Mechanical and metallurgical behaviours of GMAW-welded RHA steel joints

Armoured steels are the most popular anti-ballistic materials due to their strength, hardness and ease of fabrication. They are generally intended for armoured vehicles that require explosion protection and high ballistic resistance. The elevated carbon equivalent of rolled homogeneous armour steel renders it particularly susceptible to hydrogen-induced cracking and other detrimental issues within the heat-affected zone, necessitating welding techniques specifically designed to mitigate this risk. To weld this sort of steel, a confined arc is necessary, which typical welding procedures do not provide. Therefore, in this research work, 18 mm thick rolled homogeneous armour steel plates are welded by Gas Metal Arc Welding process using different heat input to understand the mechanical and metallurgical properties. The Tensile properties, Impact toughness and Microhardness performance of the joint are evaluated and showed excellent results for 0.70 KJ/mm heat input with 59% of joint efficiency. Further, the fracture surface was studied under scanning electron microscope for validation of the failure of the fabricated joints.