Tungsten carbide WC has a number of valuable properties whic

Tungsten carbide (WC) has a number of valuable properties, which make them the most promising material for use in various new fields of technology [8]. Tungsten carbide is a high-density ceramic with mechanical properties that make it attractive for applications related to high-velocity impacts. To utilize WC\'s high hardness and improve its toughness, it is coupled with a metallic binder. The majority of them utilize cobalt (Co) as the binder, but nickel (Ni) and chromium (Cr) are also used. From the above discussions, it is clear that both W based and Fe based carbide consumables are used for hardfacing application. Experiments related to projectiles impact resistance on Q&T steel weld metal at high velocities have produced beneficial results in recent years. The majority of these researches focused on sandwich joints of shielded metal arc (SMA) hardfaced interlayers [9–14] due to low cost, high thickness hardfacing and high dilution, to some extent， it is expected to be beneficial for the ballistic impact of SMA hardfacing process [15]. From the available literatures, it is understood that there is no published information on the comparative evaluation of ballistic performance of hardfacing consumables. Hence, in this investigation, one consumable from tungsten – based hardfacing alloy group (WC) and another consumable from iron – GSK2656157 hardfacing alloy group (CrC) were selected for depositing hardfaced middle layer to study the effect of hardfacing consumables on ballistic performance enhancement.
Materials and methods The parent metal (PM) used in this study is 18 mm thick high strength low alloy Q&T steel closely confirming to AISI 4340 specification. The heat treatment adopted for the steel was to austenitise at a temperature of 900 °C followed by oil quenching. Subsequently, the steel was subjected to tempering at 250 °C. The chemical compositions of PM and filler metals used in this investigation are presented in Table 1. SMAW process was selected as capillaries is generally employed in welding of combat vehicle construction. Austenitic stainless steel (SS) electrode was selected because it inhibits the delayed cracking tendency of the Q&T steel weldments. In this study, two different hardfacing consumables, namely tungsten carbide (WC) and chromium carbide (CrC) consumables, were used to deposit 4 mm thick hardfaced interlayer. The root and capping front layers were deposited using SS filler. The welding parameters used to fabricate the joints are presented in Table 2. Necessary care was taken to avoid joint distortion and to obtain defect free welds. The preheating and interpass temperatures were maintained at 150 °C during the welding of all the different layers to avoid both cold and hot cracking tendency. Fig. 1 shows the unequal double Vee butt joint configurations and schematic illustration of welding sequence for fabrication of the joints. Two joints were prepared. The joint with buttering layer on the beveled edge, unequal Vee joint design, SS root, WC hardfaced interlayer and SS capping font layer was labelled as WAHA (Fig. 1(a)). Similarly, the other joints with SS buttering layer, unequal Vee joint design, SS root, SMA – CrC hardfaced interlayer and SS capping font layer was labelled as CAHA (Fig. 1(b)). Here, the presence of CrC hardfaced interlayer is the only difference. In both the joints, on the unequal double Vee joint configuration, SMA – hardfacing of 4 mm thickness was sandwiched in between the root and capping weld. Table 2 shows the parameters used to fabricate the joints. The sequential welding procedure was applied to avoid distortion, as illustrated in Fig. 1(a)–(b). The fabricated joints were evaluated for their ballistic performance and the results were compared in terms of depth of penetration on weld metal and HAZ locations. Fig. 1(d) represents the weld coupon design and target plate dimensions for the fabrication of target.