阅读说明：本技术 铝合金钎焊板 (Aluminum alloy brazing sheet ) 是由 泉孝裕 鹤野招弘 木村申平 涩谷雄二 筱田贵弘 山田诏悟 大野慎吾 于 2018-05-24 设计创作，主要内容包括：一种铝合金钎焊板,具备如下：芯材,其中Mg：2.0质量％以下(含0质量％),余量由Al和不可避免的杂质构成；钎料,其中含有Si、Bi、Mg,余量由Al和不可避免的杂质构成。设钎料的Si的含量为C<Sub>Si</Sub>,设钎料的Bi的含量为C<Sub>Bi</Sub>,设钎料的Mg的含量为C<Sub>Mg－b</Sub>,设芯材的Mg的含量为C<Sub>Mg－c</Sub>,设C<Sub>Mg</Sub>＝C<Sub>Mg－b</Sub>+C<Sub>Mg－c</Sub>/2时,则满足3≤C<Sub>Si</Sub>≤13、0.13C<Sub>Mg</Sub><Sup>－0.3</Sup>≤C<Sub>Bi</Sub>≤0.58C<Sub>Mg</Sub><Sup>0.45</Sup>、C<Sub>Mg－b</Sub>≥0.1、0.2≤C<Sub>Mg</Sub>≤1.1。(An aluminum alloy brazing sheet comprising: a core material, wherein Mg: 2.0% by mass or less (including 0% by mass), the balance being Al and unavoidable impurities; the brazing filler metal contains Si, Bi and Mg, and the balance is Al and inevitable impurities. Assuming that the Si content of the brazing filler metal is C Si Let the Bi content of the brazing filler metal be C Bi Let the Mg content of the brazing filler metal be C Mg－b Let the Mg content of the core material be C Mg－c Is provided with C Mg ＝C Mg－b +C Mg－c When the ratio is/2, the condition that C is more than or equal to 3 is satisfied Si ≤13、0.13C Mg －0.3 ≤C Bi ≤0.58C Mg 0.45 、C Mg－b ≥0.1、0.2≤C Mg ≤1.1。)

1. An aluminum alloy brazing sheet comprising a core material and a brazing filler metal provided on at least one surface of the core material,

in the core material, Mg is 2.0 mass% or less and 0 mass% or less, and the balance is Al and unavoidable impurities,

the brazing filler metal contains Si, Bi and Mg, the balance is Al and inevitable impurities,

setting the Si content of the brazing filler metal as C_SiMass% of the brazing filler metal, the Bi content of the brazing filler metal is C_BiThe mass percent of Mg in the brazing filler metal is C_Mg－bMass% of the core material is C_Mg－cMass% of C_Mg＝C_Mg－b+C_Mg－cAt/2, satisfy

3≤C_Si≤13、

0.13C_Mg ^－0.3≤C_Bi≤0.58C_Mg ^0.45、

C_Mg－b≥0.1、

0.2≤C_Mg≤1.1。

2. The aluminum alloy brazing sheet according to claim 1, wherein the brazing filler metal further contains at least one selected from the following (a) to (e):

(a) mn: 2.0 mass% or less, Ti: 0.3 mass% or less, Cr: 0.3 mass% or less, Zr: 0.3 mass% or less;

(b) zn: 5.0% by mass or less;

(c) sr: 0.10 mass% or less, Na: 0.050% by mass or less of Sb: 0.5 mass% or less;

(d) rare earth elements: 1.0% by mass or less;

(e) li: 0.3% by mass or less.

3. The aluminum alloy brazing sheet according to claim 1, wherein the core material further contains at least one selected from the following (f) to (k):

(f) mn: 2.5% by mass or less;

(g) si: 1.2% by mass or less;

(h) cu: 3.0% by mass or less;

(i) fe: 1.5% by mass or less;

(j) ti: 0.5 mass% or less, Cr: 0.5 mass% or less, Zr: 0.5 mass% or less;

(k) li: 0.3% by mass or less.

4. The aluminum alloy brazing sheet according to claim 2, wherein the core material further contains at least one selected from the following (f) to (k):

(f) mn: 2.5% by mass or less;

(g) si: 1.2% by mass or less;

(h) cu: 3.0% by mass or less;

(i) fe: 1.5% by mass or less;

(j) ti: 0.5 mass% or less, Cr: 0.5 mass% or less, Zr: 0.5 mass% or less;

(k) li: 0.3% by mass or less.

5. The aluminum alloy brazing sheet according to claim 1, wherein the brazing filler metal has a thickness of 50 μm or more.

6. The aluminum alloy brazing sheet according to claim 2, wherein the brazing filler metal has a thickness of 50 μm or more.

7. The aluminum alloy brazing sheet according to claim 3, wherein the brazing filler metal has a thickness of 50 μm or more.

8. The aluminum alloy brazing sheet according to claim 4, wherein the brazing filler metal has a thickness of 50 μm or more.

Technical Field

The present invention relates to aluminium alloy brazing sheet, and in particular to aluminium alloy brazing sheet suitable for use in a brazing method not using flux, so-called fluxless brazing.

Background

When brazing members such as heat exchangers made of aluminum alloys, there is a method of performing vacuum brazing, that is, a method of performing brazing in a vacuum without using a flux.

This vacuum brazing has the following advantages as compared with flux brazing using a flux: the treatment of applying the flux is not required, and the problems accompanying the improper amount of flux can be avoided.

However, vacuum brazing requires an expensive vacuum furnace for heating the furnace in a vacuum state during brazing, which results in high operation cost, and also in difficulty in operation because control of the furnace in a vacuum state is difficult.

In order to solve such a problem, the following techniques have been proposed with respect to the research on flux-free brazing without using a flux in a non-vacuum atmosphere.

Specifically, patent document 1 discloses a fluxless brazing method for a heat exchanger having a fin in a narrow flow path, which is characterized by using an aluminum clad material containing an Al-Si-based brazing material containing 0.1 to 5.0% by mass of Mg and 3 to 13% by mass of Si on the outermost surface, wherein the Al-Si-based brazing material contains Si particles having a diameter of 0.8 μm or more in terms of equivalent circle diameter and the number of particles having a diameter of 1.75 μm or more is 25% or more, the Al-Si-based brazing material and a member to be brazed are brought into close contact with each other in a non-oxidizing atmosphere without reducing pressure, and the aluminum clad material and the member to be brazed are joined at a heating temperature of 559 to 620 ℃.

[ Prior Art document ]

[ patent document ]

[ patent document 1 ] Japanese patent No. 5619538 publication

The technique of patent document 1 relates to brazing in an inert gas atmosphere without vacuum, and studies have been made on a predetermined effect.

However, the technique of patent document 1 cannot exhibit sufficient brazing properties. Specifically, in examples 1 to 23 and 29 to 58 of patent document 1, the brazing material contains 0.1 to 3 mass% of Mg, which promotes the production of MgO on the surface of the brazing material in the temperature raising process during the brazing heating. As a result, according to examples 1 to 23 and 29 to 58 of patent document 1, MgO on the surface of the brazing material may become an obstacle when the brazing material is melted, and the brazeability may be lowered.

In examples 24 to 28 of patent document 1, although the brazing filler metal contains Bi, the brazing filler metal of examples 24 to 26 contains a small amount of Bi, and examples 27 and 28 contain a large amount of Bi, so that the brazing property cannot be sufficiently exhibited in any case.

Disclosure of Invention

Accordingly, an object of the present invention is to provide an aluminum alloy brazing sheet having excellent brazeability.

That is, the aluminum alloy brazing sheet of the present invention includes a core material in which a ratio of Mg: 2.0% by mass or less (including 0% by mass), the balance being Al and unavoidable impurities, the brazing filler metal containing Si, Bi and Mg, the balance being Al and unavoidable impurities, and the content of Si in the brazing filler metal being C_SiThe solder contains Bi in an amount of C_BiThe solder contains Mg in an amount of C_Mg-bThe core material has an Mg content of C_Mg－cMass% of C_Mg＝C_Mg－b+C_Mg－cWhen/2, satisfy 3 ≤ C_Si≤13，0.13C_Mg ^－0.3≤C_Bi≤0.58C_Mg ^0.45，C_Mg－b≥0.1，0.2≤C_Mg≤1.1。

In this way, in the aluminum alloy brazing sheet of the present invention, since the contents of the components of the core material and the brazing material, for example, the relationship between the Mg contents of the core material and the brazing material and the Bi content of the brazing material, are specified, the Mg of the core material and the brazing material reacts with (is trapped in) the Bi of the brazing material, and the production of MgO on the surface of the brazing material is suppressed. Further, when the brazing filler metal is melted during heating for brazing, Mg that reacts with Bi melts in the matrix (brazing filler metal), so that evaporation of Mg is promoted, an oxide film formed on the surface of the brazing filler metal is just destroyed during evaporation of Mg, and the Mg reacts with oxygen in the atmosphere, whereby the oxygen concentration in the atmosphere is reduced, and re-oxidation of the molten brazing filler metal is suppressed. In addition, Bi dissolved in the matrix phase improves the fluidity of the solder. As a result, the aluminum alloy brazing sheet of the present invention is excellent in brazeability.

In the aluminum alloy brazing sheet according to the present invention, the brazing filler metal may further contain Mn: 2.0 mass% or less, Ti: 0.3 mass% or less, Cr: 0.3 mass% or less, Zr: 0.3 mass% or less. In the aluminum alloy brazing sheet according to the present invention, the brazing filler metal may further contain Zn: 5.0% by mass or less. In the aluminum alloy brazing sheet according to the present invention, the brazing filler metal may further contain Sr: 0.10 mass% or less, Na: 0.050% by mass or less of Sb: 0.5 mass% or less. In the aluminum alloy brazing sheet according to the present invention, the brazing filler metal may further contain a rare earth element: 1.0 mass% or less.

Thus, the aluminum alloy brazing sheet of the present invention has excellent brazeability even when the brazing filler metal contains Mn, Ti, Cr, Zr, Zn, Sr, Na, Sb, and a rare earth element.

In the aluminum alloy brazing sheet of the present invention, the brazing filler metal may further contain Li: 0.3% by mass or less.

In this way, the aluminum alloy brazing sheet of the present invention can further improve brazeability by including Li in the brazing filler metal.

In the aluminum alloy brazing sheet according to the present invention, the core material may further contain Mn: 2.5% by mass or less. In the aluminum alloy brazing sheet according to the present invention, the core material may further contain Si: 1.2% by mass or less. In the aluminum alloy brazing sheet according to the present invention, the core material may further contain Cu: 3.0% by mass or less. In the aluminum alloy brazing sheet according to the present invention, the core material may further contain Fe: 1.5% by mass or less. In the aluminum alloy brazing sheet according to the present invention, the core material may further contain Ti: 0.5 mass% or less, Cr: 0.5 mass% or less, Zr: 0.5 mass% or less.

Thus, the aluminum alloy brazing sheet of the present invention has excellent brazeability even if the core material contains Mn, Si, Cu, Fe, Ti, Cr, and Zr.

In the aluminum alloy brazing sheet of the present invention, the core material may further contain Li: 0.3% by mass or less.

In this way, the aluminum alloy brazing sheet of the present invention can further improve brazeability by including Li in the core material.

In the aluminum alloy brazing sheet of the present invention, the brazing filler metal may have a thickness of 50 μm or more.

In this way, the aluminum alloy brazing sheet of the present invention can more reliably exhibit excellent brazeability because the thickness of the brazing material is equal to or greater than a predetermined value.

The aluminum alloy brazing sheet of the present invention has excellent brazeability because the contents of the respective components of the core material and the brazing filler metal are specified.

Drawings

Fig. 1 is a sectional view of an aluminum alloy brazing sheet according to the present embodiment.

Fig. 2A is a view for explaining a test method for evaluating brazeability, and is a perspective view of a state in which a lower member and an upper member are combined.

Fig. 2B is a diagram for explaining a test method for evaluating brazeability, and is a side view of a state in which a lower member and an upper member are combined.

Fig. 3 is a graph showing the relationship between the Bi content of the brazing material and the Mg content of the brazing material and the core material in some examples.

Fig. 4 is a graph showing the relationship between the Mg content of the brazing filler metal and the Mg content of the core material in some examples.

Detailed Description

Hereinafter, an embodiment (embodiment) of an aluminum alloy brazing sheet for carrying out the present invention will be described with reference to the drawings as appropriate.

[ aluminum alloy brazing sheet ]

The aluminum alloy brazing sheet of the present embodiment (hereinafter, referred to as "brazing sheet" as appropriate) is configured, for example, as shown in fig. 1, to include a core material 2 and a brazing material 3 provided on one surface of the core material 2.

In the brazing sheet 1 of the present embodiment, the contents of the respective components of the core material 2 and the brazing material 3 are appropriately specified.

The reason for the numerical limitation will be described in detail below with respect to the respective components of the core material and the brazing material of the brazing sheet of the present embodiment.

[ core Material ]

In the core material of the brazing sheet of the present embodiment, Mg: 2.0% by mass or less (including 0% by mass), and the balance of Al and unavoidable impurities.

The core material of the brazing sheet of the present embodiment may also contain Mn, Si, Cu, Fe, Ti, Cr, Zr, and Li as appropriate.

(Mg in the core material: 2.0% by mass or less)

Mg of the core material improves the strength. Further, Mg in the core material diffuses into the brazing material in the temperature rise process during brazing heating, evaporates into the atmosphere at the melting temperature of the brazing material, and reacts with oxygen in the atmosphere. As a result, the oxide film formed on the surface of the brazing material is destroyed just by evaporation of Mg, the oxygen concentration in the atmosphere is reduced, and re-oxidation of the molten solder is suppressed (gettering action), thereby improving the brazeability. Since Mg in the brazing filler metal also plays a role of gettering, when the Mg content of the brazing filler metal is large, the Mg content of the core material may be small, and may be 0 mass%.

On the other hand, if the Mg content is higher than 2.0 mass%, all Mg cannot be captured by Bi of the brazing filler metal, so that MgO formation on the brazing filler metal surface is promoted, and the brazeability is lowered.

Therefore, the Mg content of the core material is 2.0 mass% or less (0 mass% is contained).

(Mn of core material: 2.5% by mass or less)

Mn of the core material improves the strength. However, if the content of Mn is more than 2.5 mass%, the Al — Mn-based compound increases, and there is a possibility that cracks may occur in the material production process.

Therefore, when Mn is contained in the core material, the Mn content is 2.5 mass% or less.

In order to more surely improve the strength obtained by containing Mn, the Mn content of the core material is preferably 0.5 mass% or more.

(Si of core material: 1.2% by mass or less)

Si of the core material improves strength. However, if the content of Si is more than 1.2 mass%, the solidus temperature of the core material decreases, so the corrosion resistance decreases, and the solderability decreases because the solder fluidity decreases.

Therefore, when Si is contained in the core material, the content of Si is 1.2 mass% or less.

In order to more surely improve the strength obtained by containing Si, the Si content in the core material is preferably 0.05 mass% or more.

(Cu of core material: 3.0 mass% or less)

Cu of the core material increases the potential of the core material to improve corrosion resistance. However, if the content of Cu is more than 3.0 mass%, the solidus temperature of the core material decreases, so the corrosion resistance decreases, and the solderability decreases because the solder fluidity decreases.

Therefore, when Cu is contained in the core material, the content of Cu is 3.0 mass% or less.

In order to more surely improve the corrosion resistance obtained by containing Cu, the Cu content in the core material is preferably 0.05 mass% or more.

(Fe of core material: 1.5% by mass or less)

The Fe of the core material improves the strength by a solid solution strengthening effect. However, if the content of Fe is more than 1.5 mass%, coarse intermetallic compounds are formed, and the formability may be degraded.

Therefore, when Fe is contained in the core material, the content of Fe is 1.5 mass% or less.

In order to more surely improve the strength obtained by containing Fe, the content of Fe in the core material is preferably 0.05 mass% or more.

(Ti of core material: 0.5% by mass or less)

Ti in the core material increases the potential of the core material, thereby improving corrosion resistance. However, if the content of Ti is more than 0.5 mass%, coarse intermetallic compounds are formed, and the formability may be degraded.

Therefore, when the core material contains Ti, the content of Ti is 0.5 mass% or less.

In order to more surely improve the corrosion resistance obtained by containing Ti, the content of Ti in the core material is preferably 0.01 mass% or more.

(Cr of core material: 0.5% by mass or less)

Cr in the core material forms Al-Cr dispersed particles, and the strength of the core material is improved. However, if the content of Cr is more than 0.5 mass%, coarse intermetallic compounds are formed, and thus formability may be degraded.

Therefore, when Cr is contained in the core material, the content of Cr is 0.5 mass% or less.

In order to more surely improve the strength obtained by containing Cr, the Cr content in the core material is preferably 0.01 mass% or more.

(Zr in core Material: 0.5% by mass or less)

Zr in the core material forms Al-Zr dispersed particles, so that the strength of the core material is improved. However, if the content of Zr is higher than 0.5 mass%, coarse intermetallic compounds are formed, and thus formability may be degraded.

Therefore, when Zr is contained in the core material, the Zr content is 0.5 mass% or less.

In order to more surely improve the strength obtained by containing Zr, the Zr content in the core material is preferably 0.01 mass% or more.

If the core material contains Ti, Cr, and Zr at not more than the upper limit value, the effect of the present invention is not impaired if the core material contains one or more species, that is, if the core material contains one species, two or more species.

(Li in the core material: 0.3 mass% or less)

Li of the core material further improves the brazeability. The detailed mechanism of improving the solderability by Li is not yet understood, but it is presumed that Li does not destroy the oxide film formed on the surface of the brazing filler metal when the brazing filler metal is melted at the time of heating for brazing, and thereby the gettering action of Mg is more preferably exerted. However, if the content of Li is more than 0.3 mass%, Li diffuses to the surface layer part of the brazing filler metal during the temperature rise at the time of brazing heating, and the growth of an oxide film is promoted, so that the brazeability is lowered.

Therefore, when Li is contained in the core material, the content of Li is 0.3 mass% or less.

From the viewpoint of suppressing the growth of the oxide film, the Li content of the core material is preferably 0.05 mass% or less.

(balance of core Material: Al and unavoidable impurities)

The balance of the core material is preferably Al and inevitable impurities. The inevitable impurities of the core material include V, Ni, Ca, Na, Sr, and the like, and these elements may be contained in a range not interfering with the effect of the present invention. Specifically, V may be contained in the following range: 0.05 mass% or less, Ni: 0.05 mass% or less, Ca: 0.05 mass% or less, Na: 0.05 mass% or less, Sr: 0.05 mass% or less, other elements: less than 0.01% by mass.

Further, if these elements do not exceed the predetermined content, they are allowed to be contained not only as inevitable impurities but also as positive additions without impairing the effects of the present invention.

The Mg, Mn, Si, Cu, Fe, Ti, Cr, Zr, and Li may be positively added, but may be included as an inevitable impurity.

[ brazing filler metal ]

The brazing material for brazing sheet of the present embodiment contains Si, Bi, and Mg, and the balance is Al and inevitable impurities.

The brazing material for brazing sheet of the present embodiment may further contain Mn, Ti, Cr, Zr, Zn, Sr, Na, Sb, a rare earth element, and Li as appropriate.

(Si in the brazing filler metal is 3 to 13 mass%, and C is not less than 3 ≦ C_Si≤13)

The Si of the brazing filler metal lowers the solidus temperature of the brazing filler metal, thereby increasing the liquidus fraction at the brazing heating temperature to improve the fluidity of the brazing filler metal. When the content of Si is 3 mass% or more, the fluidity of the solder is improved, and the brazing property is improved. On the other hand, if the content of Si is higher than 13 mass%, coarse Si particles are formed, and a flowing solder is excessively generated, which may cause brazing defects such as melting of the core material.

Therefore, the Si content of the brazing filler metal is 3 mass% or more and 13 mass% or less. Further, the content of Si in the brazing filler metal is C_SiWhen mass%, 3. ltoreq. C_Si≤13。

(Bi of solder: 0.13C)_Mg ^-0.3≤C_Bi≤0.58C_Mg ^0.45)

Bi in the brazing filler metal reacts with the core material and Mg in the brazing filler metal to form a Mg-Bi compound (e.g., Bi) which hardly melts at a temperature lower than the melting temperature of the brazing filler metal₂Mg₃). As a result, the material manufacturing process is completedAnd during the temperature rise from the brazing heating to the melting start temperature of the brazing filler metal, diffusion of Mg into the surface layer portion of the brazing filler metal is suppressed, and the formation and growth of MgO (capturing action of Mg) on the surface of the brazing filler metal is suppressed, thereby improving the brazeability. Further, at the melting temperature of the brazing filler metal at the time of heating for brazing, the Mg — Bi compound is dissolved in the matrix (brazing filler metal), and therefore evaporation of Mg is promoted. Further, the oxide film formed on the surface of the brazing material is just destroyed at the time of evaporation of Mg, and this Mg reacts with oxygen in the atmosphere, so that the oxygen concentration in the atmosphere is reduced, and the action of suppressing reoxidation of the molten solder (gettering action) is improved, and as a result, the brazeability is improved. In addition, Bi improves the fluidity of the solder and improves the solderability.

In order to exhibit the above effects properly, the content of Bi in the brazing filler metal needs to be specified very precisely in relation to the content of Mg in the core material and the brazing filler metal.

Specifically, the content of Mg in the brazing filler metal is C_Mg－bMass% of the core material is C_Mg－cMass% of C_Mg＝C_Mg－b+C_Mg－cWhen the Bi content of the solder is less than 0.13C_Mg ^－0.3However, Mg is not sufficiently captured, and Mg released in the brazing material increases, and as a result, MgO is generated on the surface of the brazing material. Further, if the Bi content of the solder is less than 0.13C_Mg ^－0.3The solder fluidity is lowered, and the solderability is lowered.

On the other hand, even if the Bi content of the solder is more than 0.58C_Mg ^0.45The brazeability is still reduced. In this regard, although the detailed mechanism is not yet understood, it is presumed that the reason is not that when the content of Bi is increased relative to the content of Mg, the low melting point Bi monomer compound increases, and the compound starts to melt from the low temperature range at the time of heating of the brazing, and wets and spreads to form and grow an oxide film, which suppresses the gettering effect.

Therefore, the Bi content of the solder is 0.13C_Mg ^－0.3Above, 0.58C_Mg ^0.45The following. Further, the content of Bi in the brazing filler metal is C_BiAt mass%, 0.13C_Mg ^－0.3≤C_Bi≤0.58C_Mg ^0.45。

About "0.13C_Mg ^－0.3≤C_Bi≤0.58C_Mg ^0.45"are coefficients for a particular range of possible effects, as previously described, which are derived from the results of a number of experiments.

(solder Mg: 0.1 mass% or more, C)_Mg－b≥0.1)

The Mg of the brazing filler metal is evaporated in the atmosphere at the melting temperature of the brazing filler metal at the time of brazing heating, and reacts with oxygen in the atmosphere, similarly to the Mg of the core material. As a result, the oxide film formed on the surface of the brazing material is destroyed just by evaporation of Mg, the oxygen concentration in the atmosphere is reduced, and re-oxidation of the molten solder is suppressed (gettering action), thereby improving the brazeability. Since Mg in the core material also plays a role of gettering, when the Mg content in the core material is large, the Mg content in the brazing material may be small.

However, if the Mg content is less than 0.1 mass%, edge cracking is likely to occur during hot rolling, and the yield of the brazing sheet is deteriorated. In this regard, although the detailed mechanism is not yet understood, it is presumed that the small Mg content of the brazing filler metal increases the Bi monomer compound having a low melting point, and the compound melts during hot rolling to induce hot rolling cracks. When the content of Mg is 0.1 mass% or more, Mg reacts with Bi to form Bi having a high melting point which is difficult to melt even in hot rolling₂Mg₃Thereby, occurrence of hot rolling cracks can be prevented.

Therefore, the Mg content of the brazing filler metal is 0.1 mass% or more. Further, let the Mg content of the brazing filler metal be C_Mg－bWhen mass%, C_Mg－b≥0.1。

(Mg of the brazing filler metal and Mg of the core material: 0.2. ltoreq. C_Mg≤1.1)

Both the Mg of the brazing material and the Mg of the core material exert a gettering effect as described above, thereby improving the brazeability.

However, since Mg of the brazing material and Mg of the core material have different degrees of contribution to the gettering action and the like, it is necessary to precisely specify the Mg content of the brazing material and the Mg content of the core material in order to suitably exhibit the effect of improving the brazing property by the gettering action.

Setting the Mg content of the solder as C_Mg－bMass% of the core material is C_Mg－cMass% of C_Mg＝C_Mg－b+C_Mg－cWhen/2, if C_MgIf the amount is less than 0.2, the effect of gettering from Mg may be insufficient, resulting in a decrease in brazeability. On the other hand, if C_MgIf the content is more than 1.1, all Mg cannot be captured by Bi of the brazing filler metal, so that MgO is generated on the surface of the brazing filler metal, and the brazeability may be deteriorated.

Therefore, 0.2. ltoreq.C_Mg≤1.1。

In order to ensure the gettering effect obtained by containing Mg, C is preferred_MgIs 0.3 or more. In addition, from the viewpoint of suppressing the reduction of brazeability, C is preferable_MgIs 0.9 or less.

With respect to "C_Mg＝C_Mg－b+C_Mg－cThe coefficient of/2 "is a coefficient in consideration of the degree of contribution of Mg of the brazing material and Mg of the core material to the gettering action, and is a coefficient for specifying a range in which the effect can be achieved as described above, and is derived from the results of a large number of experiments.

(Mn of the brazing filler metal: 2.0 mass% or less)

Mn of the brazing filler metal improves corrosion resistance. Although the detailed mechanism of the improvement of corrosion resistance by Mn is not understood, it is presumed that an Al — Mn — Si based compound is generated, and a Mn-and Si-depleted layer around the compound becomes a portion having a low potential, and corrosion preferentially proceeds, so that corrosion is dispersed and corrosion resistance is improved. However, if the content of Mn is more than 2.0 mass%, Si is consumed for the formation of the Al — Mn — Si based compound, so that the Si concentration decreases and the brazeability decreases.

Therefore, when Mn is contained in the brazing material, the Mn content of the brazing material is 2.0 mass% or less.

In order to more surely improve the corrosion resistance obtained by containing Mn, the Mn content of the brazing filler metal is preferably 0.05 mass% or more. In addition, the Mn content of the brazing filler metal is preferably 1.2 mass% or less from the viewpoint of suppressing the reduction of the brazeability accompanying the reduction of the Si concentration.

(Ti of the brazing filler metal: 0.3% by mass or less)

The Ti of the brazing filler metal improves corrosion resistance. Although the detailed mechanism of the improvement of corrosion resistance by Ti is not understood, it is presumed that an Al — Ti compound is generated, a Ti-depleted layer around the compound becomes a portion having a low potential, and corrosion preferably proceeds, so that corrosion is dispersed and corrosion resistance is improved. However, if the content of Ti is more than 0.3 mass%, coarse compounds are generated during melting and casting, and cracks are likely to occur during production of the material, making production difficult.

Therefore, when the brazing material contains Ti, the content of Ti in the brazing material is 0.3 mass% or less.

In order to more surely improve the corrosion resistance obtained by containing Ti, the content of Ti in the brazing filler metal is preferably 0.05 mass% or more. In addition, the Ti content of the brazing material is preferably 0.2 mass% or less from the viewpoint of suppressing the occurrence of cracks at the time of material production.

(Cr of the brazing filler metal: 0.3% by mass or less)

Cr of the brazing filler metal improves corrosion resistance. Although the detailed mechanism of the improvement of corrosion resistance by Cr is not understood, it is presumed that Al-Cr-based or Al-Cr-Si-based compounds are generated, and a Cr-Si depleted layer around the compounds becomes a portion having a low potential, and corrosion preferentially proceeds, so that corrosion is dispersed and corrosion resistance is improved. However, if the content of Cr is more than 0.3 mass%, coarse compounds are generated during melting and casting, and cracks are likely to occur during production of the material, making production difficult.

Therefore, when the brazing filler metal contains Cr, the Cr content of the brazing filler metal is 0.3 mass% or less.

In order to more surely improve the corrosion resistance obtained by containing Cr, the content of Cr in the brazing filler metal is preferably 0.05 mass% or more. In addition, the Cr content of the brazing filler metal is preferably 0.2 mass% or less from the viewpoint of suppressing the occurrence of cracks at the time of material production.

(Zr in the brazing filler metal: 0.3% by mass or less)

Zr of the brazing filler metal improves corrosion resistance. Although the detailed mechanism of the improvement of corrosion resistance by Zr is not understood, it is presumed that an Al — Zr compound is generated, a Zr-depleted layer around the compound becomes a portion having a low potential, and corrosion preferentially proceeds, so that corrosion is dispersed and corrosion resistance is improved. However, when the content of Zr is more than 0.3 mass%, coarse compounds are generated during melting and casting, and cracks are likely to occur during production of the material, making the production difficult.

Therefore, when the brazing filler metal contains Zr, the Zr content of the brazing filler metal is 0.3 mass% or less.

In order to more surely improve the corrosion resistance obtained by containing Zr, the Zr content of the brazing filler metal is preferably 0.05 mass% or more. In addition, from the viewpoint of suppressing the occurrence of cracks at the time of material production, the Zr content of the brazing filler metal is preferably 0.2 mass% or less.

If the Mn, Ti, Cr, and Zr of the brazing filler metal do not exceed the upper limit, the effect of the present invention is not hindered by including one or more species in the brazing filler metal, that is, by including two or more species in addition to one species.

(Zn of solder: 5.0 mass% or less)

The Zn of the solder can lower the potential of the solder to form a potential difference with the core material, thereby improving the corrosion resistance by sacrificing the corrosion prevention effect. However, if the Zn content is higher than 5.0 mass%, there is a possibility that the brazing corner may be corroded early.

Therefore, when the brazing filler metal contains Zn, the Zn content of the brazing filler metal is 5.0 mass% or less.

In order to more surely improve the corrosion resistance obtained by containing Zn, the Zn content of the brazing filler metal is preferably 0.1 mass% or more. In addition, from the viewpoint of suppressing the occurrence of the early corrosion of the fillet, the Zn content of the brazing filler metal is preferably 4.0 mass% or less.

(Sr in brazing filler metal: 0.10% by mass or less)

Sr of the brazing filler metal makes eutectic Si fine, thereby suppressing crystallization of coarse Si particles that cause melting of the core material at the time of brazing heating. However, if the Sr content is more than 0.10 mass%, the fluidity of the solder is lowered, and there is a possibility that the formation of the fillet during the brazing heating is insufficient.

Therefore, when the brazing filler metal contains Sr, the Sr content is 0.10 mass% or less.

In order to more surely achieve the effect of refining eutectic Si obtained by containing Sr, the Sr content of the brazing filler metal is preferably 0.001 mass% or more.

(Na in solder: 0.050% by mass or less)

Na of the brazing filler metal refines eutectic Si, and suppresses crystallization of coarse Si particles that cause melting of the core material during brazing heating. However, if the Na content is more than 0.050 mass%, the fluidity of the solder is lowered, and the formation of a fillet during brazing heating may be insufficient.

Therefore, when the brazing filler metal contains Na, the Na content is 0.050 mass% or less.

In order to more surely achieve the effect of refining eutectic Si obtained by containing Na, the Na content of the brazing filler metal is preferably 0.0001 mass% or more.

(Sb of the brazing filler metal: 0.5% by mass or less)

Sb in the brazing filler metal makes eutectic Si fine, thereby suppressing crystallization of coarse Si particles that cause melting of the core material during brazing heating. However, if the content of Sb is more than 0.5 mass%, the fluidity of the solder is lowered, and there is a possibility that the formation of the fillet during the brazing heating is insufficient.

Therefore, when the brazing filler metal contains Sb, the content of Sb is 0.5 mass% or less.

In order to more surely achieve the effect of refining eutectic Si obtained by containing Sb, the content of Sb in the brazing filler metal is preferably 0.001 mass% or more.

If the Sr, Na, Sb content of the brazing filler metal does not exceed the upper limit, the effect of the present invention is not hindered by the inclusion of one or more species of the brazing filler metal, that is, by the inclusion of two or more species of the brazing filler metal, in addition to the inclusion of one species.

(rare earth element of brazing filler metal: 1.0% by mass or less)

The rare earth elements are a general term for 17 elements of Sc and Y plus lanthanide series (15 elements) in group 3 of the periodic Table, and include, for example, Sc, Y, La, Ce, Nd, Dy, and the like. When the rare earth element is contained in the brazing filler metal, one kind of rare earth element may be contained, or two or more kinds of rare earth elements may be contained. Although the method of adding the rare earth element to the brazing filler metal is not particularly limited, for example, an Al — rare earth intermediate alloy may be added, or two or more rare earth elements may be simultaneously added by adding a mixed rare earth.

Rare earth elements of the solder, surface oxide film (Al) of the solder during heating of the solder₂O₃) Reacts with the rare earth element or the oxide containing the rare earth element, and causes volume shrinkage of the oxide film on the surface of the brazing filler metal to break the oxide film, thereby improving the brazeability. However, if the content of the rare earth element (the total amount of two or more rare earth elements included) is more than 1.0 mass%, an oxide film containing the rare earth element is excessively generated, and the effect of breaking the oxide film is reduced, thereby reducing the brazeability.

Therefore, when the brazing filler metal contains a rare earth element, the content of the rare earth element in the brazing filler metal is 1.0 mass% or less.

In order to ensure the effect of breaking the oxide film obtained by containing a rare earth element, the content of the rare earth element in the brazing filler metal is preferably 0.001 mass% or more.

(Li in the brazing filler metal: 0.3 mass% or less)

Like Li of the core material, Li of the brazing filler metal further improves the brazeability. Although the detailed mechanism by which Li improves solderability is not yet understood, it is presumed that Li does not break the oxide film formed on the surface of the brazing filler metal when the brazing filler metal is melted during heating for brazing, and thereby the gettering action of Mg can be more appropriately exerted. However, if the content of Li is more than 0.3 mass%, Li promotes the growth of an oxide film, and thus the brazeability is lowered.

Therefore, when the brazing filler metal contains Li, the content of Li is 0.3 mass% or less.

In addition, from the viewpoint of suppressing the growth of an oxide film, the Li content of the brazing filler metal is preferably 0.05 mass% or less.

(the balance of the brazing filler metal: Al and inevitable impurities)

The balance of the brazing filler metal is preferably Al and inevitable impurities. The brazing filler metal may contain Fe, Ca, Be, and the like as inevitable impurities within a range not interfering with the effects of the present invention. Specifically, these elements, i.e., Fe, may be contained in the following ranges: 0.35% by mass or less, Ca: 0.05% by mass or less, Be: 0.01 mass% or less of other elements: less than 0.01% by mass. Further, if the content of these elements does not exceed the above-mentioned predetermined content, the elements are not only contained as inevitable impurities but also allowed to be contained without interfering with the effects of the present invention even when they are positively added.

The Mn, Ti, Cr, Zr, Zn, Sr, Na, Sb, rare earth element, and Li may be positively added or may be included as an inevitable impurity.

[ thickness of aluminum alloy brazing sheet ]

The thickness of the brazing sheet of the present embodiment is not particularly limited, but when used for a pipe material, is preferably 0.5mm or less, more preferably 0.4mm or less, and further preferably 0.05mm or more.

Accordingly, the thickness of the brazing sheet of the present embodiment is preferably 2.0mm or less, more preferably 1.5mm or less, and further preferably 0.5mm or more when used for a side support material, a pipe material, or a groove material.

The thickness of the brazing sheet of the present embodiment is preferably 0.2mm or less, more preferably 0.15mm or less, and further preferably 0.01mm or more when used for a fin sheet.

The thickness of the brazing sheet of the present embodiment is particularly preferably 0.5mm or more from the viewpoint of ensuring an appropriate thickness of the brazing material without impairing basic characteristics such as strength after brazing.

The thickness of the brazing material of the brazing sheet of the present embodiment is not particularly limited when applied to any sheet material, but is preferably 2 μm or more, and more preferably 50 μm or more. When the thickness of the brazing material is equal to or greater than a predetermined value, the absolute amount of Mg contained in the brazing material increases, and the suction effect can be more reliably exhibited. The thickness of the brazing material is preferably 250 μm or less.

The coating rate of the brazing material in the brazing sheet of the present embodiment is not particularly limited when applied to any sheet material, but is preferably 40% or less, and more preferably 30% or less. By setting the coating rate of the brazing material to a predetermined value or less, it is possible to avoid or suppress a decrease in basic characteristics such as strength after brazing, productivity, and the like.

[ other constitution of aluminum alloy brazing sheet ]

The brazing sheet of the present embodiment is described by way of example of the two-layer structure shown in fig. 1, but other structures are not excluded.

For example, in the structure of the brazing sheet of the present embodiment, a sacrificial material (sacrificial corrosion preventing material, sacrificial material) or an intermediate material may be provided on the other side (the side opposite to the side provided with the brazing material 3) of the core material 2 shown in fig. 1 according to the user's request. Further, a brazing material may be provided on the other side of the core member 2.

Further, a sacrificial material or an intermediate material may be provided on the other side of the core member 2, and a brazing material may be provided on the outer side.

In the case where the brazing sheet of the present embodiment is configured to include the brazing filler metal on both sides of the core member, the brazing filler metal on one side may be a brazing filler metal that does not satisfy the specific items of the present invention (for example, Al — Si alloys, Al — Si — Zn alloys, Al — Si — Mg alloys, and the like according to JIS 4045, 4047, 4343, and the like) as long as the brazing filler metal on the other side satisfies the specific items of the present invention. In addition, a brazing material that does not satisfy the specific matters of the present invention may be brazed by applying a flux to the surface of the brazing material.

The sacrificial material may have a known composition that exhibits sacrificial corrosion resistance, and may be, for example, pure aluminum of JIS 1000 series or Al — Zn alloy of JIS 7000 series. In addition, as the intermediate material, various aluminum alloys can be used according to required characteristics.

Further, the alloy number shown in the present specification is based on JIS H4000: 2014. JIS Z3263: 2002.

in addition, since the components and contents of the core material and the brazing material are specified, the brazing sheet of the present embodiment is also excellent in corrosion resistance. Therefore, according to the brazing sheet of the present embodiment, the structure after brazing can also cope with various use environments and use atmospheres.

Next, a brazing method of the aluminum alloy brazing sheet according to the present embodiment will be described.

[ brazing method of aluminum alloy brazing sheet ]

The brazing method of the aluminum alloy brazing sheet according to the present embodiment is so-called fluxless brazing in which no flux is used, and is a method of heating the aluminum alloy brazing sheet under a predetermined heating condition in an inert gas atmosphere.

(heating conditions: heating Rate)

When the temperature increase rate from 350 ℃ to 560 ℃ is lower than 1 ℃/min at the time of heating (brazing) the brazing sheet of the present embodiment, Mg of the core material and the brazing material is excessively diffused to the surface layer portion of the brazing material in the temperature increase process, and there is a possibility that MgO is generated on the surface of the brazing material, and the brazing property is lowered. On the other hand, if the temperature increase rate from 350 ℃ to 560 ℃ is higher than 500 ℃/min, Mg in the core material and the brazing filler metal does not diffuse properly to the surface layer part of the brazing filler metal in the temperature increase process, and the possibility of insufficient gettering increases, and the brazeability may decrease.

Therefore, the temperature rise rate from 350 ℃ to 560 ℃ is preferably 1 ℃/min or more and 500 ℃/min or less.

In order to reduce the possibility of MgO formation on the surface of the brazing material, the temperature rise rate from 350 ℃ to 560 ℃ is preferably 10 ℃/min or more. In order to more reliably exhibit the gettering effect, the temperature rise rate from 350 ℃ to 560 ℃ is preferably 300 ℃/min or less.

On the other hand, the cooling rate from 560 ℃ is not particularly limited, and may be, for example, 5 ℃/min or more and 1000 ℃/min or less.

The temperature increase rate from 560 ℃ to the actual heating temperature (the predetermined maximum reaching temperature in the range of the heating temperature described later) is not particularly limited, but may be in the same range as the temperature increase rate from 350 ℃ to 560 ℃. The temperature decrease rate from the actual heating temperature to 560 ℃ is not particularly limited, but may be in the same range as the temperature decrease rate from 560 ℃.

(heating conditions: heating temperature, holding time)

The heating temperature (brazing filler metal melting temperature) at the time of heating the brazing sheet of the present embodiment is 560 ℃ to 620 ℃, preferably 580 ℃ to 620 ℃ at which the brazing filler metal is properly melted. If the holding time in this temperature range is less than 10 seconds, the time required for the occurrence of the brazing phenomenon (the destruction of the oxide film, the decrease in the oxygen concentration of the atmosphere, and the flow of the molten solder to the joint) may be insufficient.

Therefore, the holding time in the temperature range of 560 ℃ to 620 ℃ inclusive (preferably 580 ℃ to 620 ℃ inclusive) is preferably 10 seconds or longer.

In order to more reliably cause the brazing phenomenon, the holding time in the temperature range of 560 ℃ to 620 ℃ (preferably 580 ℃ to 620 ℃), is preferably 30 seconds or longer, and more preferably 60 seconds or longer. On the other hand, the upper limit of the holding time is not particularly limited, but may be 1500 seconds or less.

(inert gas atmosphere)

The atmosphere when the brazing sheet of the present embodiment is heated (brazed) is an inert gas atmosphere, for example, a nitrogen atmosphere, an argon atmosphere, a helium atmosphere, or a mixed gas atmosphere in which these plural gases are mixed. The inert gas atmosphere is preferably an atmosphere having an oxygen concentration as low as possible, specifically, an oxygen concentration of 50ppm or less, more preferably 10ppm or less.

In addition, the brazing method of the aluminum alloy brazing sheet according to the present embodiment can be performed under normal pressure (atmospheric pressure) without requiring vacuum atmosphere.

In general, before the above-described heating (before the brazing step) is performed on the brazing sheet of the present embodiment, the member to be joined is assembled so as to be in contact with the brazing material of the brazing sheet (assembling step). Before the assembling step, the brazing sheet may be formed into a desired shape or structure (forming step).

As described above, the brazing method of the brazing sheet of the present embodiment (in other words, the method of manufacturing a structure in which the members to be joined are brazed to the brazing sheet) can be appropriately changed as long as the conditions not explicitly described are not known and the effects obtained through the above treatment are obtained.

In the brazing method of the brazing sheet according to the present embodiment, the components and contents of the core material and the brazing material of the brazing sheet to be used are specified, and therefore, excellent corrosion resistance is also exhibited. Therefore, according to the brazing method of brazing sheet of the present embodiment, the structure after brazing can also cope with various usage environments and usage atmospheres.

Next, a method for manufacturing an aluminum alloy brazing sheet according to the present embodiment will be described.

[ method for producing aluminum alloy brazing sheet ]

The method for producing the brazing sheet of the present embodiment is not particularly limited, and can be produced by a known method for producing a clad material, for example. An example thereof will be described below.

First, aluminum alloys having respective component compositions of the core material and the brazing filler metal are melted and cast, and then surface cutting (surface smoothing treatment of the ingot) and homogenization treatment are performed as necessary to obtain respective ingots. Then, the ingot of the brazing filler metal is hot-rolled to a predetermined thickness, combined with the ingot of the core material, and hot-rolled into a clad material by a conventional method. Thereafter, the clad material is subjected to cold rolling, intermediate annealing if necessary, final cold rolling, and final annealing if necessary.

Preferably, the homogenization treatment is performed at 400 to 600 ℃ for 1 to 20 hours, and the intermediate annealing is performed at 300 to 450 ℃ for 1 to 20 hours. Further, it is preferable that the final annealing is performed at 150 to 450 ℃ for 1 to 20 hours. In addition, when the final annealing is performed, the intermediate annealing may be omitted. Further, the heat treatment may be any of H1n, H2n, H3n and O (JIS H0001: 1998).

As described above, in the method for producing an aluminum alloy brazing sheet according to the present embodiment, conventionally known conditions may be used for conditions not explicitly described in the respective steps, and the conditions may be appropriately changed as long as the effects obtained through the treatments in the respective steps are obtained.