Effect of friction and back pressure on the formability of superplastically formed aluminium alloy sheet

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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 languageEnglish
Pages532-539
Number of pages8
DOIs
Publication statusPublished - 28 Mar 2011
EventSheMet Conference 2011 - Leuven, Belgium
Duration: 17 Apr 201120 Apr 2011

Conference

ConferenceSheMet Conference 2011
CountryBelgium
CityLeuven
Period17/04/1120/04/11

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Keywords

  • aluminium alloy AA7475,
  • superplastic forming
  • lubrication,
  • friction coefficient
  • back pressure
  • finite element analysis
  • FEA

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