4000 series aluminum alloy coil is silicon as the main alloying element of aluminum alloy, most of its alloys belong to heat treatment can not be strengthened aluminum alloy coil, only the alloy containing copper, magnesium and nickel, and after welding with heat treatment strengthened alloy to absorb some elements, can be strengthened by heat treatment. Due to its high silicon content, low melting point, good melt fluidity, easy shrinkage, and will not make the final product brittle, it is mainly used for the manufacture of aluminum alloy coil welding additive materials, such as brazing plates, welding rods and welding wires. In addition, due to the good wear resistance and high temperature properties of some alloys of the series, they are also used to manufacture pistons and heat-resistant parts. Alloys containing w(Si)≈5% are black-gray after anodizing, so they are suitable for building materials and manufacturing decorative parts.
The role of alloying elements and impurity elements in 4××× series aluminum alloy
- Silicon: Silicon is the main alloy component of this series of alloys, silicon content w(Si)=4.5% ~13.5%. Silicon in the alloy mainly exists in the form of α+Si eutectic and β(Al5Fesi), the increase of silicon content, the increase of its eutectic, the increase of alloy melt fluidity, and the strength and wear resistance of the alloy are also increased.
- Nickel and iron: nickel and iron can form intermetallic compounds that are insoluble in aluminum, which can improve the high temperature strength and hardness of the alloy without reducing its coefficient of linear expansion.
- Copper and magnesium: Copper and magnesium can generate Mg2Si, CuAl2 and S phases to improve the strength of the alloy.
- Chromium and titanium: Chromium and titanium can refine the grain and improve the airtightness of the alloy.