TW201636146A - Butt weld structure and butt welding method for extra thick steel plate - Google Patents

Abstract

The present invention provides a butt weld structure and butt welding method, which can butt-weld an extra thick steel plate having a thickness greater than 70 mm, ensure tensile strength of butt welding joint, inhibit or prevent the toughness of the joint from reducing, and need less number of welding path, so that the butt welding can be finished in a shorter time. In a cross section of such structure orthogonal to the butting portion of a first extra thick steel plate with a second extra thick steel plate is provided with: a plurality of butt welding joints 4, and each of them is separated by an offset amount L to prevent the heat effect among each other; and one or more boundary surface 6, connecting the adjacent butt welding joint 4, and extending in parallel with a front surface of a rear surface. Each butt welding joint has an allowable thickness T for maintaining the joint's performance during butt welding.

Description

Counter-welding structure of extremely thick steel plate and method of welding head joint

The present invention relates to a butt-welding structure and a butt welding method for an extremely thick steel plate having a thickness of more than 70 mm.

The term "welding" refers to a fusion structure and a welding method in which materials having substantially the same thickness are welded in the same plane. The head welding system integrates the welded members, and transmits the stress directly through the welded portion. Further, the head welding is provided with a groove called a "groove" in a portion (welding portion) where the base material is to be welded, and then the weld metal is incorporated into the groove, and a part of the base material is also incorporated into the slope. Integrated in the mouth.

The head welding is disclosed in, for example, Non-Patent Document 1 and Patent Documents 1 to 5.

Non-Patent Document 1 discloses "two-electrode electrothermal gas arc welding method".

The "electrothermal gas fusion joint having good toughness" in Patent Document 1 discloses a fusion metal component of electric heating gas welding.

Patent Document 2, "Two-face welding method and apparatus for metal thick plates", moves the preceding consumable welding electrode group to the lower groove The back side is welded inside, and the subsequent consumable welding electrode group is moved into the upper groove to perform front side welding. The subsequent consumable welding electrode group is started slower than the preceding consumable welding electrode group, and is moved in the same direction while performing front side welding and back side welding.

In the method of forming a welded joint of Patent Document 3, when the single-slab thick members are welded to each other, a plurality of grooves are formed in the butted portions of the two sheets, and then welded at the groove of the two sheets, The thin plate member is disposed at the groove of the upper or upper portion and the lower portion, and the groove is formed at two places separated from each other between the thin plate member and the butted member to be welded.

In the "groove joint for fusion joints" of Patent Document 4, the first step portion corresponding to the difference in thickness of the two sheets is provided on the welded end portion of the thick plate side, and the root portion corresponding to the groove surface of the thin plate side is attached (root) The second step of the thickness of the face is equivalent to the thickness of the second step, so that the flat portion is formed at the bottom of the groove of the groove in a state where the two plates are butted.

In the "two-side welding method and the two-side welded structure" of Patent Document 5, the primary layer is welded to the bottom of the groove at the center portion of the thickness of the U-shaped groove joint of the both faces or near the center portion. (uranami welding), followed by surface-side lamination until it reaches the vicinity of the remaining groove depth, and then the back side layer is welded from the bottom of the groove of the U-shaped groove joint on the back side until the final layer in the upper part of the groove, and then The surface side layer is welded from the remaining groove portion on the front side until the final layer on the upper portion of the groove.

(previous technical literature) (Non-patent literature)

(Non-Patent Document 1) 5 people including Tochigi Sage, "Development of High Energy Rate 2 Electrode Electrothermal Gas Arc Welding Method", Nippon Steel Technical Report No. 380, 2004, P57 to 63

(Patent Literature)

(Patent Document 1) Japanese Patent Laid-Open Publication No. 2005-330578

(Patent Document 2) Japanese Patent Publication No. 9-262662

(Patent Document 3) Japanese Patent Laid-Open No. Hei 6-210487

(Patent Document 4) Japanese Patent Publication No. 9-206979

(Patent Document 5) Japanese Patent Laid-Open Publication No. 2009-61483

For example, hatch side coaming or upper deck, outer panel, vertical bulkhead, etc. of large container wheels have been used for YP390 grade steel plates with a thickness of 50 to 70 mm (the yield stress exceeds 390 MPa). Steel plate).

Hereinafter, a steel plate having a thickness of 50 to 70 mm is referred to as a "thick steel plate".

In the head welding of such a thick steel plate, a V-shaped groove or an X-shaped groove has been used in terms of the shape of the groove. For example, the V-shaped groove is used for downhand welding, or it is difficult to weld from the back side, and the X-shaped groove is used for welding from both sides.

For the welding means, a multi-layer welding of CO ₂ welding (automatic or semi-automatic) or an electrogas arc welding method is employed.

On the other hand, with the enlargement of ships, it is desirable to use higher strength YP460 grade steel plates (steel plates with yield stresses exceeding 460 MPa), for example, hatch edge coamings or upper decks, outer plates, longitudinal partitions, etc. of large container wheels. It is a steel plate having a thickness of more than 70 mm (hereinafter, such a steel plate is referred to as an "extremely thick steel plate").

In this case, the welding of the extremely thick steel plate is indispensable, but the conventional welding structure and the welding method have the following problems.

(1) The weld metal (melt) used in the joint portion becomes large, and the heat input due to the thickness becomes large, so that joint properties (for example, joint toughness) are lowered.

(2) It is difficult to take into consideration both the tensile strength and joint toughness of the joint portion.

(3) The welding method with a small amount of heat input (for example, CO ₂ welding), since each pass is repeatedly welded to a diameter of about 6 to 7 mm, the number of welding channels will increase, and the welding process will drag. very long.

For example, in the electrothermal gas arc welding of Non-Patent Document 1 and Patent Document 1, although there are YP390-grade steel sheets and the thickness is 70 mm, the number of welded metal (melt) used is large, and the heat is added due to the thickness. It becomes larger, so the joint toughness will decrease.

The present invention has been made to solve the above problems. That is, the object of the present invention is to provide a butt welding of an extremely thick steel plate having a thickness of more than 70 mm, and to ensure tensile strength to a joint of a head joint and to suppress or prevent joint toughness. (Toughness) is reduced, and the number of passes is small, and the splice-welding structure and the counter-welding method of the extremely thick steel plate to be welded can be completed in a short time.

According to the present invention, there is provided a counter-welding structure of an extremely thick steel plate, wherein a counter-welding structure of an extremely thick steel plate having a thickness of more than 70 mm is a cross section orthogonal to an abutting portion of the first extremely thick steel plate and the second extremely thick steel plate. Having a plurality of butt-welded joints offset by an offset amount that avoids mutual thermal influences, and one or more joints that extend adjacent to the surface or the back surface by joining adjacent butt-welded joints interface, And each pair of head fusion joints has an allowable thickness that can maintain the joint performance when the head is welded.

Each of the first thick steel plate and the second thick steel plate is a single extremely thick steel plate, and the first thick steel plate has a first front end portion having a thickness of the allowable thickness and a first front end a second stepped steel plate having a step corresponding to a step of the allowable thickness, and a second stepped steel plate having a second step portion having a step corresponding to a thickness of the first tip end portion and having an equivalent a second tip end portion of the thickness of the step of the first step portion, the counter head fusion joint having a front side welded portion obtained by welding the first tip end portion and the second step portion to each other from the front side, and a back side The first step portion and the second front end portion are welded to each other The back side weld is formed.

The first-thickness-thickness steel sheet and the second-thickness-thickness steel sheet have a thickness of three or more times the allowable thickness and a thickness of one or more of the step obtained by subtracting the thickness of the plate from the allowable thickness twice. (In this specification, the name refers to the thickness portion other than the front end portion and the step portion), and further includes: the opposite ends of the first and second thick steel plates and the second thick steel plate An auxiliary steel plate which is welded and has a thickness of one or more of the aforementioned allowable thicknesses.

Each of the first-thickness-thickness steel plate and the second-thickness-thickness steel plate is composed of a plurality of steel plates each having a thickness of the allowable thickness, and the counter-welded joint has a plurality of pairs of the plurality of steel plates which are respectively welded to each other. Welding joint.

The first extremely thick steel plate is a single extremely thick steel plate, The first ultra-thick steel plate has a first end portion having a thickness of the allowable thickness and a first step portion located at an end of the first end portion and having a step corresponding to the allowable thickness, and the second portion The extremely thick steel plate has two steel plates having a plate thickness of the allowable thickness, and the counter-welded joint has a front side welded portion obtained by welding the first front end portion and one of the two steel plates to each other from the front side, and The back side weld portion is formed by welding the first step portion and the other of the two steel plates to the back side.

The first extremely thick steel plate has the aforementioned allowable thickness The thickness of the plate is three or more times, and the thickness of the step is one or more of the step thickness obtained by subtracting the thickness of the plate from the allowable thickness, and the second thick steel plate further has a surface to be welded to each of the remaining portions. The steel sheet having a thickness of one or more of the aforementioned allowable thicknesses.

The minimum value of the offset amount is 40% or more, 50% or more, or a maximum of two plate thicknesses of the adjacent plate-to-head fusion joint.

According to the present invention, there is provided a method for welding a very thick steel plate, wherein the method of welding the extremely thick steel plate having a thickness of more than 70 mm is orthogonal to the abutting portion of the first extremely thick steel plate and the second extremely thick steel plate. Preparing: a plurality of abutting portions that are offset by an offset amount that can avoid mutual thermal influences, and one or more interfaces that connect the adjacent butting portions and extend in parallel with the front surface or the back surface, and then Each of the abutting portions is respectively welded to the head to form a plurality of butt-welded joints having an allowable thickness capable of maintaining the joint performance.

According to the above aspect of the invention, the plurality of butt welded joints are offset from the abutting portion of the first thick steel plate and the second extremely thick steel plate, and are offset by an offset amount that can avoid mutual heat influence. It is possible to avoid the thermal influence on the adjacent butt joints when the head is welded.

Further, each of the pair of head fusion joints has an allowable thickness that maintains the joint performance at the time of head welding, so that the tensile strength of the head welded joint can be ensured.

Therefore, a combination of a plurality of butt welded joints can be formed On the other hand, an extremely thick steel plate having a total thickness of more than 70 mm is welded to the head, and the tensile strength of each of the butt welded joints is ensured, and the joint toughness is suppressed or prevented from being lowered.

Further, as long as the tensile strength of the head fusion joint can be ensured, various welding means can be employed, and the amount of welding is also small, so that the number of welding channels can be reduced, and the welding can be completed in a shorter time.

1‧‧‧First thick steel plate

1a‧‧‧First front end

1b‧‧‧The first paragraph

1c, 1d‧‧‧ remaining thick

2‧‧‧Second thick steel plate

2a‧‧‧The second paragraph

2b‧‧‧second front end

2c, 2d‧‧‧ remaining thick

4‧‧‧Front joint

4a‧‧‧Side side weld

4b, 4c‧‧‧ Back side weld

5‧‧‧Auxiliary steel plate

6‧‧‧ interface

7‧‧‧ steel plate

E‧‧‧protrusion

F‧‧‧The Ministry of Thermal Impact

t, t1, t2, t3, t4, ta‧‧‧ plate thickness

L, La, Lb, Lc‧‧‧ offset

T‧‧‧allow thickness

Tb‧‧‧

Fig. 1 (A) to (C) are views showing a first embodiment of a head-welding structure of an extremely thick steel plate according to the present invention.

Fig. 2 (A) to (C) are views showing a second embodiment of the head-welding structure of the extremely thick steel plate according to the present invention.

Fig. 3 (A) and (B) are views showing a third embodiment of the head-welding structure of the extremely thick steel plate according to the present invention.

Fig. 4 (A) and (B) are views showing a fourth embodiment of the joint welding structure of the extremely thick steel plate according to the present invention.

Figure 5 is a schematic cross-sectional view of a single butt joint.

Fig. 6 is an explanatory diagram of the offset amount when two sheets are overlapped.

Fig. 7 (A) to (D) are explanatory diagrams of the amount of offset when the thickness is twice as large or when the two sheets overlap.

Fig. 8 (A) to (D) are explanatory diagrams of offset amounts when three times thick or three sheets overlap.

Fig. 9 (A) to (D) are explanatory diagrams of the offset amount when four times thick or four sheets overlap.

Hereinafter, preferred embodiments of the present invention will be described based on the drawings. The same portions in the respective drawings are denoted by the same reference numerals, and the repeated description is omitted.

Fig. 1 is a view showing a first embodiment of a head-welding structure of an extremely thick steel plate according to the present invention.

The head-welding structure of the present invention is a counter-welding structure of an extremely thick steel plate having a plate thickness of more than 70 mm.

In the following description, the upper side of the figure is the front side, and the lower side is the back side. Moreover, the upper side (front side) and the lower side (back side) may be reversed even if they are upside down. Further, the upper side (front side) and the lower side (back side) may be horizontal planes, vertical faces, or inclined faces.

Fig. 1 (A), (B), and (C) are cross-sectional views orthogonal to the abutting portions of the first extremely thick steel plate 1 and the second extremely thick steel plate 2. In this section, the head-welding structure of the present invention has a plurality of butt-welded joints 4 and more than one interface 6. The butt joint and the butt joint 4 extend in a direction perpendicular to the plane of the paper.

In the following description, the first extremely thick steel plate 1 and the second extremely thick steel plate 2 may be arranged in opposite directions. Further, although the first extremely thick steel plate 1 and the second extremely thick steel plate 2 are preferably flat plates, the interface 6 is preferably flat, but may be curved plates and curved surfaces, respectively. Further, although the butting portion and the counter-welding joint 4 are preferably straight, they may be curved.

The plurality of counter-welded joints 4 are offset from each other by an offset amount L that avoids mutual thermal influence. The so-called offset amount L refers to the two adjacent butt welded joints 4 except the molten metal portion. The shortest distance. In this figure, although the offset amount L is a distance parallel to the front surface or the back surface, it may be an oblique distance as long as it is the shortest distance.

The offset amount L is preferably at least the maximum value of the thickness of the two thick steel sheets which are stacked one on another. The details of the offset amount L will be described later.

More than one interface 6, which joins adjacent butt joints 4, extends parallel to the surface or back. The interface 6 is an interface between the flat plates or an interface between the curved panels, and the gap is preferably substantially zero.

The extremely thick steel plate (the first extremely thick steel plate 1 and the second extremely thick steel plate 2) which is the object of the present invention is preferably used for the hatch edge coaming of the large container wheel or the upper deck, the outer panel, the vertical partition wall, and the like. Therefore, the effect on the extremely thick steel plate is mainly tensile stress, and the tensile tension acts parallel to the interface 6. Therefore, the interfaces do not need to be welded to each other, but they may be welded or joined for the purpose of handling.

In the first drawings (A), (B), and (C), each of the pair of head fusion splices 4 has an allowable thickness T that maintains the joint performance when the head is welded. The allowable thickness T is, for example, 50 to 70 mm which is equivalent to a conventional thick steel plate.

Figure 5 is a schematic cross-sectional view of a single butt joint 4 .

As shown in Fig. 5, when the two steel sheets having the thickness t are welded to each other, the projections e which are raised from the surface are formed on the front and back surfaces of the pair of welded joints 4. The protrusions e are removed by cutting or grinding as needed.

Hereinafter, the so-called allowable thickness T means the opposite end after the protrusion e is removed. The thickness of the welded portion of the fusion bonded joint 4 (the length in the thickness direction). Therefore, the allowable thickness T is substantially the same as the sheet thickness t.

In Fig. 1(A), the first extremely thick steel plate 1 and the second extremely thick steel plate 2 are each a single extremely thick steel plate.

In this example, the first extremely thick steel plate 1 and the second extremely thick steel plate 2 have a plate thickness which is twice the allowable thickness T.

In Fig. 1(A), the first extremely thick steel plate 1 has a first tip end portion 1a having a plate thickness ta of a allowable thickness T, and a tip end portion located at the end of the first tip end portion 1a and having a step difference tb corresponding to the allowable thickness T. The first step difference portion 1b is formed.

The second extremely thick steel plate 2 is composed of a second step portion 2a having a step ta corresponding to the plate thickness ta of the first tip end portion 1a, and a second tip end portion having a thickness tb corresponding to the step difference tb of the first step portion 1b. 2b is composed.

The sheet thickness ta, tb may be the same or different as long as it is equal to or less than the allowable thickness T of the joint performance.

Similarly, the plate thicknesses t1 to t4 in the seventh to ninth drawings to be described later may be the same or different as long as they are equal to or less than the allowable thickness T.

The abutting portion of the first distal end portion 1a and the second step portion 2a and the abutting portion of the first step portion 1b and the second distal end portion 2b are respectively provided with a groove for welding the head. The shape of the groove is preferably V-shaped, but may be I-shaped, U-shaped, or X-shaped.

Since the X shape is not applicable in a state in which the plates are overlapped, it can be applied to welding of the first piece of Fig. 2(A) to be described later.

In Fig. 1(A), the head fusion joint 4 is a slave a front side welded portion 4a obtained by welding the first distal end portion 1a and the second stepped portion 2a to each other, and a back side welded portion obtained by welding the first stepped portion 1b and the second distal end portion 2b to each other from the back side. 4b.

Preferably, the head welding means is an electric gas arc welding, but as long as the tensile strength of the head fusion joint 4 can be ensured, other welding methods such as CO ₂ welding and shielded metal arc welding can be used. , submerged arc welding, etc.

According to the configuration of the first FIG. 1(A), two sheets of extremely thick steel plates having a thickness of twice the allowable thickness T can be used for the two opposite-welded joints 4 of the allowable thickness T (the first extremely thick steel plate 1 and the first The two-pole thick steel plate 2) is welded to the head, and the interval between the two butt-welded joints 4 can be set to an offset amount L which can avoid mutual heat influence.

In Fig. 1(B), the first extremely thick steel plate 1 and the second extremely thick steel plate 2 are each a single extremely thick steel plate.

In this example, the first extremely thick steel plate 1 and the second extremely thick steel plate 2 have a plate thickness which is three times the allowable thickness T.

In Fig. 1(B), the first extremely thick steel plate 1 has a thickness portion 1c in addition to the first tip end portion 1a and the first step portion 1b shown in Fig. 1(A), and the remaining thick portion 1 1c has a step difference obtained by subtracting the allowable thickness T from the plate thickness. Further, the second thick steel plate 2 has a thickness portion 2c in addition to the second step portion 2a and the second tip end portion 2b shown in Fig. 1(A), and the remaining thickness portion 2c has a thickness reduction. The step difference obtained by allowing the thickness T to be twice. The step (thickness) of the thick portion 1c and the thick portion 2c is the allowable thickness T.

In Fig. 1(B), the head welding structure of the present invention is more There is an auxiliary steel plate 5 whose both ends and the thick portions 1c, 2c are welded to each other and whose thickness is an allowable thickness T. In this example, the two butt welded joints 4 located on the back surface are the back side welded portions 4c obtained by welding the thick portions 1c, 2c and the both ends of the auxiliary steel plate 5 to the head from the back side.

According to the configuration of Fig. 1(B) described above, two extremely thick steel plates (first thick steel plates 1 and 1) having a plate thickness of three times the allowable thickness T can be used for the four butt welded joints 4 of the allowable thickness T. The two-pole thick steel plate 2) is welded to the head, and the interval between the adjacent ends of the four pairs of the welded joints 4 can be set to an offset amount L which can avoid mutual heat influence.

Fig. 1(C) shows a case where the thickness of the first extremely thick steel plate 1 and the second extremely thick steel plate 2 is four times or more the allowable thickness T.

In this case, in addition to the configuration of Fig. 1(B), the head-welding structure of the present invention further has an auxiliary steel plate 5 whose both ends and the thick portions 1d, 2d are welded to each other and whose thickness is the allowable thickness T.

The auxiliary steel plate 5 is not limited to one piece, and may be two or more pieces.

According to the configuration of the first FIG. 1(C), two sheets of extremely thick steel sheets having a thickness of three times or more of the allowable thickness T can be used for the plurality of counter-welded joints 4 of the allowable thickness T (the first extremely thick steel sheet 1 and The second extremely thick steel plate 2) is welded to the head, and the interval between the adjacent pairs of the first welded joints 4 can be set to an offset amount L which can avoid mutual heat influence.

The method of the present invention is a head welding method for an extremely thick steel plate having a thickness of more than 70 mm.

The method of the present invention is as shown in Figs. 1(A), (B), and (C), and is perpendicular to the cross section orthogonal to the abutting portions of the first extremely thick steel plate 1 and the second extremely thick steel plate 2. A plurality of abutting portions that are offset from each other by an offset amount L that can avoid mutual thermal influences, and one or more interfaces 6 that extend adjacent to the front surface or the back surface by connecting adjacent butting portions.

Then, each of the butting portions is respectively welded to the head to form a plurality of butt-welded joints 4 having an allowable thickness T capable of maintaining the joint performance.

Therefore, according to the configuration of the first drawings (A), (B), and (C) described above, even if the thickness of the first extremely thick steel plate 1 and the second extremely thick steel plate 2 is twice or more the allowable thickness T, The head welding is performed, and the tensile strength of each of the head fusion joints 4 is ensured, and the reduction in joint toughness is suppressed or prevented.

Fig. 2 is a view showing a second embodiment of the head-welding structure of the extremely thick steel plate according to the present invention.

In FIGS. 2(A), (B), and (C), the first extremely thick steel plate 1 and the second extremely thick steel plate 2 are each composed of a plurality of steel sheets 7 having a thickness of the allowable thickness T. Further, the head fusion joint 4 has a plurality of counter-welding portions formed by welding a plurality of steel sheets 7 to each other.

In Fig. 2(A), the first extremely thick steel plate 1 and the second extremely thick steel plate 2 are each composed of two steel sheets 7 having a plate thickness of an allowable plate thickness T.

In the example, the head fusion joint 4 is a front side welded portion 4a obtained by fusing the front ends of the two steel sheets 7 on the front side from the front side, and the front ends of the two steel sheets 7 on the back side are welded to each other from the back side. The back side welded portion 4b is formed.

The other configurations are the same as those of the first embodiment.

In Fig. 2(B), the first extremely thick steel plate 1 and the second extremely thick steel plate 2 are each composed of three steel sheets 7 having a plate thickness of an allowable plate thickness T.

In this example, the first extremely thick steel plate 1 and the second extremely thick steel plate 2 are provided with one steel plate 7 on the back side in addition to the two steel plates 7 described above.

In this example, the surface of the back side welded portion 4b is processed to be flush, and the two sheets of the steel sheet 7 are superposed thereon, and then the head is welded. The head fusion joint 4 is a back side welded portion 4c obtained by welding both ends of the additional steel sheet 7 to the back side from the back side.

As shown in FIG. 2(C), the first extremely thick steel plate 1 and the second extremely thick steel plate 2 can be formed by using four or more steel sheets 7 respectively.

According to the configuration of the second drawings (A), (B), and (C) described above, even if the thickness of the first-thickness-thickness steel plate 1 and the second-thickness-thickness steel plate 2 is twice or more the allowable thickness T, the head can be made. The welding is performed, and the tensile strength of each of the head welded joints 4 is ensured, and the decrease in joint toughness is suppressed or prevented.

Fig. 3 is a view showing a third embodiment of the head-welding structure of the extremely thick steel plate according to the present invention.

In Fig. 3(A), the first extremely thick steel plate 1 has a single extremely thick steel plate having a plate thickness of twice the thickness T.

The first thick steel plate 1 has a first tip end portion 1a having a plate thickness ta of a allowable thickness T, and a first step portion 1b located at the end of the first tip end portion 1a and having a step difference tb corresponding to the allowable thickness T. Further, the second extremely thick steel plate 2 has two steel sheets 7 having a thickness of the allowable thickness T.

The head fusion joint 4 has a front side welded portion 4a obtained by welding one of the first front end portion 1a and one of the two steel sheets 7 from the front side, and the other of the first stepped portion 1b and the two steel sheets 7 from the back side. The back side welded portion 4b is welded to the head.

The other configurations are the same as those in Fig. 1(A).

In Fig. 3(B), the first extremely thick steel plate 1 has a plate thickness of three times the allowable plate thickness T, and has a thick portion 1c having a plate thickness minus one of the allowable thicknesses T. The resulting step difference. Further, the second extremely thick steel plate 2 further has a sheet steel plate 7 which is welded to the first thick portion 1c and has a plate thickness of the allowable thickness T.

The other components are the same as those in Fig. 3(A).

Similarly, the first extremely thick steel plate 1 may be a single extremely thick steel plate having a plate thickness of four times or more of the allowable thickness T.

According to the configuration of the third drawing (A) and (B) described above, even if the thickness of the first extremely thick steel plate 1 is twice or more the allowable thickness T, the head welding can be performed, and the respective head fusion joints 4 can be secured. Tensile strength and inhibit or prevent a decrease in joint toughness.

Fig. 4 is a view showing a fourth embodiment of the head-welding structure of the extremely thick steel plate according to the present invention.

In Fig. 4(A), the first extremely thick steel plate 1 has a single extremely thick steel plate having a plate thickness of three times the thickness T. The second extremely thick steel plate 2 is composed of an extremely thick steel plate having a thickness of twice the allowable thickness T and a steel plate 7 having a thickness of T.

The other components are the same as those in Fig. 3(B).

In Fig. 4(B), the first extremely thick steel plate 1 is composed of an extremely thick steel plate having a plate thickness of twice the allowable thickness T and a steel plate 7 having a thickness of T.

The other components are the same as those in Fig. 3(B).

According to the configuration of the fourth embodiment (A) and (B) described above, even if the thickness of the first extremely thick steel sheet 1 is three times or more the allowable thickness T, the head welding can be performed, and the respective head fusion joints 4 can be secured. Tensile strength and inhibit or prevent a decrease in joint toughness.

Hereinafter, the offset amount L will be described.

Fig. 6 is an explanatory diagram of the offset amount L when two sheets are overlapped.

The offset amount L can be determined in consideration of the range of the heat-affected zone F in accordance with the welding method employed.

As a result of the butt welding test of a thick steel plate having a thickness of 50 mm or more, the range of the heat-affected portion F from the weld metal is 5 to 12 mm at the time of automatic heat-conduction of CO _{2 with} low heat input, and electric heat at high heat input Gas arc welding is 15 to 20 mm.

Therefore, in the case of a thick steel plate having a thickness of 50 mm or more, it may be affected by heat up to a maximum thickness of 40%.

Therefore, the minimum value of the offset amount L for avoiding the heat influence is preferably a sum of two plate thicknesses when the thickness of the two thick steel plates which are overlapped as shown in Fig. 6 is t1, t2. 40% or more of t1+t2), more preferably 50% or more, and most preferably the maximum value of the two plate thicknesses.

The maximum value of the offset amount L may be equal to or greater than the minimum value of the offset amount L. In addition, the maximum value of the offset amount L is preferably ten or less times the total thickness (t1 + t2) of the thickness of the two thick steel sheets from the viewpoint of facilitating the processing and handling of the extremely thick steel sheet.

From the above viewpoints, it is preferable that the offset amount L is set within a range satisfying at least the following formula (1).

Max(t1, t2) ≦ offset L≦10(t1+t2)...(1)

Fig. 7 is an explanatory diagram of the offset amount L when double thickness or two sheets overlap. In Fig. 7, (A) is twice thick plate and plate (both sides), (B) is combined with twice thick plate (single side), and (C) is two pieces overlapping (two sides), ( D) is an example of two overlapping (single-sided).

Hereinafter, the "double-thickness plate" refers to an extremely thick steel plate having a plate thickness of twice the allowable thickness T, and the "two-piece overlap" means a pole in which two steel plates having a thickness of the allowable thickness T are overlapped. Thick steel plate. In addition, the term "two-sided" means that the head is welded from both sides, and the "single-sided" means that the head is welded from one side.

In the example of Fig. 7, when the thickness of the two step portions or the two steel sheets is t1, t2, the offset amount La is preferably set within a range satisfying at least the following formula (2).

Max(t1,t2)≦ offset amount La≦10(t1+t2)...(2)

Fig. 8 is an explanatory diagram of the offset amount L when three times thick or three sheets overlap. In Fig. 8, (A) is a plate and a plate (two sides) three times thick, (B) is a combination of three times thick plates (one side), and (C) is three pieces overlapping (two sides), ( D) is an example of three overlapping (single-sided).

In the example of Fig. 8, when the thickness of the three step portions or the three steel sheets is t1, t2, and t3, the offset amount Lb is preferably set within a range satisfying at least the following formula (3). .

Max(t2, t3) ≦ offset Lb≦10(t2+t3)...(3)

Fig. 9 is an explanatory diagram of the offset amount L when four times thick or four sheets overlap. In Figure 9, (A) is a four-fold thick plate and plate (two sides), (B) In combination with a four-fold thick plate (single-sided), (C) is four-piece overlap (two sides), and (D) is an example of four-piece overlap (one-sided).

In the example of Fig. 9, when the thickness of the four step portions or the four steel sheets is t1, t2, t3, and t4, the offset amount Lc is set to satisfy at least the following formula (4). It is better.

Max(t3, t4)≦ offset Lc≦10(t3+t4)...(4)

According to the above invention, the following effects can be obtained.

(1) By offsetting the positions of the head-welded joints 4 on both surfaces of the extremely thick steel sheet by the offset amount L, the amount of the weld metal can be reduced, the construction efficiency can be improved, and the joint performance can be improved by reducing the heat input.

(2) If the YP460 grade steel exceeds 70 mm, it is difficult to ensure joint toughness by welding with a large heat input method (one-way electric arc welding). Therefore, CO ₂ multi-layer welding has been used in the past. However, according to the present invention, since the heat input amount is reduced, it is possible to perform one-channel electric hot gas arc welding on one side of a thicker steel plate. For example, a YP460 grade steel plate with a thickness of 80 to 100 mm can be achieved.

(3) Since the weight of the manufacturing or handling process in the iron factory or in the transportation or in the shipyard is limited, the plate size of the thick plate cannot be made large in the past. However, as shown in Fig. 2, by stacking two or more steel sheets to form an extremely thick steel sheet, the weight of each sheet can be reduced, and the sheet size can be made large. As a result, it can be lengthened in the length of the ship.

In particular, in shipyards or ironworks, it is often difficult to handle such heavy steel sheets of more than 20 tons per piece. On the other hand, in order to reduce the stage in the canal The number of assembly blocks has the expectation of reducing the plate thickness to increase the size of the plate. This is the opposite of the condition in which it is desirable to use a slab in terms of the performance of the ship.

Although the size of 2 m wide by 13 m long is the limit when the thickness of the plate is 100 mm under a limit of, for example, 20 tons, the length of the block can be 2 m wide when the double plate of 50 mm is used according to the present invention. 26m long size.

(4) By overlapping the two pieces, the hatch side coaming of the ultra-thick steel plate can be achieved. In the case of high-intensity heat fusion (electric arc welding with one channel on one side of a thick plate), a plate thickness of 130 mm to 140 mm can be achieved by overlapping two sheets of 65 mm to 70 mm.

Therefore, in the case of the CO ₂ multi-layer welding, a sheet having a thickness of about 100 mm is overlapped by two sheets, and the degree of 200 mm can be doubled.

According to the present invention described above, the plurality of counter-welded joints 4 are offset from each other in a cross section orthogonal to the abutting portions of the first extremely thick steel plate 1 and the second extremely thick steel plate 2, thereby avoiding the mutual thermal influence offset. Therefore, it is possible to avoid thermal influence on adjacent butting portions during welding.

Further, each of the pair of head fusion joints 4 has an allowable thickness T which can maintain the joint performance at the time of welding the head, so that the tensile strength of the head fusion joint 4 can be ensured.

Therefore, in the combination of the plurality of counter-welding joints 4, the extremely thick steel sheets having a total thickness of more than 70 mm can be welded to the head, and the tensile strength of each of the head-welded joints 4 can be ensured, and the prevention or prevention can be suppressed or prevented. Reduced joint toughness.

Further, as long as the tensile strength of the head fusion joint 4 can be ensured, various welding means can be employed and the amount of welding is small, so that the number of welding channels can be reduced, and the welding can be completed in a short time.

The present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the spirit and scope of the invention.

1‧‧‧First thick steel plate

1a‧‧‧First front end

1b‧‧‧The first paragraph

1c, 1d‧‧‧ remaining thick

2‧‧‧Second thick steel plate

2a‧‧‧The second paragraph

2b‧‧‧second front end

2c, 2d‧‧‧ remaining thick

4‧‧‧Front joint

4a‧‧‧Side side weld

4b, 4c‧‧‧ Back side weld

5‧‧‧Auxiliary steel plate

6‧‧‧ interface

Ta‧‧‧ plate thickness

L‧‧‧ offset

Tb‧‧‧

Claims (8)

A counter-welding structure of an extremely thick steel plate, the counter-welding structure of an extremely thick steel plate having a thickness of more than 70 mm, which is perpendicular to the abutting portion of the first extremely thick steel plate and the second extremely thick steel plate: a plurality of butt-welded joints offset by offset amounts of mutual thermal influences, and one or more interfaces connecting the adjacent butt-welded joints adjacent to each other and extending in parallel with the front surface or the back surface, and each pair of head welded joints is respectively It has an allowable thickness that maintains the performance of the joint when the head is welded. The first-thickness steel plate and the second-thickness steel plate are respectively a single extremely thick steel plate, and the first extremely thick steel plate is a counter-welding structure of the extremely thick steel plate according to the first aspect of the invention. a first end portion having a thickness of the allowable thickness and a first step portion located at a distal end of the first end portion and having a step corresponding to the allowable thickness, wherein the second thick steel plate has a comparable a second step portion having a thickness difference between the first front end portion and a second end portion having a thickness corresponding to a step of the first step portion, the counter-welding joint having the first front end from the front side a front side welded portion obtained by welding the head portion and the second step portion to the head, and a back side welded portion obtained by welding the first step portion and the second front end portion to each other from the back side. For example, the opposite welding structure of the extremely thick steel plate described in the second application of the patent scope The first extremely thick steel plate and the second ultra-thick steel plate have a plate thickness of three times or more of the allowable thickness and one or more steps of the plate thickness minus two times the allowable thickness. Further, the thick portion has an auxiliary steel plate in which both ends are welded to the first thick steel plate and the second thick steel plate, and the thickness is one or more of the allowable thickness. The first-thickness-thickness steel plate and the second-thickness steel plate are each composed of a plurality of steel plates each having a thickness of the allowable thickness, as described in the first aspect of the invention. The head fusion joint has a plurality of butt welds in which the plurality of steel sheets are respectively welded to each other. The first-thickness steel plate is a single extremely thick steel plate, and the first-thickness steel plate has a plate thickness having the allowable thickness, as described in the first aspect of the invention. a first end portion and a first step portion located at a distal end of the first end portion and having a step corresponding to the allowable thickness, wherein the second thick steel plate has two steel plates having a thickness of the allowable thickness, and the The head fusion joint has a front side obtained by welding the first front end portion and one of the two steel plates to the head from the front side. a welded portion and a back side welded portion obtained by welding the first step portion and the other of the two steel sheets to each other from the back side. The first-thickness steel plate has a plate thickness of three times or more of the allowable thickness, and has the plate thickness minus the allowable thickness, as described in the fifth aspect of the invention. The second thick steel plate further includes a steel plate having a thickness equal to one or more of the allowable thicknesses, and the second thick steel plate is welded to each of the remaining thick portions. The counter-welding structure of the extremely thick steel plate according to any one of claims 1 to 6, wherein the minimum value of the offset amount is 40% or more of the sum of the thicknesses of the adjacent butt welded joints. 50% or more, or more than the maximum of two plate thicknesses. The method for welding the extremely thick steel plate to the head, the method for welding the extremely thick steel plate having a thickness of more than 70 mm is prepared in a cross section perpendicular to the abutting portion of the first thick steel plate and the second extremely thick steel plate: a plurality of abutting portions offset from each other by offsetting the mutual thermal influence, and one or more interfaces connecting the adjacent butting portions and extending in parallel with the front surface or the back surface, and then respectively aligning the respective butting portions Fusion is performed to form a plurality of butt weld joints having an allowable thickness that maintains joint performance.