a plate thickness of 30 mm or more. 前記溶接部の母材部が板厚３０ｍｍ以上の突合せ溶接継手であることを特徴とする請求項３に記載の溶接部の疲労亀裂発生抑制方法。 4. The method for suppressing the occurrence of fatigue cracks in a welded part according to claim 3, wherein the base metal part of the welded part is a butt welded joint having a plate thickness of 30 mm or more. 請求項１または２に記載の溶接部の疲労亀裂発生抑制方法を用いて施工されることを特徴とする溶接継手の製造方法。 A method for manufacturing a welded joint, characterized in that it is constructed using the method for suppressing fatigue crack generation in a welded part according to claim 1 or 2. 請求項３に記載の溶接部の疲労亀裂発生抑制方法を用いて施工されることを特徴とする溶接継手の製造方法。 A method for manufacturing a welded joint, characterized in that it is constructed using the method for suppressing fatigue crack generation in a welded part according to claim 3. 請求項４に記載の溶接部の疲労亀裂発生抑制方法を用いて施工されることを特徴とする溶接継手の製造方法。 A method for manufacturing a welded joint, characterized in that it is constructed using the method for suppressing the occurrence of fatigue cracks in a welded joint according to claim 4. 請求項５に記載の溶接部の疲労亀裂発生抑制方法を用いて施工されることを特徴とする溶接継手の製造方法。 A method for manufacturing a welded joint, characterized in that it is constructed using the method for suppressing the occurrence of fatigue cracks in a welded joint according to claim 5.
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