Blow Forming of Superplastic Alloy Sheets by Gas Generating Source

摘要

Superplastic forming(SPF) of titanium and aluminum alloy sheet and concurrent superplastic forming / diffusion bonding (SPF/DB) of titanium alloys have developed to a state of relative maturity over the past twenty years. However SPF/DB is currently limited to titanium alloys; an effective way to diffusion-bond aluminum alloys has not yet been developed because of a firm and hard aluminum oxide layer on the surface. On the other hand it is well known that if the reduction ratio, for instance in manufacturing clad metal sheets, is high enough that strong bonding on the interface can be achieved, roll bonding between similar / dissimilar metals can be successfully carried out. In this rolling process, if any geometrically designed area of the rolled sheet is left unbonded and also within this thin interface layer some material remains which plays the role of a gas-pressure source during superforming at a specific elevated temperature, gas blowing into the assembled die set is unnecessary. The manufacturing process Proposed here is termed RB/SPF(Roll Bonding/SuperPlastic Forming). Selection of a gas-pressure source which acts as STOP OFF in roll bonding and how to lock the pressure source in the thin clearance may be key factors in this new processing.