JP2020055020A - Turning welded joint excellent in fatigue strength and method of manufacturing the same - Google Patents

Abstract

To provide a boxing joint that can improve fatigue strength inexpensively and stably and a boxing method.SOLUTION: A toe on a main plate of a weld bead formed around a rectangular contact face where a gusset 2 contacts the main plate 1 is coated with a resin coating agent that, after dried and solidified, has a hardness of Hv200 or more in Vickers hardness.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technique of turning welding a main plate and a gusset, which is widely used when constructing a steel structure, and is particularly suitable for a steel structure (for example, a steel bridge, a ship, etc.) requiring excellent fatigue characteristics. The present invention relates to a run-around welded joint and a method of manufacturing the same.

  Generally, in a steel structure, as shown in FIG. 4, there are many turning welded joints in which the periphery of a gusset 2 is welded to the main plate 1 (so-called turning welding). In the turning welded joint, the weld bead 3 surrounds the gusset 2, and when a defect (for example, a crack or the like) occurs in the weld bead 3 and the shape of the weld toe is not smoothly formed, the weld bead 3 is closed. Stress concentration tends to occur at the ends. As a result, the welding residual stress caused by the turning welding and the repetitive stress caused by the external force are superimposed to generate a fatigue crack, and the fatigue crack propagates to cause fatigue failure. The external force is a load that repeatedly acts on a steel structure from the outside. For example, when the steel structure is a steel bridge, it is a load that is repeatedly generated due to natural weather conditions (for example, wind) and traffic of vehicles. When the structure is a ship, the load is generated repeatedly by wind and waves.

  In recent years, with the aging of steel structures, reports on damage caused by fatigue are increasing. In order to prevent such damage, it is necessary to periodically inspect the steel structure to control the progress of the damage, and to take measures according to the progress of the damage. In particular, if damage due to fatigue occurs on the steel bridge, it is possible to reduce the external force acting on the steel bridge by restricting the traffic of vehicles, but it will cause traffic jams and delays in distribution. Has a great adverse effect on social activities. Therefore, techniques for improving the fatigue characteristics of a turning welded joint of a steel structure have been studied.

  For example, Patent Literature 1 discloses a technique for improving fatigue characteristics by using a paste for preventing the propagation after the occurrence of fatigue cracks. However, this technique does not particularly describe a method of fixing to a welded portion, and it is difficult to apply this technique to all turning welded joints of a steel structure.

  Further, Patent Document 2 discloses a method of forming a welded joint by forming elongated beads on the upper surface of a main plate from both ends in a longitudinal direction of a gusset using a welding material having a martensitic transformation start temperature of a weld bead of 350 ° C. or less. A technique for increasing the fatigue strength of steel has been disclosed. In this technique, since expensive welding materials must be selected, the cost of turning welding is increased, and the cost of building a steel structure is increased. In addition, depending on the shape of the weld toe, it may be a starting point where fatigue cracks occur. Therefore, the fatigue strength may vary depending on the finish state of the weld toe.

  Patent Literature 3 discloses a pair of extension beads with ribs which are slightly extended on both sides of a side edge portion of a welded girder structure of a hull. However, Patent Literature 3 does not disclose a welding order, intervals having an effect of improving fatigue strength, and effects thereof.

  In Patent Literature 4, fillet welding is performed up to the corner turning welding portion, and after cooling to room temperature, the turning welding portion is set to (2 × fillet welding leg length) than (rib plate thickness + 2 × fillet welding leg length). ) Describes a method of welding so as to be longer. With this method, although the stress concentration and the tensile residual stress are reduced, the range of the weld toe is larger (longer) than the conventional welded joint, so that there is a danger that the generated and grown fatigue cracks will coalesce at an early stage. high.

  Patent Literature 5 and Patent Literature 6 describe a technique for improving fatigue life by forming elongated beads on both ends of a gusset in the longitudinal direction on the upper surface of a main plate. In this technique, it is necessary to form an elongated bead so as to cover a turning part of welding, so that not only time is required but also a burden on a welding worker is large.

  Patent Document 7 discloses a technique in which a resin block is bonded and reinforced after applying an adhesive. According to this technique, a resin block suitable for each of the turning welded joints of the steel structure must be created according to the shape and dimensions of the joint, so that the load of the operation management of the turning welding increases.

  Non-Patent Document 1 discloses a technique for improving the joint fatigue strength by extending a weld bead in order to disperse the effect of an external force on the weld bead. However, simply dispersing the action of the external force cannot prevent the occurrence of fatigue cracks due to the shape of the weld toe. Moreover, when a fatigue crack occurs, there is no description about a technique for preventing the propagation of the fatigue crack.

Patent No. 5753528 JP 2013-99764 A JP-A-8-155634 JP-A-8-19860 JP 2014-233747 A JP 2012-110950 A Japanese Patent No. 4694423

Study on Fatigue Strength of Boxing Fillet Weldments: 2nd Report: Yasumitsu Tomita, Kiyoshi Hashimoto, Kuniteru Ichikawa, Hiroshi Yamamoto, Tetsuji Fukuoka The Fifth International Offshore and Polare Engineering Conference, Jun 1995, Netherlands

  SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art and to provide a turning welded joint capable of stably improving fatigue strength at low cost and a method of manufacturing the same.

  In order to increase the fatigue strength of a turn-welded joint, the present inventor studied welding technology to prevent the occurrence of fatigue cracks and technology to prevent the length and depth of fatigue cracks from increasing (hereinafter referred to as propagation). Focusing on the toe of the weld bead 3 of the turning welded joint, particularly the toe of the weld bead 3 on the main plate 1, as shown in FIG. A study was carried out to increase the fatigue strength of turning welded joints. Then, it has been found that the generation and propagation of fatigue cracks can be prevented by applying a resin-based coating agent satisfying predetermined requirements to the toe of the weld bead 3 on the main plate 1.

  The resin-based coating agent used in the present invention is a viscous fluid when applied to the toe of the weld bead 3 and, after application, is dried and solidified with time in the state of being exposed to the atmosphere. It is. If the hardness after drying and solidification is Vickers hardness of 200Hv or more, the resin-based coating agent can reduce the stress concentration at the toe, and as a result, prevent the generation and propagation of fatigue cracks. It was found to contribute.

  As described above, the research by the present inventors has established a basic technique for improving the fatigue strength of a turning welded joint.

  However, new studies have arisen in the inventor's research on turning welded joints as shown in FIG. That is, in the above technique, the resin-based coating agent must be applied to the entire length of the toe of the weld bead formed around the rectangular contact surface (hereinafter, referred to as the rectangular contact surface) where the gusset contacts the main plate. No. Therefore, since it takes a long time to form one turning welded joint, the time required for construction (for example, construction of a new steel structure, maintenance of an existing steel structure, etc.) is prolonged, and the construction cost is increased. Invite.

  In response to such newly generated considerations, the inventor has further studied a technique for increasing the fatigue strength of the turning welded joint as shown in FIG. The welding bead formed along the short side of the rectangular contact surface (hereinafter, referred to as a short side bead) is caused to cover the weld bead formed along the long side (hereinafter, referred to as a long side bead). It has been found that the prevention of the gap can prevent the occurrence of fatigue cracks.

Next, a technique for preventing the above-described gap from being generated by using a normal welding device and a welding material in order to suppress an increase in the construction cost of turn welding was examined in detail. as a result,
(A) Weld the short side bead first, then cover the short side bead by welding the long side bead,
(B) At that time, by performing welding so that the long-side bead extends beyond the short-side bead already welded, it is possible to prevent the above-described gap from being generated, and thus, the shape of the weld toe portion It has been found that the occurrence of fatigue cracks can be prevented regardless of the above. further,
(C) It was recognized that the effect of preventing the occurrence of a gap was remarkably exhibited by welding so that the short side bead did not exceed the long side bead.

  In addition, when a fatigue crack occurs, the origin of the fatigue crack exists between the two elongated long-side beads, so that the propagation of the fatigue crack generated on the main plate side is between the two long-side beads. It has been found that it is possible to limit and thus prevent the propagation of fatigue cracks over a wide area.

  Therefore, in the turning welded joint as shown in FIG. 1, a resin-based coating agent is applied to the toe portion on the main plate 1 of the first weld bead 3a located between the second weld bead 3b and the third weld bead 3c. By doing so, it was found that the generation and propagation of fatigue cracks can be prevented. According to this technique, the portion to which the resin-based coating agent is applied is significantly reduced, so that an increase in the cost can be suppressed.

  The present invention has been made based on such findings. In the following, a weld bead formed along the short side of the rectangular contact surface is referred to as a first weld bead to clarify that the order of forming the weld bead is different from the short side bead. In addition, the weld bead formed along the long side of the rectangular contact surface is referred to as a second weld bead and a third weld bead, and it is clear that the order of forming the weld bead is different from the long side bead. To

  That is, the turning welded joint according to the present invention is a turned welded joint obtained by turning and welding a gusset to a main plate and joining the gusset to a welding bead formed around a rectangular contact surface where the gusset comes into contact with the main plate. This is a rotary welded joint in which a resin-based coating agent is applied to the toe portion on the main plate, and the hardness of the resin-based coating agent after drying and solidification is Vickers hardness of Hv 200 or more.

  Another turning welding joint according to the present invention is a turning welding joint obtained by turning and welding a gusset to a main plate and joining the gusset to the main plate, wherein the gusset is formed along a short side of a rectangular contact surface abutting on the main plate. A first weld bead formed on both sides of the short side of the rectangular contact surface on the main plate, and a first weld bead formed along the long side of the rectangular contact surface and extended on the main plate over the first weld bead; A second weld bead and a third weld bead that are formed in the same manner, and the distance M between the second weld bead and the third weld bead extending beyond the first weld bead on the main plate is 10.0 mm or less. In addition, a resin-based coating agent is applied to a toe portion on the main plate of the first weld bead located between the second weld bead and the third weld bead, and the resin-based coating agent is hardened after drying and solidification. Turning with a Vickers hardness of Hv200 or more It is a contact joint.

  In the turning welding joint of the present invention, the resin-based coating agent preferably contains iron powder, and the resin-based coating agent is preferably an adhesive.

  Also, the method for manufacturing a turning welded joint according to the present invention is a method for manufacturing a turned welded joint in which a gusset is turned on a main plate and joined by welding, wherein the gusset is formed around a rectangular contact surface where the gusset comes into contact with the main plate. This is a method of manufacturing a turn-welded joint in which a resin-based coating agent having a Vickers hardness of Hv 200 or more is applied to a toe portion on a main plate after drying and solidifying.

  Another manufacturing method of a turning welding joint according to the present invention is a method of manufacturing a turning welding joint in which a gusset is turned to a main plate and joined by welding, wherein the first welding is performed along a short side of a rectangular contact surface where the gusset contacts the main plate. A bead is formed by extending on the main plate from both sides of the short side of the rectangular contact surface, and then the second weld bead and the third weld bead are put on the first weld bead along the long side of the rectangular contact surface. Further, the first weld bead is formed so as to extend on the main plate, the distance M between the second weld bead and the third weld bead on the main plate is set to 10.0 mm or less, and the hardness after drying and solidifying is Vickers hardness. This is a method for manufacturing a turn-welded joint in which a resin-based coating agent having an Hv of 200 or more is applied to a toe portion on a main plate of a first weld bead located between a second weld bead and a third weld bead.

  In the method for producing a turning welded joint of the present invention, the resin-based coating agent preferably contains iron powder, and an adhesive is preferably used as the resin-based coating agent.

  In the present invention, the effect can be exerted by using a main plate or a gusset of any material, but in particular, since the size of the crack leading edge on the main plate side at the initial stage when the fatigue crack occurs can be limited, the fatigue crack By using a main plate having a low propagation speed (it is difficult for fatigue cracks to propagate), a longer life can be expected.

  The present invention can be applied not only to newly building a steel structure but also to repairing an old steel structure.

  ADVANTAGE OF THE INVENTION According to this invention, when newly constructing a steel structure or repairing an aging steel structure, it becomes possible to improve the fatigue strength of a turning welded joint inexpensively and stably, and it is industrially possible. It has a remarkable effect.

It is a perspective view which shows the example of a turning welding joint typically. It is a top view which shows typically the procedure of the welding construction for obtaining the turning welding joint shown in FIG. It is a top view which expands and shows FIG.2 (c). It is a perspective view which shows the other example of a turning welding joint typically. It is sectional drawing which shows typically the example which applied this invention to the turning welding joint shown in FIG. It is sectional drawing which shows typically the example which applied this invention to the turning welding joint shown in FIG.

  Generally, a steel structure provided with a rotary welded joint is repeatedly used by a load when used for a long period of time, and a fatigue crack is generated at a toe portion of a weld bead. Then, the fatigue crack propagates due to the load acting repeatedly thereafter.

  On the other hand, if the present invention is applied to a turning welded joint, it becomes possible to prevent the generation and propagation of fatigue cracks. The mechanism will be described.

  First, an example in which the present invention is applied to the turning welded joint shown in FIG. 4 will be described.

  FIG. 5 is a sectional view showing an example in which the present invention is applied to the turning welded joint shown in FIG. In the turning welding joint according to the present invention, as shown in FIG. 5, a resin-based coating agent 4 is applied to a toe portion on the main plate 1 of the welding bead 3.

  The resin-based coating agent 4 is a viscous fluid when applied to the toe of the weld bead 3 and can be easily applied to a predetermined position (ie, near the toe) when applied. . In addition, because of its viscosity, it remains at a predetermined position without being washed away even after application. Then, it is dried and solidified after a lapse of time after being exposed to the atmosphere. In the present invention, the resin-based coating agent 4 having a hardness in a dried and solidified state of 200 Hv or more in Vickers hardness is used. 5 indicates a contact area between the resin-based coating agent 4 and the main plate 1.

  By the resin-based coating agent 4 being dried and solidified in this manner, stress concentrated on the toe of the weld bead 3 on the main plate 1 can be dispersed in the contact region Q. That is, the stress concentration generated at the toe of the weld bead 3 in the conventional turning welded joint is reduced in the turned welded joint of the present invention. When the Vickers hardness of the dried and solidified resin coating agent 4 is 200 Hv or more, it becomes possible to prevent the occurrence of fatigue cracks. Further, when a fatigue crack occurs, the propagation of the fatigue crack can be prevented.

  Furthermore, by including iron powder in the resin coating agent 4, the same hardness as that of the main plate 1 can be obtained, so that the effect of dispersing stress in the contact region Q (that is, the effect of reducing stress concentration) is remarkably exhibited. Is done.

  As the resin coating agent 4, a commercially available adhesive (for example, an acrylic resin adhesive, an α-olefin adhesive, a urethane resin adhesive, an epoxy resin adhesive, a silicone adhesive, a phenol resin adhesive) Melamine resin-based adhesives) can be used simply.

  Next, after describing a welding technique for obtaining the turning welded joint shown in FIG. 1, an example in which the present invention is applied to the turning welded joint shown in FIG. 1 will be described.

  FIG. 1 is a perspective view schematically showing an example of a turning welding joint according to the present invention, and FIG. 2 is a plan view showing a procedure of welding work for obtaining the turning welding joint. In FIG. 2, the rectangular contact surface 2 a where the gusset 2 contacts the main plate 1 matches the shape of the rectangular line that projects the gusset 2 onto the main plate 1. Hereinafter, the shape of the rectangular line (ie, the gusset 2 projected on the main plate 1) in FIGS. 2A to 2C will be described as a rectangular contact surface 2a.

  In obtaining the turning welded joint according to the present invention, first, as shown in FIG. 2A, a first weld bead 3a is formed along the short side of the rectangular contact surface 2a. At this time, welding is performed such that the first weld bead 3a extends on the main plate 1 from both sides of the short side of the rectangular contact surface 2a. Therefore, the length of the first weld bead 3a is longer than the short side of the rectangular contact surface 2a. By doing so, a second weld bead 3b and a third weld bead 3c, which will be described later, can be put on the first weld bead 3a.

  However, if the first weld bead 3a is too long and extends from below the second weld bead 3b and the third weld bead 3c onto the main plate 1, the main plate 1, the first weld bead 3a, and the second weld bead 3b , Or a gap surrounded by the main plate 1, the first weld bead 3a, and the third weld bead 3c, and fatigue cracks are likely to occur.

  If the length of the first weld bead 3a is shorter than the short side of the rectangular contact surface 2a, the second weld bead 3b and the third weld bead 3c cannot be put on the first weld bead 3a, Since a gap is formed between the first weld bead 3a and the second weld bead 3b or between the first weld bead 3a and the third weld bead 3c, the occurrence of fatigue cracks cannot be prevented.

  Therefore, the first weld bead 3a is formed so that the entire portion of the first weld bead 3a extending from the short side of the rectangular contact surface 2a onto the main plate 1 can be covered with the second weld bead 3b and the third weld bead 3c. It is preferable to adjust the length of the work.

  Next, a second weld bead 3b is formed along the long side of the rectangular contact surface 2a. By doing so, the second weld bead 3b can be covered on the first weld bead 3a. Then, the second weld bead 3b is further formed on the main plate 1 from the first weld bead 3a (ie, beyond the first weld bead 3a).

  Next, a third weld bead 3c is formed along the long side of the rectangular contact surface 2a. This allows the third weld bead 3c to cover the first weld bead 3a. Then, the third weld bead 3c is further formed on the main plate 1 from the first weld bead 3a (ie, beyond the first weld bead 3a).

  By covering the first weld bead 3a with the second weld bead 3b and the third weld bead 3c in this manner, it is possible to prevent a gap from being formed between each of the weld beads 3a, 3b, 3c and the main plate 1, and as a result, the toe The generation of fatigue cracks can be prevented regardless of the shape of the portion.

  As for the second weld bead 3b and the third weld bead 3c, in FIGS. 2B and 2C, the weld bead along the long side on the left side of the rectangular contact surface 2a is referred to as the second weld bead 3b, Although the third weld bead 3c is used as the weld bead along the side, there is no problem if the left and right are reversed. That is, the present invention can be applied to a case where the weld bead along the long side on the right side of the rectangular contact surface 2a is the second weld bead 3b, and the weld bead along the long side on the left side is the third weld bead 3c.

  FIG. 3 is an enlarged view of an example (see FIG. 2 (c)) in which the respective weld beads 3a, 3b, 3c are formed in such a procedure. If the distance M between the second weld bead 3b and the third weld bead 3c extended on the main plate 1 is too large, the toe of the first weld bead 3a between the second weld bead 3b and the third weld bead 3c will A fatigue crack having a starting point is easily generated. Therefore, the interval M is set to 10.0 mm or less. However, it should be noted that even if the interval M exceeds 10.0 mm, an effect of slightly improving fatigue life can be expected as compared with a normal rotary welded joint. When the length L of the short side of the rectangular contact surface 2a is 10.0 mm or less, the interval M preferably satisfies M ≦ L. The interval M indicates the shortest distance between the second weld bead 3b and the third weld bead 3c.

  From the viewpoint of preventing the occurrence of fatigue cracks, the smaller the distance M, the better. However, when there is no interval (M = 0), a fatigue crack having a starting point at the tip of the second weld bead 3b and the third weld bead 3c is generated, and the fatigue crack is easily propagated over a wide range. In this case, although the fatigue life is slightly improved due to the longer leg length, the effect of the present invention cannot be obtained. Therefore, the interval M preferably satisfies M> 0.

  Further, as shown in FIG. 3, the distance between the tip of the second weld bead 3b extending on the main plate 1 and the short side of the rectangular contact surface 2a, and the distance between the tip of the third weld bead 3c and the rectangular contact surface 2a. The shorter one of the intervals with the short side is defined as the interval N. If the interval N is too small, fatigue cracks are likely to propagate. On the other hand, if the interval N is too large, it takes a long time to form the second weld bead 3b and the third weld bead 3c. Therefore, assuming that the second weld bead 3b and the third weld bead 3c extend beyond the first weld bead, the interval N is preferably in the range of 10 to 50 mm. However, it should be noted that even if the interval N is out of the range of 10 to 50 mm, an effect of slightly improving the fatigue life can be expected as compared with a normal turning welded joint.

  As described above, according to the study of the present inventor, the most likely occurrence of fatigue cracks in the turning welded joint shown in FIG. 1 having the effect of suppressing the occurrence of fatigue cracks is that of the second weld bead 3b. It is a toe of the first weld bead 3a located between the third weld beads 3c. Therefore, when the present invention is applied to the turning welded joint shown in FIG. 1, as shown in FIG. 6, on the main plate 1 of the first weld bead 3a located between the second weld bead 3b and the third weld bead 3c. Is coated with a resin-based coating agent 4 and further dried and solidified.

  The material and function of the resin-based coating agent 4 used are the same as those in the example shown in FIG.

  In addition, the welding means for performing the rotary welding is mainly a covered arc welding method and a gas metal arc welding method, but other means can be appropriately used, and either manual welding or automatic welding may be employed. .

  The present invention is applicable not only when newly constructing a steel structure, but also when repairing an aging steel structure.

  After preparing the main plate 1 (plate thickness: 25 mm, plate width: 80 mm, length: 500 mm) and gusset 2 (plate thickness: 25 mm, plate width: 75 mm, height: 50 mm) using the steel plates shown in Table 1, A gusset 2 was turned and welded to the main plate 1 by a gas metal arc welding method using a flux-cored wire, and a fatigue test was performed using the obtained turned welding joint (see FIG. 1). The procedure will be described.

  The flux-cored wire used was MX-Z200 (wire diameter 1.2 mm) manufactured by Kobe Steel, with welding conditions of 240 A-32 V and leg lengths of about 8 mm. As shown in FIGS. 1 and 4, since the gusset 2 is arranged at the center of the main plate 1, the rectangular contact surface 2 a is located at the center of the main plate 1. The procedure for forming the weld beads 3a, 3b, 3c of the turning welded joint shown in FIG. 1 is as shown in FIG.

In the turning welded joint of FIG. 1 thus obtained, the resin coating agent 4 is applied to the toe portion on the main plate 1 of the first weld bead 3a located between the second weld bead 3b and the third weld bead 3c. (See FIG. 6). This is referred to as Inventive Examples 2 and 3. (M = 4.2-5.3mm)
4, the resin-based coating agent 4 was applied to the entire length of the toe on the main plate 1 of the weld bead 3. This is referred to as Inventive Example 1.

  The resin coating agent 4 was used by mixing iron powder having a particle size of less than 50 μm (that is, particles having passed through a 50 μm mesh). As the resin coating agent 4, a commercially available adhesive was used.

  Next, for comparison, turning welding was performed under the same welding conditions as in Inventive Example 1, and a fatigue test was performed using the obtained turning welding joint (see FIG. 4). This is a comparative example. In the comparative example, the resin-based coating agent 4 was not used.

Table 2 shows the results of the fatigue test (stress range 100 MPa, stress ratio 0.1). The application range in Table 2 indicates the area covering the main plate side of the test piece. However, since one side is not a straight line, there is a slight error in the numerical value. Further, the joint number 1 in Table 2 is an example of the turning welding joint shown in FIG. 4, and the joint number 2 is an example of the turning welding joint shown in FIG.
As is clear from Table 2, the inventive examples have significantly improved fatigue characteristics as compared with the comparative examples.

1 main plate 2 gussets
2a Rectangular contact surface 3 Weld bead
3a First weld bead
3b 2nd weld bead
3c 3rd weld bead 4 Resin coating agent

Claims (8)

  A turn welding joint obtained by turning and welding a gusset to a main plate and joining the gusset to a toe on the main plate of a weld bead formed around a rectangular contact surface where the gusset contacts the main plate. A rotary welded joint comprising a resin-based coating agent applied thereon, and a hardness after drying and solidifying of the resin-based coating agent is Vickers hardness of Hv 200 or more.   A turning welded joint obtained by turning and welding a gusset to a main plate, wherein the gusset is formed along a short side of a rectangular contact surface abutting on the main plate, and the short side of the rectangular contact surface is formed. A first weld bead formed by extending on the main plate from both sides of the side; and a first weld bead formed along a long side of the rectangular contact surface and extending on the main plate over the first weld bead. A second weld bead and a third weld bead, wherein the distance M between the second weld bead and the third weld bead extending beyond the first weld bead on the main plate is 10.0 mm or less. A resin-based coating agent is applied to a toe portion on the main plate of the first weld bead located between the second weld bead and the third weld bead; Hardness after drying and solidification Turn welded joint, characterized in that Vickers is Hv200 or more hardness.   The turning welding joint according to claim 1 or 2, wherein the resin-based coating agent contains iron powder.   The turning welding joint according to any one of claims 1 to 3, wherein the resin-based coating agent is an adhesive.   A method for manufacturing a turn welded joint in which a gusset is turned to a main plate and joined by welding, wherein the gusset is formed on a toe portion on the main plate of a weld bead formed around a rectangular contact surface abutting on the main plate, after drying and solidifying. A method for producing a turning welded joint, comprising applying a resin-based coating agent having a Vickers hardness of Hv 200 or more.   In a method of manufacturing a turn welding joint in which a gusset is turned to a main plate and joined by welding, the gusset forms a first weld bead along a short side of a rectangular abutment surface abutting on the main plate. It is formed by extending on the main plate from both sides, and then the second weld bead and the third weld bead are put on the first weld bead along the long side of the rectangular contact surface, and the first weld bead is formed. Being stretched over the main plate, the distance M between the second weld bead and the third weld bead on the main plate is set to 10.0 mm or less, and the hardness after drying and solidifying is Vickers hardness. A turning welding joint, wherein a resin-based coating agent having an Hv of 200 or more is applied to a toe portion on the main plate of the first welding bead located between the second welding bead and the third welding bead. Manufacturing method.   The method according to claim 5, wherein the resin-based coating agent contains iron powder.   The method for producing a turning welded joint according to any one of claims 5 to 7, wherein an adhesive is used as the resin-based coating agent.

Images