Academic literature on the topic 'Die-casting. Extrusion process'

The 6061Al matrix composites reinforced with SnO2-coated aluminum borate whisker were fabricated using squeeze casting method. The composite were extruded successfully at 350°Cwith different die angles. The experiment results illustrate that the die angle have important influences on the extrusion process. The surface quality of extruded composites was improved and the extrusion load was reduced with die angle increasing from 30 to 60 degree. The <111> and <100> textures for aluminum matrix were formed in all extruded composites. The dispersion degree of the <111> texture, the alignment degree and the average length of whiskers increases with die angle increasing. There is a suitable die angle for the optimization of the extrusion process of the present composite.

Compared with any other pressure processing methods, extrusion is more prone to develop the plasticity of the metal. Extrusions have much better size precision and surface quality than products by rolling and forging. As one-shot molding process, extrusion can eliminate some machining. In addition, extrusions have very high strengths and elongations because of their compact interior structures and fine grains. This paper summarizes some experiences and plans in extrusion production of CQMST(Chongqing Magnesium Science & Technology Co.Ltd). Magnesium, a plentiful element with density of 1.78g/cm3，2/3 of aluminum and 1/4 of steel, is characterized by its high specific strength and toughness, good dumping performance, thermal conductivity and electromagnetism shielding as well as recyclability. Following the advancing technologies of magnesium smelting, high pressure processing, surface treatment and soldering since 1990’s, the prices of magnesium and its ingot stepped down. As an important light engineering material, magnesium application is growing at annual speed of 15%, much higher than aluminum, copper, zinc, nickel and steel. In China, magnesium and magnesium alloy development, application and industrialization has been placed on the National “Tenth Five-year Plans” and the National “863” Scheme, which indicated the coming of new age for magnesium and magnesium alloy development and application in China. In the past, most of the magnesium products were produced by casting, especially die casting and thixomolding. It’s always considered that the crystal structure of magnesium is hexagonal close-packed, and only two slip planes exist at room temperature, so compared with other alloys, it’s very difficult to produce magnesium parts by forging, rolling or extrusion. Nevertheless, practice showed that if heated to a certain temperature, magnesium extrusion may not be hard work, and even easier than 5056 and 2024 aluminum. When extruded with distributary die, magnesium alloy can have better soldering performance than aluminum alloys mentioned above, just because new slip system forms along with increasing temperature (>225°C) and accordingly increases the plasticity of magnesium.

Melt extrusion is a new fabrication process with the characteristics of both casting and extrusion. In this process, a metallic melt which is poured and solidified up to semisolid state in the container can be directly extruded through the die exit to form a product of bar shape without other intermediate processes. The aging behavior of Al-Cu alloys in the semisolid state was investigated. And the microstructure and mechanical properties of the melt extruded Al-Cu alloy bar were measured and its characteristics are compared with those of a hot extruded Al-Cu alloy bar. Al-Cu alloys were successfully extruded after squeezing out of liquid during melt extrusion with smaller force compared to the solid extrusion. Al-Cu alloys bar with the mean grain size of up to 200 μm was fabricated by melt extrusion process. And the mechanical properties of the melt extruded Al-Cu alloy bar were improved after the T6 treatment.

A novel way producing magnesium billets, LFEC (low frequency electromagnetic casting processing), was developed in Northeastern University in China. The high-quality magnesium billets with less macrosegregation, refined microstructure, and better surface quality were achieved because the temperature field and the flow pattern of magnesium DC casting were improved significantly after applying low frequency electromagnetic field. Extrusion is an important plastic deformation process for magnesium alloys. In this research, the magnesium billets from LFEC were extruded through a special designed die into sheets. The results of investigation on AZ31B indicated that the extrusion velocity has obvious effects on their microstructures and mechanical properties and the sheets from LFEC had finer microstructure and higher mechanical properties than that from conventional DC casting.