Extrusion of Aluminum and Aluminum Alloy
The extrusion of aluminum and aluminum alloys uses a forward extrusion method and a reverse extrusion method. The optimum extrusion speed should be chosen according to the different alloys. In order to obtain an aluminum alloy extruded product with good organization and performance, when the finished product is extruded once, the extrusion coefficient (λ) of the profile and the bar is greater than 8-12, and the λ of the blank for forging is greater than 5. Extrusion has a great influence on the quality of extruded products. Extruded bars and profiles are commonly used in flat molds, and pipes are commonly used in tapered molds. Splitting combined die and tongue die are widely used for extruding hollow profiles and pipes with complex shapes. Some use liquid nitrogen to cool the extrusion die, prolong the life of the mold and ensure the accuracy of the product. A mold can squeeze 30 tons of aluminum. Some aluminum alloy extruded products are prone to "coarse crystal ring", that is, after the heat treatment of the product, a large grain area appears in the periphery. High temperature extrusion can alleviate this phenomenon. Some heat-treated reinforced aluminum alloy extruded products have increased strength and decreased plasticity after solution aging treatment.