BR112014025358B1 - welded structure - Google Patents

Abstract

patent summary: "welded structure". welded structure provided with a fillet weld joint in which the weld end face of a joint member having a plate thickness of 50 mm or more is placed top against the front face of a joined member having a thickness of plate 50 mm or more, the joining member and the joining member being joined by fillet welding, at least one between the weld leg length and the welding width being 16 mm or less, where each weld metal of ( s) The joint weld (s) of the joint member and / or the joined member have a toughness where vtrs-w (° c) is -65 ° c or less and / or ve-20-w (j) is 140j or more, an unsoldered portion is provided on the top face, the unsoldered portion being 95% or more of the plate thickness tw of the joint member in a cross section of the weld joint (s). fillet weld joint, and vtrs (° c) and / or ve-20 (j) of fillet weld metal are adjusted to satisfy a predetermined joint member ratio . 22437350v2 1/1 22437350v2

Description

Descriptive Report of the Invention Patent for WELDED STRUCTURE.

Technical Field [001] The present invention relates to a welded structure for conveyors of mega-containers, bulk carriers, and others such as welded structures formed by the welding of thick steel sheets, and, in particular, to a welded structure that has excellent capacity interruption and is able to stop the propagation of a fragile fracture initiated in a welded joint before a catastrophic fracture occurs in the structure.

Background Technique [002] To increase characteristics such as transport capacity and efficiency of cargo handling, container and bulk carriers, for example, have few bulkheads in the hold, unlike oil and similar vessels, and have large upper openings. Therefore, in container and bulk carriers, it is necessary to reinforce or increase the thickness in particular of the outer plate of the ship's chassis.

[003] Recently, the size of container transporters has been increased, and large ships of 6,000 to 20,000 TEU (unit equivalent to 20 feet) are being built. TEU is an index of transport capacity for a container transporter represented in terms of the number of containers 20 feet long. Along with this increase in ship size, a thick steel plate 50 mm or more thick and a tensile strength of 390 N / mm ² or more now tends to be used as the outer plate of the ship's chassis.

[004] From the perspective of shortening the construction period, recently the steel plates that will become the outer plate of a ship's chassis often give butt welds, for example,

2/43 by a large heat input welding such as electric gas arc welding or similar. Such welding with high heat input can easily lead to a large decrease in toughness in an area affected by heat and, therefore, is a cause of the beginning of the fragile fracture in the weld joint. For safety, it was considered that if a fragile fracture starts in the hull structure, it is necessary to stop the propagation of the fragile fracture before a catastrophic fracture occurs in order to avoid the separation of the hull.

[005] From this perspective, Report No. 87 of the 147th Research Committee of the Shipbuilding Research Association of Japan, Evaluation of Brittle Fracture Toughness of Welded Joints of Ship under High Welding Heat Input (February 1978), pgs. 35-53, Shipbuilding Research Association of Japan (NPL 1) reports the results of an experimental test in relation to the propagation behavior of fragile fractures in the welding of steel plates used for building ships with a plate thickness of less than 50 mm. In NPL 1, the propagation path and the propagation behavior of fragile fractures formed intentionally in the weld were examined by experience. The document reports that when the toughness of the weld fracture was guaranteed to a certain degree, the brittle fracture often deviated from the weld towards the base metal due to the influence of residual welding stress. It was observed, however, that in some cases the fragile fracture spread throughout the weld. This suggests that the probability of the brittle fracture propagating linearly along the weld is not zero.

[006] However, many ships built by welding steel plates with a plate thickness of less than 50 mm in a manner similar to that of NPL1 are currently in service without problems. In addition, high tenacity steel plate base metals (eg grade E steel used for shipbuilding)

3/43 considered to have a sufficient capacity to interrupt fragile fractures. Therefore, the ability to break fragile fractures in the shipbuilding steel weld is not required by the Rules and Guidance for the Survey and Construction of Steel Ships and the like.

[007] The steel plates used to build the mega container transporters of 6,000 TEU or more have a thickness of more than 50 mm making, however, the fracture toughness decrease due to the increased thickness. In addition, since a high heat input weld with a higher heat input is used, the fracture toughness of the weld is also reduced. It has been shown that with such thick weld joints with large heat input, a brittle fracture initiated in the weld can propagate linearly instead of deviating towards the base steel and may not be interrupted even in the base metal portion of the steel plate , such as reinforcement (eg Yamaguchi et al., Development of MegaContainer Carrier - Practical Use of New High-Strength Heavy Gauge Steel Plate, Bulletin of The Japan Society PF Naval Architects and Ocean Engineers, Vol. 3, (2005), pages 70-76, November 2005 (NPL2)). Ensuring the safety of a hull structure with thick, high-strength steel plates having a plate thickness of 50 mm or more is therefore a serious problem. In addition, according to NPL 2, thick sheets having a special ability to interrupt brittle fractures are necessary to stop the spread of initiated brittle fractures.

[008] To address this problem, for example, JP 2004232052 A (PTL 1) describes a welded structure that is the outer plate of a ship's hull and is preferably 50 mm or more thick. In the welded structure, a reinforcement is placed in order to cross the butt weld, and the reinforcement is joined by fillet welding.

4/43 [009] With the technique described in PTL 1, a steel plate having a microstructure with an average grain size equivalent to 0.5 μm to 5 μιτι over a thickness of 3 mm or more in the surface layer and in the back layer, and for which the flat X-ray intensity ratio in the crystal plane (100) is 1.5 or more in, a plane parallel to the plane of the plate thickness, is used as reinforcement. Adopting the structure in which a steel sheet having such a microstructure is welded in fillet as reinforcement material can stop the propagation of a fragile fracture in the reinforcement, which is the reinforcing material, even if the fragile fracture is initiated in butt welding. , and can prevent disastrous damage such as fracture of the welded structure.

[0010] In addition, JP 2007-326147 A (PTL 2) describes a welded structure that has excellent brittle fracture breaking capacity and is provided with a fillet weld joint formed by the fillet welding of a joint member ( also referred to below as a net) to a joined member (also referred to below as a flange).

[0011] In the welded structure described in PLT 2, a non-welded portion is left on the top face between the mesh and the flange in a cross section of the fillet weld joint. The width of the non-welded portion is adjusted so that the ratio X of the width of the non-welded portion to the sum of the thickness of the mesh plate and the leg lengths of the fillet weld metal on the left and right satisfies an expression related to the toughness to interrupt the fragile fracture Kca of the joined member (flange). As a result, even if the joined member (flange) is a thick material with a sheet thickness of 50 mm or more, the propagation of a fragile fracture initiated at the joining member (net) can be stopped at the top face between the net and the flange on the fillet weld metal, thereby interrupting

5/43 the spread of the fragile fracture to the joined member (flange).

List of Citations

Patent literature [0012] PTL 1: JP 2004-232052 A [0013] PTL 2: JP 2007-326147 A

Non-Patent Literature [0014] NPL 1: The 147th Research Committee of the Shipbuilding Research Association of Japan, Evaluation of Brittle Fracture Toughness of Welded Joints of Ship under High Welding Heat Input (February 1978), pgs. 35-53, Shipbuilding Research Association of Japan [0015] NPL 2: Yamaguchi et al., Development of MegaContainer Carrier - Practical Use of New High-Strength Heavy Gauge Steel Plate, Bulletin of The Japan Society PF Naval Architects and Ocean Engineers, Vol. 3, (2005), pgs. 70-76, November 2005 Summary of the Invention

Technical Problem [0016] However, the reinforcer, which is the reinforcement material, used with the technique described in PTL 1 requires complex production steps to achieve a steel sheet having a desired microstructure. Thus, productivity decreases, leading to the problem of a difficulty in securing steel sheets stably having the desired microstructure.

[0017] The technique described in PTL 2, on the other hand, tries to stop the propagation of a fragile fracture initiated in the joint member (network) by a combination of the discontinuity of the structure and the ability to interrupt the fragile fracture of the joined member (flange) ).

[0018] As indicated by the report of the 169th Committee of the Shipbuilding Research Association of Japan (Report on Research Related to Fracture Management and Control Design for Hull Structures,

6/43 (1979), pgs. 118-136, Shipbuilding Research Association of Japan), however it has been experimentally confirmed that using a joining member (net) to interrupt a fragile fracture initiated in the joint member (flange) of the welded fillet joint is more difficult than using the joined member (flange) to interrupt a fragile fracture initiated in the joining member, (network) [0019] The reason is not clearly mentioned, although a possible cause is that the driving force fractures it (stress intensity factor) when the fracture penetrates the T joint is greater in penetrating the joining member (net) than in penetrating the joined member (flange) · [0020] Based on this consideration, the technique described in PTL 2 cannot be considered sufficient to interrupt a fragile fracture initiated in the joined member (flange) using the joining member (net), since the fragile and similar fracture breaking capacity of the joining member (net) is insufficient.

[0021] Note that PTL 2 does not take into account the ability to interrupt the fragile fracture of the union member (network).

[0022] In other words, the technique described in PTL 2 cannot be considered as having sufficient fracture interruption capacity in relation, for example, to the case provided for in ClassNK's Guideline on Brittle Crack Arrest Design (established in September 2009) in which a fragile fracture initiated in the resistance platform (corresponding to the flange) of a large container ship spreads to the side hatch brace (corresponding to the net).

[0023] In addition, with the technique described in PTL 2, it is necessary to increase the breaking toughness of the fragile fracture Kca of the flange for a smaller ratio X of the width of the non-welded portion to the sum of the thickness of the mesh and the lengths of the legs fillet weld metal on the left and right, to satisfy an ex

7/43 particular relational pressure. A higher tenacity to interrupt the fragile Kca fracture, however, leads to a higher rolling load for the production of steel sheets, lower production efficiency, and increased production costs.

[0024] To solve these problems of conventional techniques, it is an objective of the present invention to provide a welded structure that has excellent breaking capacity and that can interrupt (stop) not only that a fragile fracture initiated in the joined member (flange) propagates to the joint member (network), but also that a fragile fracture initiated in a union member (network) spreads to the joined member (flange), before the catastrophic fracture occurs.

[0025] Note that the welded structure desired by the present invention is a welded structure provided with a fillet welded joint formed by a joining member (net) and a joined member (flange), each having a sheet thickness of 50 mm or more and a butt weld joint, in which the face of a welded end of the butt weld joint of the joining member (net) is placed butt against the front face of the butt weld of the joined member ( flange) to join the joining member and the joined member by fillet welding.

Solution to the problem [0026] To achieve the above objective, the inventors have deeply investigated the various factors behind the ability to break the fragile fracture in the fillet welded joint that is formed by placing the top of the final weld face of the weld joint top of the joining member (net) against the front weld face of the top welding joint of the joined member (flange) to join the joining member and the joined member by fillet welding.

[0027] As a result, the inventors found that to stop

8/43 (interrupting) the propagation of a fragile fracture initiated from the joined member (fillet weld joint flange) under such severe conditions, it is not enough to adopt a structure that guarantees a discontinuous portion on the top face between the member of union (net) and the joined member (flange) and has a member showing excellent fragile fracture interruption capacity for having a fragile fracture tenacity Kca of a predetermined value or greater in the propagation portion of the fragile fracture.

[0028] In particular, considering that a greater plate thickness t _f (mm) of the joined member (flange) causes the rate of energy release (driving force of fracture growth) from a fracture tip to increase and make it difficult interrupting the brittle fracture, the inventors concluded that in relation to the thickness of the plate t _f (mm) of the joined member (flange), the improvement in the toughness of the fillet weld metal is essential.

[0029] The inventors also found that since the increase in the length of the weld leg or the width of the weld fillet weld metal facilitates the propagation of a fragile fracture, at least one between the length of the weld leg or the weld width of the fillet weld metal needs to be 16 mm or less.

[0030] Additionally, the inventors have discovered that the welded structure can be provided with the desired brittle fracture breaking capacity by imparting tenacity of a certain value to each weld metal of the top soda joint (s) of the united member and / or union member.

[0031] In other words, the inventors found that in a fillet weld joint formed by a joining member (net) and a joined member (flange), each having a top weld joint, on which the end face of the top weld joint of the joining member

9/43 is not placed on top with the front face of the weld joint of the joined member, the propagation to the joining member of a fragile fracture initiated in a thick joined member having a sheet thickness of 50 mm or more can be stopped (interrupted), which was difficult with conventional techniques, [0032] by guaranteeing a non-welded portion, that is, a discontinuous portion, having a predetermined length on the top welding face;

[0033] adjusting at least one between the length of the weld leg and the weld width of the fillet weld joint to be 16 mm or less;

[0034] also transmitting such tenacity to a fillet weld metal that satisfies a predetermined ratio in relation to the thickness of the plate t _f (mm) of the joined member; and [0035] further increasing the toughness of each weld metal of the top weld joint (s) of the joining member and / or the joined member.

[0036] Based on the findings mentioned above, the inventors also found that the propagation of a fragile fracture from the joint member to the joined member can also be prevented.

[0037] Initially, experimental results are described that serve as a basis for the present invention.

[0038] A large fillet weld joint was prepared with a thick joining member (net) and a thick joined member (flange), each having a top weld joint, welding the final weld face of the joint top weld of the joining member (net) against the front weld face of the top weld joint of the joined member (flange) and joining the members by fillet welding.

[0039] Note that large scale fillet weld joints have been

10/43 prepared with fillet weld metals having a variety of toughness by adjusting the material and conditions for welding, and with ratio of non-welded portions Y (%) (ratio Y being equal to (width B of the non-welded portion) in a cross section of the butt weld joints joined by fillet welding) / (thickness of the plate t _w of the joining member) x 100). In addition, at least one between the weld leg length and the weld width of each fillet weld joint has been adjusted to be 16 mm or less.

[0040] Note that the joined members (flanges) were formed by steel plates having a plate thickness of 50 mm or more, while the joining members were formed by normal steel plates grades D and E used for shipbuilding having a sheet thickness of 50 mm or greater regardless of the tenacity of breaking fragile Kca fractures. In addition, for both the joining member and the joined member, butt weld joints were prepared by arc welding of gas with large single-pass heat input (SEGARC or SEGARC double electrode), while adjusting the material and conditions for welding so that each weld metal of the weld joint (s) has a toughness in which the transition temperature of the appearance of Charpy impact test fracture is -65Ό or less and / or the energy absorbed in the Charpy impact test at -20Ό is 140 J or more.

[0041] Using the resulting large-scale fillet solder joint 9, the superscale structural test model illustrated in FIG. 3 (a), and fragile fracture propagation / interruption tests were conducted. In the superscale structural test model, a steel sheet with the same sheet thickness as the joined member (flange) 2 of a large-scale fillet-welded joint 9 was welded to the bottom of the joined member (flange) 2 with a weld by points 8.

11/43 [0042] The superscale structural test model illustrated in FIG. 3 (a) has been prepared so that the top weld joint 11 of the joined member (flange) 2 aligns with the top weld joint 12 of the joining member (net) 1 in a cross section of the weld joint in fillet 9, and the welding lines are perpendicular to each other. In addition, a mechanical notch 7 has been shaped so that its tip is positioned in the BOND section of the top weld joint 11 of the joined member (flange) 2.

[0043] In the brittle fracture interruption test, an impact was applied to the mechanical notch 7 to generate a brittle fracture, and it was observed whether the propagation of the brittle fracture was interrupted or not in the fillet weld metal. The conditions for each test were a stress of 257 N / mm ² and a temperature of -10Ό.

[0044] Note that a stress of 257 N / mm ² corresponds to the maximum allowable stress of a steel plate, used in a ship's hull, having an elastic limit of about 390 N / mm ² . In addition, the temperature of -10Ό is the design temperature of a ship.

[0045] From FIGS. 4 (a) and (b), it is clear that when the ratio of the non-welded portion Y is 95% or more, and when the toughness of the weld metal in the thickness of plate t _f of the joined member (flange) satisfies a specific relationship, so even if the load stress is 257 N / mm ² , a fragile fracture initiated in the joined member (flange) can be interrupted in the fillet weld metal and the propagation to the union member (net) of the fragile fracture it can be stopped (interrupted) without any consideration for the union member (network) Kca.

[0046] Note that FIGs. 4 (a) and (b) show the cases in which at least one between the length of the weld leg and the weld width of the fillet weld metal is 16 mm or less, and each me

12/43 such welding of the top welded joint (s) of the joined member and / or the joining member satisfies the predetermined toughness.

[0047] Note that the ratio of the non-welded portion Y is defined as the ratio of the width B of the non-welded portion in a cross section of the top welded joints obtained by placing the end face of the top weld joint 12 from top to bottom. joining member (net) against the front weld face of the top weld joint 11 of the joined member (flange) and joining the members by fillet welding up to the thickness of the plate t _w of the joining member (net), ie , (B / t _w ) x 100 (%).

[0048] These results produce the following specific relationships between the toughness of the fillet weld joint and the thickness of the plate t _f of the joined member (flange). FIG. 4 (a) produces the following report

dog: [0049] vTrsfC) <1.5 t _f (mm) + 90 (1) [0050] FIG. 4 (b) produces the following relationship: [0051] vE_2o (J) 2.75 t _f (mm) - 140 (2) [0052] When the sheet thickness t _f of the joined member (flange)

is within the range 50 <t _f (mm) <53, however Expression (2) becomes vE. ₂ o (J) 5.75 [0053] Increased plate thickness t _f (mm) of the joined member (flange) causes the rate of energy release (driving force of fracture growth) from the tip of the fracture to increase and become difficult to break the fragile fracture. Regarding this point, however, the inventors found that by adopting a welded structure (fillet weld joint) having a structural discontinuous portion with a non-welded portion Y ratio of 95% or more, the energy release rate of a propagated fragile fracture tip decreases, making it easier to stop the propagation of the fragile fracture.

[0054] In addition, the inventors found that if the low temperature toughness of the fillet weld metal is increased to the point

13/43 to satisfy Expressions (1) and (2), a fragile fracture, initiated in a thick joined member (flange) with a plate thickness of 50 mm or more can, in many cases, be interrupted within the metal of fillet welding.

[0055] The inventors also found that even if the propagation of a fragile fracture cannot be stopped in the fillet weld metal mentioned above, the propagation of the fragile fracture can be stopped at the weld (top weld joint) of the joining member ( by adjusting at least one between the weld leg length and the weld width of the fillet weld metal to be 16 mm or less, and transmitting a predetermined low temperature toughness to each weld metal of ( s) butt weld joint (s) of the joined member and / or the joined member.

[0056] Based on this consideration the inventors concluded that by taking the above measures, such as adjusting the non-welded portion, improving the low temperature toughness of the fillet weld metal, adjusting the length of the weld leg or the width of welding the fillet weld metal, and improving the low temperature toughness of each weld metal of the weld joint (s) of the joined member and / or the joining member, the propagation of a fragile fracture initiated in the member joint (flange) can be interrupted without any particular consideration for the brittle fracture breaking toughness of the steel plate used in the joining member (net).

[0057] The inventors also found that by taking the measures as mentioned above, the propagation of a fragile fracture from the joining member (net) to the joined member (flange) in the weld (butt weld joint) of the fillet weld metal or joined member (flange).

[0058] The inventors also found that not only increasing the toughness of each weld metal in the sun joint (s)

14/43 of the top of the joined member and / or the joined member ,. But also the toughness of each of the heat-affected zones (HAZ) of the joint (s) ^) welded on top of the joined member and / or the joining member as well as the toughness of the steel sheet material, it is effective to improve the capacity interruption of the fragile fracture.

[0059] The present invention was completed by further examination based on the findings above. The main features of the present invention are as follows.

[0060] [1] A welded structure provided with a fillet weld joint in which the final end of a joining member having a plate thickness of 50 mm or more is placed top against the front face of a joined member having a sheet thickness of 50 mm or more, the joining member and the joined member being joined by fillet welding, and [0061] at least one between the weld leg length and the weld width of the fillet weld joint is 16 mm or less, [0062] both the joining member and the joined member have a weld joint, each weld metal of the top weld joint (s) of the joining member and / or the joined member has a toughness in which the transition temperature of the appearance of the Charpy impact test vTrs-W (O) is -65Ό or less and / or the energy absorbed in the impact test of Charpy at -20Ό vE. ₂₀ -W (J) is 140 J or more.

[0063] a non-welded portion is provided on a butt face between the butt weld end of the butt joint weld joint at the fillet weld joint, the non-welded portion being 95% or more of the plate thickness t _w of the joining member in a cross section of the top weld joints of the fillet weld joint, and [0064] for a fillet weld metal on the fillet weld joint,

15/43 [0065] the transition temperature of the appearance of fracture of the impact test Charpy vTrs fC) of the fillet weld metal and the thickness of the plate t _f of the joined member satisfy the expression (1), and / or [0066 ] the energy absorbed from the Charpy vE impact test. ₂ o (J) at a test temperature of -20Ό in a fillet weld metal impact test Charpy and the thickness of the joined member plate t _f satisfies Expression (2).

[0067] vTrs <-1.5 t _f + 90 (1) [0068] vE_2o (J) 5.75 (when 50 <t _f (mm) <53) [0069] vE_2o (J) 2.75 t _f (mm) - 140 (when t _f (mm)> 53) (2) [0070] where vTrs is the transition temperature of the appearance of the Charpy impact test fracture (Ό) on the fillet weld metal.

[0071] vE_2o is the energy absorbed from the Charpy impact test (J) at a test temperature of -20Ό, and [0072] t _f is the plate thickness (mm) of the joined member.

[0073] [2] The welded structure according to aspect [1], where each zone affected by the heat of the top weld joint (s) of the joining member and / or the joined member has a toughness in which the The transition temperature of the fracture appearance of the Charpy impact test vTrs-Η (Ό) is -65Ό or less and / or the energy absorbed in the Charpy impact test at -20Ό vE. ₂ oH (J) is 140 J or more.

[0074] [3] The welded structure according to aspect [1] or [2] where the steel plate that constitutes the joining member and / or the steel plate that constitutes the joined member has a toughness in which the temperature of transition from fracture appearance in the Charpy vTrs-B (Ό) impact test is -65Ό or less and / or the energy absorbed in the Charpy impact test at -20Ό vE. ₂ oB (J) is 140 J or more.

[0075] [4] The welded structure according to aspect [1] where the weld metal of the top weld joint (s) of the joining member and / or the joined member preferably has a toughness in which the temper

16/43 transition texture of the appearance of fracture in the Charpy vTrs-W impact test (Ό) is -85Ό or less and / or the energy absorbed in the Charpy impact test at -20Ό vE. ₂₀ -W (J) is 160 J or more.

[0076] [5] The welded structure according to aspect [4], where each zone affected by the heat of the top weld joint (s) of the joining member and / or the joined member has a toughness in which the transition temperature of the appearance of fracture in the Charpy impact test vTrs-H (Ό) is -85Ό or less and / or the energy absorbed in the Charpy impact test at -20Ό vE. ₂₀ -H (J) is 160 J or more.

[0077] [6] The welded structure according to aspect [4] or [5], where the steel plate that constitutes the joining member and / or the steel plate that constitutes the joined member has a toughness at which the temperature The transition period for the appearance of fracture in the Charpy impact test vTrs-B (Ό) is -85Ό or less and / or the energy absorbed in the Charpy impact test at -20Ό vE. ₂₀ -B (J) is 160 J or more.

Advantageous effect of the invention [0078] According to the present invention, the propagation to the joining member (net) of a fragile fracture initiated in a joined member (flange) formed from a thick steel sheet having a thickness of 50 mm or more can be stopped (stopped) before the catastrophic fracture occurs, which conventionally was difficult. As a result, the danger of a large-scale brittle fracture in a steel structure, such as separation of the hull in mega-container carriers, bulk carriers, or the like, can be avoided. This effect is highly advantageous in terms of ensuring the safety of the hull structure and is industrially quite significant. The present invention is also effective in stopping (stopping) the propagation to the joined member (flange) of a fragile fracture initiated in a joining member (net) formed from a thick steel sheet having a thickness of 50 mm or more before the fracture occurs

Catastrophic 17/43.

[0079] In addition, by adjusting the dimension of the non-welded portion, the toughness of the fillet weld metal at the time of construction, the length of the weld leg or the weld width of the fillet weld metal, each metal weld of the top weld joint (s) of the joined member and / or the joined member, the zone (s) affected by heat (HAZ (s)), and the low toughness steel plate material temperature, it is possible to easily produce a welded structure with excellent brittle fracture breaking capacity without using special steel sheets with high brittle fracture breaking toughness and without sacrificing safety.

Brief description of the drawings [0080] The present invention will also be described below in relation to the accompanying drawings, where:

[0081] FIG. 1 schematically illustrates the structure of a fillet weld joint formed by a joining member (net) 1 and a joined member (flange) 2, each having a butt weld joint, with (a) being an external view of the fillet weld joint, and (b) schematically illustrating a cross section structure of the fillet weld joint in the position of the top weld joint;

[0082] FIG. 2 schematically illustrates another example of the cross-sectional structure of the fillet weld joint, showing the case of a joining member (net) 1 and a joined member (flange) 2 crossing on a slope;

[0083] FIG. 3 schematically illustrates the shape of the superscale structural test model used in the examples, with (a) illustrating the case of a fragile fracture that spreads from the joined member (flange) 2 to the hi joining member (net) 1, and (b ) illustrating the case of a fragile fracture that spreads from the joint member (net) 1 to the joint member (flange) 2; and

18/43 [0084] FIG. 4 contains graphs illustrating the effects of the relationship between the tenacity of the fillet weld metal and the thickness of the flange plate in stopping a fragile fracture from propagating from the joined member (flange) 2 to the joining member (net) 1.

Description of modalities [0085] A welded structure according to the present invention is a welded structure formed by a joining member (net) and a joined member (flange), each having a plate thickness of 50 mm or more and a joint of butt weld, in which the butt weld face of the butt weld joint of the joint member is placed butt against the butt weld face of the butt weld joint of the joined member, and the join member and the joined member are joined by fillet welding. FIG. 1 (a) is an external view of an example of the welded structure according to the present invention. The welded structure is provided with a fillet weld joint having a fillet weld metal 5 in which at least one between the length of the weld leg 3 and the weld width 13 is 16 mm or less. On a top face between the joining member (net) 1 and the joined member (flange) 2 of the fillet weld joint, an unsoldered portion (length) 4 is provided forming a discontinuous structural portion.

[0086] The cross section of the fillet joint in the position of the top weld joint in FIG. 1 (b) illustrates this state. FIG. 1 (b) illustrates the case of the joining member (net) 1 being connected perpendicularly to the joined member (flange) 2, although the present invention is not limited to that case. For example, as illustrated in FIG. 2, the joining member (net) 1 can be connected at an angle Θ with respect to the joined member (flange) 2. In this case, the thickness of the plate t _w of the joining member (net) used when calculating the Y ratio (%) of the non-welded portion is the length of the cross between the joining member (net) and the joined member (flange), that is, (t _w ) / cos (90 °

19/43

-θ).

[0087] As described above, the welded structure according to the present invention includes a non-welded portion (length) 4 forming a discontinuous structural portion on a top face between the joining member (net) 1 and the joining member (flange) 2 fillet solder joint. In the fillet weld joint, when a fragile fracture spreads from the joined member (flange) 2 to the joined member (net) 1, the top face between the joined member (net) 1 and the joined member ( flange) 2 becomes a brittle fracture propagation surface, and therefore, in the present invention, the non-welded portion (length) 4 is provided on the top face. Due to the presence of the non-welded portion (length) 4 is provided on the top face. Due to the presence of the non-welded portion (length) 4, the rate of energy release (driving force of fracture growth) from a fragile fracture tip that propagates in the joined member (flange) 2 is reduced, making it easy to stop the fracture fragile on the top face.

[0088] In the present invention, the fillet weld section (fillet weld metal) 5 having a toughness of a predetermined value or more is formed. Therefore, even if a fragile fracture spreads to the side of the joining member (net) 1, the fragile fracture is more easily interrupted in the fillet weld section (fillet weld metal) 5.

[0089] It is extremely unusual for a fragile fracture to begin in the base metal portion of the steel plate, which has few defects. In the majority of accidents involving a fragile fracture, the fragile fracture was started at the weld. Thus, at the fillet weld joint, as illustrated in FIG. 1 (a), formed by the joining member (net) 1 and the joined member (flange) 2 having the top weld joints 12 and 11, respectively, in which the topol weld joint 1 of the joined member (flange) 2 and the top weld joint 12 of the joining member (re

20/43 of) 1 are perpendicular to each other, to stop the propagation to the joining member (net) 1 of a fragile fracture initiated at the top weld joint 11, or the propagation to the joined member (flange) 2 of a brittle fracture initiated at the top weld joint 12, it is important that the structure is discontinuous. Therefore, the non-welded portion (length) 4 is provided on the top face between the joining member 1 and the joined member 2 in the fillet weld section.

[0090] At the fillet weld joint, as illustrated in FIG. 1 (b), in which the top weld joint 11 of the joined member (flange) 2 and the top weld joint 12 of the joined member (net) 1 are perpendicular to each other, the non-welded portion (length) 4 it is provided on the top face between the front face of the top weld joint 11 and the top end face of the top weld joint 12.

[0091] Note that the fillet weld joint production method need not be limited in particular, and any regular production method can be used. For example, steel sheets can be butt welded to the flange and other steel sheets can be butt welded to the net, and the resulting butt welds can be filleted to produce a fillet weld joint. .

[0092] In the present invention, the dimension (width B) of the non-welded portion (length) 4 in a cross section of the fillet weld joint at the position of the top weld joint is 95% or more of the thickness of the mesh plate t _w to suppress the spread of a fragile fracture. As a result, plastic deformation of the fillet weld metal becomes easier, thus easing stress around the tip of a fragile fracture that penetrates the fillet weld metal and suppressing the spread of the fragile fracture to the side of the limb connection (net) 1. Therefore, the dimension (width B) of the non-welded portion (length) 4 is limited to 95% or more of the thickness of the sheet

21/43 t _w of the union member (network). Preferably, the dimension is at least 96% and at most 100% of the thickness of the plate t _w of the joining member (net).

[0093] Furthermore, at least one between the weld leg length 3 and the weld width 13 of the fillet weld joint is 16 mm or less. As a result, the stress around the tip of a fragile fracture that spreads to the fillet weld metal is eased through plastic deformation of the fillet weld metal, and the spread of the fragile fracture is weakened. Therefore, the length of the weld leg or the weld width of the fillet weld joint is limited to 16 mm or less, which is a value that allows the fillet weld metal to easily deform. The value is preferably 15 mm or less. The length of the weld leg 3 and the weld width 13 are preferably 4 mm or more, respectively, in terms of stiffness of the weld joint structure.

[0094] If the joined member (flange) 2 and the joined member (net) 1 have a plate thickness of more than 80 mm, the length of the weld leg is preferably increased to ensure strength, while increasing toughness at low temperature of the fillet weld metal portion.

[0095] In the present invention, the fillet weld metal in the fillet weld joint is adjusted in relation to the thickness of the plate t _f of the joined member (flange) 2 in order to guarantee a toughness that satisfies the expression (1) and / or expression (2) below:

[0096] vTrs <-1.5 t _f + 90 (1) [0097] vE_2o 5.75 (when 50 <t _f (mm) <53) [0098] vE_2o 2.75 t _f (mm) -140 ( when t _f (mm)> 53) (2) [0099] where vTrs is the transition temperature of the appearance of the fracture of the Charpy (O) impact test of the fillet weld metal, [00100] vE_2o is the energy absorbed from the Charpy impact test (J)

22/43 at a temperature of -20Ό, and [00101] t _f is the thickness of the plate (mm) of the joined member (flange).

[00102] Having the toughness of the fillet weld metal satisfying the expression (1) and / or expression (2) above in relation to the thickness of the plate t _f of the joined member (flange), a welded structure in which the thickness of the plate of the joined member (flange) is 50 mm or more can be formed as a welded structure in which the ability to break the desired brittle fracture is guaranteed, as illustrated in FIG. 4. When the tenacity of the fillet weld metal is insufficient, and the propagation of the fragile fracture initiated in the joined member (flange) cannot be interrupted in the fillet weld metal portion.

[00103] Furthermore, in the present invention, it is necessary to form each weld metal of the top weld joint (s) of the joined member 2 and / or the joining member 1 while adjusting the material and conditions for welding so that the weld metal has a toughness in which the transition temperature of the appearance of the fracture in the Charpy impact test vTrs-W (O) is -65Ό or less and / or the energy absorbed in the Charpy impact test a -20Ό vE. ₂ oW (J) is 140 J or more.

[00104] If the weld metal of the top weld joint of joint member 1 has a toughness in which vTrs-W (Ό) is greater than 65Ό and vE. ₂₀ -W (J) is less than 140 J, a fragile fracture that spreads from the weld of the joined member (flange) cannot be interrupted in the fillet weld metal or in the weld of the joining member (net).

[00105] Alternatively, if the weld metal of the top weld joint of joined member 2 has a toughness in which vTrs-W (Ό) is greater than -65Ό and vE. ₂₀ -W (J) is less than 140 J, the fragile fracture that propagates from the weld of the joining member cannot be stopped in the weld metal in fillet or in the weld of the joined member (flange).

More preferably, each weld metal of the top weld joint (s) of the joining member and / or the joined member preferably has a toughness at which the transition temperature of the appearance of the fracture in the Charpy impact test vTrs-W (Ό) is -85Ό or less and / or the energy absorbed in the Charpy impact test at 20Ό vE .20-W (J) is 160 J or more.

[00107] More preferably, in the present invention, each weld metal of the top weld joint (s) of the joined member 2 and / or the joining member 1 has the aforementioned toughness and, in addition, each zone heat-affected (HAZ) has a toughness in which the transition temperature of the appearance of the fracture in the Charpy impact test vTrs-H (Ό) is -65Ό or less and / or an energy absorbed in the Charpy impact test at -20Ό vE . ₂ oH (J) is 140 J or more. More preferably, a steel plate that constitutes the joined member 2 and / or a steel plate that constitutes the joining member 1 has a toughness in which the transition temperature of the appearance of the fracture in the impact test Charpy vTrs-B (Ό ) is -65Ό or less and / or an energy absorbed in the Charpy impact test at -20Ό vE. ₂₀ B (J) is 140 J or more. The increase in toughness allows a fragile fracture to propagate from the weld of the joined member (flange) or a fragile fracture to propagate from the weld of the joining member (net) to be stopped more easily, either in that fillet weld metal or in the welding of the joining member (net) or welding of the joined member (flange).

[00108] More preferably, each heat-affected zone (HAZ) of the top weld joint (s) of the joining member and / or the joined member has a toughness in which vTrs-H (Ό) is -85 ° C or less and / or vE. ₂₀ -H (J) is 160 J or more. More preferably, the steel sheet that constitutes the joined member and / or the joined member has a toughness in which vTrs-B (Ό) is -85Ό or less and / or vE. ₂₀ -B (J) is 160 J or more.

24/43 [00109] The welded structure according to the present invention is provided with the fillet solder joint above and the butt weld joints and can, for example, be used in the structure of a hull in which the outer plate the body of the ship is the flange and the bulkhead is the net, the hull structure on which the deck is the flange and the hold is the net, or similar.

[00110] The present invention will be described below in detail based on examples.

Examples [00111] Butt weld joints were prepared by the welding methods shown in Tables 1 and 2, using steel sheets having the plate thickness and low temperature toughness listed in Tables 1 and 2, with the heat inputs of welding listed in Tables 1 and 2, and used as joined members 2 or joint members 1. Butt welding was carried out with a variety of welding materials by arc gas welding with large single pass heat input (SEGARC or Double electrode SEGARC) or by multilayer CO ₂ welding. Charpy V-notch impact specimens (each 10 mm thick) were collected from the middle portions of the weld metals and from the heat-affected zones (HAZ) (BOND sections) at the top weld joints of the members of joint and joined members thus obtained, in such a way that the surface of each specimen is positioned 1 mm or 2 mm below the surface layer, and that the longitudinal direction of the specimen is perpendicular to the weld line and the notch is perpendicular to the weld line. Charpy impact tests were conducted in accordance with JIS Z 2242, and the transition temperature of the fracture appearance vTrs (Ό) and the energy absorbed in the Charpy vE impact. ₂ o (J) at a test temperature of -20Ό were calculated. Note that the energy absorbed from im

25/43 Charpy vE pact. ₂ o (J) θ the transition temperature of the appearance of the fracture (vTrs fC) were also calculated for the base metal portions of the steel plates that constitute the joining members and the joined members.

[00112] The results of the low temperature toughness of the base metal portions of the steel plates and the low temperature toughness of the butt weld joints are listed in Tables 1 and 2.

[00113] Then, large scale fillet weld joints were prepared up to the size of a real structure in the form shown in FIGs. 3 (a) and (b). Each of the fillet weld joints was formed by placing the top weld face end of the top weld joint 12 of a joining member (net) 1 against the front weld face of the top weld joint 11 of the member joined (flange) 2, and joining joining members 1 and 2 by fillet welding. Fillet welding was conducted so that the resulting fillet weld joints have a variety of weld material toughness and a variety of weld leg lengths or weld widths shown in Tables 3 and 4 by varying the welding conditions. welding such as welding material, welding heat input, shielding gas, and the like.

[00114] In prepared fillet weld joints, non-welded portions (lengths) 4 as illustrated in FIG. 1 (b) or in FIG. 2 on the top faces between joint members 1 and joined members 2 have been modified for a variety of non-welded portion ratios Y (the ratio Y being equal to (width B of the non-welded portion in a cross section of the weld joints end pieces joined by fillet welding) / (thickness of the plate t _w of the joining member (net)) x 100) as shown in Tables 3 and 4.

[00115] In addition, a Charpy impact specimen with V-notch (10 mm thick) was collected from the weld metal in

26/43 fillet from each of the large-scale fillet solder joints thus obtained, or from a butt solder joint prepared under the same conditions as fillet solder, to determine the energy absorbed (J) at a temperature -20Ό test temperature and the transition temperature of fracture appearance vTrs (Ό) in accordance with JIS Z 2242. Tables 3 and 4 show the low temperature toughness of the fillet weld metals 5 determined by the tests.

[00116] Using the large scale fillet solder joints thus obtained, the superscale structural test models illustrated in FIG. 3, and fragile fracture propagation / interruption tests were conducted.

[00117] FIG. 3 (a) shows a superscale structural test model that has been shaped so that the final end of the mechanical notch 7 is positioned in the BOND section of the top weld joint

11, and in which the top weld joint 11 of the joined member (flange) 2 and the weld joint 12 of the joined member (net) 1 were perpendicular to each other and the brittle fracture propagates from the joined member (flange) ) 2 for the union member (network) 1.

[00118] FIG. 3 (b) shows a superscale structural test model that has been shaped so that the final end of the mechanical notch 7 is positioned in the BOND section of the top weld joint

12, and in which the top weld joint 12 of the joining member (net) 1 and the top weld joint 11 of the joined member (flange) 2 were perpendicular to each other and the brittle fracture propagates from the joining member (net) ) 1 for the joined member (flange) 2.

[00119] In the superscale structural test model shown in FIG. 3 (a), a steel plate with the same plate thickness as the joined member (flange) 2 of the large-scale fillet weld joint 9 has been welded to the bottom of the joined member (flange) 2 with spot welding 8. In the superscale structural test model shown in

27/43

FIG. 3 (b), an auxiliary plate 6 with the same plate thickness as the joining member (net) 1 of the large scale fillet weld joint 9 has been welded to the bottom of the joined member (flange) 2 with chamfered welding 10 , and the steel plate with the same thickness as the joining member (net) 1 was welded to the bottom of the auxiliary plate 6 with spot welding 8.

[00120] In the brittle fracture propagation / interruption tests, an impact was applied to the mechanical notch 7 to initiate a brittle fracture, and it was observed whether the brittle fracture propagation was interrupted or not in the fillet weld metal, the weld of the joining member (including the heat-affected zone (HAZ)) (FIG. 3 (a)), or the solder of the joined member (including the heat-affected zone (HAZ)) (FIG. 3 (b)).

[00121] The conditions for each test were a stress of 100 N / mm ² to 283 N / mm ² and a temperature of -10Ό. A stress of 100 N / mm ² is the average stress routinely applied to the ship's hull. A stress of 257 N / mm ² corresponds to the maximum allowable stress of a steel plate, used in a ship's hull, having a tensile strength of around 390 N / mm ² . In addition, a stress of 283 N / mm ² corresponds to the maximum allowable stress of a steel plate used in a ship's hull, with an elastic limit of around 460 N / mm ² . The temperature of -10Ό is the design temperature of a ship.

[00122] Table 5 shows the results of the tests.

28/43

Table 1

United member Butt weld joint Tenacity ZVH T LU> 169 159 160 152 155 CD 158 155 154 ID 149 146 143 144 T > -90 -77 -79 -75 l · - 1 O 1 -69 -72 00 CD 1 -65 -66 00 CD 1 -66 -65 Welding metal Conformity* ω ω ω ω ω ω ω ω ω ω ω ω ω ω LU> 178 165 00 CD CD 159 00 CD CD 159 158 155 154 156 148 149 EP 1—> -93 CD 00 1 ID 00 1 00 1 -82 00 1 CD 1 00 00 1 -73 l · - 1 -72 CD 1 -69 00 CD 1 Welding heat input (kJ / cm) 350 350 430 430 480 480 530 530 530 570 570 Welding method CO ₂ Multiple layers SEGARC ** SEGARC SEGARC SEGARC CO ₂ Multiple layers SEGARC CO ₂ Multiple layers SEGARC SEGARC Double electrode SEGARC Double electrode SEGARC Double electrode SEGARC Double electrode SEGARC Double electrode Base metal (steel plate) Tenacity 00 1 _ o LU > 255 259 222 235 233 251 223 221 220 192 CD 193 00 185 vTrs-B CC) O 1 -125 -121 -96 -93 -99 -98 -93 O) 1 -89 00 00 1 00 1 00 00 1 -82 Plate thickness t _f (mm) 50 50 50 09 09 09 65 65 65 70 70 70 75 75 Test model no. - CN 00 ID CD 00 CD O - CN 00

29/43

United member Butt weld joint Tenacity ZVH T LU> 145 139 120 105 165 159 *) S means satisfactory where any of these conditions is achieved: vTrs-W (Ό) <-65Ό or vE. ₂ oW (J)> 140 J. NS means unsatisfactory where none of these conditions have been achieved **) Arc gas welding T m CD 1 COI ID i 1 ml ID i 1 LO i 1 00 1 l · - 1 Welding metal Conformity* ω ω SN ω ω ω %  z ---- » LU> 150 148 128 142 172 00 CD 2 P H > CD 1 CD CD 1 COI ID i 1 mi ID i 1 CD 00 1 00 1 Welding heat input (kJ / cm) 570 610 610 610 350 610 Welding method SEGARC Double electrode SEGARC Double electrode SEGARC Double electrode SEGARC Double electrode SEGARC SEGARC Base metal (steel plate) Tenacity tn 1 _ o LU > CD 00 182 180 179 251 255 vTrs-B CC) CN 00 1 CD 1 CD 1 CN 1 00 1 -105 Plate thickness t _f (mm) ID O 00 O 00 O 00 the ID O 00 Test model no. ID CD 00 CD the C \ |

30/43

Continued Table 1

Union member Butt weld joint Tenacity ZVH T LU> 178 m 154 163 m 155 158 152 154 153 ID 146 145 T > O) 1 l · - 1 -72 POO 1 l · - 1 CO CD 1 CO CD 1 -73 -69 -66 CD 1 CO CD 1 -66 Welding metal Conformity* ω ω ω ω ω ω ω ω ω ω ω ω ω LU> CO 166 177 169 CO CD 162 159 158 157 ID 149 148 EP *> -92 00 1 -82 O) 1 00 1 -72 -74 -89 -74 -72 CD 1 -72 CO CD 1 Welding heat input (kJ / cm) 430 430 430 430 480 530 530 570 570 570 Welding method CO ₂ Multiple layers SEGARC SEGARC CO ₂ M [multiple layers SEGARC SEGARC SEGARC CO ₂ Multiple layers SEGARC Double electrode SEGARC Double electrode SEGARC Double electrode SEGARC Double electrode SEGARC Double electrode Base metal (steel sheet) Tenacity tn 1 _ o LU > 258 263 225 245 198 228 223 192 POO 195 POO 185 184 vTrs-B CC) -98 -95 -97 -102 -98 -95 -93 -92 -92 -94 POO 1 CO ID 1 CO 1 Plate thickness t _w (mm) 50 09 09 09 09 09 99 70 70 70 75 75 75 Test model no. - CN CO m CD CO CD O - CN CO

31/43

Union member Butt weld joint Tenacity ZVH T LU> 144 5 139 125 111 158 ID *) S means satisfactory where any of these conditions is achieved: vTrs-W (Ό) <-65Ό or vE. ₂₀ -W (J)> 140 J. NS means unsatisfactory where none of these conditions have been met **) Arc gas welding T -65 CD ι 1 O) | ID ι 1 s ι 1 O) | 'laugh ι 1 1 00 CD 1 Welding metal Conformity* ω ω ω ω SN ω ω %  z ---- » LU> 146 145 143 145 CN 176 177 2 P *> CD CD 1 00 CD 1 CD ID 1 CD ID 1 LO ι 1 00 1 CD 1 Welding heat input (kJ / cm) 570 610 610 610 610 430 610 Welding method SEGARC Double electrode SEGARC Double electrode SEGARC Double electrode SEGARC Double electrode SEGARC Double electrode SEGARC SEGARC Base metal (steel sheet) Tenacity tn 1 _ o LU > 185 185 180 179 00 00 223 218 vTrs-B CC) 00 1 CD 1 00 1 1 CD 1 the o 1 -98 Plate thickness t _w (mm) 75 O 00 O 00 O 00 O 00 The CD O 00 Test model no. ID CD 00 CD 20

32/43

Table 2

United member Butt weld joint Tenacity ZVH T LU> 159 158 157 155 143 001 0) 1 5 001 o> l 145 143 142 5 129 T > m CD 1 CT) CD 1 CD CD 1 CD CD 1 CD i 1 001 'T i 1 s i 1 COI 00 i 1 CD ID 1 CN | CD i 1 COI ID i 1 CDI ID i 1 COI ID i 1 Welding metal Conformity* ω ω ω ω ω SN ω SN ω ω ω ω ω LU> 163 CD 159 158 155 CN ID 107 162 163 159 148 149 29 H> 1 CT) 1 1 00 1 CD 1 LO i 1 CT) CD 1 IOC 'T i 1 l · - 1 CT) CD 1 00 CD 1 CD ID 1 CD CD 1 Welding heat input (kJ / cm) 610 430 430 430 430 530 610 530 570 570 610 Welding method SEGARC ** SEGARC SEGARC SEGARC SEGARC CO ₂ Multiple layers CO ₂ Multiple layers SEGARC double electrode SEGARC double electrode SEGARC double electrode SEGARC double electrode SEGARC double electrode SEGARC double electrode Base metal (steel plate) Tenacity tn 1 _ o LU > 248 231 228 234 243 258 218 201 198 205 205 222 213 vTrs-B CC) -121 00 CT) 1 00 CT) 1 CT ID) 1 CD CT) 1 00 CT) 1 CN CT) 1 O) 1 the CT) 1 CN CT) 1 CD 1 CN 00 1 CN 1 Plate thickness t _f (mm) O 00 The CD The CD The CD The CD CD ID The ID O O 00 O ID ID O 00 Test model no. CN CN CN 00 CN CN CN ID CD CN CN 00 CN CT) CN O 00 00 CN 00 00 00

33/43

United member Butt weld joint Tenacity ZVH T LU> 108 155 *) S means satisfactory where any of these conditions is achieved: vTrs-W (Ό) <-65Ό or vE. ₂₀ -W (J)> 140 J. NS means unsatisfactory where none of these conditions have been met **) Arc gas welding T COI CO i 1 COI you Welding metal Conformity* SN ω %  , - » LU> COI ool 133 2 P 1— > COI 'laughs 1 CD 1 Welding heat input (kJ / cm) 650 650 Welding method SEGARC double electrode SEGARC double electrode Base metal (steel plate) Tenacity tn 1 _ o LU > O 155 vTrs-B CC) mi 'laugh i 1 'laughs 1 Plate thickness t _f (mm) The CD The CD Test model no. CO m CO

34/43

Continued Table 2

Union member Butt weld joint Tenacity ZVH T LU> 00 CD 158 178 155 154 O) | 0) 1 165 O) | oo 1 145 143 142 143 T > 00 00 1 m co 1 00 00 1 00 CD 1 CD i 1 001 00 i 1 CN 1 c \ i i 1 CD i 1 Oll CD i 1 O) | ID i 1 001 ID i 1 Welding metal Conformity* ω ω ω ω ω SN ω SN ω ω ω ω LU> 00 00 CD 00 162 CD 102 00 00 001 o> l 159 160 158 ID EP *> O) 1 1 O) 1 CD 1 00 1 5 i 1 CD 00 1 my co i 1 00 CD 1 CD 1 CD CD 1 CD CD 1 Welding heat input (kJ / cm) 610 480 480 480 530 570 610 530 570 570 Welding method SEGARC SEGARC CO ₂ Multiple layers SEGARC SEGARC SEGARC double electrode CO ₂ Multiple layers SEGARC double electrode SEGARC double electrode SEGARC double electrode SEGARC double electrode SEGARC double electrode Base metal (steel sheet) Tenacity tn 1 _ o LU > 230 231 235 242 243 228 221 215 205 209 207 210 vTrs-B CC) 00 CD 1 CD CD 1 CD 1 00 CD 1 co CD 1 CD ID 1 CD 1 CD ID 1 O) 1 CN CD 1 CD 00 1 ID 00 1 Plate thickness t _w (mm) O 00 CD ID CD ID CD ID CD ID O The CD ID O 00 O ID ID Test model no. CN C \ | C \ | 00 C \ | C \ | ID C \ | CD CN CN 00 CN CD C \ | the co co CN 00

35/43

Union member Butt weld joint Tenacity ZVH T LU> 104 m COI oo 1 *) S means satisfactory where any of these conditions is achieved: vTrs-W (Ό) <-65Ό or vE. ₂ oW (J)> 140 J. NS means unsatisfactory where none of these conditions have been achieved **) Arc gas welding T COI i 1 -44 dog i 1 Welding metal Conformity* SN ω SN %  z ---- » LU> CN 162 COI oo 1 2 P *> COI m i 1 mi m i 1 COI i 1 Welding heat input (kJ / cm) 610 610 069 Welding method SEGARC double electrode SEGARC double electrode SEGARC double electrode Base metal (steel sheet) Tenacity what 1 _ o LU > 203 CD IOC hi vTrs-B CC) 00 1 mi m i 1 ^ l CO i 1 Plate thickness t _w (mm) O 00 O 00 100 Test model no. 33 34 35

36/43

Grades Ex. Of the invention Ex. Of the invention Ex. Of the invention Ex. Of the invention Ex. Of the invention Ex. Of the invention Ex. Of the invention Ex. Of the invention Ex. Of the invention Ex. Of the invention Ex. Of the invention Ex. Of the invention Ex. Of the invention Ex. Of the invention Ex. Of the invention Ex. Of the invention Ex. Of the invention Ex. Of the invention Ex. Comp. Ex. Comp. these conditions: vTrs-W fC) <-65 Ό or vE. ₂₀ -W (J)> 140 J. magnet)> 53) Fillet weld joint φ -4— 'Φ E φ φ Ό CO Φ Ό Õj Compliance with Eq. (2 ^ **** ω ω ω ω ω ω ω ω ω ω ω ω ω ω ω ω ω ω ω ω o2, í 2 φ ™ σ- Ϊ 5.75 5.75 5.75 25 25 25 38.75 38.75 38.75 52.5 52.5 52.5 66.25 66.25 66.25 ο 00 ο 00 ο 00 5.75 ο 00 ο CN / -— ·> LU > 166 27 176 26 73 45 58 105 65 ÒÕ 86 133 05 79 00 111 83 86 47 86 Φ And Ό Φ Ό Φ Compliance with Eq- (1)*** ω ω ω ω ω ω ω ω ω ω ω ω ω ω ω ω ω ω ω ω u Ό CO c Φ 1- Right side of Eq (1) *** m Ο Ο Ο -7.5 -7.5 -7.5 ιο 1 ΙΟ I ΙΟ I -22.5 -22.5 -22.5 -30 -30 -30 m -30 toughness of the weld metal achieves any of the following, and none of these conditions is achieved with 50 <tf (mm) <53), vE. _2O (J)> 2.75 t _f (mm) -140 (when t _f (rr V- Three (Ό) -55 1 -65 1 -25 Ο 1 Ο 1 00 C0 1 1 -22 -39 -52 -35 -25 00 -42 CO 1 5 1 00 -32 Φ Φ AND Φ CO Ό O Φ Φ Ό dogs Non-welded portion ratio Y (%) ** 86 97 86 97 86 100 95 97 66 96 66 97 97 96 66 86 86 95 86 86 Dimension of the non-welded portion B (mm) 49 58 59 58 59 09 63 00 (Ο 69 67 74 73 73 72 79 00 1 ^ 00 1 ^ 76 59 00 1 ^ Φ And Ό The t ~ Welding width (mm) CD CM CD 00 CM CM 25 σ> 25 σ> 00 C0 CO 30 28 33 35 c Φ E φ 1- Welding leg length (mm) m m CD (Ο 1 ^ (Ο 00 σ> 00 σ> ο ο - CM m - C0 00 27 Union member Δ φ ro φ .2 o .o 32 c το c o. ro φ ro = oo 5 TJ - 'Ό -. CO H ₍ 5 'c ro o ro φ φ ω ω ω ω ω ω ω ω ω ω ω ω ω ω ω ω ω SN ω ω *) S means satisfactory where 1 NS means unsatisfactory ond **) Y (%) = (B / t _w ) x 100 ***) Eq. (1): vTrs <-1.5 t _f + 90 * ***) Eq. (2): see. _2O (J)> 5.75 (quar United member Conformity of the toughness of the butt weld joint * ω ω ω ω ω ω ω ω ω ω ω ω ω ω ω ω SN ω ω ω Test model no. - CM CO (Ο 1 ^ 00 σ> Ο - CM C0 (Ο 00 05 20

37/43

Table 4

Grades Ex. Comp. Ex. Comp. Ex. Comp. Ex. Comp. Ex. Comp. Ex. Comp. Ex. Comp. Ex. Comp. Ex. Comp. Ex. Comp. Ex. Comp. Ex. Comp. Ex. Comp. Ex. Of the invention Ex. Of the invention Fillet weld joint φ H—> Φ E φ φ Ό CO Φ Ό rô Compliance with Eq (2 ^ **** ω ω ω ω SN ω ω ω SN SN SN SN SN ω SN o2, í 5 φ ™ σ- Ϊ O 00 25 25 25 25 38.75 5.75 52.5 ο 00 52.5 66.25 66.25 O 00 107.5 107.5 the CN / -— ·> LU > 00 00 O 5 79 00 00 104 37 20 40 CM 25 122 102 Φ And Ό Φ Ό Φ Ό Ό Φ c Φ 1- i - ± φ ro. * § E Έ and cr * ^ O l-s ω ω ω ω SN ω ω ω SN SN SN SN SN SN ω Right side of Eq (1) *** -30 O O Ο ο -7.5 ιο 1 -30 LO 1 -22.5 -22.5 -30 -45 -45 V- Three (Ό) -34 -40 -45 -65 00 -36 -29 -46 ΙΟ I 1 O 1 ^ -27 -47 Φ Φ E φ φ Ό CO Φ Ό ro Non-welded portion ratio Y (%) ** 66 85 COI ool 5) 1 86 97 92 66 86 97 0) 1 66 66 86 96 Dimension of the non-welded portion B (mm) 79 55 57 59 64 00 (Ο 55 74 00 00 CD 00 CD 74 79 00 1 ^ 96 φ And Ό O Welding width (mm) 37 O σ> 00 CM - CM 32 25 CM 22 29 CD 00 c Φ E φ 1- Welding leg length (mm) 29 CD CD CD 00 σ> σ> CO m CM Union member Δ φ ro φ 5 -§ ooc -oc q. Έ ro cn φ = a ° ₍₅ 'c ro ro φ φ ω ω ω ω ω SN ω SN ω ω ω ω SN ω SN United member Conformity of the toughness of the butt weld joint * ω ω ω ω ω SN ω SN ω ω ω ω ω SN ω Test model no. CM 22 23 24 25 26 27 28 29 30 col 32 33 34 35

Ο ω

-I

j Υ (%) = (B / t _w ) x 100

*) Eq. (1): vTrs <-1.5 t _f + 90 '**) Eq. (2): vE. _2O (J)> 5.75 (when 50 <t _f (mm) <53), see. _2O (J)> 2.75 t _f (mm) -140 (when t _f (mm)> 53)

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Table 5

Test model no. Results of brittle fracture propagation / interruption tests Grades The fragile fracture started in the Temp. of the test. CC) Test stress (N / mm ² ) Propagation / interruption Stopped at 1 United member -10 100 Stopped Fillet weld metal Example of the invention 2 United member -10 257 Stopped Welding metal mesh Example of the invention 3 Union member -10 100 Stopped Fillet weld metal Example of the invention 4 United member -10 257 Stopped Fillet weld metal Example of the invention 5 United member -10 257 Stopped Fillet weld metal Example of the invention 6 Union member -10 257 Stopped Welding metal flange Example of the invention 7 United member -10 283 Stopped Welding metal mesh Example of the invention 8 United member -10 283 Stopped Fillet weld metal Example of the invention 9 United member -10 283 Stopped Welding metal mesh Example of the invention

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Test model no. Results of brittle fracture propagation / interruption tests Grades The fragile fracture started in the Temp. of the test. CC) Test stress (N / mm ² ) Propagation / interruption Stopped at 10 United member -10 257 Stopped Fillet weld metal Example of the invention 11 United member -10 257 Stopped Fillet weld metal Example of the invention 12 United member -10 257 Stopped Fillet weld metal Example of the invention 13 United member -10 257 Stopped Fillet weld metal Example of the invention 14 United member -10 283 Stopped Metal weld mesh Example of the invention 15 United member -10 257 Stopped Fillet weld metal Example of the invention 16 United member -10 257 Stopped Fillet weld metal Example of the invention 17 United member -10 257 Stopped Fillet weld metal Example of the invention 18 Union member -10 257 Stopped Fillet weld metal Example of the invention 19 United member -10 100 Propagated Comparative example

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Test model no. Results of brittle fracture propagation / interruption tests Grades The fragile fracture started in the Temp. of the test. CC) Test stress (N / mm ² ) Propagation / interruption Stopped at 20 United member -10 257 Propagated Comparative example 21 Union member -10 257 Propagated Comparative example 22 United member -10 257 Propagated Comparative example 23 United member -10 257 Propagated Comparative example 24 United member -10 257 Propagated Comparative example 25 United member -10 257 Propagated Comparative example 26 United member -10 283 Propagated Comparative example 27 United member -10 100 Propagated Comparative example 28 United member -10 257 Propagated Comparative example 29 United member -10 257 Propagated Comparative example

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Test model no. Results of brittle fracture propagation / interruption tests Grades The fragile fracture started in the Temp. of the test. CC) Test stress (N / mm ² ) Propagation / terruption Stopped at 30 Union member -10 257 Propagated Comparative example 31 United member -10 257 Propagated Comparative example 32 United member -10 257 Propagated Comparative example 33 United member -10 257 Propagated Comparative example 34 United member -10 257 Stopped Fillet weld metal Example of the invention 35 Union member -10 257 Stopped Welding metal flange Example of the invention

Ό0123] In all examples of the invention where a fragile fracture spreads from the joined member (flange) to the joining member (net), the fragile fracture was interrupted either in the fillet weld metal of the fillet weld section or in the weld union member (network). In all examples of the invention where the fragile fracture propagates from the joining member (net) to the joined member (flange), the fragile fracture was interrupted either in the fillet weld metal of the fillet weld section or in the weld of the member attached (flange).

[00124] On the other hand, in each of the comparative examples (test models n ⁰⁵ 19 to 21), which are outside the ranges of this

42/43 invention both in terms of weld leg length and weld width, the brittle fracture spread to the joining member or joined member without being interrupted in any fillet weld metal, in the weld of the welding member union, or in the weld of the joined member, and then the propagation of the fragile fracture cannot be stopped (stopped).

[00125] In addition, in each of the test models of the comparative examples (test models n ⁰⁵ 22 to 24 and 27) having ratio of non-welded portion Y outside the ranges of the present invention, the fragile fracture initiated in the joined member is propagated to the union member and the propagation of the fragile fracture cannot be stopped (stopped).

[00126] Furthermore, in each of the comparative examples (test models n ⁰⁵ 26 and 28), which are outside the ranges of the present invention in terms of low temperature toughness of the weld metals, of the top weld joints of the union member and joint member responsible for stopping the spread of a fragile fracture, the fragile fracture has spread from the joined member to the union member and the spread of the fragile fracture cannot be stopped (stopped).

[00127] Additionally, in each of the comparative examples (test models No. 25, 29, 30, 32 and 33), which are outside the ranges of the present invention in terms of low temperature toughness of the fillet weld metal, the fragile fracture has spread from the joined member to the union member or from the union member to the joined member and so the spread of the fragile fracture cannot be stopped (stopped).

[00128] Furthermore, in the comparative example (test model No. 31), which is outside the ranges of the present invention in terms of both the ratio of non-welded portion Y and low temperature toughness of the fillet weld metal, the fragile fracture initiated in member u

43/43 nido has spread to the joint member and the spread of the fragile fracture cannot be stopped (stopped)

List of reference signs

Union member (network)

Attached member (flange)

Welding leg length

Non-welded portion

Fillet weld metal

Auxiliary sheet metal

Mechanical notch

Spot welding

Large scale fillet weld joint

Chamfer welding

Welding joint on top of the joined member (flange)

Top weld joint of union member (net)

Welding width θ Transverse angle

Claims (6)

1. Welded structure provided with a fillet weld joint (9) in which the end face of a joining member (1) having a plate thickness of 50 mm or more is placed on top against the front face of a joined member (2) having a plate thickness of 50 mm or more, the joining member (1) and the joined member (2) being connected by fillet welding, characterized by the fact that at least one between the length of the welding leg (3) and the weld width (13) of the fillet weld joint (9) is 16 mm or less, both the joining member (1) and the joined member (2) have a butt weld joint (11 , 12), each weld metal of the top weld joint (s) of the joint member (12) and / or the joined member (11) has a toughness at which the transition temperature of the appearance of fracture in the Charpy impact test vTrs-W (Ό) is 65Ό or less and / or the energy absorbed in the Charpy impact test at -20Ό vE -2o-W (J) is 140 J or more, a non-welded portion (4) is provided in u a butt face between the butt weld face of the butt weld joint (12) and the butt weld face of the butt weld joint (11) on the fillet weld joint (9) , the non-welded portion (4) being 95% or more of the thickness of the plate t _w of the joining member (1) in a cross section of the top weld joints (11, 12) of the fillet weld joint (9 ), and for a fillet weld metal (5) at the fillet weld joint (9), the transition temperature of the appearance of fracture in the Charpy vTrs impact test (Ό) of the fillet weld metal (5) and the plate thickness tf of the joined member (2) meets the expression (1), and / or Petition 870180140578, of 10/11/2018, p. 4/10 2/3 the energy absorbed in the Charpy impact test vE-20 (J) at a test temperature of -20Ό in a Charpy impact test of the fillet weld metal (5) and the thickness of the tf plate of the joined member ( 2) satisfy the expression (2); vTrs <-1.5 tf + 90 (1) vE-20 (J) 5.75 (when 50 <tf (mm) <53). vE-20 (J) 2.75 tf (mm) - 140 (when tf (mm)> 53) (2) where vTrs is the transition temperature of the appearance of fracture in the Charpy impact test (Ό) of the weld metal in fillet (5), vE-20 is the energy absorbed from the Charpy impact test (J) at a test temperature of -20Ό, and tf is the thickness of the plate (mm) of the joined member (2). 2. Welded structure according to claim 1, characterized by the fact that each zone affected by the heat of the top weld (s) of the joint member (12) and / or the joined member (11) has a toughness in which the transition temperature of fracture appearance in the Charpy impact test vTrs-Η (Ό) is -65Ό or less and / or the energy absorbed in the Charpy impact test at 20Ό vE -20-H (J) is 140 J or more. Welded structure according to claim 1 or 2, characterized by the fact that the steel plate that constitutes the joining member (1) and / or the steel plate that constitutes the joined member (2) has a toughness in the which the transition temperature of fracture appearance in the Charpy vTrs-B (Ό) impact test is -65Ό or less and / or the energy absorbed in the Charpy impact test at -20Ό vE -20-B (J) is 140 J or more. Welded structure according to claim 1, characterized in that the weld metal of the top weld joint (s) of the joining member (12) and / or the joined member (11) preferably has a toughness in which the transition temperature of Petition 870180140578, of 10/11/2018, p. 5/10 3/3 fracture appearance in the Charpy vTrs-W (Ό) impact test is 85Ό or less and / or the energy absorbed in the -20Ό vE -2o-W (J) impact test is 160 J or more. 5. Welded structure according to claim 4, characterized by the fact that each zone affected by the heat of the butt weld (s) of the joint member (12) and / or the joined member (11) has a toughness in which the transition temperature of the appearance of the fracture in the Charpy impact test vTrs-H (Ό) is -85Ό or less and / or the energy absorbed in the Charpy impact test at 20Ό vE -20-H (J) is 160 J or more. 6. Welded structure according to claim 4 or 5, characterized by the fact that the steel plate that constitutes the joining member (1) and / or the steel plate that constitutes the joined member (2) has a toughness in the what is the transition temperature of the fracture appearance in the Charpy impact test vTrs-B (Ό) is -85Ό or less and / or the energy absorbed in the Charpy impact test at -20Ό vE. ₂ oB (J) is 160 J or more.