JP2834587B2 - Butt laser welding of high carbon steel sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a butt laser welding method for continuous rolling of a high carbon strip steel sheet after rolling.

[0002]

2. Description of the Related Art Conventionally, a mechanical cutting method such as a guillotine shear has been employed for cutting an end portion of a strip steel plate in order to obtain the accuracy of a butt surface in butt welding. However, when the thickness of the material to be welded is increased, it is necessary to increase the mechanical rigidity of the shear in order to obtain an accurate and efficient cut surface, and the equipment becomes large.

[0003] Therefore, cutting by means of, for example, laser irradiation without mechanical cutting means has been attempted, but an oxide film is generated on the cut surface by the laser irradiation.

[0004] When welding is performed with a thick oxide film applied, oxygen generated from the oxide film and carbon in the steel combine to generate carbon dioxide gas, which remains in the deposited metal as blowholes and reduces mechanical strength. Let it. In particular, the tendency is strong in a high carbon steel sheet in which the material to be welded has a C content of 0.5% by weight or more, which may result in welding failure.

[0005] Conventionally, in laser welding of such high carbon steel, Ti, Zr, Nb, and H are added to the weld zone in order to prevent decarburization in the molten zone and to prevent a decrease in strength of the weld zone and the occurrence of cracks.
Japanese Unexamined Patent Publication No. Hei.
No. 27790.

Japanese Unexamined Patent Publication (Kokai) No. 62-124095 discloses that in order to prevent the occurrence of blowholes during arc welding, 0.5% to 2.5% of Si, one of Zr, Ti, and Al is used. It describes that a filler wire containing at least 0.5% to 1.0% of seeds or more is used. Although this has a certain function and effect, it is not possible to prevent the occurrence of blowholes when laser welding high-carbon steel, which is the target of the present invention, and then laser welding the filler wire. It is believed to be due to the specificity of the material to be welded and laser welding.

However, when combining laser welding at the time of butt welding of a high carbon strip steel plate with laser cutting which itself has excellent cutting ability and cutting accuracy,
There is no disclosure of means for solving the problem caused by the formed oxide film.

[0008]

The problem to be solved in the present invention is to solve the problem of the occurrence of welding defects such as blowholes due to an oxide film in the butt welding of a strip steel sheet, especially a high carbon strip steel sheet by laser, and to realize laser cutting. It is an object of the present invention to realize a continuous combination process with laser welding.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a laser welding method in which a laser cut high carbon steel sheet is welded by abutting end faces thereof, while supplying a filler wire containing 0.3 to 10% by weight of Al to a welded portion. The task was achieved by laser welding.

[0010]

When a filler wire containing 0.3 to 10% by weight, preferably more than 1.0 to 5% by weight of Al is used for laser welding, C is reduced to 0.5% by laser cutting.
Oxygen generated from an oxide film that is particularly inevitably generated on the cut surface of the high carbon steel sheet is fixed as an oxide. This oxide does not become bubbles even by welding heating at a very high temperature by a laser, and does not cause welding defects such as blowholes. However, when the amount of Al is less than 0.3% by weight, blowholes are generated and the strength of the welded portion is reduced. On the other hand, if the content exceeds 10% by weight, the welded structure may exhibit abnormalities. For this reason, the amount of Al contained in the filler wire is specified to be 0.3 to 10% by weight. 1.0 from the viewpoint of complete prevention of welding defects and securing of weld strength
More than 5% by weight is preferred. When the C content of the material to be welded is large, it is preferable to increase the Al content in the filler wire according to the amount.

[0011]

EXAMPLES The effects of the present invention will be specifically described below with reference to examples.

When the C content is 0.70%, 0.85%, 1.
A 20% high carbon steel sheet was laser cut and then butt laser welded. The Al content of the filler wire used at this time was 1.7%, 2.2%, and 3.3%.
As a comparative example, a high carbon steel sheet having a C content of 1.20% was laser-welded with a filler wire having an Al content of 0.05%, and the mechanical strength and the blow strength of the weld were determined by repeated bending tests. Hole inspection was performed. Table 1 shows the results.
Shown in

[0013]

[Table 1]

[0014]

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

(1) Since laser cutting and laser welding can be provided in series, the efficiency of continuous strip steel plate is increased.

(2) Since a mechanical cutting machine such as a guillotine shear can be eliminated, ancillary equipment for welding can be reduced in size and cost.

(3) Since the strength of the welded portion is improved, it is possible to pass the line through the welded portion.

Continuation of the front page (56) References JP-A-64-27790 (JP, A) JP-A-2-89591 (JP, A) JP-A-63-57152 (JP, B2) (58) Fields studied (Int .Cl. ⁶ , DB name) B23K 26/00 310 B23K 35/30 320

Claims (1)

(57) [Claims] When a laser cut high-carbon steel plate end face is butted and laser-welded, Al is 0.3 to 10 mm.
A butt laser welding method for a high carbon steel sheet, wherein laser welding is performed while feeding a filler wire containing wt% to a welding portion.