Abstract
This paper examines the effect of friction and back pressure on the formability of superplastically formed aluminium alloy AA7475 sheet at the temperature of 517 °C. Several experiments with lubrication and back pressure are performed using a simple box shape tool cavity. The coefficient of Coulomb friction between the formed sheet and tool has been determined indirectly using a finite element model to simulate superplastic forming of the box shape. Typical values determined for all lubricant conditions tested are in the range 0.1 < μ < 0.2. The void growth with strain was determined directly from measurements as a function of back pressure. The results show the application of back pressure at 1 MPa reduces the growth of voids from 7% to 0.3% void volume fraction at a logarithmic thickness strain of 0.65. This paper reports back pressure has a significantly greater role than friction in enhancing the formability of the alloy
Original language | English |
---|---|
Pages | 532-539 |
Number of pages | 8 |
DOIs | |
Publication status | Published - 28 Mar 2011 |
Event | SheMet Conference 2011 - Leuven, Belgium Duration: 17 Apr 2011 → 20 Apr 2011 |
Conference
Conference | SheMet Conference 2011 |
---|---|
Country/Territory | Belgium |
City | Leuven |
Period | 17/04/11 → 20/04/11 |
Keywords
- aluminium alloy AA7475,
- superplastic forming
- lubrication,
- friction coefficient
- back pressure
- finite element analysis
- FEA