JPS6033882A - Welding method of aluminum or aluminum alloy member and aluminum alloy member - Google Patents

Abstract

PURPOSE:To cool the periphery of the weld zone of aluminum or aluminum alloy members and to prevent microcracking owing to weld strain by providing passages near the weld line of said members and passing a cooling medium in said passages. CONSTITUTION:Members 4 for introducing a medium and members 4a for discharging the medium are inserted into the openings of the passages 2 provided to aluminum alloy plates 1 and the passages 2 are hermetically sealed in the stage of welding the plates 1. A refrigerant is then introduced from the parts 4 into the passages and is removed from the part 4a form the refrigerant flow in the passages 2 and thereafter the welding of a groove W is started. The heat transmitting to the heat-affected zone is thus transmitted through the walls of the aluminum plate materials to the medium in the passages 2 and is carried to the outside of the system, by which the transfer of the heat to the entire part of the materials 1 is prevented without excessive heating-up near the weld line.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for welding aluminum or aluminum alloy members without welding defects, and more specifically, to a method for welding aluminum or aluminum alloy members without welding defects.
The present invention relates to a welding method and an aluminum alloy member that can be used.

Aluminum or aluminum alloys (hereinafter typically referred to as aluminum alloys) are widely used because they have features such as light weight, good thermal conductivity, and resistance to induction. It is also being used by departments. Examples of this include the structures of railway vehicles, the hulls and superstructures of ships, and the aluminum alloy plates used in these large structures are bulky and the weld lines are long. On the other hand, due to its characteristics, aluminum is often used as a thin plate, and long thin plates are often welded together. Therefore, the generation of welding distortion is cited as the first drawback in welding work, and conventionally restraint welding and peripheral cooling welding are performed, but in the case of restraint welding, even though the equipment is large-scale, distortion The prevention effect is weak. On the other hand, for peripheral cooling welding, the only method that has been adopted is to bring water into contact with cotton cloth or a water-absorbing noncombustible cotton-like material, but the cooling effect is insufficient and the steam generated by welding heat enters the welding atmosphere. It can also become full and cause a blowhole.

Next to welding distortion, welding defects include micro-cracks due to the low melting point of intermetallic compounds in aluminum alloys and the occurrence of softened regions due to retention of welding heat, but the above-mentioned restraint welding method naturally eliminates these defects. cannot be eliminated, and even the latter peripheral cooling welding method does not have the ability to eliminate these defects due to insufficient cooling.

From this point of view, it is necessary to establish a new peripheral cooling welding method that has high cooling efficiency and does not cause the problem of contamination of the welding atmosphere due to generated air, and as a result, the present invention solves these problems. succeeded in doing so.

That is, the purpose of the present invention is to establish an efficient and safe peripheral cooling welding method to prevent the occurrence of weld distortion and obtain a welded joint free of microcracks, and further to prevent the occurrence of weld softening regions as much as possible. The welding method of the present invention to achieve the above object is to provide a method for welding aluminum alloy members together, and for this purpose to obtain a most effective member to be welded. The gist lies in the method of passing the cooling medium and the provision of a path for the cooling medium necessary for this in the welded member.

The welded joints of aluminum threaded alloy members to which the present invention is applied are applicable regardless of whether they are butted, filleted, overlapped, edged, etc., and the shape of the base metal, the shape of the groove, the welding posture, the welding method, i.e., MIG There are no special restrictions on welding, TIG# welding, etc., welding conditions, etc., but as understood from the above purpose,
It is desirable to avoid excessive welding heat input, and there must be space in the vicinity of the weld line to allow a cooling medium to pass naturally or forcedly. In order to avoid excessive welding heat input, for example, as shown in Figure 1, consideration should be given to satisfying the following condition: (base metal thickness) x (welding heat input) ≦K (where K is a constant). good. Of course, this relationship may have to be modified slightly depending on the cooling conditions, which will be explained in detail later, but the point is that the amount of heat stored in the base material is determined by the size of the cross-sectional area of the base material relative to the heat radiation surface area. It means that the welding heat input should be suppressed as the value increases, and it can be set each time.

Now, the cooling medium that passes near the weld line promotes heat radiation from the heat affected zone of the base metal, but when it passes to the arc generation side, that is, the welding side, the medium mixes into the arc. It is necessary to avoid this by creating a cooling medium passage (hereinafter simply referred to as a passage) along the weld line.
It is necessary to completely block the medium and the vapor generated from the medium from the arc atmosphere by forming a However, the method of forming the cooling medium passage along the arc generating surface side is more efficient and has a reliable cooling effect. When using gas as a cooling medium, the cooling capacity is somewhat inferior, so it is desirable to suppress welding heat input or increase the amount of air flow, which may be somewhat difficult in terms of cooling management, but liquid or mist For example, when using liquid nitrogen, cold water, hot water, etc., the cooling ability is excellent and cooling management becomes easy, so it is generally recommended to use liquid or mist.

The form of the cooling medium passage will be clarified in the examples described later, but depending on the installation position in the structure, it may be possible to leave the cooling medium passage as it is.
If a plate material is used for such a portion, the passage can be integrally formed at the same time as the extrusion molding of the aluminum alloy member, reducing the welding preparation work. On the other hand, if it is better to remove the passage after welding, prepare a square pipe-shaped or groove-shaped passage and attach it near the weld line by pressure welding or gluing. This is advantageous in terms of material costs because the hind limb passageway can be used for other welding base materials.

It is also possible to form radiation fins on the welding base metal side within the passage to increase the cooling capacity. In addition, although the above-mentioned passages are generally formed on the left and right sides with the weld line in between, mechanical distortion can be avoided by appropriately combining them on the left and right sides or front and back sides, or by connecting them with beams in the direction orthogonal to the weld line. It can also be a prevention structure. In addition, if one side of the weld base metal has a structure that does not easily cause weld distortion, or is made of a material that does not easily cause microcracks or weld softening areas, It is also possible to adopt a structure in which the passage is formed only on the material side.

The present invention will be explained below with reference to the drawings.

Figure 2 shows an aluminum alloy plate 1 formed by integrally extruding a passage 2 with a rectangular cross-section in the direction along the welding line W on the opposite side of the welding arc generating surface of the aluminum alloy plate L.
This is an explanatory diagram of butt welding, and a ■-shaped groove is formed at the butt part.

Further, 4 is a medium introduction member for inserting into the passage 2 and circulating a cooling medium (hereinafter simply referred to as medium) within the passage 2, while 4a is a medium discharging member. Although the medium introducing member 4 and the medium discharging member 4a have the same structure, the former can be freely modified into a shape suitable for introducing a medium, and the latter can be freely modified into a shape suitable for discharging a medium. FIG. 3(a) is a cross-sectional view taken along line mm showing the structure of the medium introduction member 4, in which the medium introduction member 4 covers the tip side of the nozzle 5 with a shoe 6 made of an elastic material such as rubber. are doing. The shape and size of the shoe 6 are such that it can seal or close the opening of the passage 2. Furthermore, a medium pipe 7 is connected to the knob 5.

When welding aluminum alloy plate l, the third
(b) As shown in Figure 2 (corresponding to Figure 2 showing the inserted state), the medium introduction member 4 and the medium discharge member 4a are inserted into the opening of the passage 2 of the aluminum alloy plate l to seal the passage 2 and introduce the medium. A refrigerant flow is formed in the passage 2 by introducing refrigerant from the member 4 and extracting it from the refrigerant discharge member 4a.

Once these preparations are complete, welding (MIG welding, etc.) of the groove W is started. As a result, the heat transmitted to the heat-affected zone is transmitted to the medium in the passage 2 through the wall of the aluminum alloy plate and carried out of the system, so the temperature near the weld line does not rise excessively, and the entire aluminum alloy plate It can also prevent heat transfer to. As a result, distortion of the aluminum alloy plate material due to welding heat is prevented, and problems such as the occurrence of microcracks and softened regions can also be avoided.

In the second embodiment, welding of an aluminum alloy plate material in which the cross-sectional shape of the passage 2 is rectangular has been described, but there is no particular restriction on the shape of the aluminum alloy plate material or the cross-sectional shape of the passage. Welding of aluminum alloy plates having the shape shown in FIG. 11 can be carried out in the same manner. In addition, in FIGS. 4 to 6 and 8.9, only one base material to be welded is representatively shown, and the arrows in the figures all indicate the pointing position and direction of the welding torch.

Fig. 4 shows an example in which a passage 2 with a semicircular cross-section is formed on the opposite side of the welding arc generation surface of a flat aluminum alloy plate I, and Fig. 5 shows the welding arc generation surface and An example in which passages 2 each having a rectangular cross section are formed on the surface opposite to that surface, and FIG. 6 shows an example in which two facing aluminum alloy plates 1.1 are connected by a crosspiece 8.
The cavity portions at both ends serve as passages 2, respectively. FIG. 7 shows a modification of the example shown in FIG.
and four parts 9b are formed on the other crosspiece 8a, and during welding, the convex part 9a and the concave part 9b are formed.
By fitting these, we aim to improve the resistance to thermal distortion and increase the heat transfer area from the welded area. FIG. 8 shows an example in which passages 2 each having a rectangular cross section are formed on the inner surface of both ends of a curved aluminum alloy plate l. 9th
The figure shows an example in which passages 2 each having a rectangular cross section are formed on the inner surface near both ends of a U-shaped aluminum alloy plate material 1. In these examples, the medium passage was placed a little away from the weld line, but it is also possible to place it directly below the butt weld.
Fig. 1O shows an example in which a rectangular cross-section pipe 15 (not limited to aluminum) that also serves as a backing material is attached to the lower side of the butt surface, and Fig. 11 shows an example in which a medium passage is integrated under one aluminum alloy plate. An example is shown in which the groove is extruded so as to protrude toward the bottom side, and a normal aluminum alloy plate is butted and welded to this. Next, FIG. 12 is a perspective view showing an embodiment in which fillet welding is performed, in which a groove member 1 is placed on the back side of the aluminum alloy 1b standing position of the flat aluminum alloy member I.
0 (aluminum, copper, steel, rubber, etc. are used) are brought into close contact with each other by a tightening member 11 or the like to form a passage 2. In the illustrated example, the pin attached to the longitudinal surface of the groove member is fixed by the tightening member 11, but it is also possible to switch to a band method. Further, the groove member can be replaced with a pipe having a rectangular cross section. FIG. 13 is a trunk view showing an example of butt circumferential welding between tubular aluminum alloy members la, in which first welding tubes are provided near both sides of the butt portion.
An example is shown in which band-shaped passage members 12 each having a semicircular cross section as shown in FIG. 4 (cross-sectional view taken along the line W-Xllll in FIG. effect can be obtained.

Next, MIG welding was performed on the aluminum alloy member having the shape shown in Figure 2 under the conditions shown in Table 1, and the strain, microcracks, width of the softened area, etc. were investigated, and the results shown in Table 2 were obtained. .

Material to be welded: A6063-T5 Wall thickness 2mm Table 2 Welding results In addition, each welding result was derived by the following measurement method.

(1) Welding strain ■ Lateral shrinkage: Lateral shrinkage at three locations sandwiching the weld line was measured using a contact strain gauge (gauge length 60a+m). Values indicate average values.

■Vertical shrinkage: 3011111+1 from the weld line! t
The longitudinal shrinkage at (4 locations) was measured using a contact strain gauge (gauge length 100 mm). Values indicate average values.

■Angular deformation: Out-of-plane deformation at a position 125 mm from the welding start position was measured with a dial gauge, and the angle was calculated and defined as angular deformation.

(2) Microcracking measurement method The cross section of the welded part was examined under a microscope, and eutectic melting and microcracks were quantified according to Table 3 below. The value shows the average value of 4 points.

Table 3 (3) The hardness distribution of the cross section of the welded part was measured to determine the width of the softened region.

(4) Maximum temperature As shown in FIG. 15, the temperature was measured by attaching a heat label 13 to the outer side of the medium passage 2 on the side of the aluminum alloy plate.

As shown in Table 2, compared to Al-A3, Wl-W3
It can be judged that each of these is excellent in terms of welding distortion, microcracks, and width of the softened region. Furthermore, the maximum temperature in the example remains about 110° C. lower than that in the comparative example, which also shows that running water cooling effectively prevents the temperature rise in the vicinity of the weld line.

Furthermore, in carrying out the present invention, it is desirable to adjust the cooling capacity, in other words, the amount of medium flowing through the passages, to such an extent that the above object can be achieved. Wood inventors, etc. "2 medium flow rate (
In the case of water), as a result of examining the preferable setting range, the appropriate range shown in the graphs of FIGS. 16 to 18 was obtained. In the study, experimental welding was performed using an aluminum alloy plate material having a shape as shown in FIG. 19. The symbols in the figure have the following meanings.

A: Welding current (ampere) ■・Welding voltage (volts) T: IiJ material thickness (mIB) d: Width of joint surface (IIll) d=dt+dz However, d1=d2 Note that if no groove is provided, the joint surface The width d can be replaced with the approximate bead width.

That is, FIG. 16 is a graph showing the relationship between the cooling water flow rate and the base material thickness, and the relationship between the two is α (cooling water flow rate)×(base material thickness)≧. In the case of the experimental example, Ka=40 (mm*c
Figure 17 is a graph showing the relationship between welding heat input and cooling water flow rate, and the relationship between the two is (cooling water flow ≧ β × (welding heat input). Furthermore, β = (cm3
/KJ). Figure 18 is a graph showing the relationship between heat input per width of unit joint surface and base material thickness. As mentioned above, (heat input per unit joint surface rb) x (base material thickness) ≦ α In a relationship. Note that K a = 1.2 (KJ/mm a
see).

When actually welding, determine the appropriate welding heat input from Figure 18 according to the shape of the base material (thickness and width of the joint surface), and determine the appropriate cooling water input from Figures 16 and 17. &11,
By welding, welding can be performed in such a way that welding distortion and the width of the softened region are made as small as possible without generating microcracks. In this case, the defined conditions must be included in any of the appropriate areas shown in FIGS. 16-18. Examples in which water cooling was effective are shown by X marks in FIGS. 16 to 18.

Since the present invention is constructed as shown in FIG. As a result, welding distortion and microcracks were eliminated, and the occurrence of softened areas was also extremely reduced.

[Brief explanation of drawings]

Fig. 1 is a graph showing the general relationship between welding base material plate thickness and heat input, Fig. 2 is a perspective view conceptually showing the implement of the present invention, and Fig. 3(a) is a graph showing the - in Fig. 2. M-line cross-sectional view, 3rd
(b) The figure is a corresponding diagram showing the sealing state to the passage, Nos. 4 to 11.
Figure 12 is a sectional view showing an example of the formation of a refrigerant passage made of the aluminum alloy member of the present invention, Figure 12 is a perspective view showing an example of application to fillet welding, and Figure 13 is a perspective view showing an example of application to butt welding of pipes. , Fig. 14 is a sectional view taken along the line W-W in Fig. 13, Fig. 15 is a sectional view showing the installation state of the heat label in the maximum temperature measurement method, and Fig. 16 is a diagram showing the base material thickness and cooling water flow rate. Graph showing the relationship, Figure 17 is a graph showing the relationship between cooling water flow rate and welding heat input, Figure 18 is a graph showing the relationship between base material wall thickness and heat input per unit joint surface width, Figure 19
The figure shows a cross-sectional view of the experimental weld. 1... Aluminum alloy plate material or member 2... Cold tofu passage Applicant Kobe Steel, Ltd. Figure 16 Cooling water galvanic current (bacteria/5ec) Heat input A V per unit width of joint surface -7- (KJ /sec@mm) Figure 19 Hand-kei sales official book (spontaneous) yo] l,・I 9 indications 1982 Patent Application No. 142361 2 Title of invention Method for welding aluminum or aluminum alloy members and aluminum Alloy member 3, person making amendment 17, relationship with 11 cases Patent applicant No. 3-18 Wakihama-cho, Chuo-ku, Kobe City (119) Kobe Steel, Ltd. Representative Fuyuhiko Maki 4, agent 530 Shinko Building, 2-3-7 Dojima, Kita-ku, Osaka
I will correct bJ. (2) Replace “Table 1” on pages 12-13 with an attached sheet. (3) “Kβ= (Cm /KJ)” on page 18, line 8 of the same
Correct J to ``Kβ = 3 (am3/KJ) 4.'' (4) Correct ``≦ to α'' to ``≦ to γ'' on page 18, line 11. (5) Correct "Kα" in line 12 of page 18 to "Kγ". (8) Replace Figures 15, 16, and 17 of the drawings with attached sheets.

Claims (2)

[Claims] (1) A method for welding aluminum or aluminum alloy members, characterized in that a cooling medium passage is provided near the weld line of the aluminum or aluminum alloy member, and the cooling medium is cooled by passing through the passage. (2) An aluminum alloy member characterized in that a cooling medium passage along the weld line is provided near the weld line and integrally with the weld base material.