High-Velocity Projectile Impact Behaviour of Friction Stir Welded AA7075 Thick Plates  

作　　者：R.Praveen S.R.Koteswara Rao G.Selvakumar R.Damodaram 

机构地区：[1]Department of Robotics and Automation,Karpaga Vinayaga College of Engineering and Technology,Chengalpattu603308,TamilNadu,India [2]Department of Mechanical Engineering,Sri Sivasubramaniya Nadar College of Engineering,Chennai603110,TamilNadu,India

出　　处：《Defence Technology（防务技术）》2023年第11期153-163,共11页Defence Technology

基　　金：funding from the Armament Research Board(ARMREB),Defence Research and Development Organization(DRDO),Ministry of Defence,Government of India (Grant no.:ARMREB/MAA/2018/200)。

摘　　要：In this study, high velocity impact behaviour of friction stir welded AA7075-T651 25 mm thick plates were investigated using a 7.62 mm × 51 mm lead core and 7.62 mm × 39 mm steel core projectiles. Prior to ballistic trails, mechanical and metallurgical properties of friction stir welded AA 7075-T651 25 mm thick plates were studied. Microstructural and hardness studies revealed that friction stir welds constituted three distinct regions namely Weld Nugget(WN), Thermo-Mechanically Affected Zone(TMAZ) and Heat Affected Zone(HAZ). Base Material(BM) and all three weld regions were ballistically tested as per military standard NIJ.0108.01 using lead and steel core bullets at maximum permissible velocities of 830 ± 20 and 700 ± 30 m/s, respectively. It has been found that base material(AA7075-T651)and all three weld regions of 25 mm thick plates were able to resist perforation by both types of projectiles used. However depth of penetration has been found to increase from BM to WN, HAZ and TMAZ for both types of projectiles. In all cases steel core projectiles caused higher depth of penetration compared to those caused by lead core projectiles. TMAZs of the friction stir welds were found to be the weakest zone. The fracture that occurred in the base material was spall fragmentation indicating brittle failure, whereas all zones of friction stir welded AA7075-T651 targets with a front petalling, indicating ductile failure. The post-ballistic tested samples showed no significant change in the microstructure of the BM and WN. On the other hand, TMAZ and HAZ showed severe grain deformation in the direction of projectile penetration, and the formation of adiabatic shear bands(ASB). This work showed that 25 mm thick friction stir welded AA7075-T651 joints responded well to ballistic impact loads, making them a good choice for light combat vehicles.

关 键 词：Aluminum alloy Thick plate Friction stir welding Ballistic performance Depth of penetration 

分 类 号：TG1[金属学及工艺—金属学]