Superplastic Improvement of Aluminum 7475-T4 Industrial Sheets Using a Heat Treatment

Abstract

Aeronautic industry requires a high degree of precision on final thickness of superplastically formed sheets. However, for the same qualified process, an important dispersal of results was observed on final thickness of superplastically formed aluminium 7475-T4 industrial sheets, depending on the delivered sheet batch. After several cases of sheet batches that led to unachieved acceptance limit or cracking of the sheets during the process, ACB investigated aluminium 7475-T4 sheets quality at microscopic scale. Important grain size dispersal was observed and a heat treatment was successfully applied on sheets to diminish the grain size and improve the superplasticity of the sheets.