Moscow Aviation Institute, Moscow, Russia

M. V. Zharov, Associate Professor, Candidate of Technical Sciences, e-mail: MaximZharov@mail.ru

This paper considers the results of a study that looked at irregular shape defects that may occur in aircraft plates, cowlings and other ribbed parts made of aluminium alloys by isothermal stamping and stamping in a superplasticity state. The author looked at defects forming in aircraft plates made of different groups of aviation aluminium materials. In particular, they include alloys of the following systems: Al – Mg (AMg3 and AMg6), Al – Mg – Si – Cu (AK6 and AK8), Al – Zn – Mg – Cu (V95 and V96Ts) and Al – Mg – Li (01420). The forming mechanisms were determined of the following irregular shape defects associated with the fabrication of aircraft plates by isothermal stam ping: back-end defect on the back side of the plate under the ribs; rupture of the material at the juncture between the rib and the plate that may occur at the final forming stages; clip on a side of the rib; pulled-in oxide scabs occurring in the centre of the rib. The author also analyzed how the above defects are related to the deformation temperatures and rates. A number of models was built reflecting the metal flow pattern as the die cavity is being filled, for different deformation temperatures and rates. It was established that when the die cavity is being filled the metal flow pattern is governed by the thickness of the plate workpiece, as well as the deformation temperatures and rates applied. The conducted study helped determine the deformation temperatures and rates applicable to aluminium alloys used for making defect-free aircraft parts, with the aim to minimize the consumption rates of basic materials and the scope of further mechanical treatment.

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