CN112605554A - Bismuth-containing 4-series aluminum alloy suitable for brazing flux-free brazing and preparation method thereof - Google Patents
Bismuth-containing 4-series aluminum alloy suitable for brazing flux-free brazing and preparation method thereof Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/24—Selection of soldering or welding materials proper
- B23K35/28—Selection of soldering or welding materials proper with the principal constituent melting at less than 950 degrees C
- B23K35/286—Al as the principal constituent
- B23K35/288—Al as the principal constituent with Sn or Zn
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/40—Making wire or rods for soldering or welding
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Abstract
A bismuth-containing 4-series aluminum alloy suitable for brazing flux-free brazing and a preparation method thereof relate to a 4-series aluminum alloy and a preparation method thereof. The purpose is to solve the problems of insufficient solder, missing solder and melting corrosion of the existing aluminum alloy brazing. The aluminum alloy of the invention is prepared from Si: 9.5-11%, Mg: 1.3-2.0%, Fe: less than or equal to 0.3 percent, Cu: less than or equal to 0.02 percent, Mn: less than or equal to 0.1 percent, Zn: 0.015 to 0.04%, Bi: 0.01-0.06% and the balance of Al. Preparation: smelting to obtain an alloy melt, introducing the alloy melt into a standing furnace of a resistance reverberatory furnace, introducing chlorine gas for refining, adding Na modifier, stirring, degassing, filtering and semicontinuous casting to obtain an ingot, and sequentially performing surface milling, hot rolling, coiling and cold finish rolling on the ingot to obtain a finished plate. Mg element in the alloy can avoid local corrosion, and Bi element can improve the bonding strength of the interface. The invention is suitable for preparing 4 series aluminum alloy.
Description
Technical Field
The invention relates to a 4-series aluminum alloy and a preparation method thereof.
Background
Aluminum alloy brazing is used as an important method for aluminum alloy connection, and is different from other welding methods in the aspects of welding principle, process flow, welding equipment and the like, so that the brazing has unique advantages in practical engineering application: 1. the brazing heating temperature is low and is usually far lower than the melting point of the base metal, so that the whole brazing piece can be uniformly heated, the deformation of the brazing piece is small, and the dimensional precision of the brazing piece is easy to guarantee. 2. Brazeable weldments of complex, precise construction and poor joint accessibility. 3. The production efficiency is high, and the connection of multiple seam and multiple parts can be completed at one time. 4. Can realize welding between homogeneous and heterogeneous base materials. Based on the advantages, the brazing technology is widely applied to aluminum alloy processing engineering in China in recent years. However, aluminum alloy brazing still has many technical problems, and the main problems at present are insufficient solder, missing solder and melting corrosion. The cold joint and the leakage joint are mainly caused by that the joint gap is not filled with the brazing filler metal partially or completely, or the brazing filler metal is not fused with the substrate. The main reasons for this defect include that the brazing temperature is too low, and the brazing alloy is heated unevenly to cause incomplete penetration; improper selection of the brazing flux, or reduced chemical activity of the brazing flux, cannot effectively break the surface oxide film and poor fluidity of the brazing flux. The corrosion is one of the main reasons for product scrap during brazing, and the reasons for such defects include: 1. the brazing filler metal is not properly selected, and the spreadability and wettability are poor in the melting process, so that the brazing filler metal is locally accumulated, and the penetration and leakage are caused; 2. if the brazing temperature is too high or the brazing time is too long, Si elements in the brazing filler metal can diffuse to the base metal, so that the melting point of the base metal is reduced, and the phenomenon of corrosion occurs.
Disclosure of Invention
The invention provides a bismuth-containing 4-series aluminum alloy suitable for brazing without a brazing flux and a preparation method thereof, aiming at solving the problems of insufficient solder, missing solder and corrosion existing in the existing aluminum alloy brazing.
The bismuth-containing 4-series aluminum alloy suitable for brazing flux-free brazing is prepared from the following components in percentage by mass: 9.5-11%, Mg: 1.3-2.0%, Fe: less than or equal to 0.3 percent, Cu: less than or equal to 0.02 percent, Mn: less than or equal to 0.1 percent, Zn: 0.015 to 0.04%, Bi: 0.01-0.06% and the balance of Al.
The preparation method of the bismuth-containing 4-series aluminum alloy for brazing without the brazing flux comprises the following steps:
firstly, smelting:
according to mass percentage, Si: 9.5-11%, Mg: 1.3-2.0%, Fe: less than or equal to 0.3 percent, Cu: less than or equal to 0.02 percent, Mn: less than or equal to 0.1 percent, Zn: 0.015 to 0.04%, Bi: weighing 0.01-0.06% of Al and the balance of Al, and taking Al-20% of Si intermediate alloy, Al-Bi intermediate alloy, Mg ingot, Zn ingot and aluminum ingot for remelting as raw materials; adding an aluminum ingot for remelting, adding an Al-20% Si intermediate alloy and an Al-Bi intermediate alloy, heating the furnace to 740-800 ℃, uniformly adding a Zn ingot below the liquid level of a melt in the furnace after raw materials in the furnace soften and collapse, slagging off after furnace burden is completely melted, controlling the melt temperature to 740-750 ℃ after slagging off, adding an Mg ingot, stirring for 10-15 minutes after the raw materials in the furnace are completely melted to obtain an alloy melt, and covering a flux on the surface of the alloy melt;
secondly, casting: introducing the alloy melt obtained in the step I into a standing furnace of a resistance reverberatory furnace, introducing chlorine for refining, adding Na modifier after standing, stirring to obtain a refined and modified alloy melt, staying for 30-60 min, then flowing into an online degassing device for degassing, then flowing into a filtering device for filtering after degassing, and after filtering, injecting the melt into a crystallizer through a splitter disc for semi-continuous casting to obtain an ingot;
thirdly, sequentially carrying out face milling, hot rolling, coiling and cold finish rolling on the cast ingot to obtain a finished plate; and (5) performing intermediate annealing when the thickness of the finished plate after cold finish rolling is less than 1.5 mm.
The principle and the beneficial effects of the invention are as follows:
the addition of Mg in the alloy of the invention can play a favorable role in vacuum brazing. In the brazing flux-free vacuum brazing process, the vapor pressure of Mg element is high, the boiling point is low, and the Mg element can be volatilized under the vacuum condition so as to remove residual oxygen and moisture in vacuum and improve the effective vacuum degree. On the other hand, the Mg vapor may penetrate into the surface layer of the base material under the oxide film to form a low melting point Al-Si-Mg alloy together with the diffused Si to melt, thereby breaking the bonding between the oxide film and the base material, and wetting and spreading the molten filler along the surface of the aluminum alloy. Therefore, the proper amount of Mg element can remove an oxidation film, adsorb residual water in a furnace body, reduce oxygen partial pressure, promote solder flowing, supplement burning loss of the Mg element in the alloy and avoid local occurrence of a corrosion phenomenon.
The Bi element in the alloy has very obvious improvement effect on the wettability of the aluminum alloy: the spreading performance of the brazing filler metal alloy is directly influenced by the interface tension between the liquid 4 series aluminum alloy and the base metal to be welded in the brazing process, and the interface tension is mainly determined by the surface tension of the liquid 4 series aluminum alloy. The surface tension of Bi element is very low when the Bi element is melted, and the Bi element can be used as a surface active substance to reduce the surface tension of the brazing filler metal, so that the resistance of the 4-series aluminum alloy on the surface of a base metal to be welded is reduced, and the spreading area is increased. In addition, Bi element is precipitated in a single-phase mode at high temperature, and the structure in a welding seam can be refined, so that the bonding strength of an interface is improved.
In conclusion, the 4-series aluminum alloy in the invention can remove the oxide film on the joint surface due to the beneficial effects of a proper amount of Mg element and Bi element, so that the brazing filler metal has better spreadability and fluidity, and the joint strength of the interface can be effectively improved, thereby obviously reducing the number of insufficient solder joints and missing solder joints, basically eliminating the phenomenon of corrosion and obviously improving the brazing quality.
The invention selects high-temperature smelting mainly for fully melting Si phase in the Al-Si intermediate alloy and obtaining higher supercooling degree in the solidification process. If the melting temperature and the supercooling degree are low, the Si phase cannot be fully melted and exists in the alloy in the shape of a massive Si phase, so that the brazing performance of the alloy is not facilitated; the invention has enough melting temperature and supercooling degree conditions, the Si phase can exist in the alloy in a five-star petal shape, and the structure is more beneficial to the melting and flowing of the brazing filler metal.
The brazing temperature of the finished plate obtained by the invention is 600-615 ℃ during brazing, and the brazing time is 10-30 min.
Drawings
FIG. 1 is a metallographic photograph of a sample obtained in comparative example 1;
FIG. 2 is a metallographic photograph of a sample obtained in example 1.
Detailed Description
The technical scheme of the invention is not limited to the specific embodiments listed below, and any reasonable combination of the specific embodiments is included.
The first embodiment is as follows: the bismuth-containing 4-series aluminum alloy suitable for brazing without the brazing flux in the embodiment is prepared from the following components in percentage by mass: 9.5-11%, Mg: 1.3-2.0%, Fe: less than or equal to 0.3 percent, Cu: less than or equal to 0.02 percent, Mn: less than or equal to 0.1 percent, Zn: 0.015 to 0.04%, Bi: 0.01-0.06% and the balance of Al. Fe. Cu and Mn are impurity elements.
The addition of Mg elements in the alloy of this embodiment can have a beneficial effect on vacuum brazing. In the brazing flux-free vacuum brazing process, the vapor pressure of Mg element is high, the boiling point is low, and the Mg element can be volatilized under the vacuum condition so as to remove residual oxygen and moisture in vacuum and improve the effective vacuum degree. On the other hand, the Mg vapor may penetrate into the surface layer of the base material under the oxide film to form a low melting point Al-Si-Mg alloy together with the diffused Si to melt, thereby breaking the bonding between the oxide film and the base material, and wetting and spreading the molten filler along the surface of the aluminum alloy. Therefore, the proper amount of Mg element can remove an oxidation film, adsorb residual water in a furnace body, reduce oxygen partial pressure, promote solder flowing, supplement burning loss of the Mg element in the alloy and avoid local occurrence of a corrosion phenomenon.
The Bi element in the alloy of the embodiment has very obvious improvement effect on the wettability of the aluminum alloy: the spreading performance of the brazing filler metal alloy is directly influenced by the interface tension between the liquid 4 series aluminum alloy and the base metal to be welded in the brazing process, and the interface tension is mainly determined by the surface tension of the liquid 4 series aluminum alloy. The surface tension of Bi element is very low when the Bi element is melted, and the Bi element can be used as a surface active substance to reduce the surface tension of the brazing filler metal, so that the resistance of the 4-series aluminum alloy on the surface of a base metal to be welded is reduced, and the spreading area is increased. In addition, Bi element is precipitated in a single-phase mode at high temperature, and the structure in a welding seam can be refined, so that the bonding strength of an interface is improved.
In summary, in the 4-series aluminum alloy in the embodiment, due to the beneficial effects of the appropriate amount of Mg element and Bi element, the oxide film on the joint surface can be removed, so that the solder has better spreadability and fluidity, and the joint strength of the interface can be effectively improved, thereby significantly reducing the number of cold joints and solder joints, substantially eliminating the phenomenon of corrosion, and significantly improving the soldering quality.
The brazing temperature of the finished plate obtained in the embodiment is 600-615 ℃ during brazing, and the brazing time is 10-30 min.
The second embodiment is as follows: the first difference between the present embodiment and the specific embodiment is: the bismuth-containing 4 series aluminum alloy suitable for brazing flux-free brazing is prepared from the following components in percentage by mass: 10.46%, Mg: 1.91%, Fe: 0.17%, Cu: 0.004%, Mn: 0.003%, Zn: 0.01%, Bi: 0.04% and the balance of Al.
The third concrete implementation mode: the preparation method of the bismuth-containing 4-series aluminum alloy suitable for fluxless brazing according to the embodiment is carried out according to the following steps:
firstly, smelting:
according to mass percentage, Si: 9.5-11%, Mg: 1.3-2.0%, Fe: less than or equal to 0.3 percent, Cu: less than or equal to 0.02 percent, Mn: less than or equal to 0.1 percent, Zn: 0.015 to 0.04%, Bi: weighing 0.01-0.06% of Al and the balance of Al, and taking Al-20% of Si intermediate alloy, Al-Bi intermediate alloy, Mg ingot, Zn ingot and aluminum ingot for remelting as raw materials; adding an aluminum ingot for remelting, adding an Al-20% Si intermediate alloy and an Al-Bi intermediate alloy, heating the furnace to 740-800 ℃, uniformly adding a Zn ingot below the liquid level of a melt in the furnace after raw materials in the furnace soften and collapse, slagging off after furnace burden is completely melted, controlling the melt temperature to 740-750 ℃ after slagging off, adding an Mg ingot, stirring for 10-15 minutes after the raw materials in the furnace are completely melted to obtain an alloy melt, and covering a flux on the surface of the alloy melt;
secondly, casting: introducing the alloy melt obtained in the step I into a standing furnace of a resistance reverberatory furnace, introducing chlorine for refining, adding Na modifier after standing, stirring to obtain a refined and modified alloy melt, staying for 30-60 min, then flowing into an online degassing device for degassing, then flowing into a filtering device for filtering after degassing, and after filtering, injecting the melt into a crystallizer through a splitter disc for semi-continuous casting to obtain an ingot;
thirdly, sequentially carrying out face milling, hot rolling, coiling and cold finish rolling on the cast ingot to obtain a finished plate; and (5) performing intermediate annealing when the thickness of the finished plate after cold finish rolling is less than 1.5 mm. Milling refers to removing cast scale from an ingot at room temperature.
The addition of Mg elements in the alloy of this embodiment can have a beneficial effect on vacuum brazing. In the brazing flux-free vacuum brazing process, the vapor pressure of Mg element is high, the boiling point is low, and the Mg element can be volatilized under the vacuum condition so as to remove residual oxygen and moisture in vacuum and improve the effective vacuum degree. On the other hand, the Mg vapor may penetrate into the surface layer of the base material under the oxide film to form a low melting point Al-Si-Mg alloy together with the diffused Si to melt, thereby breaking the bonding between the oxide film and the base material, and wetting and spreading the molten filler along the surface of the aluminum alloy. Therefore, the proper amount of Mg element can remove an oxidation film, adsorb residual water in a furnace body, reduce oxygen partial pressure, promote solder flowing, supplement burning loss of the Mg element in the alloy and avoid local occurrence of a corrosion phenomenon.
The Bi element in the alloy of the embodiment has very obvious improvement effect on the wettability of the aluminum alloy: the spreading performance of the brazing filler metal alloy is directly influenced by the interface tension between the liquid 4 series aluminum alloy and the base metal to be welded in the brazing process, and the interface tension is mainly determined by the surface tension of the liquid 4 series aluminum alloy. The surface tension of Bi element is very low when the Bi element is melted, and the Bi element can be used as a surface active substance to reduce the surface tension of the brazing filler metal, so that the resistance of the 4-series aluminum alloy on the surface of a base metal to be welded is reduced, and the spreading area is increased. In addition, Bi element is precipitated in a single-phase mode at high temperature, and the structure in a welding seam can be refined, so that the bonding strength of an interface is improved.
In summary, in the 4-series aluminum alloy in the embodiment, due to the beneficial effects of the appropriate amount of Mg element and Bi element, the oxide film on the joint surface can be removed, so that the solder has better spreadability and fluidity, and the joint strength of the interface can be effectively improved, thereby significantly reducing the number of cold joints and solder joints, substantially eliminating the phenomenon of corrosion, and significantly improving the soldering quality.
The brazing temperature of the finished plate obtained in the embodiment is 600-615 ℃ during brazing, and the brazing time is 10-30 min.
The fourth concrete implementation mode: the third difference between the present embodiment and the specific embodiment is that: step one, the mass fraction of Al in the aluminum ingot for remelting is not less than 99.70%.
The fifth concrete implementation mode: this embodiment is different from the third or fourth embodiment in that: step one, the flux is MgCl with the mass percent of 38-46 percent2、5％-8％BaCl2And the balance of KCl. The covering quantity of the flux can be up to the condition that no alloy melt is exposed, and the covering flux can prevent the volatilization of Mg element.
The sixth specific implementation mode: the difference between this embodiment and one of the third to fifth embodiments is: step two, the semi-continuous casting process comprises the following steps: the casting temperature is 680-720 ℃, the water pressure is 0.08-0.15 MPa, and the casting speed is 50-55 mm/min.
The seventh embodiment: this embodiment differs from one of the third to sixth embodiments in that: and step two, the Na alterant consists of 40% of NaF, 30% of NaCl and 30% of KCl in percentage by mass.
The specific implementation mode is eight: the present embodiment differs from one of the third to seventh embodiments in that: and the adding amount of the Na alterant in the step two is 0.4 percent of the total mass of the raw materials weighed in the step one.
The specific implementation method nine: this embodiment differs from the embodiment in one of three to eight: step three the cold finish rolling process is as follows: the cogging temperature is less than 50 ℃, the rolling speed is 800-1200m/s, and the pass deformation is 20 percent.
The detailed implementation mode is ten: the present embodiment differs from one of the third to ninth embodiments in that: the process of the intermediate annealing in the third step comprises the following steps: the annealing temperature is 420-460 ℃, and the annealing time is 7 h.
Example 1:
the preparation method of the bismuth-containing 4-series aluminum alloy for fluxless brazing in the embodiment comprises the following steps:
firstly, smelting:
according to mass percentage, Si: 10.46%, Mg: 1.91%, Fe: 0.17%, Cu: 0.004%, Mn: 0.003%, Zn: 0.01%, Bi: weighing Al-20% Si intermediate alloy, Al-Bi intermediate alloy, Mg ingot, Zn ingot and aluminum ingot for remelting as raw materials, wherein the Al accounts for 0.04% and the balance is Al; when charging, firstly adding an aluminum ingot for remelting, then adding Al-20% Si intermediate alloy and Al-Bi intermediate alloy, heating the furnace to 770 ℃, uniformly adding a Zn ingot below the liquid level of a melt in the furnace after raw materials in the furnace soften and collapse, slagging off after furnace burden is completely melted, controlling the melt temperature to 745 ℃ after slagging off, then adding an Mg ingot, stirring for 12 minutes after the raw materials in the furnace are completely melted to obtain an alloy melt, and covering a flux on the surface of the alloy melt;
the mass fraction of Al in the aluminum ingot for remelting is 99.70%;
the flux is composed of 42% of MgCl according to mass percentage26% of BaCl2And the balance of KCl; the covering quantity of the flux is only required to be up to the condition that no alloy melt is exposed, and the covering flux can prevent the volatilization of Mg element;
secondly, casting: introducing the alloy melt obtained in the step I into a standing furnace of a resistance reverberatory furnace, introducing chlorine for refining, adding Na modifier after standing, stirring to obtain a refined and modified alloy melt, staying for 45min, flowing into an online degassing device for degassing, flowing into a filtering device for filtering after degassing, and injecting the melt into a crystallizer through a splitter disc for semi-continuous casting after filtering to obtain an ingot;
the semi-continuous casting process comprises the following steps: the casting temperature is 700 ℃, the water pressure is 0.1MPa, and the casting speed is 52 mm/min;
the Na alterant consists of 40% of NaF, 30% of NaCl and 30% of KCl in percentage by mass; the adding amount of the Na alterant is 0.4 percent of the total weight of the raw materials weighed in the step one;
thirdly, sequentially carrying out face milling, hot rolling, coiling and cold finish rolling on the cast ingot to obtain a finished plate; after cold finish rolling, the thickness of the finished plate is 1.2mm, and intermediate annealing is carried out; milling refers to removing cast scale from an ingot at room temperature.
The cold finish rolling process comprises the following steps: the cogging temperature is 40 ℃, the rolling speed is 1000m/s, and the pass deformation is 20 percent;
the process of the intermediate annealing comprises the following steps: the annealing temperature is 440 ℃, and the annealing time is 7 h;
the principle and the beneficial effects of the invention are as follows:
the addition of Mg in the alloy of the invention can play a favorable role in vacuum brazing. In the brazing flux-free vacuum brazing process, the vapor pressure of Mg element is high, the boiling point is low, and the Mg element can be volatilized under the vacuum condition so as to remove residual oxygen and moisture in vacuum and improve the effective vacuum degree. On the other hand, the Mg vapor may penetrate into the surface layer of the base material under the oxide film to form a low melting point Al-Si-Mg alloy together with the diffused Si to melt, thereby breaking the bonding between the oxide film and the base material, and wetting and spreading the molten filler along the surface of the aluminum alloy. Therefore, the proper amount of Mg element can remove an oxidation film, adsorb residual water in a furnace body, reduce oxygen partial pressure, promote solder flowing, supplement burning loss of the Mg element in the alloy and avoid local occurrence of a corrosion phenomenon.
The Bi element in the alloy has very obvious improvement effect on the wettability of the aluminum alloy: the spreading performance of the brazing filler metal alloy is directly influenced by the interface tension between the liquid 4 series aluminum alloy and the base metal to be welded in the brazing process, and the interface tension is mainly determined by the surface tension of the liquid 4 series aluminum alloy. The surface tension of Bi element is very low when the Bi element is melted, and the Bi element can be used as a surface active substance to reduce the surface tension of the brazing filler metal, so that the resistance of the 4-series aluminum alloy on the surface of a base metal to be welded is reduced, and the spreading area is increased. In addition, Bi element is precipitated in a single-phase mode at high temperature, and the structure in a welding seam can be refined, so that the bonding strength of an interface is improved.
In conclusion, the 4-series aluminum alloy in the invention can remove the oxide film on the joint surface due to the beneficial effects of a proper amount of Mg element and Bi element, so that the brazing filler metal has better spreadability and fluidity, and the joint strength of the interface can be effectively improved, thereby obviously reducing the number of insufficient solder joints and missing solder joints, basically eliminating the phenomenon of corrosion and obviously improving the brazing quality.
The brazing temperature of the finished plate obtained in the embodiment is 600-615 ℃ and the brazing time is 10-30 min.
Comparative example 1:
the preparation method of the bismuth-containing 4-series aluminum alloy for the brazing without the brazing flux of the comparative example is carried out according to the following steps:
firstly, smelting:
according to mass percentage, Si: 10.48%, Mg: 1.5%, Fe: 0.18%, Cu: 0.037%, Mn: 0.003%, Zn: weighing Al-20% Si intermediate alloy, Mg ingot, Zn ingot and remelting aluminum ingot as raw materials, wherein the Al accounts for 0.01% and the balance is Al; putting the raw materials into a furnace, heating to 740 ℃, stirring the melt after the raw materials are completely melted, and covering a flux on the surface of the alloy melt;
the mass fraction of Al in the aluminum ingot for remelting is 99.80 percent;
the flux is composed of 42% of MgCl according to mass percentage26% of BaCl2And the balance of KCl; the covering quantity of the flux is only required to be up to the condition that no alloy melt is exposed, and the covering flux can prevent the volatilization of Mg element;
secondly, casting: guiding the alloy melt obtained in the step one into a standing furnace of a resistance reverberatory furnace, carrying out refining and modification treatment in the furnace, carrying out semi-continuous casting after on-line degassing and filtering devices, and obtaining an ingot;
the semi-continuous casting process comprises the following steps: the casting temperature is 700 ℃, the water pressure is 0.1MPa, and the casting speed is 52 mm/min;
thirdly, sequentially carrying out surface milling, hot rolling, coiling, cold finish rolling and intermediate annealing on the cast ingot to obtain a finished plate; milling refers to removing cast scale from an ingot at room temperature.
The cold finish rolling process comprises the following steps: the cogging temperature is room temperature, the rolling speed is 1000m/s, and the pass deformation is 20 percent;
the process of the intermediate annealing comprises the following steps: the annealing temperature is 440 ℃, and the annealing time is 7 h;
FIG. 1 is a metallographic photograph of a sample obtained in comparative example 1; FIG. 2 is a metallographic photograph of a sample obtained in example 1; corrosion points can be observed in the metallographic structure of fig. 1. Whereas no ablation spots were found in the metallographic picture of fig. 2.
Claims (10)
1. A bismuth-containing 4-series aluminum alloy suitable for fluxless brazing, characterized in that: the bismuth-containing 4 series aluminum alloy suitable for brazing flux-free brazing is prepared from the following components in percentage by mass: 9.5-11%, Mg: 1.3-2.0%, Fe: less than or equal to 0.3 percent, Cu: less than or equal to 0.02 percent, Mn: less than or equal to 0.1 percent, Zn: 0.015 to 0.04%, Bi: 0.01-0.06% and the balance of Al.
2. The bismuth-containing 4-series aluminum alloy suitable for fluxless brazing according to claim 1, wherein: the bismuth-containing 4 series aluminum alloy suitable for brazing flux-free brazing is prepared from the following components in percentage by mass: 10.46%, Mg: 1.91%, Fe: 0.17%, Cu: 0.004%, Mn: 0.003%, Zn: 0.01%, Bi: 0.04% and the balance of Al.
3. A method of preparing a bismuth-containing 4-series aluminum alloy suitable for fluxless brazing according to claim 1, wherein: the method comprises the following steps:
firstly, smelting:
according to mass percentage, Si: 9.5-11%, Mg: 1.3-2.0%, Fe: less than or equal to 0.3 percent, Cu: less than or equal to 0.02 percent, Mn: less than or equal to 0.1 percent, Zn: 0.015 to 0.04%, Bi: weighing 0.01-0.06% of Al and the balance of Al, and taking Al-20% of Si intermediate alloy, Al-Bi intermediate alloy, Mg ingot, Zn ingot and aluminum ingot for remelting as raw materials; adding an aluminum ingot for remelting, adding an Al-20% Si intermediate alloy and an Al-Bi intermediate alloy, heating the furnace to 740-800 ℃, uniformly adding a Zn ingot below the liquid level of a melt in the furnace after raw materials in the furnace soften and collapse, slagging off after furnace burden is completely melted, controlling the melt temperature to 740-750 ℃ after slagging off, adding an Mg ingot, stirring for 10-15 minutes after the raw materials in the furnace are completely melted to obtain an alloy melt, and covering a flux on the surface of the alloy melt;
secondly, casting: introducing the alloy melt obtained in the step I into a standing furnace of a resistance reverberatory furnace, introducing chlorine for refining, adding Na modifier after standing, stirring to obtain a refined and modified alloy melt, staying for 30-60 min, then flowing into an online degassing device for degassing, then flowing into a filtering device for filtering after degassing, and after filtering, injecting the melt into a crystallizer through a splitter disc for semi-continuous casting to obtain an ingot;
thirdly, sequentially carrying out face milling, hot rolling, coiling and cold finish rolling on the cast ingot to obtain a finished plate; and (5) performing intermediate annealing when the thickness of the finished plate after cold finish rolling is less than 1.5 mm.
4. A method of producing a bismuth-containing 4-series aluminium alloy suitable for fluxless brazing according to claim 3, wherein: step one, the mass fraction of Al in the aluminum ingot for remelting is not less than 99.70%.
5. A method of producing a bismuth-containing 4-series aluminium alloy suitable for fluxless brazing according to claim 3, wherein: step one, the flux is MgCl with the mass percent of 38-46 percent2、5％-8％BaCl2And the balance of KCl.
6. A method of producing a bismuth-containing 4-series aluminium alloy suitable for fluxless brazing according to claim 3, wherein: step two, the semi-continuous casting process comprises the following steps: the casting temperature is 680-720 ℃, the water pressure is 0.08-0.15 MPa, and the casting speed is 50-55 mm/min.
7. A method of producing a bismuth-containing 4-series aluminium alloy suitable for fluxless brazing according to claim 3, wherein: and step two, the Na alterant consists of 40% of NaF, 30% of NaCl and 30% of KCl in percentage by mass.
8. A method of producing a bismuth-containing 4-series aluminium alloy suitable for fluxless brazing according to claim 3, wherein: and the adding amount of the Na alterant in the step two is 0.4 percent of the total mass of the raw materials weighed in the step one.
9. A method of producing a bismuth-containing 4-series aluminium alloy suitable for fluxless brazing according to claim 3, wherein: step three the cold finish rolling process is as follows: the cogging temperature is less than 50 ℃, the rolling speed is 800-1200m/s, and the pass deformation is 20 percent.
10. A method of producing a bismuth-containing 4-series aluminium alloy suitable for fluxless brazing according to claim 3, wherein: the process of the intermediate annealing in the third step comprises the following steps: the annealing temperature is 420-460 ℃, and the annealing time is 7 h.
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| CN104372207A (en) * | 2013-08-12 | 2015-02-25 | 大力神铝业股份有限公司 | 4004 aluminum alloy for soldering |
| CN104694789A (en) * | 2015-03-09 | 2015-06-10 | 广西南南铝加工有限公司 | 4004 aluminum alloy containing bismuth and tellurium for brazing and production method of 4004 aluminum alloy |
| CN109798790A (en) * | 2019-02-22 | 2019-05-24 | 常州爱克普换热器有限公司 | A kind of efficient plate-fin heat exchanger |
| CN111020305A (en) * | 2019-12-17 | 2020-04-17 | 东北轻合金有限责任公司 | Aluminum alloy composite material skin material flat ingot and manufacturing method thereof |
| WO2020236373A1 (en) * | 2019-05-19 | 2020-11-26 | Novelis Inc. | Aluminum alloys for fluxless brazing applications, methods of making the same, and uses thereof |
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| JPS57140601A (en) * | 1981-02-25 | 1982-08-31 | Diesel Kiki Co Ltd | Laminate type evaporator |
| CN104372207A (en) * | 2013-08-12 | 2015-02-25 | 大力神铝业股份有限公司 | 4004 aluminum alloy for soldering |
| CN104694789A (en) * | 2015-03-09 | 2015-06-10 | 广西南南铝加工有限公司 | 4004 aluminum alloy containing bismuth and tellurium for brazing and production method of 4004 aluminum alloy |
| CN109798790A (en) * | 2019-02-22 | 2019-05-24 | 常州爱克普换热器有限公司 | A kind of efficient plate-fin heat exchanger |
| WO2020236373A1 (en) * | 2019-05-19 | 2020-11-26 | Novelis Inc. | Aluminum alloys for fluxless brazing applications, methods of making the same, and uses thereof |
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