Blow Forming of Mg Alloy Recycled by Solid-State Recycling

BlowformingcharacteristicsofAZ31Mgalloyrecycledbysolid-staterecyclingwereinvestigated.Cylindricalscrapsandmachinedchipswere recycled by hot extrusion and hot rolling in air. Oxide layers were observed in the recycled specimens by oxygen mapping with EPMA(Electron Probe Micro Analyser). The interval of the oxygen layers for the specimen from machined chips was much shorter than that for thespecimenfromcylindrical scraps.Asaresultoftensiletests,themechanicalpropertiesofthespecimenfromcylindrical scrapswerefoundtobealmost the same as those of a rolled specimen from a virgin ingot. On the other hand, at elevated temperatures, the elongation of the specimensfrom machined chips was low, compared with those of the rolled specimens from a virgin ingot. The large amount of oxide contamination islikely to be responsible for the lower elongation of the specimens from machined chips. In blow-forming tests, the specimen from cylindricalscraps exhibited excellent formability similar to the rolled specimen from a virgin ingot. However, the specimen from machined chips showedpoor formability. Thus, oxide contamination adversely affected the formability of recycled Mg alloy.(Received November 5, 2003; Accepted January 6, 2004)Keywords: magnesium alloy, solid-state recycling, tensile tests, superplasticity, blow forming