Abstract

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.

摘要

如今，人们越来越需要开发轻型防御车辆、战斗机和军舰，以提高它们的机动性和燃油经济性。它可以通过使用由铝和镁板组成的轻质结构来实现，这将减轻重量，增加车辆的有效载荷承载能力和效率。在目前的工作中，使用 7.62 毫米穿甲弹确定了镁 (AZ31B) 母材 (BM)、搅拌摩擦焊 (FSW) 和焊后热处理 (PWHT) 靶板的实验弹道性能（应用程序）。在弹道测试之前，通过 FSW 工艺为各种工具旋转和焊接速度准备镁接头。具有更好的拉伸和冲击性能的无缺陷焊缝，工具转速为 1200 rpm，焊接速度为 50 mm/min。PWHT 在退火温度为 250 °C 的情况下进行约 1 小时。研究了 FSW 和 PWHT 接头的显微硬度和微观结构。细晶粒结构获得最高硬度 (67 HV)，PWHT 靶材观察到沉淀颗粒。PWHT 靶板的穿透深度分别比 BM 和 FSW 靶板低约 17.55% 和 16.31%。射弹穿透通道的扫描电子显微镜观察显示绝热剪切带（ASB）的形成。由于 ASB 线的数量较多，与 PWHT 表面相比，弹道冲击 FSW 表面显示出更多的宏观裂纹。PWHT 接头显示没有碎裂失败，