Aluminium Brass is highly accepted and is one of the widely used materials in various industrial applications. This alloy forms a protective film with self-healing mechanical properties. The membrane relies on dissolved oxygen in the water and does not self-renew in contaminated or stagnant water.
Aluminium brass can be divided into two categories.
- One is to add a small amount of aluminium to cast brass to remove impurities and increase fluidity, casting complex castings, and the excess aluminium in the alloy does not exceed 0.5%;
- The other is to add aluminum to forged brass to increase corrosion resistance, often used as a condenser tube. , the general composition range is Al1~6%, Zn24~42%, Cu55~71%.
There are 6 grades of aluminium brass in the national standard, mainly adding manganese, iron and other element to aluminium brass to improve the overall performance of the alloy such as strength and wear resistance. The more common aluminium brass alloys are mainly HAl77-2, HAl66-6-3-2, HAl64-3-1, and others are HAl60-10-1, HAl59-3-2, etc.
What alloying elements does aluminium brass contain?
Manganese and iron elements
Due to the extremely high melting point of manganese and iron, it is difficult to reach their melting point temperature, and they are dissolved in bronze metal only by diffusion after addition. Manganese has a large solubility in bronze metal and is easily dissolved in copper at high temperatures.
Although iron has a very small solid solubility in bronze metal, its solid solubility in Cu-Mn alloys is relatively large and can be easily added. Therefore, this process adopts the method of adding Mn and iron at high temperature to add Mn and Fe elements, which not only ensures the composition of the brass alloys, but also avoids the process of manufacturing the intermediate alloy, thereby reducing the production cost and improving the production efficiency.
Mn can melt into bronze metal in a large amount to play a role in solid solution strengthening, and at the same time, it can effectively prevent the “dezincification” of brass and improve the corrosion resistance of brass.
Fe has a low solid solubility at room temperature, and the Fe-rich phase precipitates. The Fe-rich phase improves the lubricity of the material, increases the strength of the matrix, and improves the wear resistance of the alloy.
Zinc and aluminum elements
Zinc and aluminum(copper Zinc alloys) have very low melting points and are easily oxidized. When the temperature of the alloy melt is high, aluminum and zi are added, which are easily oxidized and burned.
To this end, we use the method of adding cold material (Cu or waste material) to cool down after Mn and Fe are dissolved, and then adding aluminum and Zn to produce. Due to the high solid solubility of Al and Zn in Cu, they are easily dissolved in bronze alloy, which ensures the mechanical properties of the alloy.
The Zn equivalent coefficient of aluminum is quite high (n=6), a small amount of aluminum can increase the β phase of the duplex brass, and even the brittle γ phase is formed in the complex aluminum brass, which improves the strength and hardness of the alloy (with material properties, physical properties), and at the same time Plasticity and toughness decreased significantly.
Micro-alloying elements are added in the last process, and the temperature is raised to spit fire. The addition of tin can strengthen the matrix of the material, generate a SnO2 protective film to improve the corrosion resistance, and prevent the phenomenon of “dezincification”.
However, adding too much tin will increase the brittle compounds of the material and affect the performance of the material. The addition of rare earth element can refine the grains, strengthen the matrix, and improve the cold and hot processing properties of the hardness material properties (with thermal conductivity and physical properties).
The aluminum brass series is more complicated, and some of the complex aluminum brass contain the third and fourth alloying element such as manganese, nickel, silicon, cobalt and arsenic.
HAl66-6-3-2 and HAl61-4-3-1, which have more alloying elements, are alloys composed of six elements, and some of them are complex-processed aluminum brass from special-shaped casting alloys. Different alloys tend to have different melting properties and therefore require different melting processes.
How to smelt aluminium brass?
Aluminum brass is easy to “foam” during the smelting process and is easily contaminated by aluminum or other metal oxide inclusions. A reasonable smelting process should include certain preventive measures. If there is an oxide film of aluminum on the surface of the melt, it can protect the melt to a certain extent, and it is not necessary to add a covering agent during melting.
When adding Zn to the molten pool protected by Al2O3 film, the volatilization loss of Zn can be reduced. In fact, since the boiling of Zn may damage the oxide film, only when a suitable flux is used, that is, the melt can be more reliably protected, the burning loss of Zn can be effectively avoided or reduced.
Melting problem analysis
Cryolite has become an indispensable and important component in the flux used for smelting aluminum brass. The aluminium-brass melt must never be overheated to prevent the melt from oxidizing and inhaling a lot.
If the gas content in the melt is relatively high, you can choose flux coverage for refining, or use inert gas refining, including re-fluxing and repeat refining before pouring, and using a bell jar to press chloride salt into the melt for melt refining The way.
Smelting attention requirements
The high melting point alloy element such as iron, manganese, silicon, etc. contained in complex aluminum brass should be added in the form of Cu-Fe, Cu-Mn and other intermediate alloys.
In general, bulk used charge and bronze metal should be added to the furnace first and melted, finely divided charge can be added directly to the melt, and Zn is added last at the end of smelting. When pure metals are used as the charge, they should be deoxidized with phosphorus after melting, followed by manganese (Cu-Mn), iron (Cu-Fe), then aluminum, and finally Zn. In the complex aluminum brass HAl66-6-3-2, the iron content should be controlled at 2%~3%, and the manganese content should be controlled at about 3%.
Otherwise, when their content is too high, some properties of the alloy may be negatively affected. Due to the low density of aluminum, if the melt is not stirred thoroughly, it may cause uneven chemical composition. When there is a transitional melt in the furnace, generally aluminum and part of bronze metal can be added first, and then Zn can be added after they are melted. When aluminum is added, a large amount of heat can be released due to the fusion of bronze metal and aluminum.
The exothermic process can be used to accelerate the melting process, but if the operation is not performed properly, the intense exothermic reaction may cause the local temperature of the molten pool to be too high, resulting in the violent volatilization of Zn, and in severe cases, flames may be ejected from the furnace.
The temperature of smelting HAl67-2.5 is usually 1000~1100℃, and the temperature of smelting HAl60-1-1, HAl59-3-2, HAl66-6-6-2 is usually 1080~1120℃, and the lower temperature should be used as much as possible. Melting temperature.
Dosing and Melting Procedures for Aluminum Brass
Copper+Cu-Mn+Cu-Fe+Cu-Ni+covering agent→melting→adding Al+Zn→melting→adding cryolite→stirring→slag removal→sampling analysis→heating→stirring→ out.
What is aluminium brass used for?
Brass includes a wide range of bronze metal alloy with properties such as ductility, wear resistance, color, machinability, strength, hardness, antimicrobial resistance, and electrical and thermal conductivity. Aluminum brass is a copper-zinc-aluminum alloy with high corrosion.
This datasheet provides information on the composition, physical properties, and elasticity. It also includes information on corrosion resistance as well as forming and heat treating. and joining. Widely used in machinery and equipment, injection molding industry, musical instruments, copper plates, turbines, screw rods, etc.
What is aluminium brass made of?
An alloy composed of approximately 75% bronze metal, 2% aluminum, small amounts of other elements, and the remainder of zinc. Element content (%): Cu77.5, Zn20.4, Al2, As0.1
Brass is a general term for a series of copper-zinc alloys. Aluminum alloys are based on aluminum, and the main alloying elements are Cu, Mn, Si, Mg, Mg+Si, and Zn.
What is the difference between aluminium brass and bronze?
While copper is a pure metal, brass and bronze are bronze metal alloys (brass is a combination of bronze metal and zinc; bronze is a combination of bronze metal and tin).
All three metals exhibit a unique combination of properties that make them ideal for sheet metal.