Influence of Microstructural Characteristics on Ballistic Performance and Its Mode of Failure in  Shielded Metal Arc Welded Ultra-High Hard Armor Steel Joints

The welding of ultra-high hard armour (UHA) steel is highly challenging due to their higher hardness (600 HV) and higher carbon equivalent (0.80). In this investigation, 15-mm-thick UHA steel plates are welded by shielded metal arc welding (SMAW) process using three different consumables such as austenitic stainless steel (ASS), low-hydrogen ferritic steel (LHF), and duplex stainless steel (DSS). The joints were tested against a 7.62 × 54 mm Armor-piercing (AP) projectile. All three joints successfully stopped the projectile at weld metal and interface (weld/HAZ) without perforation. The ballistic performance and mechanical properties are improved than the currently used ASS electrodes, and a new method to study the mode of failure at weld metal and interface was introduced. Striations and microcracks are preferred modes of failure than wear debris in the weld metal, and soft/hard mode is preferred over soft/soft and hard/hard modes of failure at the interface.