JPH0465752B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for butt welding nickel or nickel alloy clad steel plates. (Prior art) Nickel or nickel alloy clad steel plates are produced by applying nickel or nickel alloy as a composite material to one or both sides of a steel plate as a base material by rolling, crimping, explosion bonding,
They are bonded together by overlay welding, etc., and usually the composite material of nickel or nickel alloy provides corrosion resistance, and the base material of steel plate provides strength and toughness. For this reason, in the butt welding of nickel or nickel alloy clad steel plates, welding has been devised so that performance equivalent to that of the composite material and the base material, respectively, can be obtained. A conventionally used welding method will be explained. First, the base metal side of the steel material is welded using a welding material equivalent to the base metal, and then the composite side is welded using a welding material equivalent to the composite material using covered arc welding or MIG welding. There are 3 to 4 layers of welding inside. This is because in single-layer welding, the weld metal is diluted with iron from the base metal, and chemical components equivalent to the composite material cannot be obtained. Furthermore, in order to secure a large amount of welding by single-layer welding, it is necessary to increase the welding current and voltage, which also tends to increase the dilution ratio. (Problems to be Solved by the Invention) Although the thickness of the composite material of nickel or nickel alloy clad steel sheet is generally about 2 mm to 3 mm, as mentioned above, the composite material side has 3 to 4 layers. Since thick overlay was required, a large number of man-hours were required to grind each layer using a grinder and weld the next layer. (Means and effects for solving the problems) The present invention provides for butt welding of nickel or nickel alloy clad steel plates by determining the shape of the groove on the composite material side and using the TIG welding method with a penetration rate of 5% or less. The present invention provides a welding method for performing welding, and its configuration is as follows. In butt welding of nickel or nickel alloy clad steel plates where the base material is carbon steel or low alloy steel and the composite material is nickel or nickel alloy, the weld interface between the composite material and the base material starts from the middle part of the base material. The bevel angle of the base metal side bevel to the point close to 30 degrees to 50 degrees.
a groove on the composite material side consisting of a concave curved surface that widens from the tip of the groove further toward the surface of the composite material, and overlay welding the base metal side with a welding material with a chemical composition equivalent to the base material, This is a butt welding method for nickel or nickel alloy clad steel plates in which the composite side is further welded by TIG welding using a welding material with a chemical composition equivalent to that of the composite material with a penetration rate of 5% or less. Therefore, the groove on the base metal side should be welded with a relatively small groove angle of 30 degrees to 50 degrees, with a small amount of weld metal, and from slightly inside the bonding interface to the composite material side. It is welded along a concave curved surface, and further welded using the TIG welding method with a penetration rate of 5% or less. (Example) An example of the method for butt welding nickel or nickel alloy clad steel plates according to the present invention will be described with reference to the drawings. As an embodiment of the present invention, a schematic diagram for explaining the principle of automatic TIG welding adopted to ensure a penetration rate of 5% or less is shown in FIG. 1 is a water-cooled tungsten electrode, which is used as a cathode. 2 is a shield nozzle, and a shield gas such as argon or helium is supplied toward the tip of the shield nozzle 2 from a shield gas passage 2a. 3 is a welding wire for overlay, 4 is an arc,
5 is the weld metal, 6 is the material to be welded that will become the anode,
Arrow A indicates the direction of lateral movement of the torch and is approximately perpendicular to the direction of torch feed. In the generally used TIG welding method, water-cooled tungsten electrode 1 is used as an anode, and welding wire 3 for overlay is intermittently supplied to perform welding in a straight line. In the present invention, the TIG welding method has a penetration rate of 5.
% or less, welding wire for overlay 3
A feeding speed equivalent to that of the MIG welding method is applied to concentrate the arc heat generated from the water-cooled tungsten electrode 1 to the workpiece 6 to the overlay welding wire 3, and the shielding gas flow rate is set to approximately 25/min to 28/min.
Increase the amount to min to expand the shielding range and increase the arc voltage to perform welding. Furthermore, in order to suppress the heating of the base material due to arc heat as much as possible and perform overlay welding within a predetermined groove described later, a torch and wire feed (not shown) is applied in the direction of arrow A, which is approximately perpendicular to the torch feed direction. The guide is moved laterally to prevent the arc 4 from concentrating on one point on the material to be welded 6. By adopting the TIG welding method as described above, a penetration rate of 5% or less can be ensured,
A large amount of weld metal 5 can be secured without substantially melting the material 6 to be welded by arc heat, and therefore the chemical composition of the weld metal can be made almost the same as the chemical composition of the overlay welding wire 3. Next, in the method of butt welding nickel or nickel alloy clad steel plates according to the present invention, an example of the groove shape applied to ensure a penetration rate of 5% or less will be explained based on FIG. 2. . 7 is a composite material made of nickel or nickel alloy;
8 is a base material made of carbon steel or low alloy steel, and 9 is an adhesive interface between the composite material and the base material 8. And base material 8
A V-shaped groove on the base material side with a groove angle θ of 30 degrees to 50 degrees from the middle part to a point close to the adhesive interface 9, preferably about 1 mm to 2 mm inside the adhesive interface 9. 10, and a composite material side groove 11 consisting of double concave curved surfaces 11a, 11a whose width gradually widens from the tips 10a, 10a toward the surface of the composite material 7 is provided. The composite material side groove 11 is a double concave curved surface 11a, 11
The reason why it is formed up to the base metal 8 side at point a is to increase the welding surface and prevent poor fusion near the adhesive interface 9, and the groove angle θ on the base metal side is set to 30 degrees to 50 degrees. The reason for making it relatively small is to suppress the amount of welded metal on the base material 8 side as much as possible. Next, specific examples of embodiments according to the present invention will be described. JISH2104N2 (nickel + cobalt: 99.85%)
A composite material with a thickness of 3.5 mm was made using ASTMA387Gr12, and a nickel clad steel plate was butt welded using ASTMA387Gr12 as a base material with a thickness of 14 mm. As shown in FIG.
Up to a point around 1.0 mm, a groove 10 on the base metal side with a groove angle θ 30 degrees, and a double arc concave curved surface 11a with a radius of 7 mm from the tips 10a of the groove to the surface of the composite material 7,
11a, and a groove 11 on the composite material side. For such a groove, first, the base metal 8 up to the tips 10a and 10a of the base metal side groove is submerged arc welded using a welding material equivalent to the base metal, and the upper composite side groove is welded using submerged arc welding. In step 11, nickel welding wire with an iron content of 0.23% by weight was used.
The automatic TIG welding method was used under the following welding conditions to ensure a penetration rate of 5% or less.

[Table] After chiseling the back side of base material 8, submerged arc welding was performed using a welding material equivalent to base material 8. Radiographic inspection of the welded area and cutting of the welded area and inspection of the cross section with an optical microscope at 400x magnification revealed poor fusion,
There are no defects such as cracks, and the penetration rate is approximately 4.5%.
was secured. In addition, the chemical composition of the weld metal surface of the composite material side groove is as follows:
It was as shown in the table below.

[Table] As is known from the values in the table, sufficiently satisfactory values were obtained for the components of the weld metal, no defects were observed in the side bending test of the weld, and the weld metal was not found in the tensile test. It was found that the welded joint had a sufficiently high joint efficiency, with the fracture occurring at a location other than the welded joint. Furthermore, when the welding method according to the present invention was applied to longitudinal welding of the inner surface of a wound welded pipe made of a clad steel plate with a nickel inner surface, there were no performance problems such as chemical composition or mechanical properties of the weld metal. In addition, in a double-sided nickel or nickel alloy clad steel plate, the starting points of the base material side grooves 10 are butted together to form the base metal side grooves 10 and the composite material side grooves 11 symmetrically, so that both sides are covered by the present invention. Just apply the welding method. (Effects of the Invention) As understood from the above explanation, according to the method for welding clad steel plates according to the present invention, penetration of iron from the base metal into the weld metal can be further suppressed through welding. , the components can be made equivalent to those of the composite material, and there is no fusion failure near the weld interface between the composite material and the base metal, resulting in a good joint and making it possible to achieve a better joint than conventional multilayer welding. The production cost was reduced due to the reduction in man-hours.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram explaining the principle of the automatic TIG welding method used in the present invention, and Fig. 2 is a cross-sectional view showing the groove of a nickel or nickel alloy clad steel plate used in an embodiment of the present invention. be. 1...Water-cooled tungsten electrode (cathode), 2...
Shield nozzle, 3... Welding wire for overlay, 4
... Arc, 5 ... Weld metal, 6 ... Welded material (anode), 7 ... Compound material, 8 ... Base metal, 9 ... Adhesion interface, 10 ... Base metal side groove, 10a ... ...Tip (of the base material side groove), 11...Mixture material side groove, 11a...
Concave surface.

Claims (1)

[Claims] 1. In butt welding of nickel or nickel alloy clad steel plates where the base material is carbon steel or low alloy steel and the composite material is nickel or nickel alloy,
The groove angle of the groove on the base material side from the middle part of the base material to the point close to the bonding interface between the composite material and the base material is 30 degrees or more.
50 degrees, and a composite material side groove consisting of a concave curved surface that further widens from the tip of the groove to the surface of the composite material, and the welding material with a chemical composition equivalent to the base material is used up to the tip of the base metal side groove. butting of nickel or nickel alloy clad steel plates, characterized by overlay welding on the composite material side, and further welding on the composite material side by TIG welding with a penetration rate of 5% or less using a welding material with a chemical composition corresponding to the composite material. Welding method.