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Nowadays there is an increasing demand to develop light weight defense vehicles, fighter aircrafts and warships in order to enhance their mobility and fuel economy. It can be achieved by using the light weight structures made up of Aluminum and Magnesium plates which will reduce the weight, increase the payload carrying capacity and efficiency of the vehicles. In the present work, experimental ballistic performance of Magnesium (AZ31B) Base Metal (BM), friction-stir-welded (FSW) and post-weld-heat treated (PWHT) target plates have been determined by using the 7.62 mm Armor Piercing Projectiles (APP). Prior to ballistic testing, Magnesium joints were prepared by the FSW process for various tool rotational and welding speeds. Defect-free welds with better tensile and impact properties, were obtained with tool rotational speed of 1200 rpm and the welding speed of 50 mm/min. PWHT was carried out with the annealing temperature at 250 °C for about 1 hour. Microhardness and microstructure of the FSW and PWHT joints were investigated. Highest hardness (67 HV) was obtained for fine grain structure and precipitated particles were observed for PWHT targets. Depth of Penetration of PWHT target plates was approximately 17.55% and 16.31% lower than the BM and FSW target plates respectively. Scanning Electron Microscopic observation of projectile penetrated channel showed the formation of Adiabatic Shear Bands (ASBs). Due to a larger number of ASB lines, ballistic impacted FSW surface showed more number of macro cracks compared to PWHT surface. The PWHT joints showed the absence of fragmentation failure, lesser cracks and ASB lines which increased the ballistic performance. [ABSTRACT FROM AUTHOR]

The effect of target condition (static and dynamic) and number of projectile impacts (single and multiple) on the ballistic performance of 6061-T6 Aluminum alloy, 7075-T6 Aluminum alloy and 6061- aluminum alloy Fiber Metal Laminates (FML) have been investigated. Both numerical and experimental approaches were used to predict the nature of target deformation and its kinetic energy absorption. Ballistic experiments were conducted using armor piercing projectiles (APP) of diameter 7.62 mm with velocities ranging between 330 to 450 m/s. Irrespective of the target material (6061-T6 aluminum alloy, 7075-T6 aluminum alloy), non-linear reduction of exit velocity of the projectile was observed for a single plate target. In contrast, large plastic deformation and 'petaling' mode of failure was observed for the FML and rubber sandwiched targets. Higher impact energy absorption of the FML target and rubber intruded 7075-T6 aluminum alloy plates is mainly due to the additional resistance offered by the individual layer of metal and fiber. In addition to projectile velocity, when the target (7075-T6 aluminum alloy plate) velocity was varied in the range of 10 to 40 m/s, significant reduction in exit velocity of the projectile was observed compared to static target. This is due the fact that, moving target has altered the penetration behavior of the projectile and additional increase of target velocity caused 'ricochet' of the projectile. In addition, when the target was subjected to multiple projectile impacts, gradual reduction of ballistic performance was observed. [ABSTRACT FROM AUTHOR]