JPS63195240A - Al brazing sheet - Google Patents

Abstract

PURPOSE:To obtain an Al brazing sheet particularly improving the corrosion resistance of a heat exchanger, by cladding both sides or one side of an Al-alloy core material which contains respectively prescribed amounts of Cu, Mn, Si, and Fe and in which grain size is limited with an Al-Si or Al-Si-Mg alloy brazing sheet metal. CONSTITUTION:An Al-alloy core material which contains, by weight ratio, 0.3-0.9% Cu, 0.5-1.5% Mn, <=0.2% Si, and 0.2-1.0% Fe and in which grain size is regulated to 50-150mum is prepared. Moreover, the grain-size control of the above core material is carried out by controlling the homogenizing temp. of the core material. Then, both sides or one side of this grain size-controlled core material is clad with an Al-Si or Al-Si-Mg alloy brazing sheet metal. In this way, the Al brazing sheet having the above-mentioned characteristics, improved in strength by about 30% as compared with the conventional sheet, and capable of reducing the sheet thickness to about 0.6-0.45mm can be obtained.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is a pre-plating sheet made of AJI used for brazing an Ai heat exchanger, and particularly improves the corrosion resistance of the heat exchanger. .

[Conventional technology]

Heat exchangers such as automobile radiators, condensers and evaporators for heaters and coolers are generally made by combining corrugated Al fins between refrigerant circulation passages made of Al plating sheets and brazing them together.

For example, the Doron cup evaporator is shown in Figure 1 (a), (
Ai rough-in 1 corrugated as shown in b)
) and a press plate (2) consisting of a press-formed aluminum plating sheet (brazing metal clad on both sides) are laminated as shown in the figure, and the press plate (
2) Melt the brazing metal to join the fin (1) and press plate (2), and press plate (2) (2°)
A refrigerant circulation passage is formed between (inside the core).

The main methods for brazing are immersion brazing, which uses chloride-based flux, and vacuum brazing, which does not use 7lux, and immersion brazing, which uses JIS 3003 or 6951 alloys for the plating sheet. The core material is clad with a brazing material made of Al-8i JI34343 alloy on both sides or one side. In addition, vacuum brazing is required by JIS 3003 and 69 for plating sheets.
Al-3 i on both sides or one side of the core material made of 51 alloy.
- A cladding of Mg-based JIS 4004 alloy brazing material is used, and pure Al or JIS 3003 alloy is used for the fins.

[Problem that the invention seeks to solve]

The immersion brazing method uses a flux containing ZnC1z to form a Zn diffusion layer on the entire surface of the heat exchanger, which prevents pitting corrosion in the main components (refrigerant circulation passages). In addition, vacuum brazing does not take into account sacrificial effects in terms of materials in the law.

In an evaporator, moisture condenses on the surface, so the surface is in a moist environment when in use. Therefore, in the case of evaporators made by vacuum brazing, anti-corrosion measures such as chromic acid treatment are taken after brazing, and fins are formed.
Al also forms the refrigerant circulation passage JIS 3003 and 69
Although it becomes less noble in potential than 51 and exhibits an anticorrosive effect, no anticorrosive effect can be expected in the portions away from the fins.

On the other hand, the thickness of the plating sheet that forms the refrigerant circulation passage is approximately 0.5 to 0.6 #, but there is a demand for thinner sheets to reduce weight, and with this, there is a need to improve strength and maintain formability. is required. As a measure of formability, elongation of the material is required to be about 30%, but in high-strength materials, elongation decreases significantly, causing material cracking during press forming.

[Means for solving problems]

In view of this, as a result of various studies, the present invention has developed an Al plating sheet that improves the corrosion resistance of members forming refrigerant circulation passages, in order to improve the corrosion resistance of aluminum heat exchangers. The core material is an alloy containing 0.9wt% (hereinafter wt% is simply abbreviated as %), MrlO, 5 to 1.5%, 3i0.2% or less, FeO, 2 to 1.0%, and the balance is Al. , Al-8i or A on both or one side
It is characterized by being clad with l-5r-Mg alloy brazing material and having a core material with a crystal grain size of 50 to 150 μm.

(Function) That is, the Ai plating sheet of the present invention has the above structure, and the reason why the core material has the above alloy composition is as follows.

CLJ is added to improve strength and noble potential.
The reason why the content was limited to 0.3 to 0.9% is that if the content is less than 0.3%, there will be little effect, and if it exceeds 0.9%, elongation will decrease and formability will be impaired. . Mn is Cu
Similarly, it is added to improve strength and increase electric potential, and the content is limited to 0.5 to 1.5% because it is ineffective if the content is less than 0.5%. %, a huge A 1-M n compound will be generated and the moldability will be impaired. Si is added to refine the crystal grain size and improve strength, and the content is limited to 0.2% or less when it is contained in excess of 0.2%. This is because pitting corrosion resistance is reduced due to the function of the 3i compound as a cathode. In addition, Fe is added to refine the 3ii-like grain size and improve strength, and the reason why its content is limited to 0.2 to 1.0% is because it is ineffective if it is less than 0.2%. This is because if the content exceeds 1.0%, the pitting corrosion resistance will decrease due to the Fe compound acting as a cathode.

Next, the crystal grain size of the core material was set to 50 to 150 μm because C
This is to prevent the elongation from decreasing due to the addition of U and Mn, which deteriorates the formability. If the crystal grain size is less than 50 μm, the brazing material will diffuse greatly during heating, and the seat of the heat exchanger core will deteriorate. This is because the thickness of the core material decreases, and if the thickness exceeds 150μ, the elongation decreases significantly. Normally, plating sheets are often used with O material, but the core particle size range is the same for H material as well. The crystal grain size of the core material is controlled by controlling the homogenization temperature of the core material; the higher the temperature, the finer the grain size, and the higher the amount of Fe, the finer the grain size.

〔Example〕

A plating sheet consisting of the core material shown in Table 1 was manufactured. That is, the alloy having the composition shown in Table 1 is 60X 180X
180 trm (D mold), after 600'C
0%3i-1.5%My) was cast in the same manner, heated face-side to 500°C, and hot-rolled into a plate with a thickness of 10.5 m. This was heated to 500° C. on both sides of the core material, and hot rolled and pressed to form a plate with a thickness of 5 m. This was cold rolled into a plate with a thickness of 0.6 m, and final annealed at 360'CX for 2 hours to produce a plating sheet of O material. The particle size of the core material of the praising sheet is 30 to 140 μm.
Met.

For the core material of Nα7, the core material of the composition of Nα1 is 520
The particle size of the core material was made 170μ by homogenization treatment at ℃.

The tensile strength and elongation of the plating sheet were measured, and the moldability, corrosion resistance, and diffusion of the brazing material into the core material after brazing were also investigated. These results are also listed in Table 1.

Formability was measured using the Erichsen test according to the JIS 2247A method using samples cut into 90s squares with a diameter of 20mm.
Stretch molding was performed using a ball-head punch, and the molding height at which cracks appeared was measured. Corrosion resistance was determined by vacuum brazing the bond at 600°C for 3 minutes in a vacuum of 5 x 10-5 torr, sealing the back and edges, and subjecting the 50 x 100 shoe section to a CAST test to compare the maximum pitting depth after 200 hours of corrosion. did. Ten points with deep pitting corrosion depth were selected, the depth was determined by the depth of focus method using an optical microscope, and the depth of pitting corrosion was confirmed by polishing the cross section of the deepest one. In addition, the diffusion status of the brazing filler metal into the core material was determined by measuring the thickness of the remaining core material after brazing.

As is clear from Table 1, the present invention sheets N (all 11 to 6 have a tensile strength of 14 KI/mrA or more, an elongation of 26% or more, which is a medium strength, and an Erichsen value of 9.4 or more, and formability). It can be seen that the depth of pitting corrosion is less than 0.20 s, and the diffusion of the brazing metal into the core material is also small.In addition, the natural potential of the core material is also stable.
700mV (vs S, C.

E) and the sacrificial effect are also sufficiently effective.

On the other hand, the comparative sheets Nα7 to Nα13, which deviate from the alloy composition specified by the present invention, have poor tensile strength and elongation.

It can be seen that at least one of the Erichsen value, pitting depth, and residual core thickness is inferior. That is, the comparative sheet Nα7 with a core material particle size exceeding 150 μm and the comparative method NQ9 with a high Cu content have low Erichsen values and poor formability, and the comparative sheet Nα8 with a low Cu content and the comparative sheet N with a low Mn content
α10. Comparative sheet Nα12 with a high Si content has poor pitting corrosion resistance, while comparative sheet Nα1 with a high Fe content
It can be seen that in No. 3, the diffusion of the brazing filler metal into the core material is large. Nao M
Comparison sheet Nα11, which has a high n content, had cracks during production and could not be sampled.

〔Effect of the invention〕

As described above, according to the present invention, the pitting corrosion resistance of the plating sheet is significantly improved, and the strength is also improved by about 30% compared to conventional sheets, so the plate thickness can be increased from 0.6 to 45711.
It is possible to reduce the thickness to about 11 mm, which has significant industrial effects, such as improving the corrosion resistance of the aluminum heat exchanger and making it possible to reduce the weight.

[Brief explanation of the drawing]

Figures 1 (a) and (b) show an example of a Doron cup evaporator, and (a) is a partially cutaway perspective view;
(b) is a side view. 1, fin 2, press plate (a) (b) 1=i= ===:= ±]

Claims (1)

[Claims] Cu0.3-0.9wt%, Mn0.5-1.5wt
%, Si0.2wt% or less, Fe0.2-1.0wt%
The core material is an alloy containing the following: with the remainder being Al, and both or one side of the core material is clad with an Al-Si or Al-Si-Mg alloy brazing material, and the crystal grain size of the core material is 50 to 150 μm. Al brazing sheet.