CN102481652A - Out-of-plane gusset welded joint and fabrication method thereof - Google Patents

Abstract

The present invention provides a method of manufacturing an out-of-plane gusset welded joint including a substrate, a gusset plate protruding from the surface of the substrate, and a fillet weld. In this manufacturing method, one end in the longitudinal direction of the gusset plate is notched in the direction of the plate width (w) to form a notch, and the gusset is arranged on the surface of the substrate. plate, fillet welding is carried out in such a way that the predetermined leg length (d ₂ ) of the gusset plate side is equal to or greater than the notch height (a), and the leg length (d ₂ ′) of the gusset plate side is 1/3 or more of the plate thickness (t ₂ ) of the strut, and form the fillet length (d ₂ ′), the fillet length (d ₁ ′) on the substrate side, the penetration length (x’) and the penetration For the fillet welds where the depth angle (θ') satisfies x'+d ₁ '>d ₂ '/sinθ', at least the welding end of the fillet welds on the substrate side around the welds is improved Impact treatment for fatigue properties.

Description

Out-of-plane gusset welded joint and method of making same

technical field

The invention relates to an out-of-plane gusset welded joint for welding two plate parts by fillet welding and a method for making the same. In particular, it relates to an out-of-plane gusset welded joint with excellent fatigue resistance and a manufacturing method thereof.

Background technique

In order to reinforce the plate part of the structure or install the plate part of the structure on other parts (for example, other plate parts), on the plate part of the structure, as an accessory part, a Way fillet welds are installed with other plate components to form out-of-plane fillet welded joints.

It can be seen that when repeated stress is applied to the welded joint, for example, due to the occurrence of significant stress concentration at the welded end or the formation of tensile residual stress at the welded end, fatigue cracks are generated from the welded end , the fatigue resistance properties decreased significantly.

As a countermeasure against this, in order to suppress the stress concentration at the weld toe, for example, methods of increasing the curvature of the toe of the welded joint by grinding, TIG finishing, or overlay welding have been used. In addition, in order to reduce the tensile residual stress of the welding toe, for example, impact treatment (shot peening) such as shot peening, hammering treatment, laser shock peening, water jet peening or welding is used on the welding toe. method of post-heat treatment.

In recent years, it has been proposed to perform impact treatment using ultrasonic vibration (hereinafter, also referred to as UIT treatment (Ultrasonic Impact Treatment)), to introduce compressive residual stress into the weld toe, or to improve the shape of the weld toe.

For example, Patent Document 1 discloses a method in which, in order to improve the fatigue resistance of a material by introducing compressive residual stress, ultrasonic shock treatment is performed on the surface of the material in a direction perpendicular to the direction in which the fatigue resistance needs to be improved. In the resulting plurality of processing strips, three or more edges are formed in at least a direction at right angles to the processing strip. In addition, Patent Document 2 discloses a method in which, in order to increase the fatigue strength of the welded part, the welding is carried out so that the impact density per unit length of the welding stop part is 11 times/mm or more using an ultrasonic impact treatment device. A groove having a radius of curvature R of 2 mm or more and a width of 1 mm or more is formed near the end stop. In addition, Patent Document 3 discloses a shock treatment device and a shock treatment method using ultrasonic waves.

FIGS. 7A to 7D are schematic perspective views showing the manufacturing procedure of a conventional out-of-plane gusset welded joint, showing the state of the vicinity of the welded portion 110 of the out-of-plane gusset welded joint 101 .

A gusset 103 is fillet-welded to the substrate 102 ( FIGS. 7A to 7B ), and a fillet 109 is formed with weld stoppers 107 , 107 ′.

Further, as shown in FIGS. 7C to 7D , shock treatment is performed on the weld stopper 107 of the wraparound portion 110 in the fillet weld 109 to form a shock treatment mark 111 . In addition, FIGS. 7A to 7D show states in which impact treatment is performed on the solder stopper 107 on the substrate 102 side.

Patent Document 1: (Japanese) Unexamined Patent Publication No. 2006-167724

Patent Document 2: (Japanese) Unexamined Patent Publication No. 2006-175512

Patent Document 3: (US) Patent No. 6,171,415

As described above, by subjecting the weld toe of the out-of-plane gusset welded joint to the impact treatment, the shape of the toe toe is formed into a smooth (curved) shape in which stress is hardly concentrated, and stress at the toe to be welded and its vicinity is relieved. Tensile residual stress, compressive residual stress applied. As a result, it is possible to prevent the occurrence of cracks in the weld stop and its vicinity, and to improve the fatigue resistance. Such a method greatly suppresses the decrease in fatigue life due to fatigue cracks from the weld toe, and significantly improves the fatigue resistance. However, there is a limit to the improvement of the fatigue characteristics in the out-of-plane gusset welded joint using fillet welding.

In order to further improve the fatigue characteristics of the out-of-plane gusset welded joints, the present inventors performed ultrasonic impact treatment on the welding stop of the welded portion of the out-of-plane gusset welded joints, and studied the fatigue life thereof. As a result, it was found that most of the fatigue cracks were generated from the root of the weld, hindering the improvement of the fatigue resistance. In other words, it was found that the impact treatment on the weld toe suppressed the occurrence of cracks from the weld toe, so fatigue cracks occurred from the weld root where fatigue cracks tend to occur after the weld toe, and the fatigue cracks further extended , affecting the fatigue life of the out-of-plane gusset.

With regard to the generation of fatigue cracks from the root of the fillet weld, it has been found that if the weld of the fillet weld is formed as a fully dissolved weld, the fatigue resistance is improved because there is no root of the weld. However, in the case of performing full penetration welding, it is necessary to perform beveling in a wide range, and the time required for the welding operation is long, and it is difficult to restrict the gusset plate at the time of pre-welding of the gusset plate. Therefore, the burden on the welding operation is large, and the cost increases.

Contents of the invention

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a welded joint with further improved fatigue resistance in an out-of-plane gusset welded joint in which fatigue resistance is improved by performing an impact treatment on a weld stop and a method for producing the same.

The present inventors studied an effective method for eliminating stress concentration at the root of the weld.

6A and 6B are schematic cross-sectional views illustrating the stress concentration of the welded portion 10 of the out-of-plane gusset welded joint 1 when repeated stress is applied. The present inventors found that, as shown in FIG. 6A , by moving the position of the weld root 8 from the conventional position C (the longitudinal end portion of the gusset 3 on the substrate 2 side) shown in FIG. 6B to a lower position than the position C At position B further inside the gusset plate 3 , the leg length of the fillet weld can be controlled, thereby improving fatigue resistance. That is, as shown in FIG. 6A , by controlling the leg length of the fillet weld, the steepness of the stress dispersion path is eased, the stress concentration at the welding root 8 is avoided, and the weld seam thickness is effectively increased. Therefore, the occurrence of cracks in the weld root 8 and the bead thickness can be suppressed. Therefore, the impact treatment effect of the butt weld stop can be fully exerted, and the fatigue resistance property can be further improved. The inventors of the present invention have made the present invention based on the above-mentioned examination results.

That is, the gist of the present invention is as follows.

(1) A method of manufacturing an out-of-plane gusset welded joint according to one aspect of the present invention is a method of manufacturing an out-of-plane gusset welded joint comprising a base plate, a gusset plate protruding from the surface of the base plate, and a fillet welded portion, wherein In the w direction, one end in the plate width direction of the end portion of the gusset in the longitudinal direction is notched to form a notch having a notch height a, a notch length x, and a notch angle θ of 80° or less, so as to have the notch. The gusset plate is arranged in such a way that the end surface of the gusset plate in the direction of the plate width w is opposite to the surface of the substrate, and the predetermined leg length _d2 on the side of the gusset plate is the height of the cutout The fillet welding is carried out in the manner above a, the weld leg length d ₂ ′ on the gusset plate side is more than 1/3 of the plate thickness t ₂ of the gusset plate, and the weld leg length d ₂ ′, the For the fillet welds where the leg length d ₁ ′, penetration length x’ and penetration angle θ’ on the substrate side satisfy x’+d ₁ ′>d ₂ ′/sinθ’, at least A shock treatment for improving fatigue characteristics is applied to the solder end portion on the substrate side of the surrounding solder portion.

(2) In the method for producing an out-of-plane gusset welded joint described in (1) above, the notch angle θ may be 45° or more and 75° or less.

(3) An out-of-plane gusset welded joint according to another aspect of the present invention includes a base plate, a gusset plate protruding from the surface of the base plate, and a fillet weld, wherein in the fillet weld, the side of the gusset plate The weld leg length d ₂ ′ is more than 1/3 of the plate thickness t ₂ of the gusset plate, and the weld leg length d ₂ ′, the weld leg length d ₁ ′ on the substrate side, the penetration length x ′ and The penetration angle θ' satisfies x'+d ₁ '>d ₂ '/sin θ', and in the fillet weld, at least the weld stop on the substrate side of the fillet weld is formed with impact treatment traces.

(4) In the out-of-plane gusset welded joint described in (3) above, the penetration angle θ′ may be not less than 30° and not more than 75°.

However, at the end of the cross-section in the longitudinal direction of the gusset, the penetration length x' is the vertical foot of the perpendicular line drawn from the welding end 7' on the gusset side to the base plate, that is, point C' to the welding root 8 length. Penetration angle θ' is the angle formed by line segment 7'8 and line segment 8C'. In addition, the notch height a is the height from the surface of the board|substrate to the notch position A of the notch part of a gusset. The notch length x is the length from the corner C of the end of the gusset in the longitudinal direction on the substrate side before the notch is formed to the position B of the end of the gusset in the longitudinal direction on the substrate side after the notch is formed. The notch angle θ is the angle formed by the line segment AB and the line segment BC of the notch portion.

The base plate side corner of the longitudinal end face of the gusset plate is notched, the cut portion is provided on the gusset plate, and the gusset plate and the base plate are fillet-welded to obtain a welded joint. In this welded joint, the welded root The depth of penetration and the thickness of the weld seam can be reliably and greatly increased in the longitudinal direction of the gusset compared to the weld root when no cut is provided on the gusset. In addition, since the fillet length of the welded joint is adjusted according to the position of the welding root, the weld can be further increased compared to the case where the fillet welding is performed with the same length of the fillet length on the gusset plate side and the base plate side. seam thickness.

In this way, compared with the existing welded joints, the thickness of the weld can be increased by about 25% or more, so as shown in Figure 6A, the concentration of stress to the welded part can be eased, fatigue failure from the root of the weld can be prevented, and the weld can be greatly improved. Fatigue strength of weld wrap around out-of-plane corner bracing welded joints.

Description of drawings

Fig. 1 is a partial cross-sectional view of A-A of Fig. 4B schematically showing a welded out-of-plane gusset welded joint according to an embodiment of the present invention;

Fig. 2 is a partial cross-sectional view of the B-B arrow in Fig. 4D schematically showing the out-of-plane gusset welded joint after impact treatment in this embodiment;

FIG. 3 shows a partial cross-sectional view of another mode of the out-of-plane gusset welded joint of the present embodiment;

FIG. 4A is a schematic perspective view showing the manufacturing sequence of the out-of-plane gusset welded joint according to the present embodiment;

FIG. 4B is a schematic perspective view showing the manufacturing sequence of the out-of-plane gusset welded joint according to the present embodiment;

FIG. 4C is a schematic perspective view showing the manufacturing sequence of the out-of-plane gusset welded joint according to the present embodiment;

FIG. 4D is a schematic perspective view showing the manufacturing sequence of the out-of-plane gusset welded joint according to the present embodiment;

5 is a schematic perspective view showing another mode of the gusset plate of the out-of-plane gusset welded joint according to the present embodiment;

FIG. 6A is a schematic cross-sectional view illustrating the concentration of stress on the surrounding weld portion of the out-of-plane angle bracing welded joint when repeated stress is applied in the present embodiment;

Fig. 6B is a schematic cross-sectional view illustrating the concentration of stress to the welded portion of the out-of-plane angle bracing welded joint under the condition of repeated stress;

Fig. 6C is a schematic cross-sectional view illustrating the concentration of stress to the welded portion of the out-of-plane angle bracing welded joint under the condition of repeated stress;

FIG. 7A is a schematic perspective view showing the manufacturing sequence of a conventional out-of-plane gusset welded joint;

FIG. 7B is a schematic perspective view showing the manufacturing sequence of the conventional out-of-plane gusset welded joint;

Fig. 7C is a schematic perspective view showing the manufacturing sequence of the conventional out-of-plane gusset welded joint;

Fig. 7D is a schematic perspective view showing the manufacturing sequence of the conventional out-of-plane gusset welded joint;

Fig. 8 is a schematic cross-sectional view showing the thickness of the weld bead and the position of the bead thickness.

Mark description

1: Out-of-plane gusset welded joints (welded joints)

2: Substrate (steel plate)

3: gusset (steel plate)

4: Notch of the gusset (notch)

5: Welding metal

6: Fusion line (fusion line)

7: Solder stopper (solder stopper on the substrate side)

7': Weld stop (weld stop on gusset side)

8: Weld root

9: fillet weld

10: Around the welding part

11: Impact treatment traces (ultrasonic impact traces)

12: Ultrasonic shock treatment device (shock treatment device)

13: Position of the welded metal surface at the shortest distance from the root of the weld

A: The position of the end in the height direction of the notch of the gusset

B: The position of the longitudinal end of the notch of the gusset

C: Longitudinal end (corner) of the gusset before the notch is formed

C': Intersection point of a perpendicular line drawn from the welding end of the gusset side to the substrate and the surface of the substrate

C″: the intersection point of the perpendicular line drawn from the gusset cut position A to the substrate and the surface of the substrate

S: Gusset cut side

a: Height of the notch (mm)

x: length of notch (mm) (length from substrate-side end C of the gusset before the notch is formed to substrate-side end B of the gusset after the notch is formed)

x': Penetration length (mm) (the length from the intersection point of the perpendicular line drawn from the welding end of the gusset side to the substrate and the substrate surface to the welding root)

θ: Notch angle (°) (the angle between the substrate surface and the notch surface S)

θ': Penetration angle (°) (connection line connecting the welding end on the gusset side and the welding root, and connecting the perpendicular line drawn from the welding end on the gusset side to the substrate and the surface of the substrate The angle formed by the connecting lines of the intersection)

d ₁ : Scheduled leg length on the substrate side (mm)

d ₂ : Predetermined weld leg length on gusset side (mm)

d ₁ ′: Solder leg length on the substrate side (mm)

d ₂ ′: Length of weld leg on gusset side (mm)

f: Depth of impact treatment marks (mm)

r: Radius of curvature of impact treatment marks (mm)

t: weld thickness

Detailed ways

Hereinafter, the present invention will be specifically described.

1 is a longitudinal cross-sectional view showing the longitudinal direction of the gusset plate 3 of the out-of-plane gusset welded joint 1 of FIG. . FIG. 2 is a schematic diagram showing a cross-section taken along the line B-B in FIG. 4D , showing a state in which impact treatment is applied to the weld stop portion 7 and traces of the impact treatment are formed.

In one embodiment of the present invention, in order to improve the fatigue resistance of the welded joint, notches are provided at the corners of the gusset to ensure a large weld thickness and reduce repeated stress concentration at the root of the weld. That is, it can be seen from FIGS. 6A and 6B that the weld thickness increases. In addition, in JIS Z 3001, the weld thickness is defined as the distance from the root of the section of the fillet weld (welding root 8) to the surface, which is the distance t in Fig. 8. Therefore, depending on the position of the weld stop 7, 7' where the weld metal surface intersects the base metal surface and the shape of the weld metal penetration, the shortest distance from the weld root 8 to the weld metal surface may be between the weld root 8 and the weld stop. 7 or the distance between the welding root 8 and the welding end 7'. That is, a point 13 on the surface of the weld metal 5 (end point of the weld bead thickness) at which the distance from the weld root 8 to the surface of the weld metal 5 is the smallest may coincide with the weld stop 7 or the weld stop 7'.

In FIGS. 1 and 2 , each point and each dimension of the weld metal 5 are defined as described above. The position of the welding end 7 on the substrate 2 side is defined as point 7, the position of the welding end 7' on the gusset 3 side is defined as point 7', the position of the welding root 8 is defined as point 8, and A point C' is defined as a vertical foot of a perpendicular line drawn from the welding stop portion 7' on the side of the gusset plate 3 to the surface of the substrate 2 before welding (line segment 78). In addition, the distance between the welding root 8 and the point C' after welding is defined as the penetration length x' (mm), and the angle formed by the line segment 7'8 and the line segment 8C' is defined as the penetration angle θ' (°), The length of the line segment 7C' is defined as the fillet length d ₁ ' (mm) on the substrate 2 side, and the length of the line segment 7'C' is defined as the fillet length d ₂ ' (mm) on the gusset 3 side. In addition, the fillet length is defined as the distance from the point C' to the end of the fillet weld (welding end portion 7, 7'). As will be described later, the gusset plate 3 provided with the notch 4 and the base plate 2 are fillet-welded by changing the conditions such as the welding conditions and the length of the weld leg to form the welded joint 1 shown in FIG. 1 . The fatigue resistance of the welded joint 1 shown in FIG. 2 was investigated by a fatigue test after ultrasonic shock treatment was performed on the welded end portion 7' of the welded portion 10 of the welded joint 1 . In addition, the fillet length d ₁ ' (mm) on the substrate 2 side, the fillet length d ₂ ' (mm) on the gusset 3 side, the penetration angle θ' (°), and the penetration length x' (mm) were investigated. Respective relationship with anti-fatigue properties. In addition, the welded portion 10 is composed of a welded portion formed by the welded portion and a welded portion formed on the end surface of the gusset plate in the longitudinal direction.

As a result, it was judged that the welded joint 1 obtained by welding the gusset plate 3 with the notch portion 4 can increase the thickness of the weld bead and has excellent fatigue resistance compared to a welded joint without the notch portion provided on the gusset plate. . However, when the weld leg length d ₁ ' is small, the end point (point 13 in Fig. 8) of the weld thickness portion (the thinnest portion of the weld metal 5) approaches the point where fatigue cracks are most likely to occur from the gusset plate 3 side. Solder stop 7 on the substrate 2 side. Therefore, reducing the fillet length d ₁ ′ is not preferable from the viewpoint of improving the fatigue resistance of the solder stop portion 7 on the substrate 2 side.

Therefore, in this embodiment, the position of the weld stopper 7 on the side of the substrate 2 after welding and the minimum penetration are specified so that the penetration length x' and the fillet length d ₁ ' satisfy the following formula (1). quantity. Thereby, the end point 13 of the weld bead thickness portion can be prevented from becoming the weld stopper 7 on the substrate 2 side, and excellent fatigue resistance properties can be ensured.

x′+d ₁ ′＞d ₂ ′/sinθ′...(1)

In addition, the penetration length x' and the fillet length d ₁ ' may satisfy the following formula (1').

x′+d ₁ ′＜10d ₂ ′/sinθ′...(1′)

In addition, the deeper the penetration into the gusset 3 (the movement of the fusion line 6 into the gusset 3 ), the smaller the penetration angle θ', which is suitable in terms of ensuring the thickness of the weld bead. However, welding operation time becomes long because, for example, it takes time and labor to perform beveling in advance, or multilayer weld layers are required to ensure penetration, or it takes time and labor to fix parts before welding. Therefore, it is preferable that the penetration angle θ' is 35° to 60°. In addition, when the penetration angle θ' is greater than 75°, the penetration length x' is short, so in order to sufficiently ensure a large weld thickness, it is necessary to increase the weld leg length d ₂ ', and it is necessary to perform welding such as multi-layer overlay welding. operation, time-consuming and labor-intensive.

In order to further improve the fatigue resistance of the out-of-plane gusset welded joint, the present inventors investigated the influence of the leg length of the welded joint provided with the gusset plate in which the notch was formed. That is, use a gusset with a notch so that the weld leg length d ₂ ′ on the side of the gusset is between 1/3 times the thickness t ₂ of the gusset and 5/7 times the thickness t ₂ of the gusset Between changes and fillet welds to make welded joints. In addition, the penetration angle θ' is varied between 30° and 75° so as to satisfy the formula (1), and the fillet length d ₁ ' on the substrate side is made substantially constant. The fatigue resistance of the welded joint was investigated by a fatigue test after ultrasonic shock treatment for improving the fatigue resistance was performed on the welding end of the welded portion of the welded joint produced in this way.

As a result, in a welded joint using a gusset with a notch, if the fillet length on the side of the gusset is small, as shown in FIG. Fatigue cracks occur near the welding stop 7 ′, or fatigue cracks occur from the welding root 8 and penetrate the weld metal 5 . Therefore, shortening the fillet length on the gusset side is not preferable from the viewpoint of improving the fatigue resistance. Therefore, as a result of further examination of the leg length on the gusset side, it has been found that in order to reduce the stress acting on the weld thickness portion of the weld metal, by forming the leg length _d2 ' on the gusset side as a gusset The thickness of the plate is more than 1/3 of _t2 , which greatly improves the fatigue resistance.

Therefore, in the present embodiment, the fillet length d ₂ ′ on the side of the gusset is 1/3 or more of the plate thickness t ₂ of the gusset. In the out-of-plane gusset welded joint of this embodiment, by determining the leg length on the side of the gusset according to the plate thickness of the gusset, stress concentration in the weld thickness portion can be alleviated. Therefore, the effect of improving the anti-fatigue properties of the shock treatment to the weld stop portion 7 is effectively exerted, and the fatigue resistance properties of the welded joint can be greatly improved. In addition, considering the size of the gusset, the fillet length d ₂ ′ is equal to or less than the width w of the gusset.

In the out-of-plane gusset welded joint of this embodiment, the relationship between the leg length d ₂ ′ on the side of the gusset and the thickness t ₂ of the gusset is specified as described above, and the penetration length is specified by Equation (1) Relationship between x', penetration angle θ', leg length d ₁ ' on the substrate side, and leg length d ₂ ' on the gusset side. Due to this relationship, the bead thickness of the welded portion is sufficiently ensured, and the stress concentration in the bead thickness portion is alleviated. In addition, ultrasonic shock treatment for improving fatigue characteristics is performed on the welding end of the welded part, and the fatigue resistance characteristics are improved. Also, in order to reduce stress concentration, it is effective to increase the fillet length d ₁ ′ on the substrate side, or to smooth the shape of the solder stop portion 7 in advance.

Hereinafter, an effective method of manufacturing an out-of-plane gusset welded joint according to an embodiment of the present invention will be described.

4A to 4D are partial perspective views schematically illustrating the procedure of the method of manufacturing the out-of-plane gusset welded joint according to this embodiment. The out-of-plane gusset welded joint 1 includes a base plate 2 (plate thickness t ₁ (mm)) and a gusset plate 3 (plate thickness t ₂ (mm)) fillet-welded to the surface of the base plate 2 . In addition, the direction perpendicular to the surface of the substrate 2 (the direction of the thickness _t1 of the substrate 2) and the direction of the width w of the gusset 3 (height direction) coincide. In addition, the direction perpendicular to the direction of the plate width w and the direction of the plate thickness t2 of the gusset plate ₃ is the longitudinal direction of the gusset plate 3 . The portion of the end surface in the longitudinal direction including the side (corner) in the same direction as the plate thickness _t2 is a corner portion of the gusset plate 3 .

In the out-of-plane gusset welded joint of this embodiment, the rectangular gusset plate 3 is formed with a notch 4 ( Figure 4A). The notch 4 has a dimension of a (mm) from the corner of the gusset 3 facing the base plate 2 in the height direction of the gusset 3 (the direction of the plate width w of the gusset 3), The longitudinal direction of 3 (the direction toward the center of the longitudinal direction of the gusset 3 ) has a dimension x (mm) from the corner direction of the gusset 3 facing the base plate 2 .

The gusset plate is arranged on the base plate 2 such that the end surface of the gusset plate 3 having the notch 4 in the plate width w direction faces the surface of the base plate 2 . After that, the gusset plate 3 having the notch 4 is fillet-welded with the base plate 2 . As a result, fillet welds 9 are formed around the surface of the gusset 3 facing the substrate 2 (near the four sides), and in the fillet 9, the ends in the longitudinal direction of the gusset 3 (shown in FIG. 4B A weld wrap 10 is formed around the right end of the gusset 3 shown) ( FIG. 4B ). In the fillet weld 9 formed in this way, at least the vicinity of the weld end portions 7, 7' of the surrounding weld 10 is subjected to shock treatment for improving fatigue resistance by, for example, an ultrasonic shock treatment device 12 (FIG. 4C). As a result, impact treatment traces 11 are formed on the weld stoppers 7, 7' (FIG. 4D).

As shown in Figs. 4A to 4D, the out-of-plane gusset welded joint usually has a shape (t 2 ≤ w) in which the length in the height direction of the gusset plate (plate width w) is equal to or greater than the length in the plate thickness direction (plate thickness _{t 2} ) . That is, the gusset plate is arranged so that the end surface in the plate thickness direction faces the plate surface of the substrate, and the periphery (four sides) of the end surface are fillet-welded to the corner of the substrate to form an out-of-plane gusset welded joint having the shape shown in FIGS. 4A to 4D . Therefore, an out-of-plane gusset welded joint of the shape shown in FIGS. 4A to 4D will be described as an example.

In addition, in this embodiment, the shape of a gusset plate is not limited to the shape ( _t2≤w ) shown in FIGS. 4A-4D. For example, the shape of the gusset may be the shape shown in FIG. 5 (t ₂ >w). That is, the gusset may have a shape in which the length in the height direction (board width w) is smaller than the length in the thickness direction (board thickness t ₂ ).

In addition, the welded portions are formed at the corners (four corners of the end faces in the plate thickness direction) of the gusset plate having the notch. Here, for convenience of description, the welded portion formed at the end portion in the longitudinal direction of the gusset plate will be described as an example.

FIG. 1 shows a longitudinal cross-section of the gusset plate 3 of the out-of-plane gusset welded joint 1 of FIG. 4B in the longitudinal direction. That is, FIG. 1 is a schematic diagram showing a cross-section taken along the line A-A of FIG. 4B , and shows a state before shock treatment is applied to the weld stop portion 7 . FIG. 2 is a schematic diagram showing a cross-section taken along the line B-B in FIG. 4D , showing a state where impact treatment traces 11 after impact treatment for improving fatigue resistance properties are performed on the weld stop portion 7 are formed.

As shown in FIGS. 1 and 4B , among the corners of the ends of the gusset 3 in the longitudinal direction (the ends where the welded portions 10 are formed), the corners on the side of the substrate 2 are notched to form the notches 4 . The notch portion 4 is formed to increase the area to be joined by the weld metal 5 and ensure a sufficient thickness of the weld bead.

Each point and each dimension of the notch part 4 before fillet welding are defined in FIG. 1 . A corner on the side of the substrate 2 at the end in the longitudinal direction of the quadrangular gusset 3 before notching is defined as a corner C. As shown in FIG. Also, the position of the end face of the gusset 3 in the longitudinal direction at a height of a (mm) from the surface of the substrate 2 on the gusset 3 side in the height direction of the base 2 is defined as a position A. That is, the position A in FIG. 1 is a position from the corner C along the width w direction of the gusset plate 3 (the height direction of the substrate 2 ) from the notch height a (mm). In addition, the position from the corner C of the gusset 3 to the inner side of the gusset 3 (the direction from the end of the gusset 3 toward the center in the longitudinal direction of the gusset 3 ) is defined as position b. Also, the foot of a perpendicular line drawn from position A to the surface of the substrate 2 before soldering (line segment 78) is defined as point C″. The distance between this C″ and position B is defined as the apparent cut length x″ In Fig. 1, the triangular range surrounded by position A, position B and corner C is notched in the plate thickness direction to form a notch 4. In addition, in Fig. 1, the length x of the notch is consistent with the length x" of the appearance.

Here, in FIGS. 1 and 2 , the angle C coincides with the point C'. That is, the vertical foot of the perpendicular line drawn from the notch position A to the surface of the substrate 2 before welding (line segment 78) and from the end stop portion 7' on the side of the gusset plate 3 to the surface of the substrate 2 before welding (line segment 78) The vertical feet of the drawn perpendiculars are represented by coincident identical positions. At this time, the end surface of the gusset plate 3 in the longitudinal direction is perpendicular to the upper surface of the substrate 2 .

In addition, there are cases where the two are in a non-orthogonal relationship. For example, in the partial sectional view of the welded joint schematically shown in FIG. 3 , the shape of the gusset 3 before the cut is different from that shown in FIG. 1 . Thus, in the case of the trapezoidal gusset shown in Fig. 3, the positions of the corner C and the point C' are different. In addition, the incision length x in Fig. 3 is compared with the incision length x in Fig. 1, only the distance between the corner C and the point C" is increased. In the following, the case of the out-of-plane gusset welded joint 1 in Fig. 1 is taken as an example Explanation. In addition, in the case of the fillet welding of the arc-shaped notch, the notch length x shortens the distance between the corner C and the point C″.

This notch height a (the length from position A to corner C) needs to be set to be equal to or less than the predetermined fillet length _d2 on the gusset plate 3 side of the welded joint 1 . When the notch height a is greater than the predetermined weld leg length _d2 , a notch portion not covered by the weld metal 5 remains in the welded portion on the side of the gusset plate 3, and a complete welded portion may not be obtained. In addition, as long as the notch part 4 is formed in the gusset plate 3, the lower limit of the notch height a is not specifically limited. However, when the notch height a is too small, the area joined by welding decreases, so the effect of suppressing the occurrence of fatigue cracks decreases. Generally, when the gusset plate 3 is welded with three or less welding layers, it is preferable that the notch height a is 80 to 90% of the predetermined fillet length _d2 on the gusset plate 3 side.

That is, it is preferable that the relationship between the notch height a and the predetermined fillet length _d2 must satisfy the following formula (2), and it is preferable to satisfy the following formula (3).

0<a≤d ₂ ... (2)

0.8d ₂ ≤ a ≤ 0.9d ₂ ... (3)

In addition, the relationship between the notch height a and the fillet length d ₂ ′ on the side of the gusset plate 3 satisfies the following formula (4).

d ₂ ′＞a ...(4)

In addition, the predetermined fillet lengths d ₁ and d ₂ are target fillet lengths during fillet welding.

On the other hand, as shown in FIG. 1 , the angle formed by the line segment AB and the line segment BC is defined as the notch angle θ. The notch angle θ is an angle formed between the notch surface S of the notch portion 4 of the gusset 3 and the surface of the substrate 2 before welding (the angle formed between the line segment forming the notch surface and the line segment forming the upper surface of the substrate before welding) . Since the relationship between the notch angle θ, the notch length x, and the notch height a satisfies the following formula (5), the following formula (7) is derived from the following formula (6).

a/x=tanθ...(5)

_a≤d2 ...(6)

xtanθ≤d ₂ ... (7)

Therefore, it is necessary to set the dimensions of the notch 4 (the notch length x and the notch angle θ) so as to satisfy the above-mentioned expression (7). However, considering the situation of FIG. 3 , the apparent notch length x" and notch angle θ must satisfy the following formula (8).

x″tanθ≤d ₂ ... (8)

The incision length x (mm) (or the apparent incision length x") is not particularly specified if it satisfies the above relationship. However, if the incision length x is too long, the incision angle θ is too small. Therefore, the Part of the gap is particularly narrow near position B, and it is often difficult to feed welding materials such as welding wire and welding rod during welding. In this case, the weld metal does not reach position B sufficiently, and insufficient filling of weld metal and insufficient penetration may easily occur. Poor soldering.

In addition, when the notch angle θ increases, the notch length x decreases, and the surface area of the notch portion decreases. Therefore, the area joined by welding increases, and the effect of the notch portion 4 for reducing the stress generated at the root portion is reduced.

Therefore, in order to increase the area joined by welding, the notch angle θ and the notch length x may be selected so that x satisfies the range of the above-mentioned formula (1) so that a large notch area can be ensured without welding failure.

In addition, in order to reduce the stress concentration of the welding stop portion 7, it is preferable that the fillet length d ₁ ′ be as large as possible. In addition, in order to facilitate the subsequent ultrasonic impact treatment, it is preferable to weld the welded end portions 7 and 7' as smoothly as possible.

The inventors of the present invention prepared various gussets with notches formed in such a manner that at least one of the notch height a, notch angle θ, and notch length x was different, and produced welded joints by fillet welding with a predetermined predetermined leg length _d2 . . After ultrasonic shock treatment was performed on the welding toe of the welded portion of the welded joint, the fatigue characteristics were investigated by a fatigue test. As a result, the notch angle θ is 80° or less, and the fatigue characteristics of the welded joint can be reliably improved. Therefore, the notch angle θ of the notch portion is 80° or less. In addition, the lower limit of the notch angle θ is not particularly limited. Since the notch angle θ is 45° or more, the gap between the substrate and the gusset (the gap at the notch portion) is sufficient, so that the welding wire can reliably reach the root of the weld. In this case, sufficient penetration can be efficiently and stably obtained in a short period of time. In addition, the notch angle θ is 75° or less, and the notch length x and the weld bead thickness can be sufficiently secured. In this case, the fatigue resistance of the welded joint is sufficiently improved. Therefore, it is preferable that the notch angle θ is not less than 45° and not more than 75°. More preferably, the notch angle θ is not less than 50° and not more than 70°.

As described above, by providing a notch at the longitudinal end of the gusset plate that has been wound around and performing fillet welding, the root of the fillet weld can be separated from the weld stop compared to the case where no notch is formed. The weld thickness can be increased. As a result, it is possible to alleviate the concentration of the action of force due to repeated stress application on the root of the weld, and improve the fatigue resistance of the welded joint (see FIG. 6A ). As mentioned above, in order not to generate|occur|produce a welding defect, such as insufficient penetration, in a fillet weld, welding is normally performed, securing sufficient penetration. Also in this embodiment, sufficient penetration is ensured and welding is performed so that welding defects such as insufficient penetration do not occur at the portion including the welding root, that is, position B (see FIG. 1 and FIG. 2 ).

As described above, welding is performed in consideration of the fillet lengths d ₁ ′, d ₂ ′ and the penetration angle θ′ so that the penetration length x′ and the fillet length d ₁ ′ on the substrate side satisfy the above-mentioned formula (1). As a result, the minimum amount of penetration can be ensured at the welding end portion on the side of the substrate after welding. Therefore, it is possible to prevent the thinnest portion of the weld bead from being the end stop portion on the substrate side, and it is possible to ensure excellent fatigue resistance.

In addition, the fillet lengths d ₁ ′, d ₂ ′ satisfy the following equations (9) and (10) with respect to the predetermined fillet lengths d ₁ , d ₂ , respectively.

d ₁ ′≥d ₁ ...(9)

d ₂ ′≥d ₂ ...(10)

As described above, by providing the notch, it is possible to efficiently manufacture a welded joint satisfying the above-mentioned formula (1).

As mentioned above, in order to further improve the fatigue resistance of out-of-plane gusset welded joints, the present inventors conducted a study on the influence of the fillet lengths d ₁ ′, d ₂ ′ using a gusset plate with a cutout. investigation. As a result, it was found that when the leg length d ₂ ′ on the side of the gusset is short, the thickness of the weld bead decreases with respect to the plate thickness t ₂ of the gusset, so the stress in the bead thickness portion increases. In addition, it was found that by setting the fillet length d ₂ ′ on the side of the gusset to 1/3 or more of the thickness t ₂ of the gusset, the fatigue resistance of the welded joint was significantly improved.

Therefore, in the method of manufacturing a welded joint according to the present embodiment, the fillet length d ₂ ′ on the side of the gusset is 1/3 or more of the thickness t ₂ of the gusset (the following formula (11)). Do the welding. By controlling the relationship between the weld leg length d ₂ ′ on the side of the gusset plate and the plate thickness t ₂ of the gusset plate, a sufficient weld thickness can be further ensured, so that the stress generated at the root of the weld can be reduced, and the welded joint can be greatly improved. Anti-fatigue properties.

d ₂ ′≥t ₂ /3...(11)

Also, in normal soldering, the fillet length d ₁ ′ on the substrate side and the fillet length d ₂ ′ on the gusset side are often substantially the same length. However, the fillet length d ₁ ′ on the board side needs to satisfy the above formula (1), and the fillet length d ₂ ′ on the gusset side needs to satisfy the above formula (1) and the above formula (11).

As described above, in the method of manufacturing the out-of-plane gusset welded joint of this embodiment, a predetermined notch is provided in the gusset plate, and the thickness t ₂ of the gusset plate is defined as the fillet length d ₂ ′ on the side of the gusset plate. More than 1/3 of the way and satisfy the formula (1) to get enough penetration and fillet welding.

In addition, it is preferable to form the notch so that the notch angle θ of the gusset is 45° or more and 75° or less. In addition, it is preferable to obtain a fillet weld having a penetration angle θ′ of 30° or more and 75° or less by welding so as to obtain sufficient penetration.

In this way, by providing the notch in the gusset plate, welding can be performed while ensuring sufficient penetration, thereby increasing the cross-sectional area of each member joined by the weld metal, and ensuring a sufficient weld thickness. Therefore, the stress generated at the root of the weld can be reduced, effectively greatly improving the fatigue resistance of the welded joint.

Hereinafter, in the welded joint according to the present embodiment, impact treatment for improving the fatigue resistance of the welded end itself is performed on at least the welded end portion of the surrounding welded portion among the fillet welded portions formed as described above.

This impact treatment requires at least a weld stop portion on the substrate side of the wrap around portion where fatigue cracks are likely to occur when repeated stress is applied. However, it is also possible to perform impact treatment on all the weld ends of the wrap around weld or the fillet weld.

The impact treatment to improve fatigue resistance may also be shot peening treatment such as shot peening and hammering. The method of this impact treatment is not particularly limited. That is, it is only necessary to shock the welding toe to the extent that the position of the toe line of the welding toe before impact treatment cannot be judged, to form a smooth recess in the welding toe, and to provide compressive residual stress by plastic flow.

However, impact treatment (UIT treatment) by an ultrasonic impact treatment device is effective, and therefore it is preferable. The conditions of this UIT impact treatment performed on the weld toe are not particularly limited. In this case, it is preferable to perform appropriate UIT impact treatment according to the fatigue resistance properties required for the material (component).

Hereinafter, an example will be described in which impact treatment (UIT treatment) is performed using an ultrasonic impact device. The impact treatment is preferably such that the radius of curvature r in the cross section perpendicular to the welding line of the welding end is 1.0 mm to 10.0 mm, and the depth f from the surface of the steel material (base plate or gusset plate) to the thickness direction of the steel material is 0.05 mm. Ultrasonic impact marks 11 above and below 1.0 mm. More preferably, the depth f thereof is not less than 0.1 mm and not more than 0.4 mm.

When the curvature radius r of the impact treatment mark (ultrasonic impact mark) 11 is 1.0 mm or more, the stress concentration at the fillet weld can be sufficiently relaxed. In addition, when the radius of curvature r is 10.0 mm or less, the effect of alleviating stress concentration increases while the radius of curvature r increases. In this case, the fatigue resistance characteristics of the welded joint can be further improved. This radius of curvature r can be appropriately determined in consideration of processing time. In addition, impact treatment traces (ultrasonic impact traces) 11 are usually formed centering on the welded end portions 7, 7'. However, it is preferable that the impact treatment trace (ultrasonic impact trace) 11 is formed so as to include at least a part of the weld metal 5 and the influence of welding heat. Therefore, it is preferable to select the ultrasonic shock position and the curvature radius r of the ultrasonic shock mark in consideration of the position where the shock treatment mark 11 is formed.

In addition, if the depth f of the impact treatment trace (ultrasonic impact trace) 11 on the substrate 2 or gusset 3 is 1.0 mm or less, the depth f increases and the tensile residual stress near the weld stop 7 is released. effect or the effect of applying compressive residual stress increases. Therefore, a significant improvement in the fatigue resistance characteristics of welded joints can be expected. In addition, since sufficient time is required when the depth f is increased, the depth f is determined in consideration of efficiency. Therefore, it is preferable that the depth f of the ultrasonic shock mark 11 is 1.0 mm or less. In addition, the depth f of the ultrasonic shock marks 11 is not particularly limited. The depth f of the ultrasonic impact mark 11 may be 0.05 mm or more, for example, as an amount that cannot determine the position of the toe line of the welding toe portion before the impact treatment.

In addition, as the ultrasonic shock device 12 for performing the ultrasonic shock treatment, for example, devices disclosed in the aforementioned Patent Documents 1 to 3 can be used. The shape of the vibration terminal (pin) of the ultrasonic impact device 12 can be selected in consideration of conditions such as the shape of the ultrasonic impact mark 11 to be formed.

For example, it is preferable to set the curvature radius of the axial cross-section of the front end of the ultrasonic impact device 12 to 1.0 mm or more and 10 mm or less. The shape of the tip is the shape of the ultrasonic shock mark 11 after the shock treatment. Therefore, when the radius of curvature is too small, notch-shaped grooves are formed in the weld stop, and stress concentration increases. On the other hand, if the radius of curvature is too large, depending on the shape of the bead, it is difficult to form the ultrasonic impact mark 11 with a predetermined radius of curvature r even if the weld end is impacted by impact treatment. Therefore, in order to reliably form ultrasonic shock marks with a predetermined radius of curvature r, it is preferable that the radius of curvature of the axial cross-section of the tip of the ultrasonic shock device 12 is not less than 1.0 mm and not more than 10 mm. In addition, it is preferable that the radius of curvature is not less than 1.5 mm and not more than 5.0 mm.

The conditions of the ultrasonic shock treatment may be appropriately selected according to the fatigue resistance properties required for the application. Therefore, the conditions of the ultrasonic shock treatment are not particularly limited. For example, it is preferable to vibrate the vibrating terminal at a frequency of 20 kHz to 50 kHz, and to apply ultrasonic impact at a power of 0.01 kW to 4 kW. However, it is not necessary to impact by ultrasonic vibration, so it is also possible to impact at a low frequency below 20 kHz or in a discontinuous cycle. As a result, the metal on the surface of the weld stop part flows plastically, releasing the tensile residual stress formed with the cooling of the fillet weld, and forming a compressive residual stress field. In addition, by repeatedly performing ultrasonic impact treatment in a heat-insulated state in which heat generated by processing is not dissipated from the surface of the weld toe, the same effect as hot forging can be applied to the weld toe. As a result, the crystal structure in the vicinity of the weld stop is refined, and the fatigue resistance of the welded joint is improved.

Example

A steel plate (thickness 14mm x width 50mm x length 500mm) of the steel grade JIS SM490B described in JIS G3106 was used for the substrate. In addition, a steel plate (thickness 14 mm x width 50 mm x length 100 mm) of the same steel type as the base plate was used for the gusset plate. This gusset is arranged on the substrate as shown in FIG. 4A . That is, the longitudinal direction of the gusset coincides with the longitudinal direction of the substrate 2 , and the width direction of the gusset coincides with a direction perpendicular to the upper surface of the substrate. In addition, a gusset plate is disposed substantially in the center (central portion of the upper surface) of the substrate in the longitudinal direction and the width direction.

The gusset plates arranged as described above were fillet welded to the substrate to prepare samples of out-of-plane gusset welded joints. In addition, the same gusset plate as the gusset plate on the upper surface of the substrate is also provided on the lower surface of the substrate (not shown). The position of the gusset on the lower surface is the same as the position of the gusset on the upper surface. 20 samples of out-of-plane gusset welded joints were prepared, and 16 of the 20 samples were provided with notches on the gusset plates. In addition, for 2 of these 16 samples, a steel plate (20 mm thick x 50 mm wide x 100 mm long) of the same steel type as the base plate but thicker than the gussets of the other 14 samples was used as the gusset. In addition, the four samples in which no notches were formed on the gussets were conventional out-of-plane gusset welded joint samples, as shown in FIG. 7B .

For 16 of the above-mentioned samples, the corners on the substrate side at both ends of the gusset in the longitudinal direction were partially notched to form notches 4 . At this time, the notch height a and the predetermined fillet length _d2 are determined in such a way as to satisfy the formula (2), and the notch angle θ (the angle formed by the surface of the substrate and the notch surface of the gusset plate) is changed from 25° to 80° , changing the incision length x.

In addition, the expected fillet length _d2 on the gusset side and the expected fillet length _d1 on the substrate side are respectively set based on soldering design criteria and the like.

The above samples were all welded by carbon dioxide semi-automatic welding (GMAW: voltage 35V, current 350A, speed 3mm/sec, gas composition CO ₂ 100%) using YGW-11 (JIS Z3321: wire diameter 1.4mm) as welding wire.

Also, the fillet length d ₂ ′ on the side of the gusset is not less than 1/4 and not more than 3/4 of the thickness t ₂ of the gusset. In addition, the fillet length d ₁ ′ on the substrate side was substantially the same length as the fillet length d ₂ ′ on the gusset side except for one sample. These fillet lengths d ₁ ′, d ₂ ′ are equal to or greater than the expected fillet length d ₁ on the substrate side and the expected fillet length d ₂ on the gusset side, except for one sample.

UIT treatment was performed on the weld end portion on the substrate side of the welded portion of the sample of the out-of-plane gusset welded joint produced in this way by an ultrasonic impact treatment device, and impact treatment traces were formed. The radius of curvature of the axial section of the front end of the vibration terminal (pin) of the ultrasonic impact treatment device is 1.0-10.0 mm. In addition, the conditions of the UIT treatment were a vibration frequency of 27 kHz and a power of 1 kW. In addition, impact treatment traces having a curvature radius r of 1.0 to 10.0 mm and a surface depth f of 1.0 mm or less are formed near the solder end portion on the substrate side of the wrap around portion. In addition, for comparison, 2 of the above-mentioned 20 samples were not subjected to UIT treatment.

Fatigue tests were performed on all specimens of the final fabricated out-of-plane gusset welded joints. In this fatigue test, the number of repetitions until fracture was measured under the conditions of a stress amplitude of 100 MPa and a stress ratio of 0.1.

In addition, after the fatigue test, the gusset plate was cut in the longitudinal direction at the approximate center of the plate thickness to prepare a sample for cross-sectional observation. Corrode the vicinity of the welds at both ends of the sample (test body) in the longitudinal direction with nitric acid ethanol, and measure the penetration length (the penetration length of the weld metal) x′, the weld leg length d ₁ ′, d ₂ ′, the weld seam thickness t. In addition, the shape of the shock-treated portion of the welding toe was observed.

Table 1 shows the results.

In addition, the fillet lengths d ₁ ′, d ₂ ′ and weld bead thickness t in Table 1 are the average value of each position (4 places) where the weld wrapping portion is formed. That is, regarding the fillet lengths d ₁ ′, d ₂ ′ and the thickness t of the weld bead, the weld wraps at both ends in the longitudinal direction of the gusset and the wraps on both surfaces of the substrate are considered. Anti-fatigue properties (number of repetitions until fracture) are values for each sample.

【Table 1】

For samples Nos. 2 to 5 and 7 to 20 subjected to UIT treatment, the welding toe is formed with a radius of curvature r of 1.0 to 10.0 mm and a depth f of 1.0 mm from the surface of the steel to the thickness of the substrate. In the following impact treatment marks, the shape of the welding stop is a curve.

As shown in Table 1, in the case where the gusset plate is not provided with a notch, the conventional example No. 1 without UIT treatment is compared with the conventional example No. 2 test piece with UIT treatment. Compared with that, the anti-fatigue properties are poor. From this comparison, it was confirmed that the anti-fatigue characteristics under the UIT treatment were improved. In addition, in the No. 6 sample, sufficient cutouts are provided on the gusset, and the dimensions of the welded joint (for example, the length of the weld leg d ₁ ′, d ₂ ′) satisfy the formula (1), but it has not been implemented. UIT processing. Therefore, the number of repetitions until breaking is about 300,000 times. This number of repetitions was at the same level as that of the No. 1 sample which did not perform UIT. In this way, even when the notches are formed and the fillet lengths d ₁ ′, d ₂ ′ are ensured, the effect of improving the fatigue resistance due to the increase in the thickness of the weld is not exhibited.

In samples No. 8 and No. 11, the gussets were not provided with notches, and the dimensions of the welded joints did not satisfy the expression (1). Also, the fillet length d ₂ ′ on the side of the gusset is not long enough. Therefore, no matter whether UIT treatment is implemented or not, the fatigue resistance characteristics of welded joints cannot be improved.

In addition, in samples Nos. 9, 10, and 12, the notches were provided on the gussets, but the fillet length d ₂ ′ on the gusset side did not satisfy the above formula (11). Therefore, the fatigue resistance characteristics of the welded joint cannot be improved.

In samples Nos. 11 and 12, since the fillet length d ₂ ′ is short relative to the thickness t ₂ of the gusset plate, a weld bead thickness corresponding to the thickness t ₂ of the gusset plate cannot be obtained. Therefore, the stress in the thickness portion of the weld increased, the weld metal fractured, and the lives of No. 11 and No. 12 samples were not so long.

With respect to the above-mentioned samples, a notch having a sufficient size was formed on the gusset to perform fillet welding so as to satisfy the conditions of the size of the fillet (for example, the above-mentioned formula (1)), and it was judged that the UIT treatment was carried out. In No.3 and No.4 samples, as shown in Table 1, the fatigue resistance of welded joints is significantly improved.

In the sample No. 13, the notch angle θ was smaller than that of the sample No. 3, and the initial notch angle θ was smaller than 45°. Therefore, in order to ensure sufficient penetration to the root of the weld, the welding time increases. As a result, it was found that the final penetration amount can be sufficiently ensured, the penetration length x' can be satisfied by the formula (1), and the effect of improving fatigue resistance can be obtained. In addition, when the incision angle θ is small, high welding skills and time are required in order to secure penetration to the root of the weld. Therefore, it is industrially preferable to set the notch angle θ within an appropriate range.

In the sample No. 5, there were notches and fillets of sufficient size. Therefore, the fatigue resistance of the welded joint was improved compared to the No. 2 sample in which the notch was not formed in the gusset.

The sample No. 14 is different from the sample No. 13 in that the notch angle θ exceeds 75°. In this sample, finally, the notch was sufficiently penetrated by welding. In this case, the penetration angle θ' is 75°, and the size of the fillet satisfies the above formula (1). As a result, it was found that the fatigue life of the welded joint was extended. In addition, the penetration angle θ' of the No. 14 sample is smaller than that of the No. 5 sample, so the fatigue resistance of the No. 14 sample is higher than that of the No. 5 sample.

In the sample No. 15, the penetration angle θ' was smaller than 45°, and it was found that the fatigue life was prolonged. As in the No. 13 sample, the smaller the penetration angle θ', the better, but considering the actual welding penetration as described above, it is preferably 30° or more.

Samples Nos. 16 and 17 are examples in which the fillet length d ₁ ′ on the substrate side is small. In sample No. 16, since the size of the fillet weld did not satisfy the formula (1), the stress concentration at the weld toe increased, and the fatigue life extension effect could not be obtained. On the other hand, in the No. 17 sample, the size of the fillet weld satisfies the formula (1), which has the effect of improving the fatigue resistance of the welded joint.

In addition, the sample No. 18 is an example in which the penetration length x' is small. In this sample, since the size of the fillet weld did not satisfy the formula (1), the stress concentration at the weld toe increased, and the effect of extending the fatigue life could not be obtained.

The sample No. 19 is an example in which the notch height a is larger than the predetermined fillet length d ₂ and fillet length d ₂ ′. In this sample, a notch that was not covered with weld metal remained in the welded portion on the gusset side, and cracks occurred from the weld stop portion 7' on the gusset side, and sufficient fatigue resistance properties could not be obtained. In addition, in No. 19 sample, since the penetration angle θ' cannot be defined (symbol * in Table 1), the position A was used instead of the weld stop 7' to evaluate the penetration angle θ'.

The sample No. 20 is an example in which the notch angle θ is smaller than that of the samples No. 3 and No. 13. In this sample, sufficient penetration up to the tip of the incision could not be ensured. However, the penetration length x' satisfies the formula (1), and has the effect of improving the fatigue resistance. In addition, in No. 3 and No. 13 samples, the welding operation burden was smaller than that of No. 20 sample, and the penetration into the root of the weld could be easily ensured. Therefore, it is industrially preferable to set the notch angle θ within an appropriate range.

From these results, it was confirmed that the fatigue resistance of the welded joint can be greatly improved by producing the welded joint satisfying the above conditions.

This application claims priority based on Japanese Patent Application No. 2009-193201 for which it applied in Japan on August 24, 2009, and uses the content here.

Industrial availability

According to the present invention, in the out-of-plane gusset welded joint, the penetration depth of the welding root can be effectively increased, and the thickness of the weld seam can be increased, so that the stress concentration at the welding root can be alleviated. Therefore, the effect of improving the fatigue resistance of the weld stop portion by impact treatment such as shot peening and UIT treatment can be sufficiently produced, and the fatigue resistance of the entire out-of-plane gusset welded joint can be further improved.

Claims (4)

1. the preparation method of the outer angle brace welding point of a face, the outer angle brace welding point of this face possess substrate, from the surface of this substrate outstanding gusset and fillet welding portion, it is characterized in that,

Carry out otch processing and form notch along the end of the wide w direction of plate with cut height a, incision length x and the otch angle θ below 80 ° to the plate width direction of the end of said gusset panel length direction,

Dispose said gusset with the end face of the wide w direction of said plate of said gusset and the surperficial relative mode of said substrate, with the long d of predetermined leg of said gusset side with said notch ₂For the mode more than the said cut height a is carried out fillet welding, the long d of the leg of said gusset side ₂' be the thickness of slab t of said gusset ₂More than 1/3, and form the long d of this leg ₂', the long d of leg of said substrate-side ₁', fusion penetration length x ' and fusion penetration angle θ ' satisfy x '+d ₁'＞d ₂The said fillet welding portion of '/sin θ ',

To in the said fillet welding portion at least the welding not-go-end portion of the said substrate-side of boxing portion implement shock treatment.

2. the preparation method of as claimed in claim 1 outer angle brace welding point is characterized in that,

Said otch angle θ is more than 45 ° and below 75 °.

3. the outer angle brace welding point of a face, it possesses substrate, from the surface of this substrate outstanding gusset and fillet welding portion, it is characterized in that,

At said fillet welding portion, the long d of the leg of said gusset side ₂' be the thickness of slab t of said gusset ₂More than 1/3, and the long d of this leg ₂', the long d of leg of said substrate-side ₁', fusion penetration length x ' and fusion penetration angle θ ' satisfy x '+d ₁'＞d ₂'/sin θ ', and in the said fillet welding portion at least the welding not-go-end portion of the said substrate-side of boxing portion be formed with the shock treatment vestige.

4. as claimed in claim 3 outer gusset welding point is characterized in that,

Said fusion penetration angle θ ' is more than 30 ° and below 75 °.

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