REPUBLIC OF SERBIA

MINISTRY OF DEFENCE

www.mod.gov.rs

MINISTRY OF DEFENCE

Material Resources Sector

Defensive Technologies Department

Military Technical Institute

www.vti.mod.gov.rs

EVALUATION OF low spinnability of AlMg5 alloy during flow forming

Radović Ljubica

Military Technical Institute, Belgrade, Serbia, ljmradovic@gmail.com

MILUTIN NIKAČEVIĆ

Military Technical Institute, Belgrade, Serbia, milutin.nikacevic@gmail.com

Abstract: The preform, hot forged cup, was subjected to flow forming in industrial scale in order to form thin-walled tubes (90mm warhead shells). Deformation behavior and microstructure of AlMg5 alloy from two metallurgical heats, as well as in various stage of process has been studied by means of mechanical characterization, optical and SEM/EDS microscopy. The influence of the chemical composition and applied reduction on the surface features was also studied. The spinnability was estimated on the base of contraction during tensile testing of AlMg5 alloy and compared to the achieved in flow forming. The heat with higher content of alloying elements (Mg, Mn, Fe, Si) had higher mechanical properties of perform, as well as flow formed tubes. It has lower spinnability and the large amount the surface defects (microcracks) on the flow formed shells. It is attributed to the inhomogeneous material flow during deformation..

Key words: AlMg5, flow forming, spinnability, mechanical properties, warhead shell.