Evaluation of Magnesium Extrusion Production
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.
W.Ke, E.H.Han, Y.F.Han, K.Kainer and A.A.Luo
M. Zhou et al., "Evaluation of Magnesium Extrusion Production", Materials Science Forum, Vols. 488-489, pp. 483-486, 2005