JP2021094573A - Welding structure - Google Patents

Abstract

To provide a welded structure excellent in brittle crack propagation stop characteristics.SOLUTION: A welding structure 10 has a T joint part in which a joining member 11 is penetration welded to a member 12 to be joined in a state in which an end surface 11c of the joining member 11 abuts on a surface 12a to be joined of the member 12 to be joined. The joining member 11 has a first surface 11a and a second surface 11b, plate thicknesses of the joining member 11 and the member 12 to be joined are 50.0 mm or more, and shapes of first welding metal and second welding metal formed on the first surface 11a and the second surface 11b satisfy predetermined conditions. By using a test plate taken from the member 12 to be joined and having a surface 12c which is and corresponds to the surface 21a to be joined, a test object having first auxiliary running plate welding metal and second auxiliary running plate welding metal whose shapes satisfy a predetermined condition is formed, and a length of a crack to be developed on the test plate is reduced to a predetermined value or less when the test object is subjected to a quality evaluation test.SELECTED DRAWING: Figure 5

Description

The present invention relates to a welded structure used in a container ship or the like.

In a large container ship carrying a large amount of cargo, a large opening (hatch) for loading and unloading cargo is formed on the upper deck (upper deck). In addition, hatch side combing is provided on the upper deck so as to surround the hatch in order to prevent the inflow of seawater. The upper deck and hatch side combing are each constructed by welding a plurality of steel plates. Also, the hatch side combing is welded onto the upper deck.

When a large container ship as described above sails over the sea, a load that bends the entire hull (vertical bending load) is applied to the hull due to waves. High-strength thick steel plates are used for the upper deck and hatch side combing in order to sufficiently secure the strength (longitudinal bending strength) of the hull against such a load.

Further, as described above, the hatch side combing and the upper deck each have a structure in which a plurality of steel plates are welded together. In other words, the hatch side combing and the upper deck are formed with a plurality of welds for welding the steel plates to each other. Cracks generated at the weld tend to propagate along the weld. Therefore, for example, when a crack occurs in the welded portion of the hatch side combing, the crack may propagate toward the upper deck side along the welded portion. Therefore, in order to sufficiently improve the strength of the hull, the hatch side combing and the upper deck need to have the property of stopping the growth of cracks as described above (the brittle crack propagation stopping property).

For example, Patent Documents 1 and 2 disclose a welded structure relating to brittle crack propagation stopping characteristics.

Japanese Unexamined Patent Publication No. 2007-326147 Japanese Patent No. 5365761

By the way, in order to stop the growth of cracks generated by hatchside combing and propagated toward the upper deck side, these members are used, for example, at −10 ° C., which is an index of brittle crack propagation stopping characteristics (arrestability). It is known that it is necessary to use a thick steel plate having a Kca value of 6000 N / mm ^{1.5 or more.}

The Kca value of a steel sheet is measured by a temperature gradient type ESSO test based on WES2815, and this test evaluates the arrest property for cracks propagating in the length or width direction of the steel sheet. Therefore, it is not originally suitable for evaluating the arrest property for cracks that occur in hatch side combing and rush from the surface of the upper deck.

Therefore, when evaluating the brittle rhagades propagation stop characteristics of thick steel sheets used for upper decks in the past, a structural model arrest test using a large specimen (brittle fracture propagation stop test: brittle cracks are artificially formed on the test piece. A test) was conducted to evaluate the ability to generate brittle cracks and stop brittle cracks.

However, since it takes a lot of time and cost to carry out the large-scale structural arrest test, there is a problem that it is not easy to select a thick steel sheet having high brittle crack propagation stopping characteristics. Therefore, it is necessary to obtain a welded structure having excellent brittle crack propagation stopping characteristics at low cost by a simpler method.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a welded structure having excellent brittle crack propagation stopping characteristics.

The gist of the present invention is the following welded structure.

(1) Welding having a T-joint portion in which the joint member is partially welded to the joint member in a state where the end surface of the plate-shaped joint member is in contact with the joint surface of the plate-shaped joint member. It's a structure
The joining member has a first surface and a second surface perpendicular to the plate thickness direction of the joining member.
In the cross section perpendicular to the first surface and the surface to be joined,
The plate thickness t ₁ (mm) of the joint member and the plate thickness t ₂ (mm) of the joint member satisfy the following equations (i) and (ii).
_{The penetration depth s 1} (mm) on the member to be joined side of the first weld metal formed on the first surface side, and the welded metal on the second weld metal formed on the second surface side. The penetration depth s ₂ (mm) on the member side satisfies the following equations (iii) and (iv).
The members to be joined, in the quality evaluation test to carry out the following processes (a) ~ (d) in this order, but the following c ₁ and c ₂ are to satisfy the following (xi) and (xii) equation,
Welded structure.
(A) A test plate whose width direction corresponds to the plate thickness direction of the member to be joined and one surface in the width direction corresponds to the surface to be joined, having a plate thickness of t ₁ (mm) and a width of t 1 (mm). A _{test plate of t 2} (mm), length of 500 mm, and
It has a plate thickness of t ₁ (mm), a width of 260 mm, a length of 500 mm, has a first approach plate surface and a second approach plate surface perpendicular to the plate thickness direction, and has a notch on one side in the width direction. A run-up plate is provided, and a groove extending in the length direction is formed on the first run-up plate surface side and the second run-up plate surface side on the other side surface in the width direction.
In a state where the one side surface of the test plate is in contact with the other side surface of the run-up plate, both side partial penetration welding is performed on the groove formed in the run-up plate.
In a cross section perpendicular to the first approach plate surface and the one side surface of the test plate.
_{In the first approach plate weld metal formed on the first approach plate surface side, an acute angle β 1} (°) formed by a line passing through a toe and a root on the approach plate side and the one side surface of the test plate. _{), Partial penetration b 1} (mm) of the joint in the thickness direction of the approach plate _{, and penetration depth r 1} (mm) on the test plate side, and
_{In the second approach plate weld metal formed on the second approach plate surface side, an acute angle β 2} (°) formed by a line passing through a toe and a root on the approach plate side and the one side surface of the test plate. _{), The partial penetration b 2} (mm) of the joint in the thickness direction of the approach plate, and the penetration depth r ₂ (mm) on the test plate side satisfy the following equations (v) to (x). And
A step of forming an intermediate test piece having a plate thickness of t ₁ (mm), a width of 260 + t ₂ (mm), and a length of 500 mm.
However, α ₁ and d ₁ in the equation are the acute angle (°) formed by the line passing through the toe and the root on the joint member side and the surface to be joined in the first weld metal, respectively, and the plate. Partial penetration (mm) of the joint in the thickness direction,
α ₂ and d ₂ are the acute angles (°) formed by the line passing through the toe and the root on the joining member side and the surface to be joined in the second weld metal, and the joint in the plate thickness direction, respectively. Partial penetration (mm).
(B) Prepare an adjusting plate having a plate thickness of t ₁ (mm), a width of 240-t ₂ (mm), and a length of 500 mm, and having a groove formed on one surface in the width direction. ,
Welding is performed on the groove formed in the adjusting plate in a state where the other side surface of the test plate in the width direction is in contact with the one side surface of the adjusting plate.
A step of forming a test piece having a plate thickness of t ₁ (mm), a width of 500 mm, and a length of 500 mm.
(C) Using the test piece, the approach plate ^{is provided with σ (N / mm 2} ), which is a preset allowable stress of the member to be welded, as a test stress at a test temperature of −10 ° C. A step of applying an impact load to the notch of the above to develop a crack to the test plate via the first approach plate weld metal and the second approach plate weld metal.
_{(D) The distance c 1} in the width direction between the one side surface of the test plate and the tip of the crack extending through each of the first approach plate weld metal and the second approach plate weld metal. A step of measuring (mm) and c _{2 (mm).}
t ₁ ≧ 50.0 ・ ・ ・ (i)
t ₂ ≧ 50.0 ・ ・ ・ (ii)
s ₁ ≤ 5.0 ・ ・ ・ (iii)
s ₂ ≤ 5.0 ・ ・ ・ (iv)
α ₁ −5.0 ≦ β ₁ ≦ α ₁ +5.0 ・ ・ ・ (v)
α ₂ −5.0 ≦ β ₂ ≦ α ₂ +5.0 ・ ・ ・ (vi)
d ₁ ≤ b ₁ ≤ d ₁ +5.0 ... (vii)
d ₂ ≤ b ₂ ≤ d ₂ +5.0 ... (viii)
s ₁ ≤ r ₁ ≤ s ₁ +5.0 ... (ix)
s ₂ ≤ r ₂ ≤ s ₂ +5.0 ... (x)
c ₁ ≤ r ₁ + 10.0 ・ ・ ・ (xi)
c ₂ ≤ r ₂ + 10.0 ・ ・ ・ (xii)

(2) A welded structure having a T-joint portion in which the joint member is completely welded and welded to the joint member in a state where the end surface of the plate-shaped joint member is in contact with the joint surface of the plate-shaped joint member. The body
The joining member has a first surface and a second surface perpendicular to the plate thickness direction of the joining member.
The plate thickness t ₁ (mm) of the joint member and the plate thickness t ₂ (mm) of the joint member satisfy the following equations (i) and (ii).
The penetration depth s (mm) on the side to be joined in the weld metal formed between the joint member and the member to be joined satisfies the following equation (xiii).
In the quality evaluation test in which the following steps (a) to (d) are sequentially carried out, the following c (mm) satisfies the following formula (xv).
Welded structure.
(A) A test plate whose width direction corresponds to the plate thickness direction of the member to be joined and one surface in the width direction corresponds to the surface to be joined, having a plate thickness of t ₁ (mm) and a width of t 1 (mm). A _{test plate with t 2} (mm) and a length of 500 mm, and
A run-up plate having a plate thickness of t ₁ (mm), a width of 260 mm, and a length of 500 mm, a notch is provided on one side in the width direction, and a groove is formed on the other side surface in the width direction. , Prepare,
With the one side surface of the test plate in contact with the other side surface of the approach plate, complete penetration welding is performed on the groove formed in the approach plate to obtain the approach plate weld metal. Form and
The penetration depth r (mm) on the test plate side of the approach plate weld metal satisfies the following equation (xiv).
A step of forming an intermediate test piece having a plate thickness of t ₁ (mm), a width of 260 + t ₂ (mm), and a length of 500 mm.
(B) Prepare an adjusting plate having a plate thickness of t ₁ (mm), a width of 240-t ₂ (mm), and a length of 500 mm, and having a groove formed on one surface in the width direction. ,
Welding is performed on the groove formed in the adjusting plate in a state where the other side surface of the test plate in the plate thickness direction is in contact with the one side surface of the adjusting plate.
A step of forming a test piece having a plate thickness of t ₁ (mm), a length of 500 mm, and a width of 500 mm.
(C) Using the test piece, the approach plate ^{is provided with σ (N / mm 2} ), which is a preset allowable stress of the member to be joined, as a test stress at a test temperature of −10 ° C. A step of applying an impact load to the notch of the above to develop a crack to the test plate.
(D) A step of measuring the distance c (mm) between the one side surface of the test plate and the tip of the crack in the width direction.
t ₁ ≧ 50.0 ・ ・ ・ (i)
t ₂ ≧ 50.0 ・ ・ ・ (ii)
s ≦ 5.0 ・ ・ ・ (xiii)
s ≦ r ≦ s + 5.0 ・ ・ ・ (xiv)
c ≦ r + 10.0 ・ ・ ・ (xv)

(3) The plate thickness t ₁ (mm) of the joint member and the plate thickness t ₂ (mm) of the joint member satisfy the following equations (xvi) and (xvii).
The welded structure according to (1) or (2) above.
t ₁ > 80.0 ・ ・ ・ (xvi)
t ₂ > 80.0 ・ ・ ・ (xvii)

(4) The yield stress of the member to be joined is 400 MPa or more and 580 MPa or less, and the tensile strength is 510 MPa or more and 750 MPa or less.
The welded structure according to any one of (1) to (3) above.

(5) The Kca value of the total thickness of the member to be joined at −10 ° C. is less than ^{6000 N / mm 1.5.}
The welded structure according to any one of (1) to (4) above.

According to the present invention, a welded structure having excellent brittle crack propagation stopping characteristics can be obtained.

It is a perspective view which shows the welded structure which concerns on one Embodiment of this invention. It is a perspective view which shows the welded structure which concerns on other embodiment of this invention. It is a perspective view which shows the welded structure which concerns on other embodiment of this invention. It is a perspective view which shows the welded structure which concerns on other embodiment of this invention. It is sectional drawing of the welded structure. It is a figure for demonstrating the quality evaluation test in this invention. It is a figure for demonstrating the quality evaluation test in this invention. It is sectional drawing of the test body. It is a figure for demonstrating the brittle crack propagation test. It is a figure for demonstrating the shape of the structural model arrest test piece. It is a figure for demonstrating the quality evaluation method of a thick steel plate in an application example. It is a figure for demonstrating the quality evaluation method of a thick steel plate in an application example. It is sectional drawing of the test body.

As a result of studies by the present inventors to solve the above problems, the following findings have been obtained.

As described above, the structural model arrest test using a large test piece is generally used to evaluate the brittle crack propagation stopping property of the thick steel sheet used for the upper deck. However, if it is possible to evaluate the brittle crack propagation stop characteristics in a medium-sized test using a smaller test piece, it will be easier to select the thick steel sheet used for the welded structure, and excellent brittle crack propagation stop characteristics will be obtained at low cost. It becomes possible to manufacture a welded structure having a brittleness.

The present invention has been made based on the above findings. Hereinafter, the welded structure according to the embodiment of the present invention will be described.

1. 1. Structure of Welded Structure FIG. 1 is a perspective view showing a welded structure according to an embodiment of the present invention. The welded structure 10 according to the present embodiment includes a joining member 11 and a member to be joined 12. The joining member 11 is plate-shaped and has a first surface 11a and a second surface 11b perpendicular to the plate thickness direction. Further, the member to be joined 12 has a plate shape and has a surface to be joined 12a to which the end surface 11c of the member 11 is abutted.

Then, as shown in FIG. 1, the welded structure 10 has a T-joint portion in which the joining member 11 is welded to the joined member 12 in a state where the end surface 11c is in contact with the joined surface 12a. The welded structure having the T-joint portion includes, for example, a structure having a shape shown in FIGS. 2 and 3 in addition to the T-shaped structure as shown in FIG. Further, the joining member 11 is provided with a groove, and the joining member 11 is joined by groove welding.

In the present invention, a thick-walled joint member and a member to be joined are targeted. Specifically, the plate thickness of the joint member 11 is t ₁ (mm), and the plate thickness of the member 12 to be joined is t ₂ (mm). ), The following equations (i) and (ii) are satisfied. _{The plate thickness t 1} (mm) of the joining member 11 and the plate _{thickness t 2} (mm) of the member 12 to be joined preferably satisfy the following equations (xvi) and (xvii). The upper limit of t ₁ and t ₂ need not be specified, but can be, for example, 200 mm, 150 mm, or 120 mm.
t ₁ ≧ 50.0 ・ ・ ・ (i)
t ₂ ≧ 50.0 ・ ・ ・ (ii)
t ₁ > 80.0 ・ ・ ・ (xvi)
t ₂ > 80.0 ・ ・ ・ (xvii)

As shown in FIGS. 1 to 3, the joining member 11 and the member 12 to be joined may be joined by partial penetration welding on both sides, but as shown in FIG. 4, they are joined by complete penetration welding. May be good. The configuration of the welded structure in each case will be further described.

(1) Partial Penetration Welding on Both Sides As shown in FIGS. 1 to 3, when the joining member 11 and the member 12 to be joined are joined by partial penetration welding on both sides, the welded structure 10 has a first surface. It has a first weld metal 13a formed on the 11a side and a second weld metal 13b formed on the second surface 11b side.

The vicinity of the joint portion of the joint member 11 and the member to be joined 12 will be described in more detail with reference to FIG. FIG. 5 is a cross-sectional view of the welded structure 10 perpendicular to the first surface 11a and the surface to be joined 12a. In FIG. 5, hatching is not provided in order to avoid complicating the drawings.

As shown in FIG. 5, the first weld metal 13a is formed on the first surface 11a side of the joining portion of the joining member 11 and the member to be joined 12. Similarly, the second weld metal 13b is formed on the second surface 11b side.

Here, the crack generated from the joining member 11 propagates to the joined member 12 via the first weld metal 13a and the second weld metal 13b. That is, the shape of the weld metal affects the brittle crack propagation stopping property of the welded structure.

_{Specifically, the penetration depth s 1} (mm) of the first weld metal 13a on the side to be joined 12 _{and the penetration depth s 2} (mm) of the second weld metal 13b on the side of the member 12 to be joined are. It is necessary to control so as to satisfy the following equations (iii) and (iv).
s ₁ ≤ 5.0 ・ ・ ・ (iii)
s ₂ ≤ 5.0 ・ ・ ・ (iv)

In addition, in order to evaluate the brittle crack propagation stopping characteristic of the welded structure, it is necessary to make the shapes of the weld metal formed on the test piece described later and the weld metal formed on the welded structure equivalent.

In this embodiment, the acute angles α ₁ and α ₂ , which will be described later, and the partial penetration d ₁ and d ₂ of the joint are used as indicators of the shape of the weld metal. Specifically, in the first weld metal 13a, a line L ₁ passing through the toe and the root of the joint member 11 side acute angle and the joining surface 12a and alpha _{1 (°),} in the second weld metal 13b _{Let α 2} (°) be the sharp angle formed by the _{line L 2} passing through the toe on the joining member 11 side and the root and the surface to be joined 12a.

The range of α ₁ and α ₂ need not be particularly limited, but it is preferable that the following equations (xviii) and (xix) are satisfied, respectively.
30.0 ≤ α ₁ ≤ 70.0 ・ ・ ・ (xviii)
30.0 ≤ α ₂ ≤ 70.0 ・ ・ ・ (xix)

The joining member 11 side of the toe in the first weld metal 13a, means an intersection _{A 1} between the outer edge and the first surface 11a of the first weld metal 13a. Also, the joining member 11 side of the root of the first weld metal 13a, means an intersection _{B 1} between the outer edge and the end face 11c of the first weld metal 13a. Similarly, the bonding member 11 side of the toe at the second weld metal 13b, means an intersection _{A 2} between the outer edge and the second surface 11b of the second weld metal 13b, the bonding member 11 side in the second weld metal 13b the root mean an intersection _{B 2} between the outer edge and the end face 11c of the second weld metal 13b.

Further, the partial penetration of the joint in the plate thickness direction of the first weld metal 13a is d ₁ (mm), and the partial penetration of the joint in the plate thickness direction of the second weld metal 13b is d ₂ (mm). The partial penetration d ₁ of the joint is a virtual surface parallel to the first surface 11a and passing through the end portion of the first weld metal 13a on the plate thickness center side in the plate thickness direction of the joining member 11. It is a distance from 11f. Further, the partial penetration d ₂ of the joint is virtually parallel to the second surface 11b and passes through the end portion of the second weld metal 13b on the plate thickness center side in the plate thickness direction of the joining member 11. It is the distance from the surface 11g.

The boundaries between the first weld metal 13a and the second weld metal 13b and the joining member 11 can be easily visually identified.

(2) Complete Penetration Welding As shown in FIG. 4, when the joining member 11 and the member 12 to be joined are joined by complete penetration welding, the welded structure 10 is the joining member 11 and the member 12 to be joined. It has a weld metal 13c between and.

The crack generated from the joining member 11 propagates to the joined member 12 via the weld metal 13c. That is, the shape of the weld metal affects the brittle crack propagation stopping property of the welded structure. Specifically, it is necessary to control the penetration depth s (mm) of the weld metal 13c on the side of the member to be joined 12 so as to satisfy the following equation (xiii).
s ≦ 5.0 ・ ・ ・ (xiii)

In addition, in the case of complete penetration welding, since the joining member 11 and the member to be joined 12 are joined by the weld metal 13c over the entire surface, it is necessary to form the test piece described later by complete penetration welding.

2. Quality Evaluation Test According to the research conducted by the present inventors, by using a thick steel plate that satisfies the predetermined criteria by the medium-sized quality evaluation test described later as the member to be welded, it has excellent brittle crack propagation stopping characteristics at low cost. We have found that a welded structure can be obtained.

The test method will be described in detail. 6 and 7 are diagrams for explaining the quality evaluation test in the present invention. In the quality evaluation test in the present invention, the following steps (a) to (d) are carried out in order. Each process will be described.

(A) First Welding Step From the thick steel plate used for the member 12 to be joined, the plate thickness is t ₁ (mm), the width is t ₂ (mm), and the length is 500 mm, and one side in the plate thickness direction (FIG. The test plate 21 whose surface 21c (upper side in 6 and FIG. 7) corresponds to the surface to be welded 12a is collected. That is, the direction of the plate thickness of the member 12 to be joined is the width direction of the test plate 21.

A run-up plate 22 having a plate thickness of t ₁ (mm), a width of 260 mm, a length of 500 mm, and a groove formed on the surface 22b on the other side (lower side in FIGS. 6 and 7) in the width direction is prepared. To do. The shape and dimensions of the groove may be appropriately selected so that the shape and dimensions of the weld metal portion formed by welding described later satisfy the specified specifications.

The material of the approach plate 22 is not particularly limited, and for example, a steel plate embrittled by heat treatment can be used. Further, a notch 22a is formed on one side (upper side in FIGS. 6 and 7) of the approach plate 22 in the width direction. The shape of the notch is not particularly limited, but the shape shown in FIG. 6 can be used.

Then, in a state where the one side surface 21c of the test plate 21 is in contact with the other side surface 22b of the approach plate 22, welding is performed on the groove to form an intermediate test piece. After that, it is preferable to delete the surplus generated by welding. As a result, the intermediate test piece _{has a rectangular parallelepiped shape with a plate thickness of t 1} (mm), a width of 260 + t ₂ (mm), and a length of 500 mm.

FIG. 6 is a schematic view of the test body 20 when the joining member 11 and the member to be joined 12 are joined by partial penetration welding on both sides, and FIG. 7 shows a complete view of the joining member 11 and the member 12 to be joined. It is the schematic of the test piece 20 in the case of being joined by penetration welding.

When the joining member 11 and the member 12 to be joined are joined by partial penetration welding on both sides, the test plate 21 and the approach plate 22 need to be joined by partial penetration welding on both sides. In addition, in order to evaluate the brittle crack propagation stopping characteristic of the welded structure 10 by the test plate 21 collected from the thick steel plate used for the member 12 to be joined, between the test plate 21 and the approach plate 22. It is important to control the shape of the weld metal formed.

As shown in FIG. 6, the approach plate 22 has a first approach plate surface 22c and a second approach plate surface 22d perpendicular to the plate thickness direction. The shape of the weld metal formed between the test plate 21 and the approach plate 22 will be described in more detail with reference to FIG. FIG. 8 is a cross-sectional view of the test body 20 perpendicular to the first approach plate surface 22c and one side surface 21c of the test plate 21. In FIG. 8, hatching is not provided in order to avoid complicating the drawings.

As shown in FIG. 8, the first approach plate weld metal 23a is formed on the first approach plate surface 22c side of the joint portion between the test plate 21 and the approach plate 22, and the second approach plate surface 22d side is the second approach plate. The plate weld metal 23b is formed.

_{Then, in the first approach plate weld metal 23a, the acute angle β 1 (°) formed by the line M 1} passing through the toe on the approach plate 22 side and the root and the surface 21c on one side of the test plate 21 and the second approach plate. _{The acute angles β 2 (°) formed by the line M 2} passing through the toe on the approach plate 22 side and the root and the surface 21 c on one side of the test plate 21 in the weld metal 23b are the following (v) and (vi), respectively. Satisfy the formula.
α ₁ −5.0 ≦ β ₁ ≦ α ₁ +5.0 ・ ・ ・ (v)
α ₂ −5.0 ≦ β ₂ ≦ α ₂ +5.0 ・ ・ ・ (vi)

The test plate 21 side toe in the first run-up plate weld metal 23a, means an intersection C ₁ between the outer edge and the first run-up plate surface 22c of the first run-up plate weld metal 23a. Further, the test plate 21 side route of the first run-up plate weld metal 23a, means an intersection D ₁ of the outer edge and the other side surface 22b of the run-up plate 22 of the first run-up plate weld metal 23a. Similarly, the toe of the test plate 21 side in the second run-up plate weld metal 23b, means an intersection C ₂ of the outer edge and the second run-up plate surface 22d of the second run-up plate weld metal 23b, the second run-up plate the test plate 21 side root in the weld metal 23b, means an intersection D ₂ between the outer edge and the other side surface 22b of the run-up plate 22 of the second run-up plate weld metal 23b.

_{Further, the partial penetration b 1} (mm) of the joint in the plate thickness direction of the first approach plate weld metal 23a _{and the partial penetration b 2} (mm) of the joint in the plate thickness direction of the second approach plate weld metal 23b are as follows. Satisfy equations (vii) and (viii).
d ₁ ≤ b ₁ ≤ d ₁ +5.0 ... (vii)
d ₂ ≤ b ₂ ≤ d ₂ +5.0 ... (viii)

The partial penetration b ₁ of the joint is parallel to the first approach plate surface 22c and the first approach plate surface 22c, and is the end portion of the first approach plate weld metal 23a on the plate thickness center side in the plate thickness direction of the approach plate 22. It is a distance from a virtual surface 22f passing through. Further, the partial penetration b ₂ of the joint is parallel to the second approach plate surface 22d and the second approach plate surface 22d, and is on the plate thickness center side of the second approach plate weld metal 23b in the plate thickness direction of the approach plate 22. It is the distance from the virtual surface 22g passing through the end.

The first approach plate weld metal 23a of the test board 21 side of the penetration depth _r 1 (mm) and penetration depth of the test plate 21 side second run-up plate weld metal 23b _r 2 (mm), the following Satisfy equations (ix) and (x).
s ₁ ≤ r ₁ ≤ s ₁ +5.0 ... (ix)
s ₂ ≤ r ₂ ≤ s ₂ +5.0 ... (x)

On the other hand, when the joining member 11 and the member 12 to be joined are joined by complete penetration welding, the test plate 21 and the approach plate 22 need to be joined by complete penetration welding. The penetration depth r (mm) on the test plate 21 side of the approach plate weld metal 23c formed between the test plate 21 and the approach plate 22 satisfies the following equation (xiv).
s ≦ r ≦ s + 5.0 ・ ・ ・ (xiv)

(B) Second Welding Step The plate thickness is t ₁ (mm), the width is 240-t ₂ (mm), the length is 500 mm, and the surface 24a on one side (upper side in FIGS. 6 and 7) in the width direction , An adjusting plate 24 having a groove formed therein is prepared. There are no particular restrictions on the shape, dimensions and formation location of the groove.

Then, the other side surface 21d of the test plate 21 in the plate thickness direction is welded to the groove in a state of being in contact with the one side surface 24a of the adjusting plate 24 to form the test body 20. After that, it is preferable to delete the surplus generated by welding. As a result, the test body 20 has _{a rectangular parallelepiped shape with a plate thickness of t 1} (mm), a length of 500 mm, and a width of 500 mm.

Since the adjusting plate 24 is for adjusting the dimensions of the test body 20, there is no particular limitation on the welding method, and the test plate 21 and the adjusting plate 24 may be joined by complete penetration welding. , Both sides may be joined by partial penetration welding. The material of the adjusting plate 24 is not particularly limited, and any steel plate can be used, but the strength is preferably close to that of the test plate 21.

^{(C) Brittle crack propagation test process A state in which σ (N / mm 2} ), which is a preset allowable stress of the member to be joined 12, is applied as a test stress at a test temperature of −10 ° C. using the test piece 20. Then, an impact load is applied to the notch 22a provided on the approach plate 22 to propagate the crack to the test plate 21.

As the allowable stress of the member to be joined, which is set in advance, for example, when the welded structure is for a ship, the member to be joined is the upper deck. Since the allowable stress of the upper deck is determined by the rules established by the ship class association, that value may be adopted. The temperature of the test piece is made uniform at a predetermined test temperature, and the temperature of the approach plate 22 is not particularly specified. Other conditions are not limited as long as the crack extends to the test plate 21, but WES2815 may be compliant.

FIG. 9 is a diagram for explaining a brittle crack propagation test. As shown in FIG. 9, jigs 24a and 24b are joined to both ends of the test body 20 in the length direction by welding, and tensile stress is applied from both sides in the length direction to apply the test stress described above to the test body 20. Can be given.

Further, in this step, since it is necessary to propagate the crack to at least the test plate, it is necessary to select a material so that the crack does not stop at the approach plate or the weld metal when an impact load is applied. ..

(D) Brittle crack measurement step The crack progress state of the test plate 21 after the above steps (a) to (c) are sequentially performed is investigated. Specifically, when the joining member 11 and the member to be joined 12 are joined by partial penetration welding on both sides, the surface 21c on one side of the test plate 21, the first approach plate weld metal 23a, and the second _{The distances c 1} (mm) and c ₂ (mm) in the width direction from the tip of the crack extending through each of the approach plate weld metal 23b are measured.

On the other hand, when the joining member 11 and the member 12 to be joined are joined by complete penetration welding, the surface 21c on one side of the test plate 21 and the tip of the crack that has propagated through the approach plate weld metal 23c. Measure the distance c (mm) in the width direction.

In the quality evaluation test in which the steps (a) to (d) described above are sequentially carried out, the member 12 to be joined used in the welded structure 10 according to the present invention is partially melted on both sides. When the joints are joined by insert welding, the following equations (xi) and (xii) are satisfied, and when the joining member 11 and the member 12 to be joined are joined by complete penetration welding, the following equations (xv) are satisfied. Need to be satisfied. As a result, the welded structure 10 having excellent brittle crack propagation stopping characteristics can be obtained.
c ₁ ≤ r ₁ + 10.0 ・ ・ ・ (xi)
c ₂ ≤ r ₂ + 10.0 ・ ・ ・ (xii)
c ≦ r + 10.0 ・ ・ ・ (xv)

3. 3. Mechanical Properties of Joining Members There are no particular restrictions on the mechanical properties of the joining members used in the welded structure of the present invention. However, when the welded structure is used in a container ship or the like, the yield stress of the member to be joined is preferably 400 MPa or more and 580 MPa or less, and the tensile strength is preferably 510 MPa or more and 750 MPa or less. The yield stress of the joining member is more preferably 410 MPa or more and 570 MPa or less, and the tensile strength is more preferably 520 MPa or more and 740 MPa or less.

From the viewpoint of cost, it is preferable to use a member to be joined in which the Kca value of the total thickness at −10 ° C. is ^{less than 6000 N / mm 1.5.} The Kca value can be obtained by a temperature gradient type ESSO test based on the WES2815 standard.

4. Method of manufacturing a welded structure The method of manufacturing a welded structure is not particularly limited. For example, a step of selecting a member to be joined whose evaluation result by a quality evaluation test satisfies the above-mentioned conditions and a step of selecting the member to be joined and the member to be joined are covered. It can be manufactured by performing a process of welding to a joint member.

In the welding step, it can be manufactured by welding along the end face of the above-mentioned joint member with the end face of the joint member abutting against the surface to be joined. At this time, the side to be joined of the joining member is grooved. The groove processing may be performed over the entire end face of the joint member, or may be performed only at the joint portion with the member to be joined.

Further, the welding method is not particularly limited, and _{a known method such as CO 2} welding or shielded metal arc welding (SMAW) may be adopted. The amount of heat input is preferably, for example, 0.5 kJ / mm or more and 3.0 kJ / mm or less.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

Various steel sheets having a plate thickness t (mm) shown in Table 1 were prepared. Then, from each steel plate, a test plate having a plate thickness of 100 (mm), a width of t (mm), and a length of 500 mm was collected so that the plate thickness direction of the steel plate was the length direction of the test plate.

Subsequently, a run-up plate having a plate thickness of 100 mm, a width of 260 mm, and a length of 500 mm and having a first approach plate surface and a second approach plate surface orthogonal to the plate thickness direction was prepared. As the approach plate, a steel plate embrittled by heating at 1200 ° C. and then air-cooling was used. Then, a notch having the shape shown in FIG. 6 is provided on one side of the approach plate in the length direction. On the other side surface in the width direction of the approach plate, grooves extending in the length direction were formed on the first approach plate surface side and the second approach plate surface side, respectively.

Then, in a state where one surface of the test plate was in contact with the other surface of the approach plate having the groove formed, both side partial penetration welding or complete penetration welding was performed on the groove. Welding conditions are as shown in Table 2. In Table 2, "CO ₂ " means CO ₂ welding, and "SMAW" means shielded metal arc welding. After that, the surplus generated by welding was deleted.

Further, an adjusting plate having a plate thickness of 100 mm, a width of 240-t (mm), and a length of 500 mm was prepared. As the adjusting plate, a steel plate having the same strength grade as the test plate was used. A groove was formed on one side of the adjusting plate in the width direction. Then, in a state where the other side surface of the test plate was in contact with the one side surface of the adjusting plate having the groove formed, both side partial penetration welding was performed on the groove. After that, the surplus generated by welding was deleted. As a result, a rectangular parallelepiped test piece having a plate thickness of 100 mm, a length of 500 mm, and a width of 500 mm was produced.

In the test body, the first approach plate weld metal was formed on the first approach plate surface side of the joint between the test plate and the approach plate, and the second approach plate weld metal was formed on the second approach plate surface side. .. After that, using each test piece, the test temperature was set to -10 ° C, and the length of the approach plate was applied with the test stress corresponding to ^{the allowable stress σ (N / mm 2) of the member to be joined shown in Table 2.} An impact load was applied to the notch on one side in the direction to propagate the crack to the test plate.

After the test was completed, a load was applied to the test piece and forced fracture was performed to expose the fracture surface, and the progress of cracks that rushed into the test plate was investigated. Then, a cross section of the weld metal (first test weld metal and second test weld metal) of the test plate and the approach plate was cut out at a position 200 mm to the left and right from the center position in the load direction of the test piece. Photographs of the cross sections of the welded joints at these two locations were taken with a digital camera, the shape of the weld metal was measured from the photographic images, and the average value of the measurement results at the two locations was calculated. The results are also shown in Table 2.

Subsequently, the No. 4 tensile test piece described in JIS Z 2241: 2011 is collected from a position 1/4 of the thickness of each steel plate in a direction perpendicular to the rolling direction, and a tensile test is performed in accordance with JIS Z 2241: 2011. Yield stress (YS), tensile strength (TS) and total elongation (EL) were measured.

Further, the Kca value of the total thickness of each steel sheet at −10 ° C. was determined by a temperature gradient type ESSO test based on the WES2815 standard. The results are also shown in Table 1.

Then, the above-mentioned various steel plates were used as test plates (members to be joined 42), and the structural model arrest test piece shown in FIG. 10 was prepared and tested. A welded joint in which a steel plate having a plate thickness of 100 mm _{was joined by CO 2} welding was used as a run-up welded joint (joining member 41), and a _{welded structure 40 was produced by CO 2} welding or shielded metal arc welding (SMAW) under the conditions shown in Table 3. At that time, the joining member 41 was provided with grooves on both sides having a depth of 1/3 of the plate thickness, and the joining member 41 and the member to be joined 42 were joined by groove welding.

After that, the notch 46b was introduced into the fusion line portion 46a of the welded structure 40. Then, the welded structure 40 is cooled to the ship design temperature of -10 ° C., the allowable stress of the member to be joined 42, σ (N / mm ² ), is applied as a test stress, and only the vicinity of the notch portion is -50 ° C. It was rapidly cooled to a certain degree, and a brittle crack was generated and propagated by hitting the notch through a wedge.

Structural model after the test Using the arrest test piece, one side (first surface side) and the other side (first surface side) and the other side (first surface side) of the joining member and the member to be joined are located 250 mm to the left and right from the center position in the load direction of the test piece. A cross section of the weld metal (first weld metal and second weld metal) on the two surface sides) was cut out. Photographs of the cross sections of these two welded joints were taken with a digital camera, the shape of the weld metal was measured from the photographic images, and the average value of the measurement results at the two locations was used.

Table 3 also shows the measured shape of the weld metal and the results of the test using the above-mentioned structural model arrest test piece. When the brittle crack stopped at the test plate, it was judged as "stop", and when the test plate was broken, it was judged as "propagation".

As is clear from Table 3, when a member to be joined that satisfies the provisions of the present invention is used, excellent brittle crack propagation stopping characteristics are obtained, whereas a comparative example that does not satisfy the provisions of the present invention. When the member to be joined was used, the brittle cracks propagated to the member to be joined.

5. Quality Evaluation Method for Thick Steel Sheets As described above, in the welded structure 10 according to the present invention, the member 12 to be joined is evaluated by a quality evaluation test under the above-mentioned conditions. The quality evaluation test can be applied as a quality evaluation method for thick steel sheets. The quality evaluation method of the thick steel sheet as an application example can be expressed by the following (Appendix 1) to (Appendix 4).

(Appendix 1)
In a welded structure having a T-joint portion in which the end face of the plate-shaped joint member is in contact with the joint surface of the plate-shaped joint member and the joint member is partially welded to the joint member on both sides. A method for evaluating the quality of a thick steel plate used as a member to be welded.
The joining member has a first surface and a second surface perpendicular to the plate thickness direction of the joining member.
In the cross section perpendicular to the first surface and the surface to be joined,
The plate thickness t ₁ (mm) of the joint member and the plate thickness t ₂ (mm) of the joint member satisfy the following equations (i) and (ii).
_{The penetration depth s 1} (mm) on the member to be joined side of the first weld metal formed on the first surface side, and the welded metal on the second weld metal formed on the second surface side. The penetration depth s ₂ (mm) on the member side satisfies the following equations (iii) and (iv).
The following steps (a) to (d) are provided.
Quality evaluation method for thick steel sheets.
(A) A test plate whose width direction corresponds to the plate thickness direction of the member to be joined and one surface in the width direction corresponds to the surface to be joined, having a plate thickness of t ₁ (mm) and a width of t 1 (mm). A _{test plate of t 2} (mm), length of 500 mm, and
It has a plate thickness of t ₁ (mm), has a first approach plate surface and a second approach plate surface perpendicular to the plate thickness direction, has a notch on one side in the width direction, and has a notch on one side in the width direction. A run-up plate having a groove extending in the length direction formed on the first run-up plate surface side and the second run-up plate surface side, respectively, is prepared.
In a state where the one side surface of the test plate is in contact with the other side surface of the run-up plate, both side partial penetration welding is performed on the groove formed in the run-up plate.
In a cross section perpendicular to the first approach plate surface and the one side surface of the test plate.
_{In the first approach plate weld metal formed on the first approach plate surface side, an acute angle β 1} (°) formed by a line passing through a toe and a root on the approach plate side and the one side surface of the test plate. _{), Partial penetration b 1} (mm) of the joint in the thickness direction of the approach plate _{, and penetration depth r 1} (mm) on the test plate side, and
_{In the second approach plate weld metal formed on the second approach plate surface side, an acute angle β 2} (°) formed by a line passing through a toe and a root on the approach plate side and the one side surface of the test plate. _{), The partial penetration b 2} (mm) of the joint in the thickness direction of the approach plate, and the penetration depth r ₂ (mm) on the test plate side satisfy the following equations (v) to (x). The process of making.
However, α ₁ and d ₁ in the equation are the acute angle (°) formed by the line passing through the toe and the root on the joint member side and the surface to be joined in the first weld metal, respectively, and the plate. Partial penetration (mm) of the joint in the thickness direction,
α ₂ and d ₂ are the acute angles (°) formed by the line passing through the toe and the root on the joining member side and the surface to be joined in the second weld metal, and the joint in the plate thickness direction, respectively. Partial penetration (mm).
(B) Prepare an adjusting plate having a plate thickness of t ₁ (mm) and having a groove formed on one surface in the width direction.
A step of welding the groove formed on the adjusting plate with the other side surface of the test plate in the width direction in contact with the one side surface of the adjusting plate.
_{(C) Using a test piece having a plate thickness of t 1} (mm) formed through the steps (a) and (b), an impact load is applied to the notch of the approach plate to apply an impact load to the first approach plate. A step of developing a crack to the test plate via the plate weld metal and the second approach plate weld metal.
(D) A step of determining whether or not the thick steel sheet is excellent in brittle crack propagation stopping characteristics based on the crack growth state.
t ₁ ≧ 50.0 ・ ・ ・ (i)
t ₂ ≧ 50.0 ・ ・ ・ (ii)
s ₁ ≤ 5.0 ・ ・ ・ (iii)
s ₂ ≤ 5.0 ・ ・ ・ (iv)
α ₁ −5.0 ≦ β ₁ ≦ α ₁ +5.0 ・ ・ ・ (v)
α ₂ −5.0 ≦ β ₂ ≦ α ₂ +5.0 ・ ・ ・ (vi)
d ₁ ≤ b ₁ ≤ d ₁ +5.0 ... (vii)
d ₂ ≤ b ₂ ≤ d ₂ +5.0 ... (viii)
s ₁ ≤ r ₁ ≤ s ₁ +5.0 ... (ix)
s ₂ ≤ r ₂ ≤ s ₂ +5.0 ... (x)

(Appendix 2)
In the step (d), the width of the one side surface of the test plate and the tip of the crack extending through each of the first approach plate weld metal and the second approach plate weld metal. When the distances in the directions are c ₁ (mm) and c ₂ (mm), and c ₁ and c ₂ satisfy the following equations (xi) and (xii), the thick steel sheet has a brittle crack propagation stop characteristic. Judged to be excellent,
The quality evaluation method for thick steel sheets according to Appendix 1.
c ₁ ≤ r ₁ + 10.0 ・ ・ ・ (xi)
c ₂ ≤ r ₂ + 10.0 ・ ・ ・ (xii)

(Appendix 3)
Used for a welded structure having a T-joint portion in which the joint member is completely welded and welded to the joint member in a state where the end surface of the plate-shaped joint member is in contact with the joint surface of the plate-shaped joint member. This is a method for evaluating the quality of a thick steel plate to be a member to be welded.
The joining member has a first surface and a second surface perpendicular to the plate thickness direction of the joining member.
The plate thickness t ₁ (mm) of the joint member and the plate thickness t ₂ (mm) of the joint member satisfy the following equations (i) and (ii).
The penetration depth s (mm) on the side to be joined in the weld metal formed between the joint member and the member to be joined satisfies the following equation (xiii).
The following steps (a) to (d) are provided.
Quality evaluation method for thick steel sheets.
(A) A test plate having a plate thickness of t ₁ (mm) and a width of t ₂ (mm), and one surface in the width direction corresponding to the surface to be joined, and a test plate.
A run-up plate having a plate thickness of t ₁ (mm), having a notch on one side in the width direction and having a groove formed on the other side in the width direction was prepared.
With the one side surface of the test plate in contact with the other side surface of the approach plate, complete penetration welding is performed on the groove formed in the approach plate to obtain the approach plate weld metal. Form and
A step in which the penetration depth r (mm) on the test plate side of the approach plate weld metal satisfies the following equation (xiv).
(B) Prepare an adjusting plate having a plate thickness of t ₁ (mm) and having a groove formed on one surface in the width direction.
A step of welding the groove formed on the adjusting plate with the other side surface of the test plate in the width direction in contact with the one side surface of the adjusting plate.
_{(C) Using a test piece having a plate thickness of t 1} (mm) formed through the steps (a) and (b), an impact load is applied to the notch of the approach plate to reach the test plate. The process of developing a crack.
(D) A step of determining whether or not the thick steel sheet is excellent in brittle crack propagation stopping characteristics based on the crack growth state.
t ₁ ≧ 50.0 ・ ・ ・ (i)
t ₂ ≧ 50.0 ・ ・ ・ (ii)
s ≦ 5.0 ・ ・ ・ (xiii)
s ≦ r ≦ s + 5.0 ・ ・ ・ (xiv)

(Appendix 4)
In the step (d), when the distance c (mm) between the one side surface of the test plate and the tip of the crack in the width direction satisfies the following equation (xv), the thickness is the same. Judging that the steel sheet has excellent brittle crack propagation stop characteristics,
The quality evaluation method for thick steel sheets according to Appendix 3.
c ≦ r + 10.0 ・ ・ ・ (xv)

The quality evaluation method of the thick steel sheet in the application example will be described. The above quality evaluation method is a method for evaluating the quality of a thick steel plate used for a welded structure and serving as a member to be joined. Since the configuration of the welded structure to be evaluated for quality is as described above, the description thereof will be omitted.

11 and 12 are diagrams for explaining a quality evaluation method for a thick steel plate in an application example. The above quality evaluation method includes the following steps (a) to (d). Each process will be described.

(A) First welding step A test plate 31 is collected from a thick steel plate. The surface 31c on one side (upper side in FIGS. 11 and 12) of the test plate 31 in the width direction corresponds to the surface to be joined 12a. That is, the direction of the plate thickness of the member 12 to be joined is the width direction of the test plate 31 and the test body 30 described later.

The plate thickness of the test plate 31 is the same as the plate thickness of the joining member 11, that is, t ₁ (mm). Further, the width of the test plate 31 is the same as the plate thickness of the thick steel plate to be the member 12 to be joined, that is, t ₂ (mm). The length of the test plate 31 is not particularly limited, but is preferably 300 mm or more and 2000 mm or less. If it is too small, it will be difficult to evaluate the quality accurately, and if it is too large, it may not be possible to evaluate the quality at low cost.

A run-up plate 32 having the same thickness as the test plate 31 and the same length is prepared. That is, the thickness of the approach plate 32 is t ₁ (mm). Since the length of the approach plate 32 is the same as the length of the test plate 31, it is preferably 300 mm or more and 2000 mm or less. Further, the width of the approach plate 32 is preferably 150 mm or more and 1600 mm or less. If the width of the approach plate 32 is too small, there is a risk that sufficient driving force will not be obtained when a crack enters the test plate 31 from the approach plate 32, and if it is too large, quality evaluation at low cost will not be possible. Because there is.

Further, a groove is formed on the surface 32b on the other side (lower side in FIGS. 11 and 12) of the approach plate 32 in the width direction. The shape and dimensions of the groove may be appropriately selected so that the shape and dimensions of the weld metal portion formed by welding described later satisfy the specified specifications.

The material of the approach plate 32 is not particularly limited. For example, a steel plate embrittled by heat treatment, a butt weld joint in which a crack growth region is a welded portion, or a crack growth region is embrittled by electron beam welding. A steel plate or the like can be used. Further, a notch 32a is formed on one side (upper side in FIGS. 11 and 12) of the approach plate 32 in the width direction. The shape of the notch is not particularly limited, but the shape shown in FIG. 11 can be used.

Further, one or both of the pair of surfaces (first approach plate surface 22c and second approach plate surface 22d) orthogonal to the thickness direction of the approach plate 32 have side surfaces as shown in FIGS. 11 and 12. A groove may be formed. By having the side groove, the crack grows along the side groove and easily enters the test plate 31. As in the configuration shown in FIG. 11, the side groove may be formed in all lengths from one side to the other side in the width direction of the approach plate 32, or as in the configuration shown in FIG. 12, the side groove may be formed. It may be formed only for a part.

Then, welding is performed on the groove in a state where the surface 31c on one side in the width direction of the test plate 31 is in contact with the surface 32b on the other side (lower side in FIGS. 11 and 12) of the approach plate 32 in the width direction. Do. After that, it is preferable to delete the surplus generated by welding.

FIG. 11 is a schematic view of the test body 30 when the joining member 11 and the member to be joined 12 are joined by partial penetration welding on both sides, and FIG. 12 shows that the joining member 11 and the member to be joined 12 are completely joined. It is the schematic of the test piece 30 in the case of being joined by penetration welding.

When the joining member 11 and the member 12 to be joined are joined by partial penetration welding on both sides, the test plate 31 and the approach plate 32 need to be joined by partial penetration welding on both sides. In addition, the test plate 31 collected from the thick steel plate used for the thick steel plate used for the member 12 to be joined is formed on the test body 30 in order to evaluate the brittle crack propagation stopping characteristic of the welded structure 10. It is important to control the shape of the weld metal. The shape of the weld metal formed on the test body 30 will be described in more detail with reference to FIG. FIG. 13 is a cross-sectional view of the test body 30 perpendicular to the first approach plate surface 32c and one side surface 31c of the test plate 31. In FIG. 13, hatching is not provided in order to avoid complicating the drawings.

As shown in FIG. 13, the first approach plate weld metal 33a is formed on the first approach plate surface 32c side of the joint portion between the test plate 31 and the approach plate 32, and the second approach plate surface 32d side is the second approach plate. The plate weld metal 33b is formed.

_{Then, in the first approach plate weld metal 33a, the acute angle β 1 (°) formed by the line M 1} passing through the toe on the approach plate 32 side and the root and the surface 31c on one side of the test plate 31 and the second approach plate. _{The acute angles β 2 (°) formed by the line M 2} passing through the toe on the approach plate 32 side and the root and the surface 31 c on one side of the test plate 31 in the weld metal 33b are the following (v) and (vi), respectively. Satisfy the formula.
α ₁ −5.0 ≦ β ₁ ≦ α ₁ +5.0 ・ ・ ・ (v)
α ₂ −5.0 ≦ β ₂ ≦ α ₂ +5.0 ・ ・ ・ (vi)

The test plate 31 side toe in the first run-up plate weld metal 33a, means an intersection C ₁ between the outer edge and the first run-up plate surface 32c of the first run-up plate weld metal 33a. Further, the test plate 31 side route of the first run-up plate weld metal 33a, means an intersection D ₁ of the outer edge and the other side surface 32b of the run-up plate 32 of the first run-up plate weld metal 33a. Similarly, the test plate 31 side toe in the second run-up plate weld metal 33b, means an intersection C ₂ of the outer edge and the second run-up plate surface 32d of the second run-up plate weld metal 33b, the second run-up plate the test plate 31 side root in the weld metal 33b, means an intersection D ₂ between the outer edge and the other side surface 32b of the run-up plate 32 of the second run-up plate weld metal 33b.

_{Further, the partial penetration b 1} (mm) of the joint in the plate thickness direction of the first approach plate weld metal 33a _{and the partial penetration b 2} (mm) of the joint in the plate thickness direction of the second approach plate weld metal 33b are as follows. Satisfy equations (vii) and (viii).
d ₁ ≤ b ₁ ≤ d ₁ +5.0 ... (vii)
d ₂ ≤ b ₂ ≤ d ₂ +5.0 ... (viii)

The partial penetration b ₁ of the joint is the end portion of the first approach plate weld metal 33a parallel to the first approach plate surface 32c and the first approach plate surface 32c and in the plate thickness direction of the approach plate 32 on the plate thickness center side. It is a distance from a virtual surface 32f passing through. Further, the partial penetration b ₂ of the joint is parallel to the second approach plate surface 32d and the second approach plate surface 32d, and is on the plate thickness center side of the second approach plate weld metal 33b in the plate thickness direction of the approach plate 32. It is the distance from the virtual surface 32g passing through the end.

The first approach plate weld metal 23a of the test board 21 side of the penetration depth _r 1 (mm) and penetration depth of the test plate 21 side second run-up plate weld metal 23b _r 2 (mm), the following Satisfy equations (ix) and (x).
s ₁ ≤ r ₁ ≤ s ₁ +5.0 ... (ix)
s ₂ ≤ r ₂ ≤ s ₂ +5.0 ... (x)

(B) Second Welding Step An adjusting plate 34 having the same thickness as the test plate 31 and the same length is prepared. That is, the thickness of the adjusting plate 34 is t ₁ (mm). Since the length of the adjusting plate 34 is the same as the length of the test plate 31, it is preferably 300 mm or more and 2000 mm or less. Further, since the adjusting plate 34 is for adjusting the width of the test body 30, the width of the adjusting plate 34 may be determined according to the desired width of the test body 30.

Further, a groove is formed on the surface 34a on one side (upper side in FIGS. 11 and 12) of the adjusting plate 34 in the width direction. There are no particular restrictions on the shape, dimensions and formation location of the groove.

Then, welding is performed on the groove in a state where the surface 31d on the other side of the test plate 31 in the plate thickness direction is in contact with the surface 34a on the one side of the adjusting plate 34. After that, it is preferable to delete the surplus generated by welding.

Since the adjusting plate 34 is for adjusting the dimensions of the test body 30, there is no particular limitation on the welding method, and the test plate 31 and the adjusting plate 34 may be joined by complete penetration welding. , Both sides may be joined by partial penetration welding. The material of the adjusting plate 34 is not particularly limited, and any steel plate can be used, but the strength is preferably close to that of the test plate 31.

(C) Brittle Crack Propagation Test Step By going through the steps (a) and (b) above, a _{rectangular parallelepiped test piece 30 having a plate thickness of t 1} (mm) can be obtained. The steps (a) and (b) may be performed in any order, and the step (b) may be performed following the step (a), or the step (b) may be followed by the step (a). You may perform the process of.

The width of the test body 30 is not particularly limited, but is preferably 300 mm or more and 2600 mm or less. Further, since the length of the test body 30 is the same as the length of the test plate 31 and the approach plate 32, it is preferably 300 mm or more and 2000 mm or less.

Further, the total width of the test plate 31 and the adjusting plate 34 and the width of the approach plate 32 are preferably about the same, the width of the approach plate 32 is L (mm), and the width of the test body 30, that is, the test plate. When the total width of 31, the approach plate 32 and the adjusting plate 34 is W (mm), it is preferable that 0.4 ≦ L / W ≦ 0.7 is satisfied.

Then, using the test body 30, an impact load is applied to the notch 32a of the approach plate 32 in a state where a predetermined test stress is applied at a predetermined test temperature, and a crack is propagated to the test plate 31. The test temperature is not particularly limited and is preferably set to the operating temperature or lower of the welded structure 10, for example, −10 ° C. or lower. Further, the test stress applied to the test body 30 is not particularly limited, and for example, σ (N / mm ² ), which is a preset allowable stress of the member 12 to be joined, may be set as the test stress. ..

As the allowable stress of the member to be joined, which is set in advance, for example, when the welded structure is for a ship, the member to be joined is the upper deck. Since the allowable stress of the upper deck is determined by the rules established by the ship class association, that value may be adopted. The temperature of the test piece is made uniform at a predetermined test temperature, and the temperature of the approach plate is not particularly specified. For other conditions, it is preferable to comply with WES2815.

Further, in this step, since it is necessary to propagate the crack to at least the test plate, it is necessary to select a material so that the crack does not stop at the approach plate or the weld metal when an impact load is applied. ..

(D) Judgment step The state of crack growth is investigated for the test plate 31 after the above steps (a) to (c) are sequentially performed. Then, based on the investigation result, it is determined whether or not the thick steel sheet has excellent brittle crack propagation stopping characteristics.

The specific determination method is not particularly limited, but for example, when the joining member 11 and the member to be joined 12 are joined by partial penetration welding on both sides, the surface 31c on one side of the test plate 31 and the surface 31c on one side. _{The distances c 1} (mm) and c ₂ (mm) in the width direction from the tip of the crack extending through each of the first approach plate weld metal 33a and the second approach plate weld metal 33b are measured.

On the other hand, when the joining member 11 and the member 12 to be joined are joined by complete penetration welding, the surface 31c on one side of the test plate 31 and the tip of the crack that has propagated through the approach plate weld metal 33c. Measure the distance c (mm) in the width direction.

When the joining member 11 and the member 12 to be joined are joined by partial penetration welding on both sides, the thick steel sheet has a brittle crack propagation stop characteristic when the following equations (xi) and (xii) are satisfied. When the joining member 11 and the member to be joined 12 are joined by complete penetration welding, the thick steel sheet has a brittle crack propagation stop characteristic when the following equation (xv) is satisfied. It can be judged to be excellent.
c ₁ ≤ r ₁ + 10.0 ・ ・ ・ (xi)
c ₂ ≤ r ₂ + 10.0 ・ ・ ・ (xii)
c ≦ r + 10.0 ・ ・ ・ (xv)

As described above, according to the present invention, it is possible to obtain a welded structure having excellent brittle crack propagation stopping characteristics.

10 Welded structure 11 Joint member 11a First surface 11b Second surface 11c End surface 11f to 11i Virtual surface 12 Joint member 12a Joint surface 13 Weld metal 13a First weld metal 13b Second weld metal 13c Weld metal 20 Test Body 21 Test plate 21c One side surface 22 Run-up plate 22a Notch 22b The other side surface 22c First run-up plate surface 22d Second run-up plate surface 22f, g Virtual surface 23 Test weld metal 23a First run-up plate weld metal 23b 2nd run-up plate weld metal 23c run-up plate weld metal 24a, b jig 30 test piece 31 test plate 31c one side surface 32 run-up plate 32a notch 32b other side surface 32c 1st run-up plate surface 32d 2nd run-up plate surface 32f , G Virtual surface 33 Test weld metal 33a 1st run-up plate weld metal 33b 2nd run-up plate weld metal 33c Run-up plate weld metal 40 Welded structure 41 Join member 42 Joined member 43 Welded metal 46a Fusion line part 46b Notch

Claims (5)

A welded structure having a T-joint portion in which the joint member is partially welded to the joint member on both sides in a state where the end surface of the plate-shaped joint member is in contact with the joint surface of the plate-shaped joint member. There,
The joining member has a first surface and a second surface perpendicular to the plate thickness direction of the joining member.
In the cross section perpendicular to the first surface and the surface to be joined,
The plate thickness t ₁ (mm) of the joint member and the plate thickness t ₂ (mm) of the joint member satisfy the following equations (i) and (ii).
_{The penetration depth s 1} (mm) on the member to be joined side of the first weld metal formed on the first surface side, and the welded metal on the second weld metal formed on the second surface side. The penetration depth s ₂ (mm) on the member side satisfies the following equations (iii) and (iv).
The members to be joined, in the quality evaluation test to carry out the following processes (a) ~ (d) in this order, but the following c ₁ and c ₂ are to satisfy the following (xi) and (xii) equation,
Welded structure.
(A) A test plate whose width direction corresponds to the plate thickness direction of the member to be joined and one surface in the width direction corresponds to the surface to be joined, having a plate thickness of t ₁ (mm) and a width of t 1 (mm). A _{test plate of t 2} (mm), length of 500 mm, and
It has a plate thickness of t ₁ (mm), a width of 260 mm, a length of 500 mm, has a first approach plate surface and a second approach plate surface perpendicular to the plate thickness direction, and has a notch on one side in the width direction. A run-up plate is provided, and a groove extending in the length direction is formed on the first run-up plate surface side and the second run-up plate surface side on the other side surface in the width direction.
In a state where the one side surface of the test plate is in contact with the other side surface of the run-up plate, both side partial penetration welding is performed on the groove formed in the run-up plate.
In a cross section perpendicular to the first approach plate surface and the one side surface of the test plate.
_{In the first approach plate weld metal formed on the first approach plate surface side, an acute angle β 1} (°) formed by a line passing through a toe and a root on the approach plate side and the one side surface of the test plate. _{), Partial penetration b 1} (mm) of the joint in the thickness direction of the approach plate _{, and penetration depth r 1} (mm) on the test plate side, and
_{In the second approach plate weld metal formed on the second approach plate surface side, an acute angle β 2} (°) formed by a line passing through a toe and a root on the approach plate side and the one side surface of the test plate. _{), The partial penetration b 2} (mm) of the joint in the thickness direction of the approach plate, and the penetration depth r ₂ (mm) on the test plate side satisfy the following equations (v) to (x). And
A step of forming an intermediate test piece having a plate thickness of t ₁ (mm), a width of 260 + t ₂ (mm), and a length of 500 mm.
However, α ₁ and d ₁ in the equation are the acute angle (°) formed by the line passing through the toe and the root on the joint member side and the surface to be joined in the first weld metal, respectively, and the plate. Partial penetration (mm) of the joint in the thickness direction,
α ₂ and d ₂ are the acute angles (°) formed by the line passing through the toe and the root on the joining member side and the surface to be joined in the second weld metal, and the joint in the plate thickness direction, respectively. Partial penetration (mm).
(B) Prepare an adjusting plate having a plate thickness of t ₁ (mm), a width of 240-t ₂ (mm), and a length of 500 mm, and having a groove formed on one surface in the width direction. ,
Welding is performed on the groove formed in the adjusting plate in a state where the other side surface of the test plate in the width direction is in contact with the one side surface of the adjusting plate.
A step of forming a test piece having a plate thickness of t ₁ (mm), a width of 500 mm, and a length of 500 mm.
(C) Using the test piece, the approach plate ^{is provided with σ (N / mm 2} ), which is a preset allowable stress of the member to be welded, as a test stress at a test temperature of −10 ° C. A step of applying an impact load to the notch of the above to develop a crack to the test plate via the first approach plate weld metal and the second approach plate weld metal.
_{(D) The distance c 1} in the width direction between the one side surface of the test plate and the tip of the crack extending through each of the first approach plate weld metal and the second approach plate weld metal. A step of measuring (mm) and c _{2 (mm).}
t ₁ ≧ 50.0 ・ ・ ・ (i)
t ₂ ≧ 50.0 ・ ・ ・ (ii)
s ₁ ≤ 5.0 ・ ・ ・ (iii)
s ₂ ≤ 5.0 ・ ・ ・ (iv)
α ₁ −5.0 ≦ β ₁ ≦ α ₁ +5.0 ・ ・ ・ (v)
α ₂ −5.0 ≦ β ₂ ≦ α ₂ +5.0 ・ ・ ・ (vi)
d ₁ ≤ b ₁ ≤ d ₁ +5.0 ... (vii)
d ₂ ≤ b ₂ ≤ d ₂ +5.0 ... (viii)
s ₁ ≤ r ₁ ≤ s ₁ +5.0 ... (ix)
s ₂ ≤ r ₂ ≤ s ₂ +5.0 ... (x)
c ₁ ≤ r ₁ + 10.0 ・ ・ ・ (xi)
c ₂ ≤ r ₂ + 10.0 ・ ・ ・ (xii) A welded structure having a T-joint portion in which the joint member is completely welded and welded to the joint member in a state where the end surface of the plate-shaped joint member is in contact with the joint surface of the plate-shaped joint member. hand,
The joining member has a first surface and a second surface perpendicular to the plate thickness direction of the joining member.
The plate thickness t ₁ (mm) of the joint member and the plate thickness t ₂ (mm) of the joint member satisfy the following equations (i) and (ii).
The penetration depth s (mm) on the side to be joined in the weld metal formed between the joint member and the member to be joined satisfies the following equation (xiii).
In the quality evaluation test in which the following steps (a) to (d) are sequentially carried out, the following c (mm) satisfies the following formula (xv).
Welded structure.
(A) A test plate whose width direction corresponds to the plate thickness direction of the member to be joined and one surface in the width direction corresponds to the surface to be joined, having a plate thickness of t ₁ (mm) and a width of t 1 (mm). A _{test plate with t 2} (mm) and a length of 500 mm, and
A run-up plate having a plate thickness of t ₁ (mm), a width of 260 mm, and a length of 500 mm, a notch is provided on one side in the width direction, and a groove is formed on the other side surface in the width direction. , Prepare,
With the one side surface of the test plate in contact with the other side surface of the approach plate, complete penetration welding is performed on the groove formed in the approach plate to obtain the approach plate weld metal. Form and
The penetration depth r (mm) on the test plate side of the approach plate weld metal satisfies the following equation (xiv).
A step of forming an intermediate test piece having a plate thickness of t ₁ (mm), a width of 260 + t ₂ (mm), and a length of 500 mm.
(B) Prepare an adjusting plate having a plate thickness of t ₁ (mm), a width of 240-t ₂ (mm), and a length of 500 mm, and having a groove formed on one surface in the width direction. ,
Welding is performed on the groove formed in the adjusting plate in a state where the other side surface of the test plate in the plate thickness direction is in contact with the one side surface of the adjusting plate.
A step of forming a test piece having a plate thickness of t ₁ (mm), a length of 500 mm, and a width of 500 mm.
(C) Using the test piece, the approach plate ^{is provided with σ (N / mm 2} ), which is a preset allowable stress of the member to be joined, as a test stress at a test temperature of −10 ° C. A step of applying an impact load to the notch of the above to develop a crack to the test plate.
(D) A step of measuring the distance c (mm) between the one side surface of the test plate and the tip of the crack in the width direction.
t ₁ ≧ 50.0 ・ ・ ・ (i)
t ₂ ≧ 50.0 ・ ・ ・ (ii)
s ≦ 5.0 ・ ・ ・ (xiii)
s ≦ r ≦ s + 5.0 ・ ・ ・ (xiv)
c ≦ r + 10.0 ・ ・ ・ (xv) The plate thickness t ₁ (mm) of the joint member and the plate thickness t ₂ (mm) of the joint member satisfy the following equations (xvi) and (xvii).
The welded structure according to claim 1 or 2.
t ₁ > 80.0 ・ ・ ・ (xvi)
t ₂ > 80.0 ・ ・ ・ (xvii) The yield stress of the member to be joined is 400 MPa or more and 580 MPa or less, and the tensile strength is 510 MPa or more and 750 MPa or less.
The welded structure according to any one of claims 1 to 3. The Kca value of the total thickness of the member to be joined at −10 ° C. is less than ^{6000 N / mm 1.5.}
The welded structure according to any one of claims 1 to 4.

Images