JPH0350634B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing clad metal plates, and more particularly to a method for properly assembling and welding raw metal plates by electron beam welding.

[Prior Art] Clad metal plates, which are made by laminating and bonding two or more metal plates, are used in a wide range of fields as inexpensive structural materials that have excellent corrosion resistance, abrasion resistance, or heat resistance, and high strength.

Methods for producing clad metal plates include explosion bonding, overlaying, rolling, and the like, but rolling is the most commonly used method because it allows for the production of large-area plates with high efficiency and low cost.

The rolling method is a method in which the surfaces to be joined are cleaned, laminated, and hot or warm rolled to metallurgically join them.

When manufacturing cladding by rolling, the important point to keep in mind is the cleanliness of the atmosphere between the joint surfaces. In other words, even if the joint surfaces are clean, if there is an atmosphere between the joint surfaces, oxides etc. will be formed during heating and rolling.
This prevents metallurgical bonding and causes insufficient bonding strength to be obtained. Therefore, in order to manufacture a clad metal plate having sufficient bonding strength, it is necessary to exhaust the atmosphere existing between the bonding surfaces as much as possible during the clad assembly stage to maintain a low pressure state. Another method is to replace the atmosphere between the joint surfaces with an inert gas.
This method is inferior to the former method of creating a low pressure between the bonding surfaces because the gas between the bonding surfaces expands during heating and acts in a direction that prevents pressure bonding.

Sealed welding using electron beam welding has been proposed as a method for efficiently assembling and welding the cladding while maintaining a low pressure between the joint surfaces. In this method, the members to be assembled and welded are set in a vacuum chamber, the vacuum is evacuated to a predetermined degree of vacuum, and then the periphery of the members is hermetically welded using electron beam welding.

[Problems to be solved by the invention] The method of sealed welding using an electron beam is shown in Figure 7A.
As shown in FIG.
As shown in Figure 2, the method can be roughly divided into the method of irradiating the joint surface 4 with a parallel beam 5, but currently both methods have the problems described below, and overcoming them is a major challenge in practical application. It's summery.

(1) In the method of irradiating the beam perpendicularly to the joint surface, the shear force applied during heating and rolling must be supported by the width of the weld metal at the joint surface position. However, the width of the weld metal in electron beam welding is limited to 5 to 6 mm at most, and there is an extremely high risk that the electron beam weld bead 1a will break due to shearing force and the sealing performance will be broken. Furthermore, depending on the combination of the base material 3 and the laminate material 2, cracks may occur in the weld metal during welding. For example, in a combination of carbon steel as the base material and austenitic stainless steel as the bonding material, the microstructure of the weld metal is composed of a mixed structure of austenite and martensite, so the susceptibility to weld cracking is extremely high and cracks will occur.

(2) In the method of irradiating the beam parallel to the joint surface, the shear force during rolling is supported by the penetration depth of the weld bead 1b, so by adjusting the penetration depth, this shear force can be It can withstand enough. Therefore, this method can be said to be more practical than the method of irradiating the beam perpendicularly to the joint surface. However, this method has more problems than the vertical beam irradiation method in terms of forming a good hermetic weld bead. In other words, since electron beam welding uses a narrowly focused beam, if there is a gap between the butt surfaces that are to be hermetically welded, most of the electron beam will pass through this gap and welding will not occur in the first place, as shown in Figure 8. Almost no weld bead is formed where it should be. A weld bead 1c may be formed at the point where the beam that passed through the gap diverges and spreads, but in this case the bead throat thickness is not large enough to withstand the shearing force, and this part is cut off after rolling. As a result, not only the yield is reduced, but also the location where the bead is formed is uncertain, which is extremely problematic in practical terms.

According to experiments conducted by the present inventors, in order to hermetically weld the base material and the laminate without any trouble, the gap between the butt surfaces must be
Although it must be kept within 0.5 mm, in actual clad assembly members there are gaps larger than this, and it is almost impossible for the gaps to be less than 0.5 mm over the entire weld line. In order to control the gap to within 0.5 mm, it is necessary to strictly control the flatness of the joint surface between the base material and the laminate. To achieve this, it is necessary to machine the entire joint surface of both the base material and the laminate material to create a flat surface, but this requires a huge investment in grinding equipment and a large number of man-hours, making it difficult to implement in practice. It is almost impossible to apply.

Furthermore, even if the abutment gap between the joint surfaces is kept within 0.5 mm, there is a very high possibility that cracks will occur in the weld metal during welding, depending on the combination of the base material and the laminate, as described above.

[Means for Solving the Problems] The present inventors solved the above problems because they believe that the latter method of irradiating the joint surface with an electron beam in parallel is practical as a sealed welding method. We have considered this as much as possible. As a result, they discovered that by performing electron beam welding while supplying filler metal such as filler wire to the weld under specific conditions, it is possible to perform good hermetic welding without strictly controlling the butt accuracy of the welding surfaces. It has also been found that by performing such welding, the component values of the weld metal can be freely adjusted and optimized.

In electron beam welding, it has traditionally been difficult to weld while stably supplying filler metal to the welding area, and for this reason, no attempt has been made to put welding using filler metal into practical use. This also led to strict requirements for the butting accuracy of the groove surfaces. The inventors conducted detailed experiments on continuous filler metal supply electron beam welding, and found that even in electron beam welding, by appropriately controlling the supply angle and position of the filler metal, it is possible to form a welded part in a sufficiently stable manner. It was discovered that it is possible to supply filler metal, and its basic configuration is to connect the joint surfaces of stacked metal plates,
While supplying filler metal from the rear in the welding direction, sealing is performed by irradiating an electron beam parallel or oblique to the joint surface, and the filler metal is formed on the joint surface by the electron beam. The electron beam collides with the electron beam inside the beam hole, and the angle α with respect to the beam axis of the electron beam is 5°≦α≦
(65−0.4d)° (d (mm): weld penetration depth)
It was designed to be supplied so that

FIGS. 1 and 2 show the state of implementation of the present invention, where 1 is a weld bead and 6 is a filler metal.

In the present invention, the bonding surface between the superimposed base material 3 and the laminate material 2 is bonded with an electron beam while supplying the filler material 6.
It is hermetically welded by irradiating it with The electron beam 5 is irradiated parallel to or at an oblique angle to the joint surface to perform welding along the joint surface.

When the material to be welded is irradiated with an electron beam, the material to be welded is heated and melted, leading to partial evaporation. At this time, a beam hole 8 is formed in the molten pool 7 due to the evaporation reaction force. Collision occurs within the beam hole. As the filler material 6, in addition to a so-called filler wire, a material having an appropriate shape such as a band shape or a rod shape can be used.

The filler metal 6 supplied from the rear of the beam in the welding direction needs to have a predetermined angle α with respect to the beam axis of the electron beam 5. Specifically, the supply angle α (deg) is depth d
(mm), 5°≦α≦(65
−0.4d). The feeding angle is
If the angle is less than 5°, even a slight change in the supply position of the filler metal will cause a significant change in the collision position with the beam, making it difficult to stably melt the filler metal. Furthermore, if the supply angle exceeds (65-0.4d)°, the filler metal will come into contact with or rush into the molten pool 7 due to minute fluctuations in the supply position of the filler metal, making it impossible to melt the filler metal. Become.
In other words, when the filler metal comes into contact with or plunges into the molten pool, the molten metal around the filler metal absorbs heat and its temperature drops (in extreme cases, it may solidify).
As a result, the filler metal cannot be fed and pushed in smoothly, and if the filler metal is forcibly fed, the filler metal may become bent or the feeding direction may be misaligned, making it difficult to properly feed the filler metal. This makes melting difficult. Therefore, contacting or plunging the filler metal into the molten pool must be absolutely avoided. For this reason, the supply angle α is regulated within the above range. FIG. 3 shows the relationship between the penetration depth d and the filler metal supply angle α, and the area surrounded by diagonal lines [ ] is the appropriate area.

According to the method of the present invention, the allowable groove gap width can be expanded to about 3 mm,
This makes it possible to significantly reduce the butting accuracy of the joint surfaces. Furthermore, according to the present invention, by using the filler metal, the composition of the weld metal can be optimized, regardless of the combination of the base material and the laminate material.
A sound welded part without welding defects can be obtained.

[Example] Examples of the present invention will be described below.

Example 1 Base material SM41 80×1000×500mm Laminated material SUS304 20×1000×500mm The surfaces to be joined for each of the above materials were machined and cleaned and then stacked, but the base material and the laminated material were not brought into close contact. , the joint surfaces were butted against each other with an interval of 2 mm. After this, the parts were carried into a vacuum chamber, and after being evacuated for 10 minutes under a vacuum level of 15 Pa or less, welding was performed by irradiating the periphery of the laminated material with an electron beam in a direction parallel to the joint surface while continuously supplying filler wire. Welding conditions are acceleration voltage 150kV, beam current 100mA, welding speed 30
cm/min, filler wire SUS312 (1.2φ), filler wire feeding angle α40°, filler wire feeding amount 16m/
min, and welding was carried out in a horizontal position as shown in Fig. 1. The penetration depth of the beat at this time is approximately 30mm.
It was hot. The material hermetically welded by electron beam welding was heated uniformly at 1250°C and then rolled at a reduction ratio of 3.
The temperature at the end of rolling was 1050°C. During heating and rolling, the weld bead sufficiently withstood the shearing force without breaking.

An ultrasonic test was conducted over the entire joint surface after rolling, but no defect echo was detected. Three shear test pieces were taken from both ends and the center of the rolled material to examine the shear strength, and a value of 35 to 39 Kgf/ ^mm2 was obtained, which is in line with the shear strength specified by JIS ( ≧20Kgf/mm ² ) was obtained. Front, back, and side bending tests were also conducted, but no peeling was observed at the joint surfaces. The microstructure of the bonded surface is shown in FIG. 4, and the base material and the laminate material are sufficiently bonded.

Example 2 In Example 1, the base material and the laminate were not brought into close contact with each other, a gap of 2 mm was provided between the joint surfaces, and filler wire was continuously supplied to perform hermetic welding. Here, the material types and dimensions of the base material and the laminate material were the same as in Example 1, and the gap between the joint surfaces was 0 mm, that is, the base material and the laminate material were laminated in close contact with each other. In this case, the joint surface between the base material and the laminate material was machined to make it flat. Welding conditions other than vacuum evacuation and feed amount of filler wire were the same as in Example 1. Although the bead shape does not require the supply of filler wire, when the base material and the laminate were directly electron beam welded without filler wire, cracks often occurred in the weld metal. To prevent this cracking, electron beam welding was performed while continuously supplying SUS312 filler wire (1.2φ).

The minimum supply amount of filler wire required to prevent cracking is
However, if the feed rate of filler wire increases, the molten metal will become excessive, and the molten metal will drip from the weld surface and create a cavity defect inside the weld metal, so the upper limit of the feed rate has been set to 2.8 m/min. /
It was necessary to reduce it to below min. In actual sealed welding, electron beam welding was performed with the filler wire feed rate set at 1.8 m/min. The hermetically welded material was heated uniformly at 1250°C and then rolled at a reduction ratio of 3. The bead sufficiently withstood the shear forces during heating and rolling. An ultrasonic test was conducted over the entire joint surface of the rolled material, but no defect echo was detected.
Three shear test specimens were taken from both ends and the center of the rolled material to examine the shear strength of the joint.
A value of 34-39Kgf/ ^mm2 was obtained, which was the JIS standard value (≧20Kg
f/mm ² ) was obtained.
Front, back, and side tests were also conducted, but no peeling was observed on the joint surfaces.

Example 3 In Examples 1 and 2, the joint surfaces were machined, but
In practice, machining large-area joint surfaces involves various difficulties. Therefore, the base material (SM41) and the laminate material (SUS304) were laminated together by removing scale and cleaning the surfaces to be joined without machining them. In this case, the flatness of the base material and the mating material is not very good, and as shown in Figure 5, the gap between the butting surfaces is 0 to 0.
It varied between 3mm. The gap was measured in advance, and the amount of filler wire supplied was varied according to the gap to perform sealing welding by electronic berm welding. The basic welding conditions are the same as in Example 1. A good bead shape was obtained over the entire weld line, and no weld cracks were observed.

An ultrasonic test was conducted on the rolled material rolled under the same conditions as in Example 1, but no defect echo was detected. Three shear test pieces were taken from both ends and the center of the rolled material to examine the shear strength of the joint, and good results were obtained, with values ranging from 36 to 40 Kgf/mm ² . In addition, front, back, and side bending tests were also conducted, but no peeling of the bonded surfaces was observed.

In the example, a rolled clad was manufactured using a combination of SM41 and SUS304, but good hermetic welding could be achieved with other combinations by supplying filler wire with appropriate composition.

As described above, by applying the filler metal supply electron beam welding method of the present invention to combination welding of clad metal plates, a weld bead without weld cracking can be formed regardless of the combination of the materials of the base materials. can do. At the same time, even if a gap of about 3 mm occurs between the abutting surfaces of the joint, it can be sufficiently coped with and a good weld bead can be formed. Therefore, it has been found that good hermetic welding is possible by applying the present invention even with the current flatness of the base material and laminated material, and that the various properties of the joint after rolling are also sufficiently satisfactory. However, the effectiveness of the present invention was confirmed.

In addition, various processes can be considered for hermetic welding using an electron beam, such as welding three sides using the conventional arc welding method and then electron beam welding the remaining one side in a vacuum chamber, but in any case, the electron beam In closed welding, it is important to supply filler metal and perform welding, and this is where the present invention is applied.

Although the above hermetic welding was performed by irradiating the electron beam parallel to the joint surface, it is also effective to irradiate the electron beam at a certain angle to the joint surface, as shown in Figure 6. Ta. However, the angle θ
If θ exceeds 20°, it becomes difficult to stably supply filler metal, so the incident angle θ of the electron beam is limited to 20° or less.

Although the above is a case where the laminate material and the base material are a combination of different materials, it has been confirmed that the present invention can be used extremely effectively even when the laminate material and the base material are a combination of the same kind of materials, and the effect is even greater. ing.

Regarding the welding position, the present invention is fully applicable to welding not only in a horizontal position but also in a downward and vertical position, and it is also possible to weld in a downward or vertical position with the clad member erected.

[Effects of the Invention] According to the present invention described above, the permissible groove gap width can be significantly expanded compared to the conventional method, and as a result, the butt accuracy of the joint surfaces can be significantly relaxed, and in addition, The use of filler metal makes it possible to optimize the composition of the weld metal, and has the excellent effect of making it possible to obtain a healthy welded part without welding defects, regardless of the combination of base material and laminate material. .

[Brief explanation of drawings]

1 and 2 show the state of implementation of the present invention, with FIG. 1 being a perspective explanatory view and FIG. 2 being a partially enlarged view of a welded portion. FIG. 3 shows the relationship between weld penetration depth and filler metal supply angle. FIG. 4 is an enlarged microscope photograph showing the metal structure of the joint surface in Example 1. FIG. 5 is a perspective explanatory view showing the state of polymerization of the base material and the laminate material in Example 3.
FIG. 6 is a perspective explanatory view showing another implementation situation of the present invention. FIGS. 7A and 7B are explanatory diagrams each showing a conventional electron beam welding method. FIG. 8 is an explanatory diagram showing a welding situation in the conventional method. In the figure, 1 is a weld bead, 2 is a laminate, and 3 is a welding bead.
5 indicates a base material, 5 indicates an electron beam, 6 indicates a filler material, and 8 indicates a beam hole.

Claims (1)

[Claims] 1 Two or more metal plates of the same or different types are stacked together and hermetically welded in a vacuum using an electron beam, then
In a method of manufacturing clad metal plates by hot rolling or warm rolling, the joint surfaces of the stacked metal plates are rolled parallel or obliquely to the joint surfaces while supplying filler metal from behind in the direction of welding progress. Seat welding is performed by irradiating an electron beam with a corner,
Colliding the filler metal with an electron beam inside a beam hole formed in the joint surface by the electron beam, and
Set the angle α of the electron beam to the beam axis as 5°≦α
≦(65−0.4d)° (where d (mm): weld penetration depth).