JP4430979B2 - Dissimilar metal joint structure - Google Patents

Description

  The present invention relates to a dissimilar metal bonding structure constituting a machine, instrument, apparatus, or device used in the fields of automobiles, machines, medical care, sports, space science, telecommunications engineering industries, and the like.

  Conventionally, metallurgical joining methods such as welding, brazing, and soldering, as well as dissimilar metal joining methods, mechanical joining methods using shrinking, cooling, rivets and caulking using differences in thermal expansion coefficient, room temperature There are those using adhesives that are joined in the vicinity. However, the dissimilar metal joint structures joined by these techniques have the disadvantages that the strength is low and the variation in fracture strength is large. In addition, it is difficult to appropriately join the metal material while maintaining the corrosion resistance, heat resistance, oxidation resistance, conductivity, and the like of the metal material.

The present inventor previously proposed a technique for joining carbon fibers and metal materials (Patent Document 1). We further developed and studied the use of high-strength fibers such as carbon fibers for joining dissimilar metals. As a result, it has been found that by using high-strength fibers such as carbon fibers for joining dissimilar metals, the joining strength is high and variation in fracture strength can be suppressed.
Japanese Patent Laid-Open No. 2004-106045, Claims

  The present invention uses high-strength fibers such as carbon fibers for bonding dissimilar metals, so that the bonding strength is high and there is little variation in fracture strength, and furthermore, corrosion resistance, heat resistance, oxidation resistance, conductivity, etc. The dissimilar metal joining structure which joined appropriately in the state where it maintained is provided.

In order to solve the above problems, the configuration of the present invention is as follows.
Sheet metal joined to the first metal member made of metal or alloy, the second metal member made of metal or alloy different from the first metal member, and the first metal member and the second metal member by an electric welding method A dissimilar metal joint structure comprising high-strength fibers. The combination of different metals and alloys is arbitrary, and examples thereof include iron, iron alloy, aluminum, aluminum alloy, tungsten, tungsten alloy, titanium, titanium alloy, lithium alloy, and magnesium alloy.

  Carbon fibers are typical examples of high-strength fibers, but other examples include ceramic glass fibers and Tyranno fibers that are not oxidized or hardly oxidized. Furthermore, high-strength polymer fibers can be similarly applied in the case of low-temperature treatment.

  The high-strength fiber such as carbon fiber is preferably provided with a metal coating on the surface thereof in order to improve the familiarity with the first and second metal members. Examples of the coating metal include nickel, aluminum, titanium, noble metals, and alloys of these metals. The properties of high-strength fibers such as carbon fibers are not particularly limited. For example, a bundle shape, a woven or knitted sheet shape, etc. are mentioned. The sheet-like high-strength fiber may be a single layer or multiple layers. It is appropriately selected according to its use.

  When the use of the dissimilar metal joint structure is used at a high temperature, a brittle compound may be formed by a high temperature reaction between a component of high strength fiber such as carbon fiber and a component of the first and second metal members. Formation of a brittle compound causes deterioration of the high-strength fiber, and long-time treatment at a high temperature releases residual stress and lowers strength. In such a case, the type of coating metal and the thermal history at high temperature are important technical development points in order to prevent deterioration of the high-strength fiber due to the reaction with the metal due to heat. By setting the thickness of the coating metal in the range of several atomic layers to several micrometers, specifically about 10 nm to 2 μm, even if a brittle compound phase is formed, brittleness can be prevented.

  High-strength fibers such as carbon fibers can be joined to the first and second metal members while being elastically deformed. In this case, the amount of elastic deformation varies depending on the type of material, application, etc., but is preferably about 0.5 to 2.0%. By leaving the high-strength fibers such as carbon fibers elastically deformed, the high-temperature strength can be increased by actively utilizing the high compressive stress. In particular, when carbon fiber is used, the effect of suppressing the decrease in elastic modulus at high temperatures is remarkable. In a short time, heat resistance can be exhibited even at the recrystallization temperature of the parent phase metal material.

  Further, high-strength fibers such as carbon fibers can also be applied in the form of fiber reinforced resin, for example, CFRP, FRP, FRM.

  Furthermore, as the carbon fiber, it is also possible to use an ultra-high-strength carbon fiber that has been previously proposed in Japanese Patent Laid-Open No. 2002-371461 and irradiated with an electron beam under the irradiation dose of 40 to 200 Mrad.

  The dissimilar metal joint structure described above can be manufactured by a method of joining the first metal member and the second metal member with high-strength fibers such as carbon fibers. For example, the high-strength fiber is produced by being incorporated into the first metal member and the second metal member while being elastically deformed, and joining the first metal member and the second metal member using the high-strength fiber. Can do.

  For this joining, spot welding by an electric welding method is suitable. In this case, the spot voltage is preferably set to 160 to 230 V, particularly 180 to 190 V in order to increase the bonding strength. Specifically, the technique disclosed in Japanese Patent Application Laid-Open No. 2004-106045 can be applied to the present invention. In addition to spot welding, electrical joining, percussion welding, stuffed animals, powder metallurgy, forging, rolling, extrusion, drawing, etc. can be mentioned. As the joining structure, one or two or more grooves are formed on the abutting surfaces of the first metal member and the second metal member, respectively, and high strength fibers are inserted into these grooves, and the high strength fibers and the first and second metals are inserted. A method of joining the members, or the first metal member and the second metal member are butted together, the outer peripheral surface of the butted surface is wound with high-strength fibers, and the high-strength fibers and the first and second metal members are joined. There are methods.

  According to the present invention, by using a high-strength fiber such as carbon fiber for joining different kinds of metals, it is possible to provide a dissimilar metal joining structure having high joining strength and little variation in fracture strength.

(Joint structure)
FIG. 1 shows a method of bonding thin plates of different metals with a carbon fiber sheet, and a different metal bonding structure according to the present invention obtained by this method.
The dissimilar metal thin plates 10 and 20 are formed with grooves 10a and 20a on their opposing surfaces, respectively. The bundle 30 of carbon fiber sheets is cut to a size that fills the space formed by the grooves 10a and 20a when the dissimilar metal thin plates 10 and 20 are brought into contact with each other. Each carbon fiber sheet is coated with a metal that is compatible with the thin plates 10 and 20. A bundle 30 of carbon fiber sheets is sandwiched between the grooves 10a and 20a of the thin plates 10 and 20 of different metals, and the thin plate 10 and the bundle 30 of carbon fiber sheets, and the thin plate 20 and the bundle 30 of carbon fiber sheets are joined by spot welding. To do. Thus, the composite plate, that is, the dissimilar metal joint structure 40 according to the present invention is obtained.

A plurality of composite plates 40 shown in FIG. 1 may be further stacked to form the dissimilar metal joint structure 50 shown in FIG.
In FIG. 1, a method of joining thin plates of different kinds of metals with a carbon fiber sheet is shown. However, not only the carbon fiber sheets themselves, but also different kinds of metal members are joined with a composite block (CFRM) 60 of a bundle of carbon fiber sheets. Is also possible. FIG. 3 shows the structure.
FIG. 1 shows a method of forming a groove on the opposing surface of a thin plate made of a different metal and joining the carbon fiber sheet therein, but the different metal is formed without forming a groove on the opposing surface of the thin plate made of a different metal. It is also possible to butt the thin plates, cover the butt surface and the outer peripheral surface in the vicinity thereof with a carbon fiber sheet, and then bond the carbon fiber sheet and the thin plates of these different metals. This is shown in FIG.

(Example)
Example 1 In the dissimilar metal joint structure of FIG. 1, an iron alloy was used as the first metal member, a solder alloy was used as the second metal member, and a carbon fiber cross mat having a carbon fiber cross-sectional area ratio of 50% was used as the high-strength fiber. . The carbon fiber sheet and the first and second metal members were joined by electric spot welding (voltage 190V). The dimensions of the butting surfaces of the first and second metal members are 20 mm in length and 5 mm in width, and the dimensions of the groove are 20 mm in length, 1 mm in width and 10 mm in depth. Accordingly, the carbon fiber cloth mat has a length of 20 mm, a width of 1 mm, and a length of 20 mm. The tensile breaking stress of the carbon fiber itself is 2 to 4 GPa. When an iron alloy and carbon fiber are subjected to electric spot welding, the tensile breaking strength of the carbon fiber is in the range of 0.3 GPa to 3 GPa. In the dissimilar metal joint structure according to this example, the joint bending strength was about 0.2 to 0.4 GPa.
That is, unlike conventional metallurgical joining methods, mechanical joining methods, methods using adhesives, etc., since carbon fiber is used in Example 1, corrosion resistance, heat resistance, oxidation resistance, conductivity, etc. are improved. It can be retained sufficiently.

Example 2 In the dissimilar metal joint structure of FIG. 1, an iron alloy was used for the first metal member, an aluminum alloy was used for the second metal member, and a carbon fiber cross mat having a carbon fiber cross-sectional area ratio of 50% was used as the high-strength fiber. . The carbon fiber was coated with nickel or titanium, which is a metal that can be bonded to both an iron alloy and an aluminum alloy. Other conditions are the same as in Example 1. In the dissimilar metal joint structure according to this example, the joint bending strength was about 0.2 to 0.4 GPa.
That is, in the Fe—Al alloy, a very hard and brittle compound phase is formed at the bonding interface. For this reason, it is difficult to weld, and even if it can be joined, the fracture strength is small, and even if a joint strength is occasionally high, it is vulnerable to impact and the variation in fracture strength and fatigue strength fracture frequency is abnormally high.

According to the joining method of Example 2, since the embrittlement phase is not formed at the joining interface, the fracture strength is improved and the variation in the values is small.

Example 3 In the dissimilar metal joint structure of FIG. 1, an iron alloy was used for the first metal member, a copper alloy was used for the second metal member, and a carbon fiber cross mat having a carbon fiber cross-sectional area ratio of 50% was used as the high-strength fiber. . Carbon fibers were coated with nickel, gold, palladium, or titanium, which is a metal that can be bonded to both iron alloys and copper alloys. Other conditions are the same as in Example 1. In the dissimilar metal joint structure according to this example, the joint bending strength was about 0.2 to 0.4 GPa.
That is, in the Fe—Cu alloy, two-phase separation occurs without forming an alloy layer at the bonding interface. For this reason, welding is difficult, even if it can be joined, the fracture strength is low, and the variation in the fracture strength and the number of fractures of fatigue strength is abnormally high. According to Example 3, since a two-phase separation phase is not formed at the bonding interface, the fracture strength is improved, and these values are close to the design strength and the variation is small.

Example 4 In the dissimilar metal joint structure of FIG. 1, a titanium alloy is used for the first metal member and an aluminum alloy is used for the second metal member, and a carbon fiber cross mat having a carbon fiber cross-sectional area ratio of 50% is used as the high strength fiber. It was. Carbon fiber was coated with nickel as a metal that can be bonded to both titanium and aluminum alloys. Other conditions are the same as in Example 1. In the dissimilar metal joint structure according to this example, the joint bending strength was about 0.2 to 0.4 GPa.
That is, a very hard and brittle compound phase is formed at the Ti-carbon fiber bonding interface. For this reason, it is difficult to weld, even if it can be joined, the fracture strength is low, and even if it can be made with a high joint strength, it is vulnerable to impacts, and the variation in fracture strength and fatigue fracture frequency is abnormally high. According to Example 4, not only the embrittlement phase is not formed at the joint interface, but also the strength of aluminum is fiber-reinforced with carbon fibers, so that the fracture strength is improved and the variation of those values is small.

Example 5 In the dissimilar metal joint structure of FIG. 1, a lithium alloy is used for the first metal member and an aluminum alloy is used for the second metal member, and a carbon fiber cross mat having a carbon fiber cross-sectional area ratio of 50% is used as the high strength fiber. It was. The carbon fiber was coated with nickel, which is a metal that can be bonded to both a lithium alloy and an aluminum copper alloy. Other conditions are the same as in Example 1. In the dissimilar metal joint structure according to this example, the joint bending strength was about 0.2 to 0.4 GPa.
That is, since the coating metal prevents the carbon fiber from deteriorating when it is combined, the present bonding method improves the breaking strength, and the variation in these values is small.

  In addition, this invention is applicable also to the dissimilar metal joining of a tungsten alloy or a titanium alloy, and an iron alloy, a titanium alloy, an aluminum alloy, and a magnesium alloy.

  INDUSTRIAL APPLICABILITY The present invention can be effectively used for manufacturing machines, instruments, apparatuses, and devices used in the fields of automobiles, machines, medicine, sports, space science, telecommunications engineering industries, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the dissimilar-metal joining structure based on the method which joins the thin plates of the dissimilar metal based on this invention with a carbon fiber sheet, and this method obtained by this method, (a) is the state before joining, (b ) Shows the state after joining. The figure which shows the dissimilar-metal joining structure which concerns on this invention formed by joining the composite board obtained by joining the thin plates of the dissimilar metal which concern on this invention with a carbon fiber sheet, respectively. The figure which shows the dissimilar metal joining structure which concerns on this invention formed by joining the components of the thin metal plates of the present invention according to this invention by the composite block (CFRM) of the bundle | flux of a carbon fiber sheet, respectively. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a method for wrapping (wrapping) and bonding the outer surface of a dissimilar metal joint according to the present invention with a carbon fiber sheet, and a dissimilar metal joint structure according to the present invention obtained by this method. Indicates a state before bonding, and (b) indicates a state after bonding.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... 1st metal member 20 ... 2nd metal member 30 ... Carbon fiber (high-strength fiber)
40 ... Joint metal structure (composite plate)
50 ... Dissimilar metal joint structure 60 ... Composite block of bundles of carbon fiber sheets (CFRM)

Claims (3)

Sheet metal joined to the first metal member made of metal or alloy, the second metal member made of metal or alloy different from the first metal member, and the first metal member and the second metal member by an electric welding method A dissimilar metal joint structure comprising high-strength fibers. The dissimilar metal joining structure according to claim 1, wherein the high-strength fibers are carbon fibers. The dissimilar metal joint structure according to claim 1, wherein the high-strength fiber has a metal coating on a surface thereof.

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