JPH09308975A - Manufacture of box type steel structural member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent low temperature cracking even in the high tensile steel by temporarily assembling two webs, two flanges and diaphragms into a box shape, performing the non-consumable nozzle type electroslag welding to the flanges and webs, and welding four corners formed of four side plates. SOLUTION: A diaphragm 3 is placed inside four steel side plates 1, 2 of 580-1050MPa in tensile strength and 30-120mm in thickness, and temporarily assembled into a box-shaped structure. Holes 5 are made in an outer flange 1 so as to be communicated with columnar grooves 7 for welding the diaphragm, and the non-consumable nozzle type electroslag welding is performed. Then, the structure is turned by 90 deg., holes 6 are made in the inner side webs 2, and the non-consumable nozzle type electroslag welding is performed. Corner joint manual welding 8 of four corners formed of side plates is performed. Because the corner welding of the side plates is not performed, the restriction force after the electroslag welding is small, and low temperature cracking is difficult to generate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a box-type steel structural material using a side plate having a tensile strength of 580 MPa or more and a plate thickness of 30 mm or more such as a box column of a skyscraper.

[0002]

2. Description of the Related Art A box type structural material has a structure in which a diaphragm is attached by welding inside four side steel plates having a square cross section with four corners welded, and various manufacturing methods have been proposed. For example, four side plates are assembled into a rectangular shape. At this time, a diaphragm having a columnar groove for welding is installed in advance. Then, after welding the four corners by submerged arc welding, etc., the side plates are perforated by electroslag welding so as to reach the columnar groove between the side plate and the diaphragm, further rotated by 90 degrees, and the remaining two sides are similarly electroplated. The method of slag welding is common.

On the other hand, in Japanese Examined Patent Publication No. 8-4948, after temporarily assembling into a box type structure, the diaphragm portion is electroslag welded first, and then four corners formed by four side plates are formed. A method of corner welding has been proposed. This prevents gap formation between the diaphragm and the side plate due to corner welding, and enables stable electroslag welding.

[0004]

On the other hand, in recent years, studies on high-strength steel for super high-rise buildings, super-span buildings, etc. have begun. Welding of high-strength steel is more likely to cause cracking, especially cold cracking, than low-strength steel. Since this cold cracking is governed by the restraint force during welding and the amount of diffusible hydrogen, the higher the strength and the thicker the plate, the easier it is to crack, and it is necessary to select a structure or welding procedure that reduces the restraint force. Measures for low-diffusivity hydrogenation of materials and pre-heating and post-heating are taken. Therefore, the present invention provides a method for manufacturing a box-type structural material that is free from cold cracking even in high-strength steel.

[0005]

The present invention is to solve the above-mentioned problems and has a tensile strength of 580 to 1050 MPa,
In the production of a box-type structural material having four steel plates having a plate thickness of 30 to 120 mm as side plates and having a diaphragm inside,
Of the side plates, two inner steel plates (webs), two outer steel plates (flange), and a diaphragm having welding columnar grooves on four sides are temporarily assembled in a box-type structure to form a flange. A non-consumable nozzle type electro-slag welding is performed by opening a hole leading to the columnar groove of the diaphragm, then the web is perforated and the columnar groove along the inner surface of the flange is non-consumable nozzle type electro-slag welding, and then four side plates. Is a method for manufacturing a box-type structural material of high-strength thick steel plate, which is characterized in that the four corners are welded.

Furthermore, the tensile strength is 580 to 1050M.
In the production of a box-type structural material having Pa and a plate thickness of 30 to 120 mm as side plates and having a diaphragm inside, three of the four side plates are U-shaped structures, and at least one side has at least one side. A diaphragm with a columnar groove for electroslag welding is incorporated, and three sides where the side plate and the diaphragm are in contact are welded by gas shield arc welding, submerged arc welding, coated arc welding, or non-consumable nozzle type electroslag welding, and then The remaining one side plate is attached and temporarily assembled in a box-type structure, the side plate is perforated to the columnar groove of the diaphragm, non-consumable nozzle electroslag welding is performed, and then four corners composed of four side plates. Is a box-type structural material for high-strength steel plates, which is characterized by performing corner welding.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the side plate has a tensile strength of 580 to 1050 MPa and a plate thickness of 30 to 120 mm. A steel material softer than a tensile strength of 580 MPa has a low restraining force and the effect of the present invention is small, so that it is set to 580 MPa or more. Further, even when the plate thickness is less than 30 mm, the binding force is low and the effect of the present invention is small. Since the extremely thick material exceeding 120 mm still requires preheating or post-heating, the thickness is set to 120 mm or less.

1A to 1F show an example of the manufacturing method of the present invention in the order of steps. FIG. 1 (c) shows a state in which the side plates are temporarily assembled. Normally, the two side plates located outside, which are called flanges 1, have no grooves at both ends, but may have grooves. Further, the two side plates located inside, which are usually called the web 2, usually have grooves at both ends, but those without grooves in combination with flanges can also be used. The diaphragm 3 is added to this,
Temporarily assemble into a box type. Temporary assembly is performed by intermittent welding of small beads that are intermittent or continuous. This welding is gas shielded arc welding or covered arc welding. Naturally, it is preferable to take measures against low temperature cracking such as preheating, postheating or selection of low diffusible hydrogen welding material corresponding to high strength steel.

The diaphragm 3 usually has a strength equal to or lower than that of the side plate, and most of the cracks occur in the side plate, so the strength is not specified. The plate thickness is also not specified because cracks occur in the side plates. The diaphragm is shown in FIG. It usually has ears 3a and is fitted with a dowel 4 for electroslag welding. However, when welding the diaphragm before temporarily assembling it in the box type, adopt a shape suitable for each welding.

As shown in FIG. 1 (c), the diaphragm is first installed in a predetermined position, temporarily assembled in a box shape, and the side plate (flange) 1 located on the outer side is connected to the columnar groove 7 for welding the diaphragm. Drill 5 and perform non-consumable nozzle type electroslag welding. Then, as shown in Fig. 1 (d), 90
After rotating, the side plate (web) 2 located inside is perforated 6 and non-consumable nozzle type electro-slack welding is performed. After that, as shown in FIGS. 1E and 1F, corner welding 8 is performed on the four corners of the side plate.

FIGS. 2A to 2F show another example of the manufacturing method of the present invention in the order of steps. As shown in FIG. 2 (c),
Three of the four side plates have a U-shaped structure, a diaphragm is incorporated, and three sides of the diaphragm are first welded 9. After that, as shown in FIG. 2D, the remaining one side plate 1 is incorporated into a box structure, and then a perforation 10 is formed through the columnar groove of the unwelded diaphragm to perform non-consumable nozzle electroslag welding. After that, the corner welding 8 is performed. In addition to a U-shaped structure with three side plates, a method of assembling the H-type with two side plates and welding the diaphragm, and then assembling the remaining two side plates, or a diaphragm after being assembled into the U-type Two sides can be welded.

The method of preliminarily welding the diaphragm is in a released state without a side plate in one direction, and any of gas shielded arc welding, submerged arc welding, coated arc welding, and non-consumable nozzle type electroslag welding can be applied. It is also possible to combine these welding methods. The corner welding is submerged arc welding or gas zirud arc welding, which is one-pass or multi-pass welding. At this time, the groove shape is prepared in advance for the part disturbed by the non-consumable nozzle type electroslag welding in the previous step.

Compared with the conventional method of welding the corners of the four side plates and then welding the diaphragm, the manufacturing method of the present invention provides stable electroslag welding as disclosed in Japanese Patent Publication No. 8-4948. It will be possible. Furthermore, since the side plates are not angle-welded, the restraining force at the time of electroslag welding is reduced, and cold cracking is less likely to occur.

In addition to this, the amount of diffusible hydrogen can be reduced by specifying electroslag welding as non-consumable nozzle type electroslag welding. In combination with this, cold cracking can be prevented even when welding high-tensile thick plates. it can. That is, electroslag welding includes consumable nozzle type electroslag welding and non-consumable nozzle type electroslag welding. Consumable nozzle electroslag welding uses water glass to coat the nozzle with a flux similar to a coated arc welding rod. This melts as welding progresses. Therefore, the water contained in the coating flux is absorbed by the weld metal, and the amount of diffusible hydrogen increases. On the other hand, non-consumable nozzle type electroslag welding is a method in which the nozzle rises and withdraws as the welding progresses, and only the wire melts and welds.Flux is usually added at the start of welding and a small amount is added at abnormal times. You can weld just by doing. In addition, this flux can be used in a form without using water glass and having a very small water content. Therefore, the amount of diffusible hydrogen in the non-consumable nozzle type electroslag welding can be markedly lower than that in the consumable nozzle type electroslag welding.

It should be noted that the present invention may be used in combination with preheating, postheating, heat retention, or a soft joint technique for lowering the strength of the weld metal, which is usually used for welding high-strength steel.

[0016]

The present invention will be described in detail with reference to the following examples. In Example 1, the side plate is HT580 (tensile strength 620 MPa).
No. 110 mm material, and the diaphragm was manufactured using the SM490 (tensile strength 530 MPa) 50 mm material by the process described in FIG.

First, as shown in FIG. 1 (a), groove processing was performed on both ends of two side plates, and electroslag welding metal plates 4 were attached to the diaphragm 3 as shown in FIG. 1 (b). This was temporarily assembled in a box-type structure as shown in FIG. The temporary welding was carbon dioxide welding with a target heat input of 17 kJ / cm.

Next, as shown in FIG. 1C, the flange 1 is drilled 5 so as to communicate with the columnar space 7 for electroslag welding between the diaphragm 3 and the web 2,
Non-consumable nozzle electroslag welding was applied to this. Flux is MnO for non-consumable nozzle type electroslag welding.
The melt flux for -SiO ₂ system, wire diameter 1.6
Using a 500 MPa class of mm, current 380A,
The voltage was 48 V, the wire feeding speed was 8.5 m / min, and the nozzle oscillation was 35 mm wide. At this time, a metal was placed at the intersection of the consumable nozzle electroslag welding and the corner joint groove to prevent molten steel from flowing out. Next, rotate the box-shaped structure 90 degrees as shown in FIG.
Next, the web 2 was perforated 6 and then non-consumable nozzle type electroslag welding was performed.

Next, after repairing the groove for the angular welding disturbed by the non-consumable nozzle type electroslag welding, the corner joint welding 8 is performed by the submerged arc welding as shown in FIG. 1 (e).
did. Further, this was rotated 180 degrees, and corner joint welding 8 was carried out in the same manner as shown in FIG. 1 (f). In the corner joint submerged arc welding, multi-layer welding of 6 passes with 2 electrodes was performed by using a firing type flux and a 600 MPa class wire having a diameter of 4.8 mm and 6.4 mm. Preheating was 50 ° C. After being manufactured in this way, the sample was left for about 3 days and then subjected to an ultrasonic flaw detection test, but no crack was observed.

In Example 2, the side plate is made of HT950 (tensile strength 1010 MPa) 40 mm material, and the diaphragm is SM.
It was manufactured using the 30 mm material of 590 (tensile strength 620 MPa) by the process shown in FIG.

First, as shown in FIG. 2 (a), groove processing was performed on both ends of the four side plates, and electroslag welding metal was attached to one side of the diaphragm 3 as shown in FIG. 2 (b). As shown in FIG. 2C, three side plates were formed into a U-shaped structure, and the diaphragm was attached to this with the side having the groove for electroslag welding facing up.

Thereafter, carbon dioxide welding 9 (FIG. 2 (d)) was performed on the three sides where the side plate and the diaphragm contact each other. Carbon dioxide welding uses a 600 MPa class wire with a diameter of 1.6 mm,
The preheating temperature was 80 ° C., and the heat input was 34 to 64 kJ / cm 2. Thereafter, as shown in FIG. 2D, the remaining one side plate is temporarily assembled into a box-type structure, and as shown in FIG. 2E, a columnar groove for electroslag welding between the diaphragm 3 and the flange 1 is formed. The web 2 was perforated with a drill 10 so that it could be communicated, and non-consumable nozzle type electroslag welding was carried out.

Next, after the groove for the angular welding disturbed by the non-consumable nozzle type electroslag welding was repaired, FIG.
As in (f), corner joint welding 8 was performed by high heat input gas shield arc welding, and this was further rotated 180 degrees, and corner joint welding was performed in the same manner. For the corner joint welding, a 1000 MPa class wire with a diameter of 4 mm was used for large heat input gas shield arc welding, and multi-pass welding for 8 passes was performed for long-pole alternating current two-electrode welding. Preheating was 50 ° C. After manufacturing, this was also left for about 3 days for an ultrasonic flaw detection test, but no crack was observed.

Example 3 is a comparative example, and the side plate is HT780.
(Tensile strength 810 MPa) 100 mm material, diaphragm is SM590 (tensile strength 620 MPa) 60 mm
Wood was used. First, after incorporating the diaphragm and temporarily assembling it into the box structure, square joint welding was performed by submerged arc welding, and then diaphragm welding was performed by consumable nozzle electroslag welding. This was also left for about 3 days and then subjected to an ultrasonic flaw detection test. As a result, cracks were observed in the heat-affected zone of the side plate of the electroslag welded portion.

[0025]

INDUSTRIAL APPLICABILITY The present invention improves the manufacturing process in the production of a box-type steel structural material of a high-strength thick plate, particularly a box column for construction, and the electroslag welding used for this is a low diffusion hydrogen welding. By using a consumable nozzle type electroslag welding, welding cracks are prevented. Compared with the conventional method, there is no problem that the work is complicated or the cost is high, and a high quality product can be manufactured even with a high strength thick plate material.

[Brief description of drawings]

FIG. 1 is a diagram showing a manufacturing process of the present invention, in which FIG.
(F) shows a process order.

FIG. 2 is a diagram showing a manufacturing process of the present invention, in which FIG.
(F) shows a process order.

[Explanation of symbols]

 1 Side Plate (Flange) 2 Side Plate (Web) 3 Diaphragm 3a Ear 4 Electroslag Welding Metal 5,6 Arrows indicating the drilling direction 7 Electroslag Welding Columnar Groove 8 Corner Joint Welding 9 Welding with pre-welded diaphragm 10 Arrows indicating the direction of drilling

Claims (2)

[Claims] 1. In the production of a box-type structural material having four steel plates having a tensile strength of 580 to 1050 MPa and a plate thickness of 30 to 120 mm as a side plate and having a diaphragm inside, two steel plates located inside the side plates (web). ) And two steel plates (flange) located on the outer side and a diaphragm having a columnar groove for welding on four sides are temporarily assembled in a box-type structure, and the flange is provided with a hole leading to the columnar groove of the diaphragm. Consumable nozzle type electroslag welding is performed, then the web is pierced, the columnar groove along the inner surface of the flange is non-consumable nozzle type electroslag welding, and then the four corners composed of four side plates are corner welded. And a method for manufacturing a box-type structural material of high-strength thick steel plate. 2. In the production of a box-type structural material having four steel plates having a tensile strength of 580 to 1050 MPa and a plate thickness of 30 to 120 mm as a side plate and having a diaphragm inside, three of the four side plates are U-shaped structures. As a result, a diaphragm having a columnar groove for electroslag welding is incorporated in at least one side thereof, and the side plate and the diaphragm are in contact with each other.
Side gas shield arc welding, submerged arc welding,
Weld by either coated arc welding or non-consumable nozzle type electroslag welding, then attach the remaining one side plate and temporarily assemble it into a box-type structure, and form a side plate with a hole that leads to the columnar groove of the diaphragm. A method for manufacturing a box-type structural material of high-strength thick steel plate, which comprises exhausting nozzle-type electroslag welding, and then corner-welding four corners composed of four side plates.