Fine control of aluminum alloy smelting and casting processes: a comprehensive analysis of 6063 aluminum alloy introduction.

Composition control of aluminum alloys is the key to ensuring material performance. In the production process of 6063 aluminum alloy, in addition to controlling the content of main alloy elements, such as the ratio of magnesium and silicon, impurity elements such as iron, copper, manganese, etc. also need to be strictly controlled. Although these elements have little effect on alloy properties in trace amounts, once they exceed a certain limit, they will seriously affect the mechanical properties and corrosion resistance of the material. Especially zinc, if its content exceeds 0.05%, white spots will appear on the surface of the profile after oxidation, so the control of zinc content is particularly important.

The chemical composition of 6063 aluminum alloy is based on the GB/T5237-93 standard, which mainly includes 0.2-0.6% silicon, 0.45-0.9% magnesium and up to 0.35% iron. This alloy is a heat-treatable strengthened aluminum alloy, and its main strengthening phase is Mg2Si. During the quenching process, the amount of solid solution Mg2Si determines the final strength of the alloy. The eutectic temperature is 595°C. At this time, the maximum solubility of Mg2Si is 1.85%, which drops to 1.05% at 500°C. This shows that the control of quenching temperature is crucial to the strength of the alloy. In addition, the ratio of magnesium to silicon in the alloy has a significant impact on the solid solubility of Mg2Si. In order to obtain a high-strength alloy, it is necessary to ensure that the ratio of Mg:Si is less than 1.73.

Smelting is the primary process step in producing high-quality cast rods. The melting temperature of 6063 aluminum alloy should be strictly controlled between 750-760°C. Too low a temperature will lead to the generation of slag inclusions, while too high a temperature will increase the risk of hydrogen absorption, oxidation and nitriding. The solubility of hydrogen in liquid aluminum rises sharply above 760°C. Therefore, controlling the melting temperature is the key to reducing hydrogen absorption. In addition, the selection of flux and the application of refining technology are also crucial. The fluxes currently on the market are mainly chloride and fluoride. These fluxes easily absorb moisture. Therefore, the raw materials must be kept dry during production, sealed and packaged and properly stored. Powder spray refining is currently the main method for refining 6063 aluminum alloy. Through this method, the refining agent can fully contact with the aluminum liquid to maximize its effectiveness. The nitrogen pressure used in powder refining should be as low as possible to reduce the risk of oxidation and hydrogen absorption.

Casting is a key step in determining the quality of cast rods. Reasonable casting temperature can avoid the occurrence of casting defects. For 6063 aluminum alloy liquid that has undergone grain refinement treatment, the casting temperature can be appropriately increased to 720-740°C. This temperature range is conducive to the flow and solidification of liquid aluminum while reducing the risk of pores and coarse grains. During the casting process, turbulence and rolling of the aluminum liquid should be avoided to prevent the rupture of the oxide film and the generation of slag inclusions. In addition, filtering the aluminum liquid is an effective method to remove non-metallic slag. It should be ensured that the surface scum of the aluminum liquid is removed before filtration to ensure smooth filtration.

Homogenization treatment is an important heat treatment process to eliminate casting stress and chemical composition imbalance within the grains. Non-equilibrium crystallization will lead to casting stress and chemical composition imbalance between grains. These problems will affect the smooth progress of the extrusion process, as well as the mechanical properties and surface treatment properties of the final product. The homogenization treatment promotes the diffusion of aluminum alloy elements from the grain boundaries into the grains by maintaining heat at high temperatures, thereby achieving uniformization of the chemical composition within the grains. The size of the grains has a significant impact on the time of homogenization treatment. The finer the grains, the shorter the homogenization time. In order to reduce the cost of homogenization treatment, measures such as grain refinement and optimization of heating furnace segmentation control can be taken.

The production of 6063 aluminum alloy is a complex process involving strict composition control, sophisticated smelting and casting technology, and critical homogenization processing. By comprehensively considering and controlling these key factors, high-quality aluminum alloy cast rods can be produced, providing a solid material foundation for subsequent profile production. With the advancement of science and technology and optimization of processes, the production of aluminum alloys will be more efficient and environmentally friendly, making greater contributions to the development of modern industry.