Abstract
Complex sheet metal components can be formed from lightweight aluminum and magnesium sheet alloys using superplastic forming technologies. Superplastic forming typically takes advantage of the high strain-rate sensitivity characteristic of grain-boundary-sliding (GBS) creep to obtain significant ductility at high temperatures. However, GBS creep requires fine-grained materials, which can be expensive and difficult to manufacture. An alternative is provided by materials that exhibit solute-drag (SD) creep, a mechanism that also produces elevated values of strain-rate sensitivity. SD creep typically operates at lower temperatures and faster strain rates than does GBS creep. Unlike GBS creep, solute-drag creep does not require a fine, stable grain size. Previous work by Boissière et al. suggested that the Mg-Y-Nd alloy, essentially WE43, deforms by SD creep at temperatures near 400°C. The present investigation examines both tensile and biaxial deformation behavior of ElektronTM 43 sheet, which has a composition similar to WE43, at temperatures ranging from 400 to 500°C. Data are presented that provide additional evidence for SD creep in Elektron 43 and demonstrate the remarkable degree of biaxial strain possible under this regime (>1000%). These results indicate an excellent potential for producing complex 3-D parts, via superplastic forming, using this particular heat-treatable Mg alloy.
Published Version
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