KR20140071412A - Welded structure - Google Patents

Abstract

(Leg length) or welding width of at least one of the welded joint length (leg length) or the weld width, which is obtained by bringing the end face of the joint member into contact with the surface of the to-be-welded member having a plate thickness of 50 mm or more, 16㎜ in the fillet than a welded structure having the welded joint and the surface back to the surface of the section member to be bonded and the joining member, the joint cross section (斷面) at least 95% of the thickness t _w of the bonding members in the US (未) having portions bonded, by adjusting an additional fillet weld, the fillet weld metal, the thickness t _f of the fillet weld metal fracture transition temperature vTrs (℃) and the bonded member, the relationship vTrs≤-1.5t _f +70 , and / or test temperature: the absorbed energy vE _-20 (J) and the member to be bonded at -20 ℃ the plate thickness _{t f, vE -20 (J)} ≥2.75t f (㎜) the relation -105 , It is possible to obtain a welded joint from a member to be welded having a welded joint portion having a thickness of 50 mm or more The propagation of the generated brittle crack is blocked by the fillet welding rapid portion.

Description

{WELDED STRUCTURE}

The present invention relates to a welded steel structure, such as a large container wire or a bulk carrier, which is welded by using a steel plate, and more particularly, to a welded steel structure which is capable of preventing propagation of brittle cracks , And a welded structure excellent in brittle crack propagation stopping property that can be stopped before reaching a large scale destruction of a structure.

Container ships or bulk carriers have a structure in which, for example, a partition wall is smaller in a hold than a tanker or the like, and an opening of the ship-like portion is enlarged in order to improve the loading capacity and the loading efficiency. Therefore, in a container ship or a bulk carrier, it is particularly necessary to strengthen or thicken the hull sheathing.

In addition, container ships have recently become large-sized, and large ships such as 6,000 to 20,000 TEU have been constructed. The TEU (Twenty feet Equivalent Unit) represents the number converted into a container having a length of 20 feet, and indicates an index of the loading capacity of the container line. With such a ship becoming larger, the outer shell of the ship has a plate thickness of 50 mm or more, and a steel sheet having a yield strength of 390 N / mm < 2 >

In recent years, the steel sheet to be the outer shell of the ship is often butt-welded by large heat input welding such as, for example, electro-gas arc welding in view of shortening of the construction period. Such large heat welding is liable to be connected to a large reduction in toughness in the weld heat affected zone, which is one cause of the generation of brittle cracks from the weld joint portion.

From the viewpoint of safety in the hull structure in the past, it is thought that it is necessary to stop the brittle crack propagation before reaching a large scale fracture to prevent the separation of the hull even if brittle fracture occurs.

Based on this thinking, non-patent reference 1 reports experimental results on the propagation behavior of brittle cracks in welds in a steel sheet for shipbuilding with a plate thickness of less than 50 mm.

In Non-Patent Document 1, the propagation path and the propagation behavior of the brittle crack forcedly generated in the weld are experimentally investigated. In this case, if the fracture toughness of the welded portion is secured to some extent, there is a result that the brittle cracks often deviate from the welded portion to the base material side due to the influence of the welding residual stress. However, Has been confirmed. This suggests that brittle fracture can not be assured that there is no possibility of propagating straight along the weld.

However, it has been reported that the welds equivalent to the welding applied in the non-patent document 1 are applied to steel plates less than 50 mm in thickness and that the dried vessels are operated without any problems. In addition, ) Is not sufficiently required to keep the brittle crack propagation stopping property of the welded portion of the steel for shipbuilding from the recognition that the ability to stop the brittle crack is sufficiently retained (retained).

However, in a recent large container ship exceeding 6,000 TEU, the plate thickness of the steel sheet used exceeds 50 mm, and the fracture toughness is lowered by increasing the plate thickness. In addition, large heat input welding with larger heat incoming heat is employed, and the fracture toughness of the welded portion tends to be lowered further. It has been shown that brittle cracks generated from the welded portion of the heat-welded joint of the rear heat of the subsequent meat are not likely to stray to the base material side but go straight, and may not stop at the base material portion of the steel sheet such as an aggregate (for example, refer to Non-Patent Document 2) . Therefore, securing the safety of the hull structure to which the high strength steel plate having the plate thickness of 50 mm or more is applied is a big problem.

Non-Patent Document 2 also points out that a post-steel plate having a specific brittle crack propagation stopping characteristic is required for stopping the propagation of a brittle crack, which is generated in particular.

In view of such a problem, for example, Patent Document 1 discloses a welded structure having a shell thickness of 50 mm or more, preferably having a plate thickness of 50 mm or more, wherein an aggregate is disposed so as to cross the butt weld portion, welded structure is described.

In the technique described in Patent Document 1, the aggregate has an average circle equivalent particle diameter of 0.5 to 5 탆 over the thickness of 3 mm or more in the surface layer portion and the back layer portion, 100) crystal face having an X-ray plane intensity ratio of 1.5 or more. By adopting a structure in which the steel plate having such microstructure is reinforced by fillet welding, even when brittle cracks are generated in the butt welded joint portion, the propagation of the brittle crack can be stopped by the aggregate as the reinforcing material, It is said that damage can be prevented.

Patent Document 2 discloses a brittle crack propagation stopping property which is provided with a fillet welded joint formed by a fillet welding of a joining member (hereinafter also referred to as a web) to a joining member (hereinafter also referred to as a flange) This excellent welded structure is described.

In the welded structure described in Patent Document 2, an unfused portion remains on the face of the flange of the web at the fillet welded joint cross-section. The ratio X of the width of the unhardened portion to the sum of the thickness of the web plate and the sum of the leg lengths of the fillet welded portion and the width of the web plate satisfies the relationship of the brittle crack propagation and suspension toughness Kca of the member to be welded Adjust the width of the unsealed part so as to satisfy a special relation. Thus, even when the member to be joined (flange) is made of a post material having a plate thickness of 50 mm or more, the propagation of the brittle crack generated in the joining member (web) is stopped at the contact surface of the web of the fillet weld and the flange, It is possible to prevent propagation of a brittle crack in the flange (flange).

Japanese Laid-Open Patent Publication No. 2004-232052 Japanese Patent Application Laid-Open No. 2007-326147

 The 147th Research Meeting of the Japanese Society of Naval Architects of Japan: "A Study on the Evaluation of Brittle Fracture Strength of High Heat Strength Steel Plate for Hull", No. 87 (February 1978), p.35 ~  Yamaguchi Kinya et al .: "Development of Ultra-Large Container Ship - Practical Application of New High Strength Extreme Steel Plates", Journal of the Japan Ship and Ocean Engineering Society, No. 3 (2005), pp.70-76, November 2005

However, the aggregate, which is the reinforcing material described in Patent Document 1, requires a complicated process in order to obtain a steel sheet having a desired structure. For this reason, there has been a problem that it is difficult to secure a steel sheet having a desired structure in a stable manner because the composition is lowered.

The technique described in Patent Document 2 is a technique to prevent the propagation of a brittle crack generated in a joining member (web) by a combination of a discontinuity in structure and a brittle crack propagation stopping property of the member to be bonded (flange) .

However, as shown in the Report of the 169th Committee of Japan Shipbuilding Research Association ("Study on Control Design of Hull Structure, Report -", (1979), p.118 ~ 136, Japan Shipbuilding Research Association 169 Committee) Generally, to stop the brittle crack generated in the member (flange) of the fillet welded joint from propagating in the joint member (web) is to stop propagating the brittle crack generated in the joint member (web) In contrast, difficult things have been confirmed experimentally.

Although the reason for this is not explicitly stated, as one factor, the fracture driving force (stress intensity factor) at the time of cracking into the T joint portion is higher than that in the case where the fracture driving force (stress magnification coefficient) It is conceivable that the size of the case in which the protruding portion is in contact with the protruding portion increases.

In view of this, in order to cause the brittle crack generated in the member to be joined (flange) to stop propagating in the joining member (web), the technique described in Patent Document 2 has a problem in that the brittle crack propagation stopping property, etc. of the joining member , Not enough technology.

In Patent Document 2, no attention is paid to the brittle crack propagation stopping property of the joining member (web).

That is, the technique described in Patent Document 2 is, for example, a brittle crack (crack) generated in a strength deck (equivalent to a flange) of a large container ship, which is assumed in the "Design Guide for Brittle Crack Arrres" issued by NK Classification Society It can not be said that it has a sufficient crack propagation stopping characteristic with respect to the case of propagating to this hatch side coaming (equivalent to a web).

It is an object of the present invention to solve such a problem of the prior art and to provide a brittle crack propagation which can stop (impede) the propagation of a brittle crack to a joining member (web) generated in a member to be bonded (flange) And to provide a welded structure excellent in stopping characteristics.

Further, the welded structure to which the present invention is applied is a welded structure including a fillet welded joint in which the end face of the welded member (web) is bonded to the surface of the welded material (flange) by fillet welding.

In order to achieve the above object, the inventors of the present invention have extensively studied various factors affecting brittle crack propagation stopping characteristics in a fillet welded joint.

As a result, in order to stop (stop) the propagation of the brittle cracks generated from the member to be bonded (flange), a discontinuous portion is secured on the abutting surface of the member to be bonded (flange) and the bonding member (web) Or more of the brittle crack propagation stopping property having the above-mentioned brittle crack propagation stop toughness Kca is not sufficient.

Particularly, considering that the plate thickness t _f (mm) of the member to be joined (flange) becomes large, the energy release rate (crack propagation driving force) of the brittle crack tip is increased and the brittle crack becomes difficult to stop, , It is necessary to improve the toughness of the fillet welded portion in relation to the plate thickness t _f (mm) of the steel plate.

Further, it has also been recognized that when the length of the fillet welded part or the welded width is long, the propagation of the brittle crack becomes easy, so that it is necessary to set at least one of the fillet welded portion or the welding width to 16 mm or less.

In the fillet welded joint, the non-welded portion, that is, the discontinuous portion, is formed on the face of the surface of the member to be bonded and the end face of the welded member at least 95% or more of the plate thickness t _w of the welded member And at least one of the fillet weld width and weld width is set to 16 mm or less and the toughness of the fillet welded portion is set to a high value (high) satisfying a predetermined relationship in relation to the plate thickness t _f ) Toughness, it has been found for the first time that the propagation of the brittle crack to the joining member, which occurred in the member to be welded at the thickness of 50 mm or more, which was difficult in the conventional technique, .

That is, the inventors of the present invention have found that the technique described in Patent Document 2 preserves and maintains the low temperature toughness of a predetermined value or more in the fillet welded metal portion of the fillet welded joint, which is not considered at all, It is possible to prevent the propagation of brittle cracks entering from the member (flange) into the joining member (web).

Even when the member to be joined is not a base metal but a butt welded joint and the joining member is a butt welded joint instead of a base metal, And found that the wave can be blocked by the fillet weld metal part.

First, experimental results that are the basis of the present invention will be described.

(The width B of the non-welded portion in the cross section of the fillet welded joint) / (the thickness t _w of the jointed member) x 100 (mm) ), And a fillet welded joint having a variety of low-temperature toughness and shell lengths.

A steel plate having a butt weld joint portion and a plate thickness of 50 mm or more was used for the member to be welded (flange). Further, ordinary joining D-E class steels were used for bonding members (webs), which did not give any consideration to brittle crack propagation stop toughness Kca.

The butt weld joints were also fabricated by one pass high-dose electro-arc arc welding (SEGARC or two-electrode SEGARC) or carbon dioxide gas arc welding (multi-layer stacking).

Using the obtained large fillet welded joint, a very large-scale structural model test body shown in Fig. 4 (b) was prepared, and a brittle crack propagation stop test was carried out. The very large structural model test body welded a steel sheet having the same plate thickness as that of the flange 2 to the welded joint 8 below the member to be welded (flange) 2 of the large fillet welded joint 9.

The very large structural model test body shown in Fig. 4 (b) is manufactured such that the butt welded joint portion 11 of the member to be welded (flange) is made orthogonal to the joint member (web) To be a BOND part of the butt weld joint part (11).

Further, in the brittle crack propagation stop test, a mechanical notch was hit to generate a brittle crack, and whether or not the propagation of the brittle crack stopped at the fillet welded portion was examined. All tests were carried out under the conditions of a stress of 257 N / mm 2 and a temperature of -10 캜.

The stress of 257 N / mm 2 is equivalent to the maximum permissible stress of the steel sheet having a yield strength of 390 N / mm 2 applied to the hull. Temperature: -10 ° C is the ship's design temperature.

The obtained results are shown in Fig. 5 (a) and Fig. 5 (b).

In the case of the Figure 5 (a), Figure 5 (b) from, cosmetic chakbu ratio Y is more than 95%, and the thickness of the fillet weld toughness and to be joined member (flange) t _f satisfy a specific relationship, Even when the load stress is 257 N / mm < 2 >, the brittle crack generated in the member to be welded (flange) can be stopped at the fillet weld metal portion without giving any consideration to Kca of the joint member (web) It is found that it is possible to stop (stop) the propagation to the member (web).

The unfit welded portion ratio Y is a value defined by a ratio (B / _tw ) x 100 (%) of the width B of the non-welded portion to the welded portion (web) plate thickness t _{w in} the section of the fillet welded joint.

From these results, as a specific relationship between the toughness of the fillet welded portion and the plate thickness t _f of the member to be welded (flange)

5 (a)

vTrs (占 폚)? 1.5t _f (mm) +70 (1)

From Fig. 5 (b)

vE- ₂₀ (J)? 2.75t _f (mm) -105 (2)

Is obtained.

When the plate thickness t _f (mm) of the member to be joined (flange) is increased, the energy release rate (crack propagation driving force) of the brittle crack tip increases, and the brittle crack becomes difficult to stop. However, regarding this point, when the welded structure (fillet welded joint) having the structure discontinuity portion with the unfitted portion ratio Y of 95% or more is used, the energy release rate of the propagated brittle crack tip is lowered and the propagation of the brittle crack is stopped It was easy to see.

Further, in addition to the setting of the untreated portion, if the low-temperature toughness of the fillet welded metal portion is further increased until the above formulas (1) and (2) are satisfied, the brittle It becomes possible to stop the crack in the weld metal of the fillet welded joint portion.

When the measures such as the setting of the unapplied portion and the remarkable improvement in the low temperature toughness of the fillet welded portion as described above are performed, the steel sheet used for the joining member (web) is not subjected to brittle crack propagation, It is possible to prevent the propagation of brittle cracks in the member (flange).

The present invention is based on this recognition and is completed by further review. That is, the gist of the present invention is as follows.

1. Fillet welding in which at least one of the welding leg length or weld width formed by joining the end surface of the joining member to the surface of the member to be joined having a plate thickness of 50 mm or more and joining the joining member and the member to be joined by fillet welding is 16 mm or less A welded structure having a joint,

Wherein a surface of the fillet welded joint facing the end surface of the joint member and the surface of the member to be welded is at least 95% of the plate thickness t _w of the joint member at a cross- Having a non-

Further, with respect to the fillet weld metal of the fillet welded joint,

To the plate thickness t _f of the to-be-bonded member and the Charpy impact test fracture transition temperature vTrs (℃) of that fillet weld metal (1) relationship of the formula, and / or,

This test temperature in the Charpy impact test of the fillet weld metal: satisfying the Charpy impact test absorbed energy vE _-20 (J) and the to-be-relationship of the joining members to the plate thickness t _f 2 of the formula in the -20 ℃ Welded structure < RTI ID = 0.0 >

group

vTrs ≤ 1.5t ≤ _{f +} 70 (1)

vE _-20? 2.75t _f -105 (2)

Here, vTrs: Charpy impact test of fillet weld metal Wavefront transition temperature (캜),

vE- ₂₀ : Test temperature: Charpy impact test at -20 DEG C Absorbed energy (J),

t _f : plate thickness of the member to be bonded (mm).

2. The welded structure according to the above 1, wherein the member to be welded having a plate thickness of 50 mm or more has a butt welded joint portion so as to intersect with the welded member.

3. The welding method according to the above 2, wherein the joining member has a butt welded joint portion, and the joining member is arranged so that the butt welded joint portion of the joining member crosses the butt welded joint portion of the joined member. Welded structure.

According to the present invention, the propagation of a brittle crack to a joining member (web) generated on a member to be joined (flange) made of a steel plate having a plate thickness of 50 mm or more, which has been difficult conventionally, can be stopped . As a result, it is possible to avoid the risk of large-scale brittle fracture such as separation of steel structures, particularly hulls such as large-sized container ships and bulk carriers, and thus has a great effect in securing the safety of the hull structure. .

In addition, by adjusting the dimensions of the non-welded portion and the toughness of the fillet welded metal at the time of construction, it is possible to easily manufacture a welded structure excellent in brittle crack propagation stopping property without sacrificing safety without using a special steel plate Can be effective.

1 is an explanatory diagram schematically illustrating a cross-sectional configuration of a fillet welded joint. 1 (a) is a cross-sectional view of a joining member (web) 1 and a member to be joined (flange) 2 when the joining member (web) 1 and the member to be joined 1 (c) shows a case where a clearance is spread between the joining member (web) 1 and the member to be joined (flange) 2 when the joining member 2 is obliquely intersected, (A web) 1 and a member to be joined (flange) 2, and a spacer is inserted in the gap.
2 is an explanatory diagram schematically showing another example of the configuration of a fillet welded joint. Fig. 2 (a) is an external view, and Fig. 2 (b) is a sectional view.
3 is an explanatory diagram schematically showing another example of the configuration of the fillet welded joint. Fig. 3 (a) is an external view, and Fig. 3 (b) is a sectional view.
4 is an explanatory diagram schematically showing the shape of a very large structural model test body used in the embodiment. 4 (b) shows a case where the member to be welded (flange) 2 has a butt welded joint portion, FIG. 4 (c) shows a case where the welded joint (flange) (Web) 2 and a member to be welded (flange) 2 have a butt welded joint portion.
5 is a graph showing the influence of the relationship between the toughness of the fillet weld metal and the thickness of the flange plate on the suspension of brittle cracks.

(Mode for carrying out the invention)

The welded structure according to the present invention has a structure in which the end face of the welding member (web) 1 is brought into contact with the surface of the welded member (flange) 2 having a thickness of 50 mm or more and the welded member (web) (Flanges) 2 are joined by fillet welding. The welded structure comprises a fillet welded joint having a fillet weld metal (5) having at least one of a weld length (3) or a weld width (13) of 16 mm or less. In addition, on the face of abutment between the joining member (web) 1 and the member to be joined (flange) 2 of the fillet welded joint, an unfit portion 4 which is a structural discontinuity is provided.

This state is shown in Fig. 1 as a joint section. 1 (a) shows a case where the joining member (web) 1 is attached upright to the member to be joined (flange) 2, but the present invention is not limited to this. For example, as shown in Fig. 1 (b), the joining member (web) 1 may be attached to the member to be joined (flange) 2 at an angle? In this case, the joining member (web) thickness t _w to be used when available cosmetic ratio Y fuser unit (%), the joint material (the web) and to be joined member (flange) long cross-section with, (t _w) / cos (90 [deg.] - [theta]). In the drawings, reference numeral 3 denotes a welding leg, 4 denotes an unfilled portion, 5 denotes a fillet weld metal, and 13 denotes a welding width.

1 (c), a gap 14 may be formed between the joining member (web) 1 and the member to be joined (flange) 2. 1 (d), a gap 14 is opened between the joining member (web) 1 and the member to be joined (flange) 2, and the spacer 14 15 may be inserted.

In the case of Figs. 1 (c) and 1 (d), the welding width 13 is the welding width on the side of the welding member (web) 1. It is sufficient that the welding width 13 satisfies a predetermined value (16 mm or less). 1 (d), the fillet weld metal 5 may be dissolved in the spacer 15.

As described above, the welded structure of the present invention is a welded structure in which the structure is discontinuous at the contact surface between the joint member (web) 1 and the member to be welded (flange) 2 in the fillet welded joint 4). In the fillet welded joint, since the abutting surface of the bonding member (web) 1 and the member to be bonded (flange) 2 becomes a propagating surface of brittle cracks, in the present invention, Lt; / RTI > The presence of the non-applied portion 4 lowers the energy release rate (crack propagation driving force) at the tip of the brittle crack propagated on the member to be bonded (flange) 2, and the brittle crack becomes easy to stop on the abutting surface .

Further, even if a brittle crack propagates on the side of the joining member (web) 1, since the fillet weld metal 5 for holding and holding a predetermined toughness is formed in the present invention, (5).

In addition, brittle cracks occur very little in the steel plate base material portion with few defects. Most of the brittle fracture incidents occurred in the welds in the past. 2 is a plan view of a welded joint (welded joint) 11 in which a welded member (flange) 2 is made of a steel plate bonded by a butt welded joint 11 and a welded member (web) Welded joint portion) 11 crossing the butt welded joint portion (11). 3 shows a state in which both the joining member (web) 1 and the member to be welded (flange) 2 are steel plates having the butt weld joints 11 and 12, Welded joint portion 11 of the joint member (web) 1 and the butt welded joint portion 12 of the joint member (web) 1 intersect each other. Even in the case of such a fillet welded joint, it is important that the discontinuity of the structure exists in order to prevent the brittle crack generated from the butt welded joint portion 11 from propagating to the joint member (web) 1. Therefore, even in these cases, the non-applied portion 4 is provided on the contact surface between the member to be bonded and the bonding member in the fillet welded portion.

Fig. 2 (a) shows the appearance of the fillet welded joint, and Fig. 2 (b) shows the cross-sectional shape of the butt welded joint part 11. Fig.

3 shows a case where both the joining member (web) 1 and the member to be welded (flange) 2 are steel plates having the butt welded joint portions 11 and 12, and the joined member (flange) Welded joint portion 11 of the joint member (web) 1 and the butt weld joint portion 12 of the joint member (web) 1 intersect with each other. Fig. 3 (a) shows the external appearance of the fillet welded joint, and Fig. 3 (b) shows the joint cross-sectional shape in the butt welded joint portions 11 and 12. Fig.

2 and 3 show the case where the butt weld joint portion 11 and the web 1 are orthogonal to each other. However, the present invention is not limited to this. Needless to say, crossing at an angle is good.

The method of manufacturing the fillet welded joint is not particularly limited, and any of ordinary manufacturing methods can be applied. For example, the flange welded joints may be welded to each other by flange-to-web steel plates, and the obtained butt welded joint may be fillet welded to produce the fillet welded joint.

Further, a pair of web steel plates before butt weld may be welded to the flange, then the web steel plates may be butt welded together, and the obtained butt welded joint may be welded (fillet welded) to the flange to produce a fillet welded joint.

In the present invention, the dimension of the non-applied portion 4 in the section of the fillet welded joint is set to 95% or more of the web plate thickness t _w in order to suppress the propagation of brittle cracks. Accordingly, since the fillet weld metal is easily subjected to plastic deformation, the stress in the vicinity of the crack tip of the brittle crack protruding into the fillet weld metal is alleviated, and the propagation of the brittle crack toward the joint member (web) have. Therefore, the dimension (width B) of the non-applied portion 4 is limited to 95% or more of the bonding member (web) plate thickness t _w capable of suppressing the propagation of brittle cracks. Further, it is preferably 96% or more and 100% or less.

Also, at least one of the welding leg lengths or welding widths of the fillet welded joints is set to 16 mm or less. As a result, the fillet weld metal is easily subjected to plastic deformation, so that the propagation of the brittle crack can be suppressed. For this reason, at least one of the welding leg length and the welding width of the fillet welded joint is limited to 16 mm or less, which tends to cause plastic deformation of the high-phosphorus fillet weld metal. Preferably 12 mm or less.

Further, in the present invention, the fillet weld metal in the fillet welded joint is formed so as to secure toughness satisfying the following expressions (1) and / or (2) with respect to the plate thickness t _f of the member to be welded (flange) Adjust to:

vTrs ≤ 1.5t ≤ _{f +} 70 (1)

vE _-20? 2.75t _f -105 (2)

(Here, vTrs: Charpy impact test transition temperature wave front of the fillet weld metal _{(℃), vE -20 (J} ): test temperature of the fillet weld metal: Charpy impact test absorbed energy (J) at the -20 ℃, t _f : thickness of the member to be bonded (mm)).

Of the fillet weld metal toughness, with respect to the thickness t _f of the members to be joined member (flange), by satisfying the above expression (1) and / or formula (2), as shown in Figure 5, the bonded member ( Flange) having a thickness of 50 mm or more can be made a welded structure securing the desired brittle crack propagation stopping property. In the case where the toughness of the fillet weld metal does not satisfy all of the above-mentioned formulas (1) and (2), the toughness of the fillet weld metal is insufficient and the brittle crack Can not be prevented from propagating in the fillet welded metal part.

As described above, when the fillet weld metal is a welded structure satisfying the above-described conditions in relation to the plate thickness t _f of the member to be welded (flange), brittle cracks generated in the welded member (flange) can do.

Further, the welded structure of the present invention includes the above-described fillet welded joint. For example, the welded structure of the present invention can be used as a hull structure in which the outer shell of a ship is a flange and the partition wall is a web, And the like.

Hereinafter, the present invention will be described in detail based on examples.

Example

The post-steel plate having the plate thickness shown in Table 1 was used as the joining member (web), the post-steel plate having the plate thickness shown in Table 1 was used as the member to be joined (flange) 4 (b) and 4 (c) were fabricated.

1 (a), 1 (c), or 1 (d) is formed on the abutting surface between the joining member 1 and the member to be joined 2 in the manufactured fillet welded joint, And the ratio Y of the unapplied portion (= (width B of the unfolded portion / plate thickness t _{w of the} joined portion (web)) was changed variously.

4 (b) and 4 (c)) having the butt welded joint and the joint member (flange) 4 (b)), or a post-steel plate having a butt weld joint (Fig. 4 (c)).

The butt weld joints were fabricated by 1-pass arrays of electrogas arc welding (SEGARC and 2-electrode SEGARC) or multilayer CO ₂ welding.

In addition, the fillet welded joint was made into a fillet welded joint having fillet weld metal of various toughness, various welding leg lengths, and welding widths by changing the welding conditions such as welding material, welding heat input and shielding gas. In addition, the toughness of the fillet weld metal was determined by taking a Charpy impact test piece (10 mm in thickness) from a butt weld joint manufactured under the same conditions as the fillet weld metal or fillet weld, and measuring the test temperature: -20 absorbed energy at ℃ vE _-20 (J), it was determined the wave front transition temperature vTrs (℃).

Further, in some fillet welded joints, a gap is spread between the joining member (web) 1 and the member to be joined (flange) 2. Further, in a part of the fillet welded joint, a spacer was inserted into a gap between the joint member (web) 1 and the member to be welded (flange) 2 to produce a fillet welded joint.

Using the obtained large fillet welded joint, a very large structural model test body as shown in Fig. 4 was produced, and a brittle crack propagation stop test was carried out. The very large structural model test specimen is a welded joint 8 formed under the member to be welded (flange) 2 of the large fillet welded joint 9 and made of a steel plate having the same thickness as the member to be welded (flange) .

In the very large structural model test body shown in Fig. 4 (b), the butt welded joint portion 11 of the member to be joined (flange) was made to be perpendicular to the joining member (web). 4C, the butt welded joint portion 11 of the member to be welded (flange) and the butt welded joint portion 12 of the welded member (web) were intersected with each other. Then, the tip of the machine notch 7 was machined to be the BOND portion of the butt weld joint portion 11, or the weld metal WM.

In the brittle crack propagation stop test, brittle cracks were generated by striking mechanical notches, and it was examined whether brittle crack propagated under the following test conditions stopped at the fillet welded portion. All tests were conducted under the conditions of a stress of 100 to 283 N / mm 2 and a temperature of -10 캜. The stress of 100 N / mm 2 is the average value of the stress normally acting on the hull. The stress of 257 N / mm 2 is equivalent to the maximum permissible stress of the steel sheet having a yield strength of 390 N / mm 2 applied to the hull. The stress of 283 N / mm 2 is a value corresponding to the maximum allowable stress of the steel sheet having a yield strength of 460 N / mm 2 applied to the hull. The temperature -10 ° C is the ship's design temperature.

The obtained results are shown in Table 2.

In the present invention, all the brittle cracks propagate from the member to be welded (flange) to the fillet welded metal of the fillet welded portion and stopped. On the other hand, in the comparative example deviating from the scope of the present invention, the brittle crack propagated without stopping at the fillet welded portion, and it was impossible to prevent the propagation of brittle cracks in the fillet welded metal.

1: web
2: Flange
3: Legs
4: Cosmetic application
5: Fillet welded metal
7: Machine notch
8:
9: Large fillet welded joint
11: Butt welded joint part of flange
12: butt welded joint portion of web
13: Welding width
14: Clearance
15: Spacer
θ: cross angle

Claims (3)

(Leg length; weld length) formed by bringing the end face of the joining member into contact with the surface of the to-be-joined member having a thickness of 50 mm or more and joining the joining member and the member to be joined together by fillet welding, leg length or welding width of not more than 16 mm, the welding structure comprising:
Wherein the fillet welded joint is formed on the surface of the welded joint and the surface of the welded member opposite to the surface of the welded joint so that at least 95% of the plate thickness t _w of the welded joint in the cross- ) Welded portion,
Further, with respect to the fillet weld metal of the fillet welded joint,
To the plate thickness t _f of the to-be-bonded member and the Charpy impact test fracture transition temperature vTrs (℃) of that fillet weld metal (1) relationship of the formula, and / or,
This test temperature in the Charpy impact test of the fillet weld metal: satisfying the Charpy impact test absorbed energy vE _-20 (J) and the to-be-relationship of the joining members to the plate thickness t _f 2 of the formula in the -20 ℃ Welded structure < RTI ID = 0.0 >
group
vTrs ≤ 1.5t ≤ _{f +} 70 (1)
vE _-20? 2.75t _f -105 (2)
Here, vTrs: Charpy impact test of fillet weld metal Wavefront transition temperature (캜),
vE- ₂₀ : Test temperature: Charpy impact test at -20 DEG C Absorbed energy (J),
t _f : plate thickness of the member to be bonded (mm). The method according to claim 1,
Wherein the member to be welded having a thickness of 50 mm or more has a butt welded joint portion so as to intersect with the welded member. 3. The method of claim 2,
Wherein the welding member has a butt welded joint portion and the welding member is disposed such that the butt welded joint portion of the welding member crosses the butt welded joint portion of the welded member.

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