Cryoforming evaluation using gold-5% copper

This report deals with gold-5 percent copper, which exhibited serious instability even in its higher strength states. The uniaxial specimens in this investigation make such instabilities appear even worse. The major effect of higher strain rates and lower forming temperatures was to extend the homogeneous deformation range, which generally allowed higher attainable strengths. Biaxial testing could suppress the low-strength instabilities but probably not the higher-strength instabilities. However, it was possible to produce a 110-ksi, 7 percent-elongation material by cryoforming at a relatively low deformation (23 to 32 percent). The literature indicates a minimum 50 percent deformation for this material is usual, which would produce a 150- to 200-ksi strength. If the instabilities can be suppressed, then room temperature (RT) working might be as effective as cryoforming. Cryogenic (or RT) spinning/forming could then produce an exceptionally strong structural material. For more material on cryoforming, see UCID-17265.)