JP2021053659A - Welding method, welding device, and method for manufacturing structure body - Google Patents

Abstract

To enable joining the first plate-shaped member and the second plate-shaped member with high joining strength.SOLUTION: A welding method (S1) of the present invention arranges a first plate-shaped member (W1) and a second plate-shaped member (W2) made of dissimilar metals so that a lower surface of the first plate-shaped member (W1) and an upper surface of the second plate-shaped member (W2) are overlapped each other in surface contact; and irradiates the upper surface of the first plate-shaped member (W1) with a laser beam (L) to perform welding. The welding method (S1) of the present invention comprises a setting step (11) of setting welding conditions so that a penetration depth from the first plate-shaped member (W1) to the second plate-shaped member (W2) becomes 0.2 mm or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a welding method and a welding apparatus for welding two plate-shaped members made of dissimilar metals using a laser beam. The present invention also relates to a manufacturing method for manufacturing a structure including two plate-shaped members made of dissimilar metals.

Conventionally, it has been considered difficult to obtain high bonding strength in dissimilar metal bonding. Reasons for this include the fact that an intermetallic compound having low toughness is likely to be formed at the boundary between different types of metals, and that the coefficient of linear expansion and thermal conductivity differ between different types of metals.

However, in recent years, there has been an increasing need for dissimilar metal bonding capable of obtaining high bonding strength. For example, at the manufacturing sites of automobiles and aircraft, where both energy saving and safety are required, aluminum members with excellent lightness and iron members with excellent robustness are joined with high joint strength. There are strong expectations for the technology to be used.

Dissimilar metal welding is roughly classified into resistance welding, friction stir welding, and laser welding. Of these, in resistance welding, when a joint point is generated between members by welding, a current flows between the members through the joint point, so that a new joint point cannot be provided in the vicinity of the joint point. Therefore, resistance welding has a problem that it is difficult to increase the joint area and improve the joint strength. Further, in the friction stir welding, there is a problem that high bonding strength cannot be obtained unless the surfaces of the members to which the rotating tools are brought into contact with each other are aligned with each other with high accuracy. Laser welding does not cause these problems. For this reason, attention is increasing to dissimilar metal bonding using laser welding. Documents disclosed about laser welding include, for example, Patent Documents 1 to 4.

JP-A-2017-152703 JP-A-2019-000878 International Publication No. 2013/1672440 Japanese Unexamined Patent Publication No. 2012-135811

However, the first plate-shaped member made of a dissimilar metal and the second plate-shaped member are overlapped with each other so that the lower surface of the first plate-shaped member is in surface contact with the upper surface of the second plate-shaped member. When welding by irradiating the upper surface of the plate-shaped member of No. 1 with a laser beam, there are the following problems.

That is, when the upper surface of the first plate-shaped member is irradiated with the laser beam, the first metal constituting the first plate-shaped member is melted around the irradiation point to form a molten pool. The molten pool reaches the lower surface of the first plate-shaped member, and the molten first metal melts into the second plate-shaped member. At this time, an intermetallic compound having low toughness is formed at the joint between the first plate-shaped member and the second plate-shaped member. Then, brittle fracture is likely to occur at the joint portion between the first plate-shaped member and the second plate-shaped member. As a result, the joint strength between the first plate-shaped member and the second plate-shaped member is reduced.

One aspect of the present invention has been made in view of the above problems, and makes it possible to join a first plate-shaped member made of a dissimilar metal and a second plate-shaped member with high joining strength. With the goal.

In the welding method according to the first aspect of the present invention, a first plate-shaped member and a second plate-shaped member made of dissimilar metals are used, and the lower surface of the first plate-shaped member is the upper surface of the second plate-shaped member. This is a welding method in which the upper surface of the first plate-shaped member is welded by irradiating the upper surface of the first plate-shaped member with a laser beam, and is welded from the first plate-shaped member to the second plate-shaped member. It is characterized in that it includes a setting step of setting welding conditions so that the penetration depth of the laser beam is 0.2 mm or less.

According to the above method, the penetration depth from the first plate-shaped member to the second plate-shaped member is 0.2 mm or less, so that the boundary between the first plate-shaped member and the second plate-shaped member is formed. In, it is difficult to form an intermetallic compound having low toughness. Therefore, brittle fracture is unlikely to occur at the joint between the first plate-shaped member and the second plate-shaped member. Therefore, it becomes possible to join the first plate-shaped member and the second plate-shaped member with high joining strength.

In the welding method according to the second aspect of the present invention, in addition to the features of the welding method according to the first aspect, the first plate-shaped member and the second plate-shaped member perform linear motion in the irradiation of the laser beam. At the same time, it is carried out in a state where the irradiation point of the laser beam performs elliptical motion, and the locus of the irradiation point that performs elliptical motion is the velocity of the first plate-shaped member and the second plate-shaped member that perform linear motion. It has the feature of drawing an ellipse having a minor axis parallel to the direction and a major axis perpendicular to the velocity direction.

According to the above method, the locus of the irradiation point of the laser beam drawn on the upper surface of the first irradiation point is densely arranged along the velocity direction of the first plate-shaped member and the second plate-shaped member that move linearly. Can be placed. Therefore, the joint area between the first plate-shaped member and the second plate-shaped member can be increased, and as a result, the joint strength between the first plate-shaped member and the second plate-shaped member is further increased. be able to.

In the welding method according to the third aspect of the present invention, in addition to the features of the welding method according to the second aspect, in the setting step, the penetration depth from the first plate-shaped member to the second plate-shaped member is determined. The width of the welding mark formed on the upper surface of the first plate-shaped member so as to be 0.2 mm or less is the locus of the irradiation point of the laser beam drawn on the upper surface of the first plate-shaped member. It has a feature that it is a step of setting the welding conditions so as to have a pitch equal to or higher than the above.

According to the above method, the width of the welding mark formed on the upper surface of the first plate-shaped member is equal to or larger than the pitch of the trajectory of the laser beam irradiation point drawn on the upper surface of the first plate-shaped member. The locus of the laser beam irradiation point drawn on the upper surface of the first irradiation point can be arranged without a gap along the velocity direction of the linearly moving first plate-shaped member and the second plate-shaped member. Therefore, the joint area between the first plate-shaped member and the second plate-shaped member can be further increased, and as a result, the joint strength between the first plate-shaped member and the second plate-shaped member can be further increased. Can be enhanced.

In the welding method according to the fourth aspect of the present invention, in addition to the features of the welding method according to any one of the first to third aspects, the first plate-shaped member having the same material and thickness as the first plate-shaped member. The sample member and the second sample member having the same material and thickness as the second plate-shaped member are superposed so that the lower surface of the first sample member is in surface contact with the upper surface of the second sample member. Further includes a trial welding step of performing trial welding by irradiating the upper surface of the first sample member with a laser beam, and the setting step is a step of setting the welding conditions based on the result of the trial welding. It has the feature of.

According to the above method, welding conditions can be easily set.

The method for manufacturing a structure according to the fifth aspect of the present invention is a method for manufacturing a structure including two plate-shaped members made of dissimilar metals, and according to the welding method according to any one of the first to fourth aspects. It is characterized by including a welding process of welding two plate-shaped members.

According to the above manufacturing method, it is possible to manufacture a structure in which the first plate-shaped member and the second plate-shaped member are joined with high joining strength.

In the welding apparatus according to the sixth aspect of the present invention, the first plate-shaped member and the second plate-shaped member made of dissimilar metals are provided, and the lower surface of the first plate-shaped member is the upper surface of the second plate-shaped member. A welding device that welds by irradiating the upper surface of the first plate-shaped member with a laser beam so as to be in surface contact with the first plate-shaped member, from the first plate-shaped member to the second plate-shaped member. It is characterized in that the welding conditions are set so that the penetration depth of the laser beam is 0.2 mm or less.

According to the above configuration, the first plate-shaped member and the second plate-shaped member can be joined with high joining strength.

According to one aspect of the present invention, it is possible to join the first plate-shaped member and the second plate-shaped member with high joining strength. Further, according to one aspect of the present invention, it is possible to manufacture a structure in which the first plate-shaped member and the second plate-shaped member are joined with high joining strength.

It is a perspective view which shows typically the structure of the welding apparatus which concerns on one Embodiment of this invention. It is a top view which shows typically the upper surface of the work welded by the welding apparatus shown in FIG. It is an SEM image which shows the cross section of the work welded by the welding apparatus shown in FIG. It is a flowchart which shows the flow of the welding method which concerns on one Embodiment of this invention. It is a figure which shows the Example (the iron plate and the aluminum plate are welded so that the penetration depth is 0.20 mm or less, and the irradiation locus is spiral). (A) is an SEM image showing a cross section of the work. (B) is an SEM image showing the upper surface of the second work that has been tension-peeled. (C) is an SEM image showing the lower surface of the first work that has been tension-peeled. (D) is an X-ray analysis image showing the distribution of aluminum in the cross section of the work. (E) is an X-ray analysis image showing the aluminum distribution in the cross section of the work. (F) is an enlarged SEM image of the fractured joint on the upper surface of the second work that has been tension-peeled. (G) is an enlarged SEM image of the joint portion broken on the lower surface of the first work that has been tension-peeled. It is a figure which shows the 1st comparative example (the iron plate and the aluminum plate are welded so that the penetration depth becomes larger than 0.20 mm, and the irradiation locus becomes spiral). (A) is an SEM image showing a cross section of the work. (B) is an SEM image showing the upper surface of the second work that has been tension-peeled. (C) is an SEM image showing the lower surface of the first work that has been tension-peeled. (D) is an X-ray analysis image showing the distribution of aluminum in the cross section of the work. (E) is an X-ray analysis image showing the aluminum distribution in the cross section of the work. (F) is an enlarged SEM image of the fractured joint on the upper surface of the second work that has been tension-peeled. (G) is an enlarged SEM image of the joint portion broken on the lower surface of the first work that has been tension-peeled. It is a figure which shows the 2nd comparative example (the iron plate and the aluminum plate are welded so that the penetration depth becomes larger than 0.20 mm, and the irradiation locus becomes linear). (A) is an SEM image showing a cross section of the work. (B) is an SEM image showing the upper surface of the second work that has been tension-peeled. (C) is an SEM image showing the lower surface of the first work that has been tension-peeled. (D) is an X-ray analysis image showing the distribution of aluminum in the cross section of the work. (E) is an X-ray analysis image showing the aluminum distribution in the cross section of the work. (F) is an enlarged SEM image of the fractured joint on the upper surface of the second work that has been tension-peeled. (G) is an enlarged SEM image of the joint portion broken on the lower surface of the first work that has been tension-peeled.

(Structure of welding equipment)
The configuration of the welding apparatus 1 according to the embodiment of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 is a perspective view schematically showing the configuration of the welding apparatus 1.

The welding device 1 is a device for welding the work W1 and the work W2 using the laser beam L. The work W1 is a plate-shaped member made of metal (including an alloy). In the present embodiment, an iron plate or a copper plate is assumed as the work W1. The work W2 is a plate-shaped member made of a metal (including an alloy) different from that of the work W1. In this embodiment, an aluminum plate is assumed as the work W2. The works W1 and W2 are superposed so that the lower surface of the work W1 made of a metal having a relatively high melting point is in surface contact with the upper surface of the work W2 made of a metal having a relatively low melting point.

The welding device 1 includes a laser device 11, a delivery fiber 12, a processing head 13, and a stage 14.

The laser device 11 is a device for generating the laser beam L. In this embodiment, a continuous oscillation type fiber laser is used as the laser device 11. The laser device 11 is not limited to the fiber laser. Any device capable of continuously oscillating the laser beam L, such as a continuously oscillating solid-state laser, a liquid laser, or a gas laser, can be used as the laser device 11.

The delivery fiber 12 is an optical fiber for transmitting the laser beam L generated by the laser apparatus 11. In this embodiment, a single mode fiber is used as the delivery fiber 12. The delivery fiber 12 is not limited to single mode fiber. For example, a multimode fiber (optical fiber having 2 or more waveguide modes) such as a fumode fiber (optical fiber having 2 or more and 25 or less waveguide modes) can be used as the delivery fiber 12.

The processing head 13 is a device for irradiating the workpieces W1 and W2 with the laser beam L transmitted through the delivery fiber 12. The processing head 13 has an irradiation point moving mechanism 131. The irradiation point moving mechanism 131 is a mechanism for moving the irradiation point Q of the laser beam L. In this embodiment, a galvano scanner is used as the irradiation point moving mechanism 131. The irradiation point moving mechanism 131 is not limited to the galvano scanner. Any mechanism capable of moving the irradiation point of the laser beam L can be used as the irradiation point moving mechanism 131.

The stage 14 is a device for moving the works W1 and W2. In this embodiment, a biaxial stage (XY stage) is used as the stage 14. The stage 14 is not limited to the two-axis stage. Any device capable of moving the works W1 and W2 can be used as the stage 14.

The movement of the irradiation point Q caused by the operation of the irradiation point moving mechanism 131 is an elliptical movement in the plane on which the upper surface of the work W1 is arranged when viewed from the coordinate system fixed to the ground. Further, the movements of the works W1 and W2 generated by the operation of the stage 14 are linear movements parallel to the plane on which the upper surface of the work W1 is arranged when viewed from the coordinate system fixed to the ground. Therefore, the motion of the irradiation point Q generated by the operation of the stage 14 and the irradiation point moving mechanism 131 is a spiral motion that combines a linear motion and an elliptical motion when viewed from the coordinate system fixed to the works W1 and W2. Therefore, according to the welding device 1, wobbling welding of the workpieces W1 and W2 becomes possible. The locus of the irradiation point Q that moves in an ellipse has an ellipse having a short axis parallel to the speed direction of the linearly moving works W1 and W2 and a long axis perpendicular to the speed direction of the linearly moving works W1 and W2. Draw. Therefore, the spiral locus of the irradiation point Q drawn on the upper surface of the work W1 is densely arranged along the speed direction of the works W1 and W2 as compared with the case where the irradiation point Q makes a circular motion.

FIG. 2 is a plan view schematically showing the upper surface of the work W1 welded by the welding device 1.

Assuming that the velocity of the linear motion of the works W1 and W2 is v [mm / s] and the frequency of the elliptical motion of the irradiation point Q (the number of rotations per second) is f [Hz], the irradiation point Q is the work W1. A spiral locus with a pitch p [mm] is drawn on the upper surface. Here, the pitch p [mm] is given by p = v / f. Hereinafter, the locus of the irradiation point Q drawn on the upper surface of the work W1 will be described as an irradiation locus (with the symbol T if necessary), and the pitch of the irradiation locus T will be referred to as the irradiation locus pitch (the symbol p if necessary). Attach).

(Penetration depth and welding mark width)
When the upper surface of the work W1 is irradiated with the laser beam L using the welding device 1, the material of the work W1 (iron or copper in this embodiment) is melted around the irradiation point Q to form a molten pool. .. This molten pool reaches the lower surface of the work W1, and the material of the molten work W1 melts into the work W2. In this specification, the depth at which the material of the molten work W1 melts into the work W2 is referred to as "melting depth" (with the symbol d if necessary). Further, when the molten pool is cooled and the material of the work W1 solidifies, welding marks are formed on the surface of the work W1. In this specification, the width of the welding mark is referred to as "welding mark width" (with the symbol w if necessary). The penetration depth d [mm] and the welding mark width w [mm] are the linear motion speed v [mm / s] of the workpieces W1 and W2, the elliptical motion frequency f [Hz] of the irradiation point Q, and the irradiation point Q. The major axis radius a [mm] of the elliptical orbit, the minor axis radius b [mm] of the elliptical orbit at the irradiation point Q, the elliptical coefficient r = a / b of the elliptical orbit at the irradiation point Q, the power P [W] of the laser beam L. , The beam profile of the laser beam L, the material of the works W1 and W2, the thickness of the works W1 and W2, and the like.

FIG. 3 is a SEM (Scanning Electron Microscope) image showing a cross section of the workpieces W1 and W2 welded using the welding apparatus 1. In FIG. 3, the penetration depth d and the welding mark width w are illustrated by arrows. As is clear from FIG. 3, the penetration depth d and the weld mark width w can be measured with reference to the cross-sectional images of the welded workpieces W1 and W2. The welding mark width w can also be measured with reference to the top surface image of the work W1.

In FIG. 3, the existence range (dark color region) of the material of the work W1 (iron or copper in the present embodiment) and the existence range (aluminum in the present embodiment) of the material of the work W2 (light color). The boundary with the region) can be easily specified because the penetration depth d is suppressed to 0.18 mm. If the penetration depth d exceeds 0.2 mm, the boundary between the existing range of the material of the work W1 and the existing range of the material of the work W2 cannot be easily specified. This is because an intermetallic compound is likely to be formed between the two.

(Flow of welding method)
The flow of the welding method S1 using the welding apparatus 1 will be described with reference to FIG. FIG. 4 is a flowchart showing the flow of the welding method S1.

The welding method S1 includes a setting step S11, a trial welding step S12, a measurement step S13, a determination step S14, and a main welding step S15.

The setting step S11 is a step in which the operator or the computer controlling the welding device 1 sets the welding conditions (in the present embodiment, the values of the parameters that can be adjusted in the welding device 1). The welding conditions that can be set include the speed v [mm / s] of the linear motion of the workpieces W1 and W2, the frequency f [Hz] of the elliptical motion of the irradiation point Q, and the major axis radius a [mm] of the elliptical orbit at the irradiation point Q. ], The minor axis radius b [mm] of the elliptical orbit at the irradiation point Q, the elliptical ratio r = a / b of the elliptical orbit at the irradiation point Q, the power P [W] of the laser beam L, and the like. In the setting step S11 performed for the first time, a part or all of these welding conditions are set to, for example, predetermined initial conditions. Further, in the setting step S11 performed from the second time onward, a part or all of these welding conditions are set according to, for example, the result of trial welding described later.

The trial welding step S12 is a step in which the operator or the computer controlling the welding device 1 wobbles the sample work SW1 and the sample work SW2 using the welding device 1 according to the welding conditions set in the setting step S11. is there. Here, the sample work SW1 is a plate-shaped member having the same material metal and thickness as the work W1. Further, the sample work SW2 is a plate-shaped member having the same material metal and thickness as the work W2. The sample works SW1 and SW2 are trial-welded in a state where the lower surface of the sample work SW1 is overlapped so as to be in surface contact with the upper surface of the sample work SW2.

In the measurement step S13, the operator or the computer controlling the welding apparatus 1 determines the penetration depth d [mm] and the welding mark width w [mm] with respect to the sample works SW1 and SW2 wobbling welded in the trial welding step S12. This is the process of measuring. In the measurement step S13, for example, the penetration depth d and the welding mark width w are measured with reference to the cross-sectional images of the sample works SW1 and SW2 that have been wobbling welded.

The determination step S14 is a step in which the operator or the computer controlling the welding apparatus 1 determines whether or not the following conditions A and B are satisfied.

Condition A: The penetration depth d measured in the measurement step S13 is 0.2 mm or less.

Condition B: The welding mark width w measured in the measurement step S13 is equal to or larger than the irradiation locus pitch p. Here, the irradiation locus pitch p is calculated according to p = v / f from the speed v of the linear motion of the works W1 and W2 and the frequency f of the elliptical motion of the irradiation point Q set in the setting step S11. To.

When the determination result that both the above conditions A and B are satisfied is obtained in the determination step S14, the main welding step S15 described later is carried out. On the other hand, when the determination result that one or both of the above conditions A and B are not satisfied is obtained in the determination step S14, the above-mentioned setting step S11, trial welding step S12, measurement step S13, and determination step S14 is re-implemented.

For example, when the determination result that the condition A is not satisfied is obtained in the determination step S14, the welding condition adjustment for reducing the penetration depth d is performed in the subsequent setting step S11. As the welding condition adjustment for reducing the penetration depth d, for example, (1) increase the speed v of the linear motion of the workpieces W1 and W2, and (2) increase the frequency f of the elliptical motion of the irradiation point Q. Adjustments can be made to (3) increase the major axis radius a of the elliptical orbit at the irradiation point Q, (4) increase the minor axis radius b of the elliptical orbit at the irradiation point Q, and (5) decrease the power P of the laser beam L. Can be mentioned.

Alternatively, when the determination result that the condition B is not satisfied is obtained in the determination step S14, in the subsequent setting step S11, the welding condition is adjusted to increase the welding mark width w, and the irradiation locus pitch p. Welding conditions are adjusted to reduce the size. The welding condition adjustment for increasing the welding mark width w includes, for example, (1) reducing the speed v of the linear motion of the workpieces W1 and W2, and (2) reducing the frequency f of the elliptical motion of the irradiation point Q. Adjustments can be made to (3) reduce the major axis radius a of the elliptical orbit at the irradiation point Q, (4) reduce the minor axis radius b of the elliptical orbit at the irradiation point Q, and (5) increase the power P of the laser beam L. Can be mentioned. The adjustments for reducing the irradiation locus pitch p include, for example, (1) reducing the velocity v of the linear motion of the works W1 and W2, and (2) increasing the frequency f of the elliptical motion of the irradiation point Q. Can be mentioned.

This welding step S15 is a step in which a worker or a computer controlling the welding device 1 wobble welds the work W1 and the work W2 using the welding device 1 in which the welding conditions are set in the setting step S11. At the stage where the main welding step S15 is carried out, the welding conditions of the welding apparatus 1 are set so as to satisfy the above conditions A and B. Therefore, in the workpieces W1 and W2 welded in the main welding step S15, the penetration depth d is 0.2 mm or less, and the welding mark width w is equal to or more than the irradiation locus pitch p.

When the penetration depth d is 0.2 mm or less, it is difficult to form an intermetallic compound having low toughness at the joint between the work W1 and the work W2. Therefore, brittle fracture is unlikely to occur at the joint between the work W1 and the work W2. Therefore, according to the welding method S1, wobbling welding with high bonding strength can be realized.

Further, when the welding mark width w is equal to or larger than the irradiation locus pitch p, the joint portion between the work W1 and the work W2 is densely formed at the boundary between the work W1 and the work W2. Therefore, the joint strength is unlikely to decrease due to the insufficient joint area. Therefore, according to the welding method S1, it is possible to realize wobbling welding having a higher joining strength.

In particular, in the present embodiment, the locus of the irradiation point Q that moves elliptical has a short axis parallel to the speed direction of the linearly moving works W1 and W2 and a long axis perpendicular to the speed direction of the linearly moving works W1 and W2. Draw an ellipse with. Therefore, by increasing the ellipticity of this ellipse, the irradiation locus pitch p can be increased without increasing the speed v of the linear motion of the works W1 and W2 and increasing the frequency f of the elliptical motion of the irradiation point Q. It can be made smaller. In other words, by increasing the ellipticity of this ellipse, the irradiation locus pitch p can be reduced without increasing the penetration depth d.

In the present embodiment, a configuration is adopted in which the parameters of the welding apparatus 1 are set so as to satisfy both the above conditions A and B, but the present invention is not limited to this. That is, a configuration may be adopted in which the welding conditions of the welding apparatus 1 are set so as to satisfy only the above condition A or only the above condition B. With any configuration, wobbling welding with high joint strength can be realized.

(Work variation)
In the present embodiment, the combination of aluminum and iron and the combination of aluminum and copper are assumed as the combination of dissimilar metals to be welded, but the application target of the present invention is not limited to these combinations. For example, 2 arbitrarily selected from the group consisting of mild steel, high-tensile steel, stainless steel (SUS), aluminum, iron, copper, silver, platinum, tin, lead, magnesium, nickel, titanium, Inconel, tantalum, molybdenum, and tungsten. A combination of two metals can be the target of welding.

(Examples and comparative examples)
Examples of the present invention will be described with reference to FIG. In this embodiment, the workpieces W1 and W2 are welded using the welding device 1 so that the penetration depth d is 0.20 mm or less and the irradiation locus T is spiral. An aluminum plate was used as the work W1. An iron plate was used as the work W2.

FIG. 5A is an SEM image showing a cross section of the workpieces W1 and W2. FIG. 5B is an SEM image showing the upper surface of the work W2 that has been tension-peeled. FIG. 5C is an SEM image showing the lower surface of the work W1 that has been tension-peeled. FIG. 5D is an X-ray analysis image showing the distribution of aluminum in the cross section of the workpieces W1 and W2. FIG. 5 (e) is an X-ray analysis image showing the aluminum distribution in the cross section of the workpieces W1 and W2. FIG. 5 (f) is an enlarged SEM image of the fractured joint on the upper surface of the work W2 that has been tension-peeled. FIG. 5 (g) is an enlarged SEM image of the fractured joint on the lower surface of the work W1 that has been tension-peeled.

In the tensile peeling, the work W1 is pulled by a first force parallel to the joint surface with the work W2, and a second force parallel to the joint surface with the work W1 (opposite to the first force). It means that the works W1 and W2 are peeled off by pulling the work W2 with the force of).

In this embodiment, the parameters of the welding apparatus 1 are set so that the penetration depth from the work W1 to the work W2 is 0.2 mm or less. For example, the power P of the laser beam L was set to 80 W. Therefore, as shown in FIGS. 5 (d) and 5 (e), the formation of intermetallic compounds at the boundary between the work W1 and the work W2 could be sufficiently suppressed. As a result, as shown in FIGS. 5 (f) and 5 (g), the fracture that occurs at the joint between the work W1 and the work W2 is not a brittle fracture but a ductile fracture. As a result, according to this embodiment, it was confirmed that welding with high joint strength can be realized.

Next, the first comparative example will be described with reference to FIG. In this comparative example, the workpieces W1 and W2 were welded using the welding device 1 so that the penetration depth d was larger than 0.20 mm and the irradiation locus T was spiral. As the work W1, an aluminum plate was used as in the examples. Further, as the work W2, an iron plate was used as in the examples.

FIG. 6A is an SEM image showing a cross section of the workpieces W1 and W2. FIG. 6B is an SEM image showing the upper surface of the work W2 that has been tension-peeled. FIG. 6C is an SEM image showing the lower surface of the work W1 that has been tension-peeled. FIG. 6D is an X-ray analysis image showing the distribution of aluminum in the cross section of the workpieces W1 and W2. FIG. 6 (e) is an X-ray analysis image showing the aluminum distribution in the cross section of the workpieces W1 and W2. FIG. 6 (f) is an enlarged SEM image of the fractured joint on the upper surface of the work W2 that has been tension-peeled. FIG. 6 (g) is an enlarged SEM image of the fractured joint on the lower surface of the work W1 that has been tension-peeled.

In this comparative example, the parameters of the welding apparatus 1 are set so that the penetration depth from the work W1 to the work W2 is larger than 0.2 mm. For example, the power P of the laser beam L was set to 100 W. Therefore, as shown in FIGS. 6 (d) and 6 (e), the formation of the intermetallic compound at the boundary between the work W1 and the work W2 could not be sufficiently suppressed. As a result, as shown in FIGS. 6 (f) and 6 (g), the fracture that occurs at the joint between the work W1 and the work W2 is not ductile fracture but brittle fracture. From this, it was confirmed that the bonding strength of the workpieces W1 and W2 bonded by the above-described example exceeds the bonding strength of the workpieces W1 and W2 bonded by this comparative example.

Next, a second comparative example will be described with reference to FIG. 7. In this comparative example, the workpieces W1 and W2 were welded using the welding device 1 so that the penetration depth d was larger than 0.20 mm and the irradiation locus T was linear. As the work W1, an aluminum plate was used as in the examples. Further, as the work W2, an iron plate was used as in the examples.

FIG. 7A is an SEM image showing a cross section of the workpieces W1 and W2. FIG. 7B is an SEM image showing the upper surface of the work W2 that has been tension-peeled. FIG. 7C is an SEM image showing the lower surface of the work W1 that has been tension-peeled. FIG. 7D is an X-ray analysis image showing the distribution of aluminum in the cross section of the workpieces W1 and W2. FIG. 7 (e) is an X-ray analysis image showing the aluminum distribution in the cross section of the workpieces W1 and W2. FIG. 7 (f) is an enlarged SEM image of the fractured joint on the upper surface of the work W2 that has been tension-peeled. FIG. 7 (g) is an enlarged SEM image of the fractured joint on the lower surface of the work W1 that has been tension-peeled.

In this comparative example, the parameters of the welding apparatus 1 are set so that the penetration depth from the work W1 to the work W2 is larger than 0.2 mm. Therefore, as shown in FIGS. 7 (d) and 7 (e), the formation of the intermetallic compound at the boundary between the work W1 and the work W2 could not be sufficiently suppressed. As a result, as shown in FIGS. 7 (f) and 7 (g), the fracture that occurs at the joint between the work W1 and the work W2 is not ductile fracture but brittle fracture. From this, it was confirmed that the bonding strength of the workpieces W1 and W2 bonded by the above-described example exceeds the bonding strength of the workpieces W1 and W2 bonded by this comparative example.

(Additional notes)
The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in the above-described embodiments are also included in the technical scope of the present invention. Further, the above-described embodiment can be applied to a method for manufacturing a structure including two plate-shaped members made of dissimilar metals. Among the methods for manufacturing such a structure, a method for manufacturing a structure including a welding step of welding two plate-shaped members according to the above-described embodiment is included in the scope of the present invention.

1 Welding device 11 Laser device 12 Delivery fiber 13 Processing head 131 Irradiation point movement mechanism 14 Stage S1 Welding method S11 Setting process S12 Trial welding process S13 Measuring process S14 Judgment process S15 Main welding process

Claims (6)

A first plate-shaped member made of a dissimilar metal and a second plate-shaped member are superposed so that the lower surface of the first plate-shaped member is in surface contact with the upper surface of the second plate-shaped member. It is a welding method in which welding is performed by irradiating the upper surface of the plate-shaped member of No. 1 with a laser beam.
It includes a setting step of setting welding conditions so that the penetration depth from the first plate-shaped member to the second plate-shaped member is 0.2 mm or less.
A welding method characterized by that. The laser beam irradiation is performed in a state where the first plate-shaped member and the second plate-shaped member perform linear motion and the irradiation point of the laser beam performs elliptical motion.
The locus of the irradiation point that performs elliptical motion includes a short axis that is parallel to the velocity direction of the first plate-shaped member and the second plate-shaped member that performs linear motion, and a long axis that is perpendicular to the velocity direction. Draw an ellipse with
The welding method according to claim 1. The setting step is formed so that the penetration depth from the first plate-shaped member to the second plate-shaped member is 0.2 mm or less and is formed on the upper surface of the first plate-shaped member. This is a step of setting the welding conditions so that the width of the welding mark is equal to or greater than the pitch of the locus of the irradiation point of the laser beam drawn on the upper surface of the first plate-shaped member.
The welding method according to claim 2, wherein the welding method is characterized by the above. A first sample member having the same material and thickness as the first plate-shaped member and a second sample member having the same material and thickness as the second plate-shaped member are provided on the lower surface of the first sample member. Further includes a trial welding step of superimposing the second sample member so as to make surface contact with the upper surface of the second sample member and performing trial welding by irradiating the upper surface of the first sample member with a laser beam.
The setting step is a step of setting the welding conditions based on the result of the trial welding.
The welding method according to any one of claims 1 to 3. A method for manufacturing a structure including two plate-shaped members made of dissimilar metals.
A welding step of welding the two plate-shaped members according to the welding method according to any one of claims 1 to 4 is included.
A method for manufacturing a structure. A first plate-shaped member made of a dissimilar metal and a second plate-shaped member are superposed so that the lower surface of the first plate-shaped member is in surface contact with the upper surface of the second plate-shaped member. A welding device that welds by irradiating the upper surface of the plate-shaped member of No. 1 with a laser beam.
Welding conditions are set so that the penetration depth from the first plate-shaped member to the second plate-shaped member is 0.2 mm or less.
Welding equipment characterized by that.

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