Effect of failure modes on ballistic performance of Gas Metal Arc welded dissimilar armour steel joints

Abstract

In this study, Ultra-high Hard Armor (UHA) steel is welded with Rolled Homogenous Armor (RHA) steels using Gas Metal Arc Welding (GMAW) process with Austenitic Stainless Steel (ASS), Duplex Stainless Steel (DSS), and Low Hydrogen Ferritic (LHF) fillers. Ballistic resistance against Weld Metal (WM) is determined using 7.62 × 39 mm BALL projectile. Three new modes of failure were identified from the ballistic testing (i) Finer Wear Debris with Cleavage (FWDC) (ii) Coarser Wear Debris with Cleavage (CWDC) (iii) Cleavage failure (C), based on the fractured surface. All joints stopped the ball projectile at the weld metal region without perforation. However, the joint fabricated using ASS electrodes shows superior ballistic performance than other joints with Cleavage mode of failure (C) mainly due to the absence of wear debris. ASS weldment (5% Delta ferrite and 95% austenite) performs better in ballistic resistance because of the plastic deformation along with energy absorption properties of the austenite phase than DSS (69 Delta ferrite and 31% austenite) and LHF (100% ferrite). Migration of Chromium (Cr) from the weld metal to base metal results in an unmixed zone and martensitic band in the HAZ of ASS joint.