JPH0636985B2 - Welding method for shaped steel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a method for welding a shaped steel material in which a character-shaped steel material is welded to an object to be welded.

(Prior Art) Stainless steel is often used for storage tanks and equipment such as chemical treatment plants and nuclear power generation plans, and fillet welded joints are very often applied in these fields.

Conventionally, a method of fillet-welding a structural material such as a plate material or a square material to a flat-shaped work piece is simply to butt the end face of the structural material to the work piece in a vertical or horizontal T-shape and weld it from both sides, or Complete penetration welding is performed after groove processing is applied to the butt surfaces of the materials. If complete penetration welding can be performed from both sides as described above, strong welding can be performed and problems are unlikely to occur.

However, as shown in FIG.
In the case of welding the section-shaped steel material 2 to, the welding torch cannot be incorporated and welded from the inside of the steel material 2, so that one-sided welding is performed from the outside. In particular, when the inner space 3 of the shaped steel material 2 has a depth h of 100 mm or less and a width W of 100 mm or less and a deep shaped steel material, it is extremely difficult to weld both sides. Therefore, the one-sided welding 4 as partially shown in FIGS. 7 to 11 is performed. That is, FIG. 7 shows an example in which the shaped steel material 2 is simply butted to the object to be welded 1 and one-side welding 4 is performed. FIG. 8 is an example in which a L-shaped groove 5 having an inclination angle θ is formed on the end surface of the shaped steel material 2 and then one-side welding 4 is performed, and FIG. 9 is an example in which a gap g is welded similarly to FIG. Is. FIG. 10 shows an example in which a ν-shaped groove 6 having a root portion f is formed on the end surface of the shaped steel material 2 and then one-side welding 4 is performed, and FIG. 11 is an example in which a gap g is welded similarly to FIG. Is shown.

(Problems to be Solved by the Invention) The welding method described above has the following drawbacks. In the case illustrated in FIG. 7, a gap (clevis) is formed on the contact surface between the work piece 1 and the shaped steel material 2, which has a drawback of causing crevice corrosion. Further, in the cases of FIGS. 8 and 10, there is a drawback that welding defects such as fusion defects, cracks, and penetration defects are likely to occur at the root portion. Further, when a large pressure difference is generated between the inner space 3 and the outer space, it may be broken, and especially when repeated stress is generated in the inner space 3, there is a risk that the root part is broken due to fatigue. is there. Further, when the root gap g is provided as illustrated in FIGS. 9 and 11, the TIG welding method is used for temporary welding and then full penetration welding is performed. However, there is a drawback that a defect occurs in the root portion at the time of temporary welding. is there. In addition, there is a drawback in that when the first layer is welded, welding is performed from above the temporary attachment portion, resulting in defective penetration. This welding method is extremely difficult, and unless a skilled welder is used, a sound backwater cannot be produced.

Furthermore, when temporary tacking is performed in the groove, the root interval of the groove is narrowed due to the welding thermal stress at the time of the first layer welding, and the root interval becomes 1 mm or less that can not perform sound welding. is there.

For example, when repair welding of nuclear equipment is performed in a high radiation environment, as shown in Fig. 6, the thickness is 6 mm.
When welding the W-shaped steel material 2 having a width (W) of 600 mm, a height (h) of 85 mm, a length of 2500 mm and a thickness of 3 mm to the work piece (liner plate) 1 in a vertical position, remote automatic welding (TIG ). If the welded portion has the simple shape shown in FIG. 7, the welding is easy, but the opening 7
Steam or high-temperature water flows in from there to cause a pressure difference between the inner space 3 and the outer space, stress concentration occurs in the root portion, and the weld metal 4 fractures due to fatigue. Therefore, it is desirable to use a welding method in which a groove shape is formed to provide a root gap as shown in FIG. 9 or FIG. 11 and a back wave is formed. However, it is extremely difficult to perform welding to form a back wave having a V-shaped groove shape with the current remote automatic welding machine. The reason for this is that since the tip of the shaped steel material 2 having a thickness of 3 mm has a checkered or ν shape, the thickness of the tip is thin, and the shaped steel material 2 side is melted and a hole is formed before welding. Umami does not occur.

Therefore, we have to rely on the skill of the welder by making full use of the shielding technology, but even if the shield is used, the radiation exposure dose of the welder increases, so a welding method that easily causes backwater is required. .

The present invention has been made to solve the above problems, and in a chemical processing plant, nuclear equipment, etc., in a method of butt and complete penetration welding, for example, a stainless steel character-shaped steel material to, for example, a stainless steel plate workpiece to be welded. ,
When repetitive stress is applied to the root part of the groove of the V-shaped steel material, it is possible to form a back wave with a smooth curved surface shape by complete penetration welding, and even if there is pressure fluctuation from the inner space. With a joint shape that is extremely strong against fatigue,
Moreover, it is another object of the present invention to provide a method for welding a shaped steel material in which crevice corrosion does not occur even if water is present in the inner space.

[Configuration of the Invention] (Means for Solving the Problems) The present invention relates to a groove processing step of forming a groove inclined outward from an end face in a welded portion of a character-shaped steel material, and a welded object for welding the shape steel material. The build-up seat mounting step of welding a plurality of strip-shaped build-up seats scattered along the welding line of the object and the groove formed in the shaped steel material are applied to the build-up seat installed on the workpiece. A main welding step of contacting and completely penetrating welding from the outside of the groove to form a back wave to integrally integrate the shaped steel material with the object to be welded.

(Operation) The flat weld is installed in the welded part of the flat work piece so that the back wave is formed by full penetration welding. When the groove of the shaped steel material is brought into contact with the build-up seat and complete penetration welding is performed, the build-up seat is melted together with the weld metal by the welding heat, and the welded object, the shaped steel material and the joining surface of the build-up seat are fused. Then, at the end of welding, a backside wave on the curved surface where the overlay is melted is formed on the inner end surface of the shaped steel material. Since this back wave is uniformly fused and formed inside the shaped steel material to which the object to be welded is welded, no gaps or cracks occur in the welded part. The curved back Uranami formed in the welded part creates a joint shape that is extremely resistant to fatigue,
There is no need to worry about crevice corrosion.

(Example) An example of the method for welding a shaped steel material according to the present invention will be described with reference to FIGS. 1 to 5.

In FIG. 1, reference numeral 1 is, for example, a stainless steel plate-shaped object to be welded, 2 is a thickness to be welded to the object to be welded 2, for example, 3
mm-shaped steel material. In the groove processing step, the welded portion 2a of the shaped steel material 2 is machined with a ν-shaped groove 6 inclined outward from the end face thereof, for example, by grinding. The groove 6 has an inclination angle θ and a root face f. On the other hand, as shown in FIGS. 2 and 3, the welding object 1 has a buildup seat 8 with a pitch P along the installation position of the shaped steel material 2, that is, along the weld line 1a as shown in FIGS. They are installed at almost equal intervals by full penetration welding. Incidentally, FIG. 3 shows XX ′ of FIG.
In the sectional view taken along the line, the single build-up seat 8 is attached to the workpiece 1. This pad 8 is in the form of a strip,
It has a width W ₁ and a height h ₁ , but is attached to the object to be welded 1 as follows, for example. That is, the welding rod Y-
308L is used, the width (W ₁ ) is about 5 mm, the length is 10 mm, the height is 2 to 4 mm on the welding line 1a of the work piece 1, the pitch (P) interval is 80 mm, and it is completely completed by the TIG welding method. Penetration welding was performed to spot the weld overlay. After that, the height (h ₁ ) of the weld overlay was finished by a grinder so as to be ₁ to 3 mm to form the weld overlays 8 in a scattered manner as shown in FIG. When the pitch P of the build-up seat 8 exceeds 100 mm, the route interval of 1 to 3 mm provided during the first layer welding is 1 mm.
This is not preferable because it is less than the above range and only causes defects in the root portion.

Next, the process proceeds to a main welding step in which the shaped steel material 2 is welded and integrated with the object to be welded 1 having the build-up seat 8 attached in the above-mentioned build-up seat attaching step. That is, in this main welding process, as shown in FIG. 4, the holding plate 9 is placed on the upper surface of the shaped steel material 2, and the hydraulic cylinder 10 is attached to the holding plate 9. The steel cylinder 2 is pressed against the work piece 1 by the hydraulic cylinder 10 so as not to move.

In this state, the welding conditions are TIG welding, current 130
A, welding voltage 10.5 V, welding speed 7 cm / min, first position welding in a vertical position. When the remaining layers are sequentially welded (three passes), a back surface having a smooth curved surface is finally formed inside the weld metal 11 of the workpiece 1 and the shaped steel material 2 as partially shown in FIG. The finished state is formed with the waves 12. In this case, the back wave 12 is formed with a smooth curved surface regardless of the portion where the build-up seat 8 exists and the portion where it does not exist, so that the root portion is sound even if pressure is repeatedly applied to the inner space 3. In addition, since there are no welding defects (poor fusion, poor penetration, etc.) in the root portion, there is no gap in the root portion, and even if water is present on the inner space 3 side, the stress of stainless steel that causes crevice corrosion as an initial phenomenon It also has the secondary effect of not causing corrosion cracking.

[Advantages of the Invention] According to the present invention, the backside wave can be formed on the welded surface, so that the joint shape is strong and the joint shape is very strong against fatigue. Further, because of full penetration welding, there is no gap in the welded portion, and crevice corrosion does not occur even if water is present in the inner space.

[Brief description of drawings]

1 to 5 are views for explaining a method of welding a shaped steel material according to the present invention, and FIG. 1 is a vertical cross-sectional view showing a state where the shaped steel material is in contact with a build-up seat on an object to be welded. Fig. 2 is a plan view showing a state in which the build-up seat is attached to the object to be welded, Fig. 3 is a sectional view taken along the line XX 'in Fig. 2, and Fig. 4 is in the state shown in Fig. 1. FIG. 5 is a partial cross-sectional view showing a state in which the hydraulic cylinder and the holding plate are attached in a partial cross-section, FIG. 5 is an enlarged partial cross-sectional view showing a portion welded by the method of the present invention, and FIGS. FIG. 6 is a view for explaining a welding method, FIG. 6 is a longitudinal sectional view showing a state in which a character steel is welded to an object to be welded, and FIGS. 7 to 11
The figure is a partial vertical cross-sectional view showing a state of welding by various welding methods. 1 ... Workpiece 2 ... V-shaped steel material 3 ... Inner space 4 ... V-shaped groove 6 ... L-shaped groove 7 ... Opening hole 8 ... Overhead seat 9 ... Holding plate 10 …… Hydraulic cylinder 11 …… Weld metal 12 …… Uranami

Claims (1)

[Claims] 1. A groove forming step of forming a groove inclined outward from an end face in a welded portion of a V-shaped steel material, and a plurality of strip-like shapes along a welding line of an object to be welded with the shaped steel material. A build-up seat mounting step of welding the build-up seat in a scattered manner, and abutting the groove formed in the shaped steel material to the build-up seat mounted on the object to be welded,
A method for welding a shaped steel material, which comprises a main welding step of completely melting and welding from the outside of the groove to form a back wave to integrally integrate the shaped steel material with the object to be welded.