Thixoforming of magnesium AZ91D, where slugs of feedstock material having a rosette structure are heated to a semi-solid state to obtain a globular structure before the material is formed into components in a die casting machine or forging press, was investigated. Experimental thixotropic feedstock of magnesium alloy AZ91 was prepared using CANMET casting simulator with electromagnetic stirring. The paper presents results of the optimized heating of 3-inch diameter and 6 inch long slugs of AZ91D alloy prepared under laboratory conditions. The optimized heating procedure was established to achieve a globular structure with rapid and homogeneous heating of slugs. Forging trials were conducted at MTL/CANMET while die casting of a number of components was carried out at IMI. The optimal casting and forging parameters (slurry temperature, die temperature ram speed and metal pressure) are given. Results on morphological change in the microstructure of the feed stock material during heating are presented. It is shown that the material heated to 580 deg C should be held at this temperature for 30-90 seconds to achieve globularisation of the primary solid phase without excessive grain growth. The microstructure at various locations in the final product was analyzed. At the optimum casting and forging conditions no significant liquid segregation is observed in the final part.
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