The aluminum brass series is more complicated, and some of the complex aluminum brass contain the third and fourth alloying elements 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.
First of all, 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.
Theoretical analysis: When adding zinc to the molten pool protected by Al2O3 film, the volatilization loss of zinc can be reduced. In fact, since the boiling of zinc 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 zinc can be effectively avoided or reduced. Cryolite has become an indispensable and important component in the flux used for smelting aluminum brass. The aluminum-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. The high melting point alloy elements 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 copper should be added to the furnace first and melted, finely divided charge can be added directly to the melt, and zinc is added last at the end of smelting. When pure metals are used as the charge, they should be deoxidized with phosphorus after their melting, followed by manganese (Cu-Mn), iron (Cu-Fe), then aluminum, and finally zinc. 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 copper can be added first, and then zinc can be added after they are melted. When aluminum is added, a large amount of heat can be released due to the fusion of copper 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 zinc, 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.
Post time: Jul-07-2022