Mechanical and ballistic properties ofpowder metal 7039 aluminium alloy joined by friction stir welding
(1. Mechanical Engineering Department, Inonu University, Malatya 44280, Turkey;
2. Metallurgy and Materials Engineering Department, Technology Faculty, Gazi University, Ankara 06560, Turkey;
3. Technical Science Vocational School, Gazi University, Ostim, Ankara 06374, Turkey;
4. Ankara Chamber of Industry 1st Organized Industrial Zone Vocational School,
Hacettepe University, Ankara 06935, Turkey)
2. Metallurgy and Materials Engineering Department, Technology Faculty, Gazi University, Ankara 06560, Turkey;
3. Technical Science Vocational School, Gazi University, Ostim, Ankara 06374, Turkey;
4. Ankara Chamber of Industry 1st Organized Industrial Zone Vocational School,
Hacettepe University, Ankara 06935, Turkey)
Abstract: 7039 Al alloy plates which were used as armor materials were produced by powder metallurgy method. The prepared mixed powders were pressed and plated by extrusion process. These plates, after being subjected to T6 heat treatment, were joined double-sided by friction stir welding method. Microstructure and microhardness of the welded plate were investigated. It was determined that the finest grain structure and the lowest hardness value occurred in the stir zone as 2-6 mm and HV 80.9, respectively. In order to determine the ballistic properties of welded plates, 7.62 mm armor piercing projectiles were shot to the base metal (BM), heat affected zone (HAZ), and thermomechanically affected zone+stir zone (TMAZ+SZ). Ballistic limits (v50) of these zones were determined. The ballistic limits of the BM, TMAZ+SZ, and HAZ of the plate were approximately 14.7%, 15.3%, and 17.9% lower than that of the standard plate at the same thickness, respectively. It was determined that the armor piercing projectiles created petaling and ductile hole enlargement failure types at the armor plate. Ballistic and mechanical results can be enhanced by hot-cold rolling mills after extrusion and particle reinforcement.
Key words: powder metal 7039 Al alloy; ballistic limit; microstructure; mechanical properties