Effect of Hardfacing Consumables on Ballistic Performance of Q&T Steel Joints

This study was carried out to evaluate the effect of hardfacing consumables on ballistic performance of armour grade quenched and tempered (Q&T) steel welded joints. To evaluate the effect of hardfacing consumables, joints were fabricated using 4 mm thick tungsten carbide (WC)/chromium carbide (CrC) hardfaced middle layer; above and below which austenitic stainless steel (SS) layers were deposited on both sides of the hardfaced interlayer. Shielded metal arc welding (SMAW) process were used to deposite all (hardfaced layer and SS layers) layers. The fabricated joints were evaluated for its ballistic performance, and the results were compared with respect to depth of penetration (DOP) on weld metal and heat-affected zone (HAZ) locations. From the ballistic test results, it was observed that both the joints successfully stopped the bullet penetration at weld center line. Of the two joints, the joint made with CrC hardfaced interlayer (CAHA) offered better ballistic resistance at weld metal. This is because its hardness is higher due to the presence of primary carbides of needle shape, polyhedral shape and eutectic matrix containing a mixture of γ + M7C3 carbides in the CrC hardfaced interlayer. The scattering hardness level in the WC interlayer, the matrix decomposition resulted lower hardness and the co-existence of δ ferrite in the interface between hardfacing and SS root/SS cap could be attributed to the inferior ballistic resistance of the joint made with WC hardfaced interlayer (WAHA joint).