JPH0424155B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method of forming a composite material by overlapping a composite material on a base material, and rolling and joining the composite material to obtain a clad material (so-called open sandwich rolling joining method). The present invention relates to a method for reliably obtaining a cladding material having excellent bondability. [Prior art] For example, clad steel sheets, which are made by joining other alloy steels or non-ferrous alloys to the surface of steel materials such as carbon steel, low carbon steel, and high alloy steel, can be machined by making use of the characteristics of each material. It is a metal material that has a variety of properties such as mechanical strength, corrosion resistance, heat resistance, abrasion resistance, and cracking resistance, and is used in a wide range of fields such as oil plants, seawater desalination equipment, and pressure vessels. There is.
One of the methods for manufacturing such clad steel sheets is the above-mentioned open sandwich rolling joining method, which is attracting attention because the joining operation is simple. Figure 9 is an explanatory diagram showing the cross-sectional structure of Composite K in the open sandwich rolling joining method.
Composite K is base material 2 with each joint surface cleaned.
The laminated material 1 is stacked on top of the other, and the peripheral edges of the joint surfaces are welded to restrain the laminated material 1 on the base material 2. When welding the peripheral edge, in order to prevent flux from entering the joint surface,
Gas-shielded arc welding methods that do not use flux, such as TIG welding, MIG welding, and carbon dioxide arc welding, are used. By the way, when the composite obtained as described above is hot-rolled, the welds may be damaged and the laminated material may peel off.This type of joint uncertainty is a serious problem in the open sandwich rolling joint method. It has become a defect. [Problems to be Solved by the Invention] In view of the above circumstances, the present inventors have conducted various studies to prevent the peeling of the laminate during hot rolling, and have determined that the cause of the peeling is the high-temperature mechanical properties of the welded part. We have come to the conclusion that this may be the case. In other words, TIG welding and MIG welding, which were conventionally applied to peripheral welding,
It has been found that gas-shielded arc welding methods that do not use flux, such as welding or carbon dioxide arc welding, generally have large penetration, and the high-temperature ductility of the welded part is low due to dilution by the base metal.
As a result, it was estimated that the welded part could not follow the large plastic deformation during rolling, and cracks occurred in the weld bond or weld metal, leading to peeling of the laminate. The present invention was completed as a result of further research based on these findings, and its purpose is to provide a method for reliably obtaining clad steel having excellent bonding properties in the open sand German trench rolling bonding method. It is something. [Means for Solving the Problems] The method of the present invention, which has achieved the above object, involves forming a composite by overlapping a laminated material on a base material, and rolling it to obtain a clad material. Sometimes, the gist is to first perform gas-shielded arc welding on the periphery of the contact area between the laminated material and the base material without using flux, and then perform electroslag strip-shaped electrode welding to cover the resulting weld bead. [Function] As mentioned above, the cause of laminated material peeling is that the high temperature ductility of the welded area around the contact area between the base metal and the laminated material is low, and if a welding method that provides a welded area with high high temperature ductility is applied, the problem can be solved. It is thought that it is possible to solve the problem. However, this welding method must not contaminate the interface between the base material and the composite material, and conditions must be met such that the amount of slag generated is small, preferably without the use of flux. However, no practical welding method has been developed to meet these demands, and it has become clear that the problem cannot be solved if the above policy is adhered to. Therefore, the inventors of the present invention felt that it was necessary to change their way of thinking, so they proceeded with further research and decided to weld the peripheral edges of the base material and the mating material in two stages, and in the first stage, the base material and the mating material By adopting a welding method that does not allow impurities such as slag to enter the interface between the two stages, and by completely covering the first stage welded area with the second stage welding, there is no chance of cracking in the first stage welded area during rolling. We have established a policy to prevent this from spreading to the peeling of the laminated material even if it occurs. Since it is necessary to avoid penetration into the base metal as much as possible, it is necessary to use a welding method with low penetration, that is, a welding method that can obtain a welded part with excellent high-temperature ductility, for the second stage welding. There is. As a result of repeated consideration based on this idea,
The present invention as shown in the above structure has been completed. That is, in the present invention, a gas-shielded arc welding method that does not use flux, such as TIG welding, MIG welding, or carbon dioxide arc welding, is used for the first stage welding. Since these welding methods generate almost no slag or the like, they do not contaminate the interface between the base material and the composite material and provide a good interfacial contact state. However, since the penetration into the base metal becomes deep, a decrease in the high temperature ductility of the weld cannot be avoided. On the other hand, in the second stage of welding, since the contact interface between the base material and the composite material is sealed by the first stage welding, there is no risk of contaminating the interface. Therefore, in the two-stage welding process, flux is used, but the electroslag strip electrode method, which has little penetration into the base metal, is used to encapsulate the first-stage weld. Further, when covering the first stage welded portion, the second stage welding may be performed in two or more layers. With the above configuration, it is possible to weld the periphery of the contact area between the base material and the mating material without contaminating the interface between the two, and furthermore, when hot rolling is performed for joining, gas-shielded arc welding does not use flux, which is the inner layer. Even if a crack occurs in the electroslag welded part, the crack does not occur in the electroslag welded part on the outer periphery, so the propagation of the crack is prevented and peeling of the laminated material can be reliably prevented. [Example] Fig. 1 is a cross-sectional explanatory diagram showing one embodiment of the method of the present invention. A laminated material 1 is overlaid on a base material 2, and the periphery of the contact portion is first welded by gas-shielded arc welding without using flux. The beads 5 of the first layer are formed. Next, electroslag strip electrode welding is performed in two steps from above the first layer bead 5,
The first layer bead 5 is completely covered by the second layer bead 6 and the third layer bead 8. (In the following example, the first layer bead is formed by gas-shielded arc welding without using flux, and the second and third layer beads are formed by electroslag strip electrode welding, as in the present example.) The shielding gas and air remaining in the gap between the surfaces 3 of the composite K to be joined are forcibly exhausted through an exhaust hole previously provided in the base material, and after the exhaust hole is sealed, hot rolling is performed to improve bonding properties. It is possible to reliably obtain an excellent cladding material. Figures 2 to 8 are cross-sectional explanatory views showing composites according to other embodiments, and Figure 2 shows a composite K on the first layer bead 5, which is gas-shielded arc welded without using flux, similar to Figure 1. When covering the second layer bead 6a, the composite K
Electroslag strip-shaped electrode welding was performed after tilting in the direction of arrow A. By tilting and rotating, the first layer bead is covered only with the second layer bead 6a. Figures 3 and 4 show an example in which the end of the laminated material 1 has a stepped structure. In Figure 3, the first layer bead is covered with two beads, the second layer bead 6 and the third layer bead 8. In FIG. 4, similar to FIG. 3, the composite K is tilted so that it is covered only with the second layer bead 6a. 5 to 8, the ends of the laminated materials are formed into a tapered surface or a stepped shape having a tapered surface, and
4 shows examples in which the welding methods corresponding to those shown in FIG. 4 are applied. In any of the above-mentioned FIGS. 2 to 8, a cladding material with excellent bondability can be obtained as in the example shown in FIG. Example: In order to confirm the effect of the present invention, as a laminating material
Using SUS304 and SS41 as the base material, composites were prepared according to the conventional method and the method of the present invention, and rolling experiments were conducted. In the conventional method, only MIG welding is performed, but in the method of the present invention, welding in the manner shown in Figures 1 to 4 (first layer: MIG welding, second and third layers:
electroslag strip electrode welding). Furthermore, as a reference example, we prepared the embodiments shown in FIGS. 2 and 4 in which electroslag strip electrode welding was performed without tilting the composite. The result is the first
It was as shown in the table.

[Table] As shown in Table 1, in all cases according to the method of the present invention, no peeling of the laminated material occurred and it was possible to obtain a clad steel plate exhibiting good bondability. On the other hand, in the conventional example and the types shown in Figures 2 and 4 in which tilting was not performed (the first layer was not completely encapsulated), the interlaminar material peeled off during rolling, forcing the rolling to be stopped. I didn't get it. [Effects of the Invention] The present invention is configured as described above, and it is possible to reliably produce a cladding material having excellent bonding properties in the open sandwich rolling bonding method.

[Brief explanation of drawings]

1 to 8 are explanatory diagrams showing the cross-sectional structure of a composite according to the present invention, and FIG. 9 is an explanatory diagram showing the cross-sectional structure of a conventional composite. 1... Joining material, 2... Base material, 3... Joining surface, 5...
1st layer bead, 6, 6a... 2nd layer bead, 8
...Third layer bead, K...Composite.

Claims (1)

[Claims] 1. When forming a composite by overlapping the laminated material on the base material and rolling it to obtain the clad material, first, when forming the composite, the periphery of the contact area between the laminated material and the base material is gas-shielded arc welded without using flux. A method for manufacturing a clad material, characterized in that electroslag strip electrode welding is performed so as to cover the obtained weld bead.