HAL77-2 aluminum brass
HAL77-2 aluminum-brass alloy is a new material used in the construction of new icebreakers at the factory. The material has high corrosion resistance, good cold and hot processing performance, and better mechanical properties than pure copper materials, and is a special brass by adding aluminum and other elements to ordinary brass. HAL77-2 aluminum-brass alloy has good thermal conductivity and corrosion resistance, and is used as a condenser pipe and other corrosion-resistant parts in ships and seashore thermal power stations, and is also the most commonly used material in low-temperature multi-effect distillation desalination plants.
HAL77-2 Material Characteristics:
HAL77-2 material is to add aluminum and other metal elements to ordinary brass to become a special brass-aluminum brass alloy, which has high strength, hardness and good plasticity, can be processed under pressure in cold and hot states, has good corrosion resistance to seawater, and is resistant to impact corrosion, but has a tendency to dezincification and corrosion cracking.
HAL77-2 chemical composition
cu76.0～79.0
al1.8～2.3
as0.03～0.06
ZN Margin. fe0.06
pb0.05
sb0.05
bi0.002
p0.02 The sum of impurities is 03
Weldability of HAL77-2 material
The weldability of HAL77-2 aluminum brass alloy material is relatively poor, which is mainly manifested in the following two aspects: Poor weld formability. During welding, it is easy to have appearance defects such as difficult dissolution, impermeable butt weld and poor surface forming. This is mainly due to the strong thermal conductivity of copper, the heat is quickly conducted out of the heating zone during welding, and it is difficult for the welding area to reach the melting point temperature, and the base metal and the filler metal are insoluble. For this purpose, a strong heat source with concentrated capacity is used for welding, and preheating should be carried out if necessaryIt is easy to form pores. At high temperatures, more hydrogen and copper-insoluble CO2 or water vapor are produced, and there is no time to overflow or generate reactive pores. Therefore, the existence time of the weld pool and the use of strong deoxidizers such as aluminum and titanium should be used to prevent the formation of porosity.
Selection of welding materials. Welding HAL77-2 aluminum brass should meet the general process requirements, that is, in addition to the chemical composition and mechanical properties of the welding material are equivalent to those of the base metal, the main thing is to control the impurity content and provide the deoxidation ability of the filler metal, so as to avoid defects such as thermal cracks and porosity. Enhance the deoxidation ability of the weld, add alloying elements such as deoxidizer silicon and manganese to the welding wire, and the deoxidizer silicon can also inhibit the burning loss of zinc. Through the analysis and study of the material characteristics and welding properties of HAL77-2 aluminum brass alloy to avoid possible welded joint defects, the aluminum bronze welding wire CUL8 with bronze and oxygen absorber is adopted, and the main chemical components are copper and aluminum, and the beneficial metal elements such as silicon, iron, zinc, tin, etc., are added to avoid defects such as thermal cracks and porosity and improve the metal structure of the weld, improve the strength, plasticity, corrosion resistance and improve the process performance of the welding wire.