CN101798645B - Aluminum alloy for heat exchanger fins and preparation method thereof - Google Patents

Abstract

An aluminum alloy for heat exchanger fins in the technical field of metal materials and a preparation method thereof, the composition ratio of the obtained alloy is: Mn: 1.0-1.3wt%, Si: 1.0-1.3wt%, Fe: 0.3-0.6wt% %, Cu: 0.05-0.2wt%, Zr: 0.05-0.2wt%, and the rest is Al. The invention realizes alloying by adding zirconium element to the high-silicon medium-manganese aluminum alloy, adopts zinc-free design, and adopts casting, hot-rolling and cold-rolling processes to prepare corresponding plate, strip and foil materials.

Description

Aluminum alloy for heat exchanger fins and preparation method thereof

technical field

The invention relates to an alloy in the technical field of metal materials and a preparation method thereof, in particular to an aluminum alloy with a yield strength of about 53 MPa and an elongation as high as 14% for heat exchanger fins after brazing and its preparation method.

Background technique

3xxx series aluminum alloys are widely used in the manufacture of automobiles, construction, consumer electronics and other fields due to their high specific strength, good thermal conductivity, easy formability and good corrosion resistance. In recent years, my country's automobile industry has developed rapidly, and the demand for automobile heat exchangers has increased rapidly. As a heat transfer material that can replace pure copper, 3003Al alloy is widely used in automotive heat exchangers (such as radiators, condensers, and evaporators) to reduce costs, reduce vehicle weight, and save energy. In the case of dwindling oil resources, for the purpose of environmental protection, energy saving and emission reduction, the design standards of automobiles and parts are increasing, which puts forward higher requirements for the mechanical properties of heat exchanger fin alloys, so It is necessary to continuously improve the mechanical properties of 3003Al alloy, especially the strength and plasticity of the alloy.

Alloy plate, strip and foil for heat exchanger fins are mostly manufactured by casting + rolling (hot rolling, cold rolling), and there are many factors that affect the final performance of the plate, strip and foil, including alloy composition, casting process, hot rolling and cold rolling process , heat treatment process, etc. Since there is not much room for improving the performance of 3003Al alloy from the perspective of process improvement, the alloy composition is considered to be the key to control the processing performance of the alloy foil and the final brazing performance. Therefore, it is expected to develop a new type of alloy with high strength and high plasticity to replace the traditional 3003Al alloy through reasonable alloying design.

After searching the prior art, it was found that SAPA, a Swedish manufacturer of heat transfer materials (www.sapagroup.com/pages/399484/Sapa_6815.pdf), provided a high-quality alloy with a composition close to that of 3003Al alloy and a small amount of zinc. Manganese (1.4-1.8wt%) low-silicon (0.65-1.0wt%) aluminum alloy (commercial brand FA6800), the heat exchanger fins made of this alloy have a tensile strength of about 130MPa after brazing with aluminum alloy foil, and the yield The strength is about 50MPa. The traditional AA3003 alloy foil has a tensile strength of only 110MPa and a yield strength of 40MPa after brazing. Due to the development of high-performance heat exchangers, the mechanical properties of the above-mentioned alloy foils after brazing still need to be continuously improved. The Chinese patent "Aluminum alloy for heat exchanger fins and its preparation method" (patent application number CN200610085354.6) applied by the inventor of this patent has invented a kind of medium manganese (1.0-1.3wt%) high Silicon (1.0-1.3wt%) aluminum alloy has good strength properties, but because it contains zinc element, the corrosion potential of this alloy is relatively negative, which cannot meet the needs of some heat exchanger fins.

Contents of the invention

Aiming at the above-mentioned deficiencies in the prior art, the present invention provides an aluminum alloy for heat exchanger fins and a preparation method thereof, which realizes mechanical strengthening and corrosion performance design by adopting high-silicon, medium-manganese, and zinc-free alloying designs. The corresponding strips and foils were prepared by casting, hot rolling and cold rolling processes.

The present invention is achieved through the following technical solutions:

The invention relates to an aluminum alloy for heat exchanger fins, the composition and weight percentage of which are: Mn: 1.0-1.3wt%, Si: 1.0-1.3wt%, Fe: 0.3-0.6wt%, Cu: 0.05- 0.2wt%, Zr: 0.05-0.2wt%, the rest is Al.

The present invention relates to the preparation method of aluminum alloy for above-mentioned heat exchanger fin, comprises the following steps:

The first step, sequentially select Al, Mn, Si, Fe, Cu and Zr or the alloy containing said Al, Mn, Si, Fe, Cu and Zr, melt and pour into a cast alloy billet of 20-100mm, and then mill the surface, Then hot-roll the cast alloy billet after face milling to obtain alloy strips, in which: Mn element, Si element, Fe element, Cu element and Zr element account for 1.0-1.3wt% and 1.0-1.3wt% of the total mass respectively , 0.3-0.6wt%, 0.05-0.2wt% and 0.05-0.2wt%.

The smelting and pouring refers to: Al, Mn, Si, Fe, Cu and Zr are uniformly melted at 700-760° C. in a smelting furnace protected by an inert gas, and then poured into a steel mold and cooled to obtain a casting alloy billet.

The hot rolling refers to: preheating the milled cast alloy billet in a heating furnace at 500° C. to 520° C. and then hot rolling it to a thickness of 2-4 mm.

In the second step, the alloy strip is cold-rolled for multiple passes, then annealed at a medium temperature and continued to be cold-rolled to obtain a cold-rolled alloy foil for heat exchanger fins.

The multi-pass cold rolling refers to rolling alloy strips into 0.15mm alloy foil.

The medium temperature annealing refers to: annealing under the environment of 360°C-420°C;

The multi-pass cold rolling refers to rolling alloy strips into alloy foils with a thickness of 0.15mm.

The continuous cold rolling refers to rolling the annealed alloy foil to a thickness of 0.10mm.

The present invention conducts performance evaluation by the following method: the cold-rolled aluminum alloy foil is subjected to simulated brazing heat treatment, kept in a heat treatment furnace at 600°C for 5 minutes, then taken out of the furnace and cooled to room temperature, and then tested on the tensile mechanical properties at room temperature on an electronic tensile testing machine .

The aluminum alloy prepared by the method can have a post-weld tensile strength of up to 136MPa, a yield strength of about 53MPa, and an elongation of up to 14%, and can be used in the fin manufacturing field of heat exchangers.

Detailed ways

The embodiments of the present invention are described in detail below. This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating procedures are provided, but the protection scope of the present invention is not limited to the following implementation example.

Example 1

In this example, Al-1.2Mn-1.1Si-0.5Fe-0.05Cu-0.2Zr alloy plate (thickness: 30mm) is prepared by smelting and casting methods, milled to a thickness of 25mm, heated at 500°C for 1 hour, and then hot-rolled 4mm, then cold-rolled to 0.15mm, annealed at 380°C and then cold-rolled to 0.10mm, the mechanical properties of the alloy foil were tested with an electronic tensile testing machine after simulated brazing heat treatment, the tensile strength of the alloy foil was 136MPa, Yield strength was 53 MPa, and elongation was 14%. The strength characteristics of the alloy foil are significantly better than the post-weld tensile strength and yield strength of the commercial 3003 aluminum alloy, and also better than the strength characteristics of the FA6800 alloy.

Example 2

First prepare Al-1.1Mn-1.2Si-0.4Fe-0.05Cu-0.10Zr alloy plate (thickness 35mm) by smelting and casting method, face milling to thickness 28mm, heat at 500°C for 1 hour and hot roll to 2.6mm , then cold-rolled to 0.15mm, and then cold-rolled to 0.10mm after annealing at 380°C. After simulated brazing heat treatment, the tensile strength of the tested alloy foil was greater than 130MPa, and the elongation was greater than 13%.

Example 3

First prepare Al-1.3Mn-1.1Si-0.6Fe-0.1Cu-0.08Zr alloy plate (thickness 25mm) by smelting and casting method, after milling to a thickness of 20mm, heat at 500°C for 1 hour and then hot-roll and cold-roll To 0.15mm, cold rolled to 0.10mm after annealing at 390°C, after simulated brazing heat treatment, the tensile strength of the tested alloy foil is greater than 135MPa, and the elongation is greater than 14%.

Obviously, compared with heat exchanger fin alloys (commercial 3003 aluminum alloy and FA6800 alloy), the alloy prepared in this example has the characteristics of high strength and high plasticity, and the yield strength after welding can be about 53MP, and the elongation is 13- 14% alloy foil for heat exchanger fins. The above performance is mainly due to the reasonable composition design, that is, the moderate manganese content in the aluminum alloy to reduce the generation of coarse manganese-containing compounds, the high silicon content to improve the post-weld strength, and the addition of a small amount of zirconium to produce the second phase strengthening effect. Zinc is not added to control the corrosion characteristics and change the corresponding mechanical properties.

Claims (3)

1. the preparation method of an aluminum alloy for heat exchanger fins; The component of this aluminum alloy for heat exchanger fins and weight percent are: Mn:1.0-1.3wt%, Si:1.2-1.3wt%, Fe:0.3-0.6wt%, Cu:0.05-0.2wt%, Zr:0.05-0.2wt%, all the other are Al; It is characterized in that, said method comprising the steps of:

The first step, choose Al, Mn, Si, Fe, Cu and Zr or contain the alloy of said Al, Mn, Si, Fe, Cu and Zr successively; Mill face become the casting alloy base of 20-100mm through smelting and pouring after; Then the casting alloy base that mills behind the face is carried out hot rolling; Obtain alloy sheet strip, wherein: Mn element, Si element, Fe element, Cu element and Zr element account for 1.0-1.3wt%, 1.2-1.3wt%, 0.3-0.6wt%, 0.05-0.2wt% and the 0.05-0.2wt% of total mass respectively;

Second step, alloy sheet strip is carried out the cold rolling after medium annealing of multi-pass and continues cold rollingly, obtain to be used for the cold rolling Alloy Foil of heat-exchanger fin;

Described smelting and pouring is meant: adopt the inert gas shielded melting stove after 700-760 ℃ of fusing evenly, to be poured into the steel die internal cooling and obtain the casting alloy base;

Described hot rolling is meant: the casting alloy base that will mill face is hot-rolled down to thickness after the preheating in 500 ℃-520 ℃ process furnace be 2-4mm;

Described medium annealing is meant: annealing under 360 ℃-420 ℃ environment.

2. the preparation method of aluminum alloy for heat exchanger fins according to claim 1 is characterized in that, described multi-pass is cold rolling to be meant, alloy sheet strip is rolled into the Alloy Foil that thickness is 0.15mm.

3. the preparation method of aluminum alloy for heat exchanger fins according to claim 1 is characterized in that, described continuation is cold rolling to be meant: it is 0.10mm that the Alloy Foil after will annealing is rolling to thickness.