DEVELOPMENT OF THE WARM FORMING TEST CELL AND PROCESS SOLUTIONS FOR AA7075-T6

Aluminium 7075 (Al-Zn-Mg-Cu alloy) is a popularly used material for aerospace structural component. However, this alloy has limited formability at room temperature. Therefore, thermal-mechanical process is used to form this alloy.

This paper introduces an innovative and practical warm forming (WF) test cell and a practical manufacturing solution for warm forming aluminium 7075-T6 alloy using the test cell. The developed test cell is capable to monitor and control the heating and forming temperatures for aluminium 7075-T6 during heating, part transferring, and press forming. A cross-form die was used to determine the preferred WF process window in terms of temperature, blank holder force, and draw depth. Recommended process parameters were found to change with the type of aluminium alloys and thickness. The final recommended WF process window can be applied for aerospace structures. This paper also compares finite element (FE) prediction results of the warm forming process between advanced material yield function model, Barlat 2000, and a conventional model, Hill 48. The Barlat 2000 model gave a superior correlation to warm forming experimental results compared with the Hill 48 model.