Method and apparatus for continuous extrusion of thixo-magnesium into plate or bar shaped extrusion products

摘要

A method for extrusion of magnesium based alloys for obtaining net shapes, or near net shapes in the form of plate or bar shaped extrusion products. The extrusion product of the method has a thixotropic structure and stable shape. The method includes providing magnesium based alloy feed stock and converting at least a portion of the feedstock into a thixotropic slurry. The method further exerts a driving force on the feedstock, upstream of the thixotropic slurry, to advance the feedstock in a downstream direction and subjecting a downstream end of the thixotropic slurry to controlled rapid cooling to obtain a thixotropic structure. The method further allows a downstream end of the converted feedstock to escape through a shaping die, so as to obtain bar stock having a predefined cross-sectional shape. An extrusion device for carrying out the method is also provided. The extrusion device includes a supply arrangement for feeding feedstock, a conversion chamber, agitation means, cooling means and a shaping die. The agitation means advantageously includes an inductive heater that electromagnetically agitates any liquid or semi-liquid metal in the conversion chamber.