The use of AA7075-T651 Alloy in Combat Vehicles Offers Superior Properties Compared to Steel, Providing Enhanced Strength and Durability: A Review


Amal C Kumar
Department of Mechanical Engineering SNIT Adoor
Abey Vishnu Narayana
Department of Mechanical Engineering Snit Adoor


Friction stir welding (FSW) is a solid-state welding method that is widely used in industries such as aerospace and automotive. It is particularly effective in joining non-heat-treatable aluminium alloys like the 3xxx and 5xxx series, as well as the heat-treatable 7075 aluminium alloy. The 7075 alloy, developed by Alcoa in 1943, is composed of copper, zinc, magnesium, chromium, and small amounts of other elements. It exhibits high strength after undergoing a heat treatment process, surpassing that of many other aluminium alloys. Different temper designations, such as 7075-T-6, T-651, T-7351, T-73, T-76, T-7651, and W5-1, guide the use of the 7075 alloy. In this study, the focus was on the resistance of 25-millimetre-thick plates made of AA7075-T651 (a specific form of the 7075 alloy) to penetration by two types of projectiles. The base material and all three zones of the welded plates (weld nugget, heat-affected zone, and thermo-mechanically affected zone) showed resistance to penetration. Steel core bullets exhibited better penetration than lead core projectiles. The thermo-mechanically affected zone (TMAZ) was found to be the weakest region after friction stir welding, with signs of fracture including splinter fragmentation in the base material and front petalling in all zones of the welded plates. Microstructural analysis revealed no significant changes in the base material and weld nugget after the ballistic experiment. However, the TMAZ and heat-affected zone showed the formation of adiabatic shear bands, indicating localized deformation due to projectile impact. Overall, the study demonstrated that 25-millimetre-thick friction stir-welded AA7075-T651 intersections exhibited excellent performance under ballistic impact loads. This suggests that FSW could be a promising option for lightweight combat boats, providing increased strength and protection. These joints could also be beneficial for defence vehicles in various applications.

December 22, 2023
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