KR101103295B1 - Joining method of different materials - Google Patents

Abstract

PURPOSE: A joint method for different materials is provided to prevent a metal compound layer formed in a junction part by employing short-circuit arc welding. CONSTITUTION: A joint method for different materials is as follows. A first sheet(10) of SACD and a second sheet(20) of aluminum are overlaid. A welding wire(30) of AlSi_3Mn is located on a surface to be welded to the first sheet. Short-circuit arc welding, which alternately creates short-circuit and arc, is implemented in a junction part of the first and second sheets. Down-up-down motion is repetitively implemented while the welding wire is melted at the cycle of 0.6m/min. At the same time, the overlaid first and second sheets are advanced at a specified speed and the junction part is solidified to form a bead. The first and second sheets are welded while being advanced at the speed of 5mm/sec.

Description

Joining method of different materials

The present invention relates to a dissimilar metal bonding method, specifically, to induce an interfacial reaction through short-circuit operation between SACD and aluminum, thereby minimizing the compound layer between SACD and aluminum, thereby reducing productivity and manufacturing cost. It relates to a bonding method.

In general, most of the various components constituting the vehicle is used an iron-based material, and since these iron-based materials have a sense of weight, some aluminum-based materials are used to reduce the weight. As a method of joining the iron-based material and the aluminum-based material, a soldering method using an aluminum-based brazing material is a common method of joining the iron-based material and the aluminum-based material.

The joining of such iron-based materials and aluminum-based materials is usually widely used when joining a protector to a muffler or exhaust manifold of a vehicle. The exhaust manifold is a pipe for collecting exhaust gas discharged from a plurality of cylinders provided in the engine of the vehicle into one place, and is connected to an exhaust port provided on one side of the cylinder head of the engine.

The exhaust gas inputted to the exhaust manifold is a high temperature of about 600 to 900 ° C., and the vehicle is discharged to the rear side while passing through a catalytic converter, an exhaust pipe, a silencer, etc. continuously connected to the rear of the exhaust manifold. Therefore, a significant amount of heat is dissipated to the outside of the exhaust system including the exhaust manifold and the muffler, and heat protector (Heat) is prevented to prevent the heat emitted to the outer surface of the exhaust manifold from being thermally applied to the engine peripherals. Protector) is formed to cover the outside of the exhaust manifold and muffler.

Such exhaust manifolds, mufflers and heat protect joints are generally soldered using aluminum-based brazing as a method of joining between iron-based and aluminum-based materials. The above solder is generally used as a method of joining the same material. In the melt welding method such as laser welding, a brittle Al-Fe-based intermetallic compound such as Al ₃ Fe is generated at an interface between an aluminum-based material and an iron-based material, and thus, between the aluminum-based welded material and the iron-based welded material. There was a problem of significantly lowering the joint strength.

In order to solve this problem, instead of soldering, an aluminum-based material and an iron-based material may be joined by spot welding, and a laser roll method of dissimilar metals is also proposed. This method is a method of joining both metal plates by performing plastic deformation after heating only the first metal plate in accordance with laser irradiation, pressing the heating part of the first metal plate to the second metal plate by using a pressure welding roller, and then adhering to the second metal plate. .

Despite these advantages, however, when joining dissimilar metals (or alloys) that are not homogeneous by the brazing joining method, in most cases intermetallic compounds, which are very fragile due to reaction between two base metal components or intercalating alloy components, There is a problem of lowering the toughness of the joint is formed, and furthermore, the development of technology to overcome the problem that the steel plate is oxidized after a long time because the aluminum plating layer of the steel sheet is damaged.

The present invention has been invented to solve the above problems, and its object is to provide a dissimilar metal joining method capable of joining SACD and aluminum through a short-circuit transfer method to a joining wire formed of AlSi ₃ Mn. have.

The present invention for achieving the above technical problem is a step of overlapping each other the first plate formed of SACD material and the second plate formed of aluminum material; Positioning the bonding wire formed of AlSi ₃ Mn on the surface to be bonded to the first plate and the short circuit for generating a short circuit and an arc alternately to the portion to be bonded to the first and second plate material While the wires are melted at a rate of 0.6 m / min, the descending-rising-down movement is repeatedly performed, and the overlapping first and second plates are moved at a predetermined speed to solidify the joints, thereby creating beads. It is characterized in that the plate and the second plate is joined.

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In one embodiment, during the joining operation, the first plate and the second plate is advanced at a speed of 5mm / sec, the aluminum wire is supplied with a current of 80A, a voltage of 12.4V, the length of the arc 30 % And pulses are characterized by three.

In one embodiment, characterized in that at the end of the second plate during the joining operation.

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In one embodiment, the first plate and the second plate during the joining work is characterized in that the joining work with a space of 0.2mm.

According to the dissimilar metal joining method of the present invention, since metals having different materials are joined through a short-circuit performing method, the metal compound layer that has previously occurred is eliminated at the joining part, and thus the work process is not performed after the joining work. The simplicity and economy of the effect is increased, and the aluminum layer coated on the base material is left as it is, it is a great effect to lengthen the life of the workpiece.

1 is a view for showing the order of progress in the dissimilar metal bonding method of the present invention.
2 is a view showing the results of the experiment of Example 1 of the dissimilar metal bonding method of the present invention.
3 is a view showing the results of the experiment of Example 2 of the dissimilar metal bonding method of the present invention.
4 is a view showing the results of the experiment of Example 3 of the dissimilar metal bonding method of the present invention.
5 is a view showing the results of the experiment of Example 4 of the dissimilar metal bonding method of the present invention.
6 is a view showing the results of the experiment of Example 5 of the dissimilar metal bonding method of the present invention.

In order to fully understand the present invention, preferred embodiments of the present invention will be described with reference to the accompanying drawings. Embodiment of the present invention may be modified in various forms, the scope of the invention should not be construed as limited to the embodiments described in detail below. This embodiment is provided to more completely explain the present invention to those skilled in the art. Therefore, the shape of the elements in the drawings and the like may be exaggerated to emphasize a more clear description. It should be noted that the same members in each drawing are sometimes shown with the same reference numerals. In addition, detailed descriptions of well-known functions and configurations that are determined to unnecessarily obscure the subject matter of the present invention are omitted.

Hereinafter, by describing the preferred embodiment of the present invention with reference to the accompanying drawings, it will be described in detail the dissimilar metal bonding method of the present invention.

Firstly, short circuiting arc welding, also known as short-circuit welding, involves keeping the arc length short so that arcs and shorts alternate with each other and pinch the short-circuit current that flows when the wire volume is shorted to the substrate. It refers to a method of welding using a phenomenon in which a volume shifts due to an effect).

This welding method uses a dip-transfer type transition phenomenon to prevent a sudden increase in current during a short circuit by inserting a reactor into the welding circuit. There is no burn-through and the volume moves quietly. It is a welding method suitable for welding light alloys or thin plates due to low penetration.

And SACD used in the present invention, the molten aluminum plated steel sheet is called aluminized steel sheet. Since aluminum is plated on the surface, it is a steel plate used where not only the corrosion resistance of the body but also heat resistance is required.

Hereinafter, the method for joining dissimilar metals of the present invention will be described.

In the following examples, tensile strength and bead shape according to welding current, welding speed, and gap change, which are variables of representative short-circuit method, for the analysis and evaluation of heterojunction welding phenomenon with SACD material in low heat input pulse MIG welding of thin aluminum alloy The characteristics of.

In order to select proper welding condition for heterojunction, welding was performed within the range of 50 ~ 96A and welding speed was within 0.4 ~ 1m / min. The torch angle was welded in the overlap welding by 10 ° advance and 65 ° angle with the base metal. The protective gas was 100% Ar, the flow rate was 15 / min, CTWD (contact tip to workpiece distance) was fixed at 14mm, and in the case of tensile specimens the overlap interval was 30mm. The low heat MIG Pulses arc welder will use Fronius' CMT TransPlus Synergic 3200.

In order to find out the proper welding conditions for dissimilar metal joints of Al 6k21 material with a thickness of 1mm and SACD, an aluminum plating material with a thickness of 1.6mm, the analysis was performed according to the change of welding current and welding speed. Table 1 shows the results of the welding of dissimilar metals performed up to the determination of proper welding conditions, and shows the bead shape generated by welding in FIG. 2.

No current
(A) voltage
(V) welding speed (m / min) Mode Etc result One 50 11.2 0.4








AlSi5 1.2 CMT








1.2 mm
4047
Wire Narrow bead width,
Shape convexity 2 50 11.2 0.6 Narrow bead width,
Shape convexity 3 59 11.5 0.4 Good 4 59 11.5 0.6 Bead width not wide,
Shape convexity 5 69 12.0 0.4 Good, bead slightly larger 6 69 12.0 0.6 Good 7 69 12.0 0.8 Bead width thin and narrow 8 80 12.4 0.4 Bead hypertrophy 9 80 12.4 0.6 Very good 10 80 12.4 0.8 Very good 11 80 12.4 1.0 Bead width narrowing arc instability 12 89 12.6 0.6 Beads are wide and big 13 89 12.6 0.8 Good 14 89 12.6 1.0 Good side, small bead size 15 96 12.7 0.8 Good 16 96 12.7 1.0 Good 17 96 12.7 1.2 Arc anxiety at high speed,
Bead irregular

In the above 17 conditions, the first and second plates 10 and 20 are overlapped with each other, and the aluminum wire 30 is shorted 100 times per second to the aluminum wire 30 mounted on the rotating means 40. Melt and settle on the joint.

As shown in FIG. 1, first, the aluminum wire is lowered toward the junction (a), and when the junction is reached, the short circuit and the arc are repeated to rise while melting the aluminum wire at the junction ((b)-(c)). -(d) process). After (e) in the last step to finish the aluminum wire is lowered.

Repeatedly performing such a task is to join a predetermined section.

Thereafter, after the predetermined time has elapsed, the molten part is solidified to join the first plate and the second plate.

When this operation is completed, a bead (bead) is generated in the joint surface as shown in FIG.

As shown in FIG. 2, in the no. 1 and no. 2 conditions, the bead width was narrow and the shape was convex upward due to the low welding current. The no.3 condition shows good bead width on the surface, but tends to be biased towards the lower SACD material from the middle of the bead. The no.4 condition is the result of welding by increasing the welding speed to 0.6 m / min under the no.3 condition. The bead width is thin and does not spread widely. In condition no.5, the welding was performed by increasing the current by 10A, and the overall welding was good, but the bead width was slightly larger. The no.6 condition is the result of welding by increasing the welding speed to 0.6 m / min under the no.5 condition. Overall, the welding is good but the bead width is slightly narrow. The no.7 condition is the result of welding by increasing the welding speed to 0.8 m / min. It can be seen that the bead width is narrow and narrow, and the brazing between the upper and lower plates is not performed properly. The no.8 condition shows that the bead width is very large due to the high current and low welding speed. The no.9 condition is the result of welding by increasing the welding speed to 0.6 m / min under the no.8 condition and showed very good weldability. The no.10 condition is the result of welding with a higher welding speed of 0.8 m / min. The bead width is narrower than the no.9 condition, but the overall welding characteristics are good. The condition no.11 is the result of welding by increasing the welding speed to 1m / min. It can be seen that the bead width became narrow and the arc became unstable. The condition no.12 shows that the bead is wide and bloated because it is not proportional to the welding current and speed. No.13 showed good weldability in general, but it could be seen that the molten pool was biased to the bottom plate after the middle of the bead. No.14 showed good weldability in general, but slightly narrower bead shape than no.9. The conditions no.15 and no.16 showed good weldability overall. No.17 condition showed arc instability due to fast welding speed and irregular bead shape. The most suitable welding condition by adjusting the welding current and welding speed, which is the basic welding condition, is to make the most ideal bead.

Further experiments were carried out to determine the welding characteristics by adjusting the arc length% based on the current 80A and the welding speed 0.6 m / min in the most appropriate welding conditions of the results of Example 1 above.

Table 2 shows the results of the overlap welding performed up to determine the proper welding condition and shows the bead shape in FIG. 3. As shown in the figure, the most suitable weldability was shown at an arc length of + 30%.

No current (A) voltage (V) welding speed (m / min) Mode Arc
Length result One
80
12.4
0.6 AlSi5 1.2 CMT

30% Good 2 -30% Bead shape misalignment 3 15% Poor quality

Further experiments were performed to analyze the welding characteristics according to the pulse value control under the conditions of Examples 1 and 2. Table 3 shows the results of the overlap welding carried out to determine the appropriate welding conditions and shows the bead shape in FIG. 4.

As shown in the figure, as the pulse value increases in the + direction under no.1, no.2, and no.3 conditions, the bead width increases, and as the value decreases in the-direction, the bead width becomes thinner and convex. Indicates. The best weldability was obtained under the condition of No. 1 with a pulse value of 3. Under no.5 conditions, the bead width was enlarged and melting with the top plate was not performed properly.

No current (A) voltage (V) welding speed (m / min) Mode Pulse result One 60 14.4 0.6
AlSi5 1.2 CMT
Pulse 3 Very good,
Bead spreads wide 2 60 14.4 0.6 5 Bead width very wide spread 3 60 14.4 0.6 -3 Bead Width Thinner 4 60 14.4 0.8 3 Good 5 80 15.0 0.8 3 Bead width

According to the embodiment described above, while the first plate and the second plate proceeds at a speed of 5 mm / sec during the shorting operation, the aluminum wire is melted at a cycle of 0.6 m / min, but the current is 80 A, the voltage is When supplied at 12.4V, the arc length is 30% and the pulse is 3, it can be seen that the junction between dissimilar metals is ideally achieved.

Hereinafter, experiments were conducted to find out where the most ideal bead is produced when the location of the aluminum wire was placed in the bonding operation under the conditions of the above embodiments, and the results are shown in FIG. 5.

Referring to FIG. 5, in the position (a), the molten pool movement to the steel sheet did not occur, and thus the joining itself was not performed. In addition, in the positions of (c) and (d), although aluminum and steel are joined to some extent, spatter is generated a lot, and thermal deformation is severe due to direct arc heat input to the steel plate, and separation due to deformation occurs after welding. do. In addition, the arc tends to occur toward aluminum, resulting in irregular bead shapes. Therefore, as shown in (b), the joining work in the state where the aluminum wire is located at the aluminum end creates the most ideal bead.

Hereinafter, two tensile strength experiments were performed to determine the tensile strength under the conditions of Examples 1 to 4, and the results are shown in Table 4, and the shape of the bead cross section is shown in FIG. 6.

No current (A) voltage (V) welding speed (m / min) Gap (mm) Tensile Strength Result (Mpa) One


80


12.4


0.6 0 161.4 (Weld Break) 168.9 (Weld Break) 2 0.2 226.7
(Al base material fracture) 228.6
(Al base material fracture) 3 0.3 148.6 (Weld Break) 163.6 (Weld Break) 4 0.5 154.6 (Surface Break) 213.2 (Surface Break)

As described in the above embodiment, as can be seen from the tensile strength results, the welding was performed with a gap of 0.2 mm, showing the highest tensile strength and tensile failure. In the case of welding with a gap of 0.5 mm, tensile fracture occurred at the weld interface between aluminum and SACD.

Therefore, compared to the conventional joining method, the weakness of the joint interface is overcome, and the joint strength is increased, the metal compound layer generated after the conventional welding work is not generated, and the work process is simplified. The effect is to improve long.

Embodiment of the dissimilar metal bonding method of the present invention described above is merely illustrative, and those skilled in the art to which the present invention pertains that various modifications and equivalent other embodiments are possible from this well. You will know. Therefore, it will be understood that the present invention is not limited to the forms mentioned in the above detailed description. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims. It is also to be understood that the present invention includes all modifications, equivalents, and substitutes within the spirit and scope of the invention as defined by the appended claims.

10: first plate 20: second plate
30: aluminum wire 40: rotation means

Claims (6)

Superposing a first plate formed of SACD and a second plate formed of aluminum;
Placing a joining wire formed of AlSi ₃ Mn on a surface to be joined to the first plate; and
While repeatedly performing the falling-up-down movement while melting the joining wires at a cycle of 0.6 m / min through short-circuit transitions alternately generating short circuits and arcs at the portions to be joined to the first and second plates, A method of joining dissimilar metals, characterized in that the first and second dissimilar sheets are joined by advancing the overlapping first and second sheets at a predetermined speed so that the joints are solidified to generate beads. delete delete The method according to claim 1,
In the joining operation,
The first and second plates are advanced at a rate of 5 mm / sec, and the aluminum wire is supplied with a current of 80 A and a voltage of 12.4 V, with an arc length of 30% and a pulse of 3, respectively. Dissimilar metal bonding method. The method according to claim 1,
When joining
Dissimilar metal bonding method characterized in that at the end of the second plate. The method according to claim 1,
When joining
Dissimilar metal joining method, characterized in that the first plate and the second plate is bonded at intervals of 0.2mm.

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