WO2020136777A1

WO2020136777A1 - Welded structure

Info

Publication number: WO2020136777A1
Application number: PCT/JP2018/047975
Authority: WO
Inventors: 鉄平大川; 祐介島田; 直樹小田
Original assignee: 日本製鉄株式会社
Priority date: 2018-12-26
Filing date: 2018-12-26
Publication date: 2020-07-02
Also published as: JP6562189B1; CN111315650A; KR102105614B1; CN111315650B; JPWO2020136777A1

Abstract

A welded structure 10 having a T joint section where a joining member 11 is partial-penetration welded at both sides thereof to a joined member 12 while an end surface 11c of the joining member 11 is in contact with a joined surface 12a of the joined member 12, wherein the joining member 11 has a first surface 11a and a second surface 11b, the plate thickness t (mm) of the joining member 11 satisfies the expression [t≥50.0], and the nil-ductility transition temperatures according to an NRL drop-weight test using type P3 test specimens respectively taken from locations at 1mm depth in the first surface 11a and the second surface 11b of the joining member 11 are -60°C or less, and satisfy the expressions [NDTT1≤-30.5×ln(h1)-14.0] and [NDTT2≤-30.5×ln(h2)-14.0] in relation to the distance h1 (mm) between the first surface 11a and the farthest point of a first heat-affected section 15a of a first weld section 13a, and the distance h2 (mm) between the second surface 11b and the farthest point of a second heat-affected section 15b of a second weld section 13b.

Description

Welded structure

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

Large container vessels that carry a large amount of cargo have a large opening (hatch) formed in the upper deck (upper deck) for loading and unloading cargo. A hatchside combing is provided on the upper deck so as to surround the hatch to prevent the inflow of seawater. The upper deck and the hatch side combing are each constructed by welding a plurality of steel plates. Hatchside combing is also welded on the upper deck.

When a large container ship such as the one above is sailing at sea, due to waves, a load (vertical bending load) that bends the entire hull is added to the hull. In order to sufficiently secure the strength (longitudinal bending strength) of the hull against such loads, high strength thick steel plates are used for the upper deck and the hatchside combing.

Also, as mentioned above, each of the hatchside combing and the upper deck has a structure in which a plurality of steel plates are welded. In other words, the hatchside combing and the upper deck are formed with a plurality of welds for welding the steel plates to each other. The crack generated in the weld easily propagates along the weld. Therefore, for example, when a crack occurs in the hatch side combing weld, the crack propagates toward the upper deck side along the weld, and the propagated crack propagates to the weld in the upper deck. There are cases. Therefore, in order to sufficiently improve the strength of the hull, the hatchside combing and the upper deck must have the characteristics (brittle crack propagation stopping characteristics) that can stop the crack growth as described above.

For example, Patent Documents 1 and 2 disclose welded structures relating to brittle crack propagation arresting properties.

JP, 2007-326147, A Patent No. 5365761

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

In addition to the above example, a crack may be generated from the upper deck and propagated toward the hatchside combing side. Then, according to the results of the verification test carried out in the joint research between the Japan Maritime Association and the Japan Welding Association, in order to stop the propagation of cracks that occur in the upper deck and propagate toward the hatchside combing side, It has been found that it is necessary to use a thick steel plate having an extremely high Kca value of 8,000 N/mm ^1.5 or more.

However, there is a problem that it is difficult from a technical and cost standpoint to stably manufacture a thick steel plate having such a high brittle crack propagation arresting property. Therefore, it is necessary to obtain a welded structure having excellent brittle crack propagation arresting properties at low cost by a more rational method.

The present invention has been made to solve such a problem, and an object thereof is to provide a welded structure having excellent brittle crack propagation arresting properties.

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

(1) Welding having a T-joint portion in which the joining member is partially welded to both sides of the joining member while the end face of the joining member is in contact with the joining surface of the joining member having the plate shape A structure,
The joining member has a first surface and a second surface perpendicular to the plate thickness direction of the joining member,
The plate thickness t (mm) of the joining member satisfies the following formula (i),
A distance in the plate thickness direction of the joining member between the highest point of the first heat-affected zone of the first welded portion formed on the first surface side and the first surface is a distance h ₁ (mm), and the second When the distance in the plate thickness direction of the joining member between the highest point of the second heat-affected zone of the second welded portion formed on the surface side and the second surface is a distance h ₂ (mm),
An NRL drop using a type P3 test piece defined in ASTM E208, which was taken from each of the first surface and the second surface of the joining member at a depth of 1 mm and whose thickness direction coincides with the plate thickness direction. A non-ductile transition temperature by a heavy test is −60° C. or lower and satisfies the following formulas (ii) and (iii),
Welded structure.
t≧50.0 (i)
NDTT ₁ ≦−30.5×ln(h ₁ )−14.0 (ii)
NDTT ₂ ≦−30.5×ln(h ₂ )−14.0 (iii)
However, NDTT ₁ and NDTT ₂ are the non-ductile transition temperature (° C.) measured by the NRL drop weight test using the type P3 test piece defined in ASTM E208, which is sampled from the 1 mm depth positions of the first surface and the second surface, respectively. ).

(2) The plate thickness t (mm) of the joining member, the distance h ₁ (mm) and the distance h ₂ (mm) satisfy the following equations (iv) and (v),
The welded structure according to (1) above.
h ₁ ≦t/4 (iv)
h ₂ ≦t/4 (v)

(3) In a cross section perpendicular to the first surface and the surface to be joined,
An acute angle α ₁ (°) formed by a line passing through a toe and a route on the side of the joining member and the surface to be joined in the first weld portion, and partial penetration d ₁ (mm) of the joint in the plate thickness direction. And a distance s ₁ (mm) between the toe on the member-to-be-joined side and the first surface, and a line passing through the toe and route on the member-to-be-joined side in the second weld and the surface to be joined. The acute angle α ₂ (°) formed by and the partial penetration d ₂ (mm) of the joint in the plate thickness direction and the distance s ₂ (mm) between the toe on the joined member side and the second surface are as follows. Satisfies the expressions (vi) to (xi),
The welded structure according to (1) or (2) above.
45.0≦α ₁ ≦70.0 (vi)
45.0≦α ₂ ≦70.0 (vii)
d ₁ ·sec (α ₁ )·cos (α ₁ / ₂ ) ≧0.35t ··· (viii)
d ₂ ·sec(α ₂ )·cos(α ₂ /2)≧0.35t (ix)
s ₁ ≧d ₁ (sec(α ₁ )−1) (x)
s ₂ ≧d ₂ (sec(α ₂ )-1) (xi)

(4) The plate thickness t (mm) of the joining member satisfies the following formula (xii),
The welded structure according to any one of (1) to (3) above.
t>80.0 (xii)

(5) The yield stress of the joining member is 400 to 580 MPa, and the tensile strength is 510 to 750 MPa.
The welded structure according to any one of (1) to (4) above.

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

It is a perspective view showing a welding structure concerning one embodiment of the present invention. It is a perspective view which shows the welding structure which concerns on other embodiment of this invention. It is a perspective view which shows the welding structure which concerns on other embodiment of this invention. It is sectional drawing of a welded structure. It is a figure for demonstrating the shape of a structural model arrest test body.

As a result of the inventors' investigations to solve the above problems, the following findings have been obtained.

As described above, in order to improve the brittle crack propagation arresting property over the entire thickness of the member used for the welded structure, for example, it is necessary to use a thick steel plate having a Kca value of 8000 N/mm ^1.5 or more. ..

However, for example, in the case where a crack propagates from the upper deck toward the hatchside combing side, the structure is such that the crack entry area is limited to only the surface layer area of the thick steel plate used for hatchside combing. If it is possible to improve the brittle crack propagation stopping property in the surface layer region of the thick steel plate, it becomes possible to stop the crack growth. As a result, it becomes possible to improve the brittle crack propagation arresting property of the entire welded structure at low cost.

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

1. Configuration of Welding Structure FIG. 1 is a perspective view showing a welding structure according to an embodiment of the present invention. The welded structure 10 according to the present embodiment includes a joining member 11 and a joined member 12. The joining member 11 is plate-shaped and has a first surface 11a and a second surface 11b that are perpendicular to the plate thickness direction. The member 12 to be joined is plate-shaped, and has a face 12a to be joined with which the end surface 11c of the joining member 11 abuts.

Then, as shown in FIG. 1, the welded structure 10 has a T joint portion in which the joining member 11 is partially welded to both sides of the joined member 12 in a state where the end surface 11c is in contact with the joined surface 12a. .. In addition to the T-shaped structure as shown in FIG. 1, the above-mentioned welded structure having the T-joint portion includes, for example, structures having the shapes shown in FIGS. 2 and 3.

Further, the joining member 11 and the joined member 12 may be joined by fillet welding, but from the viewpoint of joining strength, the joining member 11 is provided with a groove and is joined by groove welding. Is preferred.

In the present invention, a thick joining member is targeted, and specifically, when the plate thickness of the joining member 11 is t (mm), the following formula (i) is satisfied. The plate thickness t (mm) of the joining member 11 preferably satisfies the following formula (xii). The upper limit of t need not be specified in particular, but can be set to 200 mm, 150 mm, or 120 mm, for example.
t≧50.0 (i)
t>80.0 (xii)

The plate thickness of the members to be joined is not particularly limited, but like the joined members, it is preferably 50.0 mm or more, and more preferably more than 80.0 mm.

Further, as shown in FIG. 1, the welded structure 10 has a first welded portion 13a formed on the first surface 11a side and a second welded portion 13b formed on the second surface 11b side.

The vicinity of the joint between the joint member 11 and the jointed member 12 will be described in more detail with reference to FIG. FIG. 4 is a cross-sectional view of the welded structure 10 perpendicular to the first surface 11a and the surface 12a to be joined. In FIG. 4, hatching is not added in order to avoid making the drawing complicated.

As shown in FIGS. 1 and 4, a first weld metal 14a is formed on the first surface 11a side of the joining portion of the joining member 11 and the joined member 12. A first heat-affected zone 15a is formed at the boundary between the first weld metal 14a and the joining member 11 and the joined member 12. Similarly, the second weld metal 14b is formed on the second surface 11b side, and the second heat-affected zone 15b is formed at the boundary between the second weld metal 14b and the joining member 11 and the joined member 12. Has been formed.

In the present specification, the welded portion means a portion in which the weld metal and the heat affected zone are combined. That is, the area where the first weld metal 14a and the first heat-affected zone 15a are combined is the first weld zone 13a, and the area where the second weld metal 14b and the second heat-affected zone 15b are combined is the second weld zone. 13b.

Here, in order to limit the penetration region of the crack generated from the member to be joined 12 and propagating to the joining member 11 to only the surface layer side of the joining member 11, the highest peak of the first welding portion 13a from the first surface 11a. And the depth from the second surface 11b to the apex of the second weld 13b need to be controlled.

Specifically, the distance h ₁ (mm) in the plate thickness direction of the joining member 11 between the highest point of the first heat-affected zone 15a of the first welded portion 13a and the first surface 11a and the second distance of the second welded portion 13b. It is preferable that the distance h ₂ (mm) in the plate thickness direction between the highest point of the heat-affected zone 15b and the second surface 11b satisfies the following equations (iv) and (v).
h ₁ ≦t/4 (iv)
h ₂ ≦t/4 (v)

The lower limits of the distance h ₁ and the distance h ₂ need not be particularly limited, but even when the joining member 11 and the joined member 12 are joined by fillet welding, thermal influence is exerted up to a depth of about 1 mm. Parts are formed. Therefore, 1 mm is the practical lower limit of the distance h ₁ and the distance h ₂ .

The highest point of the first heat-affected zone 15a means the tip in the plate thickness direction of the first heat-affected zone 15a, and similarly, the highest point of the second heat-affected zone 15b means the second heat-affected zone 15b. Means the tip in the plate thickness direction. Further, as shown in FIG. 4, the distance h ₁ is a distance between the first surface 11a and a virtual surface 11d that is parallel to the first surface 11a and passes through the tip of the first heat-affected zone 15a in the plate thickness direction. And the distance h ₂ is a distance between the second surface 11b and a virtual surface 11e that is parallel to the second surface 11b and passes through the tip of the second heat-affected zone 15b in the plate thickness direction.

In addition, in the first welded portion 13a, the acute angle α ₁ (°) formed by the line L ₁ passing through the toe and the route on the joining member 11 side and the route and the joined surface 12a, and the second welding portion 13b on the joining member 11 side. It is preferable that the acute angle α ₂ (°) formed by the line L ₂ passing through the toe and the route and the joined surface 12 a satisfy the following equations (vi) and (vii), respectively.
45.0≦α ₁ ≦70.0 (vi)
45.0≦α ₂ ≦70.0 (vii)

The toe on the joining member 11 side in the first welded portion 13a means the intersection A ₁ between the outer edge of the first weld metal 14a and the first surface 11a. In addition, the route on the joining member 11 side in the first welded portion 13a means the intersection B ₁ between the outer edge of the first welded metal 14a and the end surface 11c. Similarly, the bonding member 11 side of the toe at the second weld portion 13b, means an intersection _{A 2} between the outer edge and the second surface 11b of the second weld metal 14b, the bonding member 11 side in the second welding portion 13b Means the intersection B ₂ between the outer edge of the second weld metal 14b and the end surface 11c.

Further, the partial penetration d ₁ (mm) of the joint in the plate thickness direction of the first welded portion 13a and the partial penetration d ₂ (mm) of the joint in the plate thickness direction of the second welded portion 13b are respectively the following (viii). It is preferable to satisfy the formula and the formula (ix). Here, the values calculated on the left side of the following formulas (viii) and (ix) represent effective throat thicknesses Td ₁ (mm) and Td ₂ (mm), respectively.
d ₁ ·sec (α ₁ )·cos (α ₁ / ₂ ) ≧0.35t ··· (viii)
d ₂ ·sec(α ₂ )·cos(α ₂ /2)≧0.35t (ix)

The partial penetration d ₁ of the joint is a virtual surface that passes through the first surface 11a and the end on the plate thickness center side of the first weld metal 14a parallel to the first surface 11a and in the plate thickness direction of the joining member 11. It is the distance from 11f. Further, the partial penetration d ₂ of the joint is an imaginary line that passes through the second surface 11b and the end portion of the second weld metal 14b in the plate thickness direction of the joining member 11 on the plate thickness center side in parallel with the second surface 11b. This is the distance from the flat surface 11g.

Further, in the plate thickness direction of the first welded portion 13a, the distance s ₁ (mm) between the toe on the joined member 12 side and the first surface 11a and the toe on the joined member 12 side in the second welded portion 13b. It is preferable that the distance s ₂ (mm) between the second surface 11b and the second surface 11b satisfies the following expressions (x) and (xi), respectively.
s ₁ ≧d ₁ (sec(α ₁ )−1) (x)
s ₂ ≧d ₂ (sec(α ₂ )-1) (xi)

The distance s ₁ and the distance s ₂ are the weld leg lengths in the plate thickness direction of the first welded portion 13a and the second welded portion 13b, respectively. Specifically, the distance s ₁ is an imaginary line passing through the first surface 11a and an end portion that is parallel to the first surface 11a and that is opposite to the plate thickness center of the first weld metal 14a in the plate thickness direction of the joining member 11. This is the distance from the target surface 11h. In addition, the distance s ₂ is a virtual surface that passes through the second surface 11b and an end portion that is parallel to the second surface 11b and that is opposite to the plate thickness center of the second weld metal 14b in the plate thickness direction of the joining member 11. It is the distance from 11i.

The boundaries between the first weld metal 14a and the second weld metal 14b and the joining member 11 can be easily visually identified. Also, the tip positions of the first heat-affected zone 15a and the second heat-affected zone 15b can be easily determined by exposing them by nital corrosion.

Even if the above equations (vi) to (xi) are not satisfied, the brittle crack propagation arresting property can be improved, but from the viewpoint of ensuring higher joint strength, the above (vi) to ( It is preferable that the formula (xi) is satisfied.

2. Non-ductile transition temperature of the joining member As described above, in order to improve the brittle crack propagation arresting property over the entire thickness of the joining member, for example, a steel sheet having a Kca value of 8000 N/mm ^1.5 or more is used as the joining member. However, there is a problem that it is difficult to secure a steel sheet having such characteristics. However, by improving the brittle crack propagation stopping property at least in the surface layer portion of the joining member according to the depth of the region into which the crack penetrates, it becomes possible to stop the propagation of the crack.

That is, it becomes possible to stop the crack growth by controlling the non-ductile transition temperature in the surface layer of the joint member according to the depth from the surface to the highest point of the weld. Specifically, as the depth from the surface to the apex of the weld is larger, cracks are more likely to grow, so it is necessary to lower the non-ductile transition temperature in the surface layer.

Therefore, the non-ductile transition temperature by the NRL drop weight test using the type P3 test piece specified in ASTM E208, which is sampled from the 1 mm depth positions of the first surface 11a and the second surface 11b, is set to −60° C. or less. And it is necessary to satisfy the following expressions (ii) and (iii).
NDTT ₁ ≦−30.5×ln(h ₁ )−14.0 (ii)
NDTT ₂ ≦−30.5×ln(h ₂ )−14.0 (iii)
However, NDTT ₁ and NDTT ₂ are non-ductile transition temperatures (° C.) according to the NRL drop weight test using the type P3 test piece collected from the 1 mm depth positions of the first surface 11a and the second surface 11b, respectively.

The method for measuring NDTT ₁ and NDTT ₂ will be described in detail. First, a type P3 test piece specified in ASTM E208 is taken from each of the first surface 11a side and the second surface 11b side. The type P3 test piece is a test piece having a length of 130 mm, a width of 50 mm and a thickness of 16 mm. At this time, each of the first surface 11a and the second surface 11b is shaved by 1 mm, and then the test piece is sampled so that the thickness direction thereof matches the plate thickness direction of the bonding member 11. That is, the test piece is sampled from the region from the 1 mm depth position to the 17 mm depth position of the first surface 11a and the second surface 11b.

Also, as will be described later, the test is conducted so that cracks occur on the surface perpendicular to the longitudinal direction of the test piece. In the welded structure, a crack is generated on a surface perpendicular to the extending direction of the first welded portion 13a and the second welded portion 13b. Therefore, the test piece is sampled so that its longitudinal direction coincides with the extending direction of the welded portion of the welded structure.

After that, using the above test piece, NRL drop weight test based on ASTM E208 is carried out. Specifically, first, a weld bead extending in a direction parallel to the longitudinal direction of the test piece is formed on the surface of the surface of the joining member which is perpendicular to the thickness direction of the test piece. At that time, as the welding material, a welding material with low toughness specified in ASTM E208 is used. The length of the weld bead is adjusted to 60 to 70 mm and the width is adjusted to 12 to 16 mm. Then, a cutout parallel to the width direction of the test piece is formed on the weld bead. At this time, the width of the notch is 1.5 mm or less, and the distance between the groove bottom of the notch and the test piece is adjusted to be in the range of 1.8 to 2.0 mm.

Then, the surface of the test piece on which the weld bead is formed faces downward, and after supporting both ends in the longitudinal direction, the surface opposite to the side on which the weld bead is formed is subjected to impact bending load due to falling weight. Add. After that, Break (with crack propagation) or No Break (without crack propagation) is determined by investigating the state in which the brittle crack generated from the notch propagates to the test piece. When the brittle crack generated from the notch propagates on the surface of the test piece in the width direction of the test piece and propagates to the end thereof, the test result is determined to be Break (with crack propagation). If the crack does not reach the widthwise end, the test result is judged as No Break (no crack propagation).

In the drop weight test described above, two test pieces are used, for example, starting from a condition of −100° C. and changing the test temperature at 5° C. intervals (in the case of No Break, decrease by 5° C., Break In the case of 5°C increase), the temperature that is 5°C lower than the lowest test temperature at which No Break was obtained for both two test pieces is the non-ductile transition temperature.

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

4. Manufacturing method of welded structure The manufacturing method of the welded structure is not particularly limited, but, for example, a step of selecting a joining member whose non-ductile transition temperature of the surface layer portion satisfies the above-mentioned conditions, and It is possible to manufacture by performing the process of welding to the joining member.

In the welding process, it can be manufactured by welding along the end face of the joined member, with the end face of the joined member abutting against the joined face of the joined member. At this time, it is desirable that the joining member side of the joining member be groove processed. The groove processing may be performed over the entire end surface of the joining member, or may be performed only at a joining portion with the joined member.

The welding method is also not particularly limited, and a known method such as CO ₂ welding or covered arc welding (SMAW) may be adopted. At this time, in order to reduce the width of the heat-affected zone (the length represented by (h ₁ -d ₁ ) and (h ₂ -d ₂ ) in FIG. 4), the heat input amount is 0.5 to 3. It is preferably 0 kJ/mm.

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

After preparing various steel plates having the plate thicknesses shown in Table 1, for each steel plate, the non-ductile transition temperature in the surface layer portion of the one surface (first surface) and the other surface (second surface) was investigated. .. Specifically, after the first surface and the second surface were each shaved off by 1 mm, the thickness direction of the test piece coincided with the plate thickness direction of the steel plate and the longitudinal direction of the test piece was welded from each surface. The type P3 test piece specified in ASTM E208 was sampled so as to match the stretching direction of the part. Then, using the test piece, an NRL drop weight test according to ASTM E208 was carried out, and non-ductile transition temperatures NDTT ₁ (°C) and NDTT ₂ (°C) were obtained.

Next, the No. 4 tensile test piece described in JIS Z 2241 was sampled in a direction perpendicular to the rolling direction from the 1/4 position of the thickness of each steel plate, and a tensile test was performed in accordance with JIS Z 2241 to yield stress. (YS), tensile strength (TS) and total elongation (EL) were measured. The results are also shown in Table 1.

After that, the above various steel plates were used as test plates (bonding members 11), and the structural model arrest test body shown in FIG. 5 was produced and tested. A welded joint obtained by joining a steel plate having a plate thickness of 100 mm by CO ₂ welding was used as a run-up welded joint (member to be joined 12), and a welded structure 10 was produced by CO ₂ welding or covered arc welding (SMAW) under the conditions shown in Table 2. ..

After that, the notch 16b was introduced into the fusion line portion 16a of the welded structure 10. Then, the welded structure 10 is cooled to a ship design temperature of −10° C., a test stress of 257 MPa corresponding to the design stress of EH40 is applied, and only the vicinity of the notch is rapidly cooled to about −50° C. An impact was applied through the wedge to generate and propagate a brittle crack.

Using the structural model arrest test body after the test, at one side (first surface side) and the other side (second side) of the joining member and the joined member at a position 250 mm left and right from the center position in the longitudinal direction of the test body. The cross section of the welded portion (first welded portion and second welded portion) on the front side) was cut out. After that, the metal was polished and subjected to nital corrosion to expose a weld metal portion and a weld heat affected zone (area heated to Ac ₁ transformation point or higher during welding). A photograph of the cross section of the welded joint at these two locations was taken with a digital camera, the shape of the welded portion was measured from the photographed image, and the average value of the measurement results at the two locations was used.

The measured shape of the weld is also shown in Table 2, and the results of the test using the above structural model arrest specimen are shown in Table 3. When the brittle crack stopped at the test plate, it was judged as stopped, and when the test plate was broken, it was judged as broken.

As is clear from Table 3, when a joining member satisfying the requirements of the present invention was used, excellent brittle crack propagation arresting characteristics were obtained, whereas comparative examples not satisfying the requirements of the present invention were obtained. When the joining member of No. 2 was used, brittle cracks propagated to the joining member.

Also, test No. In Nos. 1, 2, 4 and 5, since the formulas (vi) to (xi) were further satisfied, the joint strength was high and the result was even better.

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

10 Welding Structure 11 Joining Member

11a First Surface

11b Second Surface

11c End Face 11d-i Virtual Surface 12 Joined Member 12a Joined Surface 13a First Welding Part 13b Second Welding Part 14a First Welding Metal 14b Second Welding metal 15a First heat-affected zone 15b Second heat-affected zone 16a Fusion line section 16b Notch

Claims

A welding structure having a T-joint part in which the joining member is partially welded to both sides of the joined member while the end face of the joined member is in contact with the joined surface of the joined member. There
The joining member has a first surface and a second surface perpendicular to the plate thickness direction of the joining member,
The plate thickness t (mm) of the joining member satisfies the following formula (i),
A distance in the plate thickness direction of the joining member between the highest point of the first heat-affected zone of the first welded portion formed on the first surface side and the first surface is a distance h 1 (mm), and the second When the distance in the plate thickness direction of the joining member between the highest point of the second heat-affected zone of the second welded portion formed on the surface side and the second surface is a distance h 2 (mm),
An NRL drop using a type P3 test piece defined in ASTM E208, which is taken from the 1 mm depth position of the first surface and the second surface of the joining member, and the thickness direction thereof coincides with the plate thickness direction. A non-ductile transition temperature by a heavy test is −60° C. or lower and satisfies the following formulas (ii) and (iii),
Welded structure.
t≧50.0 (i)
NDTT 1 ≦−30.5×ln(h 1 )−14.0 (ii)
NDTT 2 ≦−30.5×ln(h 2 )−14.0 (iii)
However, NDTT 1 and NDTT 2 are the non-ductile transition temperature (° C.) measured by the NRL drop weight test using the type P3 test piece defined in ASTM E208, which is sampled from the 1 mm depth positions of the first surface and the second surface, respectively. ).
The plate thickness t (mm) of the joining member, the distance h 1 (mm) and the distance h 2 (mm) satisfy the following equations (iv) and (v),
The welded structure according to claim 1.
h 1 ≦t/4 (iv)
h 2 ≦t/4 (v)
In a cross section perpendicular to the first surface and the surface to be joined,
An acute angle α 1 (°) formed by a line passing through a toe and a route on the side of the joining member and the surface to be joined in the first weld portion, and partial penetration d 1 (mm) of the joint in the plate thickness direction. And a distance s 1 (mm) between the toe on the member-to-be-joined side and the first surface, and a line passing through the toe and route on the member-to-be-joined side in the second weld and the surface to be joined. The acute angle α 2 (°) formed by and the partial penetration d 2 (mm) of the joint in the plate thickness direction and the distance s 2 (mm) between the toe on the joined member side and the second surface are as follows. Satisfies the expressions (vi) to (xi),
The welded structure according to claim 1 or 2.
45.0≦α 1 ≦70.0 (vi)
45.0≦α 2 ≦70.0 (vii)
d 1 ·sec (α 1 )·cos (α 1 / 2 ) ≧0.35t ··· (viii)
d 2 ·sec(α 2 )·cos(α 2 /2)≧0.35t (ix)
s 1 ≧d 1 (sec(α 1 )−1) (x)
s 2 ≧d 2 (sec(α 2 )-1) (xi)
The plate thickness t (mm) of the joining member satisfies the following formula (xii),
The welded structure according to any one of claims 1 to 3.
t>80.0 (xii)
The yield stress of the joining member is 400 to 580 MPa, and the tensile strength is 510 to 750 MPa.
The welded structure according to any one of claims 1 to 4.