State Enterprise “Antonov”, Kiev, Ukraine:
V. N. Korol, First Vice-President, Chief Executive Officer
A. G. Yasinskiy, Leading Engineer

Nowadays, high-strength aluminium alloys with Al – Cu – Mg – Mn and Al – Zn – Cu – Mg alloying system are recommen ded for manufacturing of airplane structures. The materials are joint together by mechanical method, because the base material does not possess the good fusion weldability. The aluminium alloy AD37 (АД37) was developed for the products, which work in all climate conditions, mainly for outer skin and internal set of airframe (including welded designs). The complex of positive characteristics allows to apply AD37 alloy in airframe, including welded modification. The friction stir welding is applied in aerospace industry. The favorable thermal cycle of process does not reduce the mechanical characteristics of welded material, which gives the possibility to make the welding of parts in preliminary strengthened condition, keeping high strength properties. There is studied the influence of heat treatment in the different modes before and after welding of butt joints of AD37 alloy, obtained by friction stir welding. There are given the results of mechanical tests and metallographic studies. There is established the change of the alloy structure in different seam zones, caused by thermomechanical impact upon welding and heat treatment. The possibility of increasing of strength of joints in case of samples' welding in artificial aging conditions is shown together with the same possibility, using rehardening with artificial aging after welding. In this case, thermal hardening of welded joints allows to increase their strengthening up to 400 MPa.

1. Ishchenko A. Ya. Avtomaticheskaya svarka — Automatic welding. 2004. No. 9. pp. 16–26.
2. Rabkin D. M. Metallurgiya svarki plavleniem alyuminiya i ego splavov (Metallurgy of welding by fusion of aluminium and its alloys). Kiev : Naukova dumka, 1986. 256 p.
3. Thomas W. M., Nicholas E. D., Needham J. C. Improvements relating to friction welding. European Patent Specification, No. 0615480B1. Published: 1995.
4. O. T. Midling, E. J. Morley, A. Sandvik (Nors Hydro, rights transterred to TWI). Friction Stir Welding. European Patent, No. 95907888.2. Published: 1995.
5. Shinoda T., Endo S. Recent development of friction welding of aluminium alloys and dissimilar materials. Journal of Light Metal Welding and Construction. 1995. No. 7. pp. 19–26.
6. Vollertsen F., Schumacher J., Schneider K., Seefeld T. Innovative welding strategies for the manufacture of large aircraft. Technical trends and future prospectives of welding technology for transportation. Osaka, 15–16 July 2004. pp. 231–247.
7. Silis M. I., Barabokhin N. S., Logunov A. V. et al. Tekhnologiya legkikh splavov — Technology of light alloys. 2007. No. 1. pp. 47–53.
8. Haşim Kafali, Nuran AY. Mechanical Properties of 6013-T6 Aluminium Alloy Friction Stir Welded Plate. 13^th International Conference on Aerospace Sciences & Aviation Technology, ASAT — 13, 26–28 May 2009. Paper: ASAT-13-MS-14.