Near net shape magnesium alloy components by superplastic forming and thixoforming

Abstract

Various near net shape items have been produced by superplastic forming and thixoforming magnesium alloys. Fine grained EA55RS magnesium alloy has been superplastically formed to produce sabot petals and various other items without obvious increase in grain size. Although the laminated appearance of the starting material was less pronounced after processing, the microstructure of superplastically formed material varied throughout any particular piece. ZC71 magnesium alloy has been thixoformed to produce items with a finer grained microstructure than that of the start material. The thixoformed items had an average grain size of about 25 gm and exhibited only a little local variation in their microstructures.

Suppression of Macroscopic Defects through the Control of Friction between Workpiece and Dies in a Forged Magnesium Alloy Part with Ribs

“…To form various parts of magnesium alloys, methods to fabricate plate-or sheet-form parts with ribs and/or bosses need to be developed, and forging is one of the promising methods to accomplish this. [2][3][4][5][6][7][8] The authors have already successfully fabricated plate-form parts with a boss in magnesium alloys by superplastic forging. 9,10) One of the principal types of defect in closed-die forging is extrusion-type defects, 11) which are formed when centrally located ribs and bosses, formed by extrusion-type flow, draw too much metal from the main body of the forging.…”

Influence of thermomechanical processing on superplastic forming of Mg–Al alloys

“…[5][6][7][8] Alternative high temperature technologies, such as thixoforming and superplastic forming, are also envisioned as potentially viable routes for the fabrication of Mg parts. 9 In particular, superplastic forming, consisting of applying a hot air pressure on a sheet until it adopts the shape of a customised mould, allows producing homogeneous parts of complex shapes in one single operation. 10 It is well known that superplasticity takes place preferentially in fine grained materials (d,10 mm).…”

“…However, these materials exhibit low room temperature ductility due to the lack of a sufficient number of active slip systems and thus Mg parts are usually fabricated by casting and extrusion [5][6][7][8]. Alternative high temperature technologies, such as thixoforming and superplastic forming, are also envisioned as potentially viable routes for the fabrication of Mg parts [9]. In particular, superplastic forming, consisting on applying a hot air pressure on a sheet until it adopts the shape of a customized mould, allows producing homogeneous parts of complex shapes in one single operation [10].…”