JPS62238066A - Joining method for aluminum and steel material - Google Patents

Abstract

PURPOSE:To join an aluminum material and steel material with strong strength by brazing the aluminum coated joining part of a steel material and the joining part of the aluminum material by using an aluminum base brazing filler metal and flux. CONSTITUTION:In case of joining the aluminum material of an aluminum alloy pipe, etc. and the steel material of a steel pipe, etc., an aluminum plating is made on the joining part at least of the above steel material side. The above aluminum plating is preferably by the hot dipped aluminum coating using an pure aluminum alloy. The aluminum coated joining part of the above steel material and the joining part of the aluminum material are then brazed by using the aluminum base brazing filler metal of Al-Si, etc., and a flux. As for the above flux, a fluorine flux is suitable. In this way the product with good joining operability and good corrosion resistance on the joining part and high reliability in the joining strength and airtightness as well is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for joining steel materials such as Aluminum 11 material.

[Prior art] In general, between different metals! Intense bonding involves various problems and difficulties due to the chemical or physical properties of these metals. This is no exception when joining aluminum materials and steel materials. For example, when aluminum alloy pipes and steel pipes are connected in series in piping for platform scales for ships and refrigerators, the construction site Since it is difficult to directly join the two, the aluminum alloy pipe joint that is joined to the aluminum alloy pipe is joined to the steel pipe! ! 4-Pipe joints Aluminum alloy pipe/steel pipe fittings with joints are manufactured in advance, and these aluminum alloy pipe/steel pipe fittings can be used to connect similar metal pipes using common joining methods such as brazing or welding. are doing.

In this way, various problems and difficulties arise when joining aluminum and steel materials, but on the other hand, there is a need to do so, so methods for joining the two have been studied for a long time, such as , Shrink fitting method with strict temperature control,
Hot welding method, cold welding method, 1? A friction welding method, a diffusion welding method, etc. are known.

However, these conventional baking methods, hot pressure welding methods,
Cold welding method, abrasion! Depending on the A welding method or the diffusion welding method, for example, when manufacturing the above-mentioned aluminum alloy pipe/M pipe joint, it is difficult to ensure sufficient joint strength and airtightness at the joint part, and there are problems with equipment, cost, etc. This method was not necessarily practical due to limitations on the diameter of the cutter and the meat 17.

For this reason, when manufacturing aluminum 1 cum alloy pipes and steel pipe joints that require high joint strength and airtightness at joints, for example, aluminum alloy pipes and steel pipes are superimposed and explosively bonded. A pipe is manufactured, this clad pipe is cut to a predetermined size, and both ends are machined, leaving a joint of an appropriate length in the center, and one end is machined by cutting off the m-tube section and using an aluminum alloy. Leaving the pipe part, and scraping off the aluminum alloy pipe part on the other end side to leave the fpI pipe part, form a joint part that will be in contact with the aluminum alloy pipe or steel pipe respectively to form an aluminum alloy pipe/steel pipe joint. The explosive bonding method is used.

[Problem to be Solved by the Invention 1] However, the joining of aluminum and steel materials by the Ha6 method does not allow the joining of the joint to produce a highly reliable product in terms of joint strength and airtightness (7). However, it is necessary to manufacture a clad material by bonding it in advance, and then cut this clad material to assemble the desired product.The production process is complicated and there is a lot of material waste. The cost was high, and there were 111 problems in response to the diversification of products from the production process.

Roughly solder the aluminum material and uA material
It is possible to join by gluing, but in the case of hanging, there is a problem with the corrosion resistance of the joint, and the product has a low melting temperature and may be heated by means such as welding. There is a problem that it cannot be used, and in the case of brazing, aluminum and steel are directly brazed, and the l"c-△
Since the adhesion between the j-8i alloy and the Fe interface is weak, a satisfactory bonding strength of only 1 W cannot be achieved. Furthermore, when using chloride-based flux, which has been commonly used in the past, cleaning is not only essential after completion of bonding in order to prevent corrosion caused by chlorides, but also the wetting and spreading properties of the brazing material on the bonding surface. There was a problem in that the product Y1 became unstable because it was not 1-minute.

There is a problem.

[Means for Solving the Problems] The present invention has been developed in view of this point of view, and therefore not only has good workability during joining and corrosion resistance of the joint, but also improves the corrosion resistance of the joint. The present invention provides a method for joining aluminum and steel materials that can produce products with high reliability in terms of joint strength and airtightness.

However, in the present invention, when joining an aluminum material and M44, aluminum plating is applied to at least 6 joint parts on the steel material side, and the aluminum plated joint part and the joint part of the aluminum material are coated with aluminum. This is an Ij method for joining aluminum and steel materials by brazing using a base brazing material and fluoride flux.

The materials and shapes of the aluminum and steel materials to which the method of the present invention is applied are determined by the intended use of the joined products, and are not particularly limited. Δj of
! -Mn-based alloys, AI-M such as 6061 and 6063 (2-Si alloys, △l of 7003.7NO1, etc.) -Z n
Examples of the steel materials include carbon steel, stainless steel, etc., and the shapes of these aluminum materials and steel materials include tube materials, plate materials, and mold materials. etc. can be mentioned.

In the method of the present invention, the method of aluminum plating applied to at least the joint portion of the steel material may be any method as long as it can form an aluminum plating layer on the surface of the steel material, such as electroplating or hot-dip plating. method, vacuum heating method in which aluminum-based metal is evaporated in vacuum and attached to the surface of steel material, metal penetration method in which steel material is diffused without heating together with aluminum-based metal, and molten metal is dispersed in atomized form. Metallicon method, which is sprayed with
Examples include an electroless plating method in which a reducing agent is added to an aluminum salt solution, and preferably A is applied to the surface of the steel material.
This is molten aluminum plating using a pure aluminum alloy that forms a pure aluminum alloy layer with a high melting temperature even on brazing materials such as l-8i type 17 material. The aluminum plating applied to the steel material side may be applied partially (one piece may be applied) only to the joints on the steel material side, or depending on the intended use of the resulting product (or aluminum plating may be applied to the steel material pot). It's so nice.

In this way, the steel material that has been subjected to the aluminum plating treatment is then joined to the aluminum material. To be done.

As the aluminum Jt material used in this process, an Aj-8i alloy is used.

In addition, the fluxes used during LJ are: (1) (,f) A mixture of +yfluoro[1potassium aluminate and aluminum fluoride; A mixture, which is obtained by mixing and melting potassium atrafluoroaluminate and potassium fluoride, is obtained from finely divided aluminum and potassium fluoride, or a flux of these is mixed with lithium fluoride, calcium fluoride, Examples include monofluoride fluxes, such as those made by adding a small amount of additives such as sodium fluoride. Potassium chloride (KF) 40-50ff11% and =
Fluorization? ) Ii minium (A !l F3 > 50~6
It is a fluoroaluminate salt having a composition of 41% and a small amount of unavoidable impurities. When this fluoride flux is used, cleaning after brazing can be omitted.

Furthermore, there are no particular restrictions on the method of waxing using these aluminum alloys and fluoride fluxes, such as heating in a furnace, high frequency heating, It is desirable to use a heating method that has a heating rate higher than that of a heating shade.
It can be carried out under waxing conditions of 0 to 610°C, preferably 595 to 605°C, and a holding time of 2 minutes or less, preferably 1 minute or less.

[Function] If the method of the present invention is used, aluminum plating is applied to at least the joint portion of the steel material side before waxing the aluminum material and the steel material using an aluminum base wax and a fluoride flux. As a result, the uniform aluminum alloy layer formed on the surface of the steel material enables uniform brazing, and also forms a stable aluminum alloy layer between the aluminum material and the steel material. be able to.

[Example] Hereinafter, the method of the present invention will be specifically explained based on Examples and Comparative Examples.

Example 1 SUS304 pipe (outer diameter 42 mm, wall thickness 3.5 mm) was used as the steel material.
mm and length 70 mm), and pure aluminum alloy (1050) was used on the surface of
Molten aluminum was applied to the steel material under conditions of immersion in molten metal at 50° C. for 1 minute to form an aluminum alloy layer on the surface of the steel material.

On the other hand, as an aluminum material, aluminum "Ri 11 alloy pipe" (
Material n3oo3, outer diameter 50#φ, wall thickness 4 mm and length 5
0 mm), open one end of the tube to a depth of 20M, and adjust its inner diameter to O65 from the outer diameter of the SUS304 pipe mentioned above.
A larger cut was made by #φ, and a SUS304 pipe was inserted into this part.

Next, the aluminum alloy tube and the 5t JS304 tube are placed vertically with the 5US304 tube inserted into the aluminum alloy tube facing upwards, and a shape is formed between the upper end surface of the aluminum alloy tube and the outer peripheral surface of the 5US304 tube. Brazing material formed in a ring shape on the stepped part (Material 40'/! 7.2,4M
φ), and apply potassium fluoride (KF) 43f to the joint of this brazing material, aluminum alloy tube, and 5US304 tube.
flfffi% and aluminum trifluoride <AlF3>57
A fluoride flux having a composition of fim% was applied and dried, and these aluminum alloy tubes and 5tJS30
Inner diameter 7 using 6 #φ steel pipe with 4 pipes in the same position as A
5Nφ, 7-stage high-frequency induction heating coil (Shimada Riri Kogyo)
Set in a T-50 type (made by Kiki), voltage 158V, current 22A1R4 speed 300℃/min, maximum heating temperature 605℃
The joints of the aluminum alloy tube and the 5US304 tube were heated under the conditions of 10 seconds of holding time, and the joint portion of the aluminum alloy tube and the 5US304 tube was rolled to produce an aluminum alloy tube/S LJ S 30 /I pipe joint.

Both ends of the 5-wood aluminum alloy pipe and 5US304 pipe joint made in this way were sealed.
20 Kg/CIi of nitrogen gas in it. A submergence airtightness test was conducted by immersing each aluminum alloy pipe and 5US304 pipe joint in water and observing the leakage of nitrogen gas. Result t Which aluminum alloy tube/5U
It was also found that the S304 pipe fittings had no leakage of nitrogen gas and were joined airtightly.

In addition, two of the above aluminum alloy pipes and 5US304 pipe joints were used, and the aluminum alloy pipe side and the 5US3
On the 04 pipe side, one is TIG welded and the other is gas welded with aluminum alloy pipes of the same material and diameter, and 5tJ.
S304 pipes were connected and a tensile load was applied in the longitudinal direction of the connected pipes to examine the shear strength of the joint of the aluminum alloy pipe/5US30/I pipe joint. The result is TIGFR
In both cases of welding and gas welding, rupture occurred in the aluminum alloy tube near the joint (tensile breaking load: approximately 4,110 to 4.155 N9), and no rupture was observed from the joint.

Example 2 A carbon steel pipe (STPG pipe, outer diameter 42sφ, wall thickness 3.5mm, and length 65mm) was used as the steel material, and pure aluminum alloy (1050) was used on the surface of the pipe to obtain a 730~7
Hot-dip aluminum plating was applied in step f1 of immersing the steel material in FJm at 50° C. for 1 minute to form an aluminum alloy layer on the surface of the steel material.

On the other hand, an aluminum alloy pipe (material 1) is used as an aluminum shrine.
6063, outer diameter 50sφ, wall thickness 4 mIR and quality 50
nm), and its inner diameter is 0°2 nvnφ from the outer diameter of the above carbon steel pipe over a depth of 15M from one end side.
I cut it out and inserted an IA steel pipe into this part.

Next, a brazing material (441140
45, 2, 4 #φ), and potassium fluoride (KF
) 39.0 mold assembly%, aluminum trifluoride (Yari F3) 5
6.3 weight%, and Libram fluoride (liF) 4.7 weight Φ
A fluoride-based flux having a composition of
Propane gas 13I while rotating at a speed of about 1/min.
The tube was heated for about 3 minutes using an LPG gas burner to which compressed air was supplied at 1701/min and the maximum heating temperature was 610° C. to braze the joint between the aluminum alloy pipe and the carbon steel pipe.

For the 5-wood aluminum alloy pipe/carbon steel pipe joint that had been treated in this way, a submersion airtightness test was conducted in the same manner as in Actual W Example 1. It was found that there was no deviation of 51M and that the joint was airtight.

In addition, for the two aluminum alloy pipes and carbon steel pipe joints mentioned above, assuming that it takes 11 days to go from -40°C to 120°C in 4 minutes, the load is -1-recycle for 10 cycles. After that, the shear strength of the joint of the aluminum alloy pipe and carbon steel pipe joint was examined in the same manner as in Example 1.

The results are for TIG welding and gas welding,
Fracture occurred in the aluminum ram alloy tube near the joint (tensile breaking load: approximately 5,000 to 5.070 kg), but no fracture was observed from the joint.

Comparative Example A carbon steel pipe (STPG pipe, outer diameter 42 mm, wall thickness 3.5 mm, and length 65#) was used as the uA shrine, while an aluminum alloy pipe (+J i 606) was used as the aluminum material.
3. Using a carbon steel pipe with an outer diameter of 50mφ, a wall thickness of 4m, and a height of 50M, the inner diameter is cut to a depth of 15fi from one end side by 0°2sφ larger than the outer diameter of the carbon steel pipe, and a carbon steel pipe is attached to this part. I inserted it.

Next, in the same manner as in Example 1 above, a brazing material (material/104
5.2.4mmφ), and potassium fluoride (KF
) 39.0fffffi%, aluminum trifluoride (8I
F3') 56.3% by weight, and lithium fluoride (L i
F) Apply a fluoride flux having a composition of 4.7 fIiffi%, dry it, and set the aluminum alloy pipe and carbon steel pipe on a turntable with a torch solder in an upright position with the carbon steel pipe facing up. Rotate the attached turntable at a speed of about 30 times/minute.
while propane gas 131/min and compressed air 17/min
Heat for about 3 minutes with an LPG gas burner supplied with
The joint between the aluminum alloy pipe and the carbon steel pipe was brazed by heating at a maximum heating temperature of 610°C.

Two aluminum alloy tubes manufactured in this way
For carbon steel pipe fittings, -/10℃ to 120℃ in 4 hours
After applying a heat cycle of 101 cycles, one cycle of which is RU up to ℃, the shear strength of the joint of the aluminum alloy pipe and carbon steel pipe joint was determined in the same manner as in Example 1.
I looked into the good. In both cases, the tensile breaking load required to break from the joint is 2.960 to 3.500 Kf.
f). However, no leakage was observed in water immersion airtightness test 1 in either case.

[Advantageous Effects of the Invention 1] According to the method of the present invention, when joining aluminum 11 materials and 44 materials, aluminum plating is applied to at least the joint portion of at least 6 pieces of steel material, and the aluminum plated joint portion and the aluminum material are bonded together. By brazing the joints using an aluminum-based brazing material and fluoride flux, not only the workability during joining and the corrosion resistance of the joints are good, but also the joint strength of the joints is increased. We can produce products with high reliability in terms of airtightness, such as aluminum alloy pipes and steel pipes used when connecting aluminum alloy pipes and steel pipes for various types of piping, such as for ships and refrigerators. This is a very unique method for fitting joints, etc.

Patent applicant: Kuchiki Light Metal Co., Ltd. Representative: Patent attorney: Tomohiro Nakamura (
2 people outside)

Claims (5)

[Claims] (1) When joining aluminum materials and steel materials,
A method of combining aluminum and steel materials, characterized in that at least the joint portion of the steel material side is plated with aluminum, and the aluminum plated joint portion and the joint portion of the aluminum material are brazed using an aluminum-based brazing material and flux. Joining method. (2) The method for joining aluminum and steel materials according to claim 1, wherein the aluminum plating method is hot-dip aluminum plating. (3) The method for joining aluminum material and steel material according to claim 2, wherein a pure aluminum alloy is used as the hot-dip aluminum plating. (4) The method for joining aluminum materials and steel materials according to any one of claims 1 to 3, wherein the flux is a fluoride flux. (5) The method for joining an aluminum material and a steel material according to any one of claims 1 to 4, wherein the aluminum material and the steel material are an aluminum alloy pipe and a steel pipe, respectively.