JPH11245063A - Jointing method of titanium cladded steel plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply joint a titanium cladded steel without generating corrosion and crack of a weld zone or disturbing workability by laser-welding a titanium plate while pressurizing the plate so that a spacing between the titanium cladded steel plate and the titanium plate becomes a given value or less. SOLUTION: A laser welding device comprises, for example, a pressing cylinder 12 which is mounted to a robot arm 15 and connected with a pressing roller 11 for continuously pressing a titanium cladded steel from above a titanium plate 4, a laser welding torch 13 mounted to a rear part of the pressing cylinder 12, and an inert gas shield box 14. The titanium plate 4 is pressed towards a titanium cladding material 3 side of the titanium cladded steel plate by means of the pressing cylinder 12 and the pressing roller 11, so that a spacing between the titanium plate and the titanium cladded steel plate becomes 0.5 mm or less. If the spacing is 1 mm or more, the titanium plate 4 and the titanium cladding material 3 are not short-circuited by a molten metal, and not jointed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for joining titanium clad steel sheets by laser welding, and more particularly to a method for welding lap joints between titanium clad materials of titanium clad steel sheets and titanium sheets.

[0002]

2. Description of the Related Art A titanium clad steel sheet is a composite steel sheet in which titanium (called a composite material) having extremely excellent corrosion resistance is bonded to the surface of a steel sheet (called a base material) as a strength member. Due to its advantages, its applications are expanding in fields such as marine structures, chemical plants, and power plants, which have severe usage environments. For example, it is used as a lining member for steel structures and pipes. However, it has not yet been used in large quantities because of the welding problems described below. When a titanium clad steel sheet is welded by a normal method, a brittle intermetallic compound or a carbonitride compound of titanium is generated at a portion where the dissimilar metals of titanium and steel are fused (called a dissimilar material weld), so that the weld is easily cracked. It is becoming.

In order to solve such welding problems,
Conventionally, several methods have been proposed. For example, JP-A-2-280969 and JP-A-2-280970.
Japanese Patent Publication No. JP-A-2005-64131 discloses a method in which a groove is provided in a base material from which a joining material (titanium) of a butt portion to be welded is removed, and the base materials are welded to each other, and then a titanium plate of the same quality as the titanium joining material is overlapped and welded. Is disclosed. As a welding method, TIG welding or plasma welding shown in FIG. 3 is used.
In the figure, 1 is a titanium clad steel sheet, 2 is a base material of titanium clad steel 1, 3 is a titanium composite material of titanium clad steel sheet 1, 4 is a titanium plate, 5 is a welded portion, and 6 is a torch for TIG welding. However, when the titanium composite material 3 and the titanium plate 4 are welded by this welding method, the molten metal becomes
, And iron is mixed in from the base material 2 of the titanium clad steel sheet 1, and the welded portion 5 becomes brittle and the corrosion resistance is deteriorated. Therefore, it is practically difficult to use general-purpose arc welding.

[0004] Japanese Patent Application Laid-Open Nos. Hei 7-214336 and Hei 7-232277 disclose an electric resistance welding method capable of performing high-efficiency joining without mixing of iron. In this welding method, a pair of upper and lower disk-shaped electrodes 7 made of copper as shown in FIG. 4 or a disk-shaped power supply electrode 8 and a welding electrode 9 as shown in FIG. This is a method in which an electric current is applied at the same time as the pressurization of No. 1 and the titanium plate is joined by utilizing the electric resistance heat generation. Although this welding method can provide a welded portion 5 having a high joining speed and a high corrosion resistance without the inclusion of iron in the molten metal, it has the following problems. The pressure required for joining is 20
This is as high as 00N or more, and the apparatus becomes large-scale and the cost increases, and the structure to be welded needs to be strong enough to withstand the pressing force, and the applicable structure is restricted. In addition, in the electric seam welding method, since the joining proceeds while applying pressure, energizing, and cooling with a pair of disc-shaped electrodes, the thickness of the titanium plate 4 that can be stably welded is limited. That is, when the titanium plate has a thickness of 1 mm or more, the cooling capability of the disc-shaped welding electrode 9 is insufficient, the molten metal penetrates the titanium composite material 3, and iron is mixed in from the titanium clad steel plate base material 2. In addition, there arises a disadvantage that the welded portion 5 becomes brittle and the corrosion resistance is deteriorated. Therefore, in order to stably join the titanium clad steel sheet base material 2 by suppressing the incorporation of iron by this welding method, the thickness of the titanium plate 4 needs to be 1 mm or less, preferably 0.5 mm or less. There are restrictions on the applicable plate thickness of the titanium plate. When the thickness of the titanium plate is as thin as about 0.5 mm, when building or using a steel structure,
Due to external factors, the titanium plate has holes in the titanium plate, which may significantly deteriorate the corrosion resistance of the structure. further,
This welding method has a problem that it is difficult to join a bent portion such as a corner portion, although a straight one-way joining can be easily performed due to its configuration.

[0005]

As described above, the conventional joining method has a problem in that it is not possible to cover the corrosion-resistant metal titanium plate at low cost and to provide long-term durability. The present invention has been made in order to solve such a problem, and it is an object of the present invention to provide a simple method of joining a titanium clad steel sheet without causing corrosion or cracking of a welded portion and not impairing workability. Aim.

[0006]

According to the present invention, there is provided a method for joining a titanium clad steel sheet, comprising: applying a titanium sheet to a titanium laminated material side of a titanium clad steel sheet in which titanium is joined to the surface of a steel base material; In a method of lap welding a plate, the welding is performed using a laser beam.

In addition, the laser welding is performed while pressing the titanium plate so that the gap between the titanium clad steel plate and the titanium plate is 0.5 mm or less.

[0008]

FIG. 1 shows an example of the configuration of a welded joint according to the method of the present invention. The welding location is the overlapped portion of the titanium cladding 3 of the titanium clad steel sheet 1 and the titanium plate 4 superposed on the surface of the titanium cladding 3. Laser light 1
0 indicates that the welding heat input can be precisely controlled, so that the penetration depth at the welded portion 5 can be controlled with high precision, so that the weld metal does not penetrate the titanium composite material 3 and thus the titanium clad steel plate 1 It is possible to reliably weld only the titanium plate 4 and the titanium composite material 3 without mixing iron from the base material 2.

FIG. 2 shows an example of the configuration of a laser welding apparatus used in the method of the present invention. This device is mounted on, for example, a robot arm 15 and has a pressure cylinder 12 connected with a pressure roller 11 for continuously pressing the titanium clad steel plate 1 from above the titanium plate 4, and a rear portion of the pressure cylinder 12. It comprises a laser welding torch 13 and an inert gas shield box 14 attached. In the figure, reference numeral 16 denotes an optical fiber. The titanium plate 4 is pressed against the titanium cladding material 3 side of the titanium clad steel plate 1 by the pressure cylinder 12 and the pressure roller 11 to make the gap between the titanium plate 4 and the titanium clad steel plate 1 0.5 mm or less. If there is a gap of 1 mm or more between the two, the molten metal cannot short-circuit the titanium plate 4 and the titanium composite material 3 and cannot join them. In the case of a titanium plate about 3 mm thick, at most 10
With a pressure of 0 kg, the gap can be reduced to 0.5 mm or less. Behind the roller 11 for pressing the titanium plate 4, a laser beam is irradiated from the torch 13 to perform laser welding. As the laser beam used for welding, any laser beam such as a carbon dioxide laser beam, a YAG laser beam, an iodine laser beam, a carbon monoxide laser beam, and an excimer laser beam can be used as long as it is a beam used for welding. The titanium melted by the irradiation of the laser beam 10
It reacts easily with oxygen and nitrogen in the atmosphere to form titanium oxides and nitrogen compounds, embrittles the weld metal, and has adverse effects such as cracking and reduced corrosion resistance. To shield the molten metal with an inert gas. As the inert gas, argon gas,
Helium gas or the like is used.

[0010]

EXAMPLE A titanium plate having a width of 500 mm and a length of 500 mm was applied to a titanium clad steel plate having a width of 500 mm and a length of 500 mm. The welding method shown in FIG. 1 according to the present invention and the welding method shown in FIGS. By the method, the titanium bonding material 3 of each test piece
And the titanium plate 4 were welded. Table 1 shows the thickness of the titanium clad steel sheet base material 2, the titanium composite material 3, and the titanium plate 4, the welding method and welding conditions, and the evaluation results. The quality of the welded test piece was evaluated by the method shown in Table 2.

[0011]

[Table 1]

[0012]

[Table 2]

In the weld metal part hardness test, when welding the titanium composite material and the titanium plate, if the iron of the titanium clad steel plate base material is mixed in, the hardness of the weld metal is hardened, and cracking and corrosion resistance deteriorate. A case where the Vickers hardness was 300 or less was evaluated as good, and a case where the Vickers hardness was 300 or more was evaluated as poor.

In Table 1, Test No. 1 to 6 are examples of the present invention. For laser welding, use a YAG laser welding machine and output 1
000-3000W. The base material thickness of the titanium clad steel sheet is 3 mm and 4 mm.
The test was performed by changing the range in a wide range from 2.0 to 2.0 mm and 0.3 to 3.0 mm. In any combination, by welding under appropriate conditions, the titanium composite material and the titanium plate can be welded without dilution from the base metal, and the hardness of the weld metal becomes 165 or less in Vickers hardness. ing. Also, in the tensile and bending tests, no cracking or peeling of the weld was observed, and the airtightness was good. As described above, good welding can be performed even when the thickness of the titanium plate is 1 mm or more. For this reason, when a titanium clad steel plate is used for lining a structure, a titanium plate having a thickness of 1 mm or more can be used, which has an effect of ensuring long-term corrosion resistance of the structure.

In the comparative examples, Test No. Reference numerals 7 and 8 denote welded joints manufactured by TIG welding. In each case, there was dilution from the base metal at the weld and the hardness was 5 Vickers hardness.
Hardened to more than 00. Further, cracks occurred in the welded portions in the tensile / bending tests, and water leakage was also observed in the airtight tests. In the comparative examples, Test No. 9-11 are
This is a welded joint produced by seam welding. Test No. 9
Has a thickness of 0.2 m for the titanium bonding material and titanium plate
m, 0.5 mm. In this case, good results were obtained in the hardness, tensile / bending test, and airtightness test. In 10 and 11,
Dilution from the base metal was observed in the welded portion, and the hardness was hardened to Vickers hardness of 500 or more. In addition, cracks and peeling were observed in the welds in the tensile / bending tests, and water leakage was observed in the airtight tests. In addition, Test No. produced by the laser welding method of the present invention example. Test No. 1 produced by seam welding of a comparative example evaluated as having a good overall evaluation under the same test material thickness conditions. Compared to 9,
In the example of the present invention, welding can be performed at a welding speed four times as high, and welding can be performed efficiently.

[0016]

As described above, according to the present invention,
Because the titanium cladding of titanium clad steel sheet and the titanium plate are lap welded by laser welding, the mechanical properties and airtightness of the welded joint are extremely excellent, and the effect that welding can be carried out easily and efficiently There is.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a method for joining a titanium clad steel sheet of the present invention.

FIG. 2 is a configuration diagram of a laser welding apparatus used in the method of the present invention.

FIG. 3 is a diagram showing an example in which lap fillet welding is performed by a conventional TIG welding method.

FIG. 4 is a diagram showing an example of performing seam welding by a conventional direct resistance welding method.

FIG. 5 is a diagram showing an example of performing seam welding by a conventional indirect resistance welding method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Titanium clad steel plate 2 Base material of titanium clad steel plate 3 Titanium clad material of titanium clad steel plate 4 Titanium plate 5 Welded part 10 Laser beam 11 Pressure roller 12 Pressure cylinder 13 Torch for laser welding 14 Inert gas shield box 15 Robot arm 16 Optical fiber

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigeru Nakagawa 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Yasuki Takeichi 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Sun (72) Inventor Toshio Takano 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd.

Claims (2)

[Claims] 1. A method for applying a titanium plate to a titanium cladding material side of a titanium clad steel plate having titanium bonded to the surface of a steel base material, and welding the titanium clad steel plate and the titanium plate using a laser beam. A method for joining a titanium clad steel sheet. 2. The method for joining titanium clad steel sheets according to claim 1, wherein the laser welding is performed while pressing the titanium sheet so that the gap between the titanium clad steel sheets is 0.5 mm or less.