High-Velocity Impacts of Pyrophoric Alloy Fragments on Thin Armour Steel Plates

The terminal ballistics effects of Intermetallic Reactive Materials (IRM) fragments have been the object of intense research in recent years. IRM fragments flying at velocities up to 2000 m/s represent a realistic threat in modern warfare scenarios as these materials are substituting conventional solutions in defense applications. The IRM add Impact Induced Energy Release (IIER) to the mechanical interaction with a target. Therefore, the necessity of investigations on IIER to quantify potential threats to existing protection systems. In this study, Mixed Rare Earths (MRE) fragments were used due to the mechanical and pyrophoric affinity with IRM, the commercial availability and cost-effectiveness. High-Velocity Impacts (HVI) of MRE were performed at velocities ranging from 800 to 1600 m/s and recorded using a high-speed camera. 70 MREs cylindrical fragments and 24 steel fragments were shot on armour steel plates with thicknesses ranging from 2 mm to 3 mm. The influence of the impact pitch angle (α) on HVI outcomes was assessed, defining a threshold value at α of 20°. The influence of the failure modes of MRE and steel fragments on the critical impact velocities (CIV) and critical kinetic energy (Ekin crit) was evaluated. An energy-based model was developed and fitted with sufficient accuracy the Normalised EKin crit (E˜kincrit) determined from the experiments. IIER was observed in all the experiments involving MRE. From the analyses, it was observed that the IIER spreads behind the targets with velocities comparable to the residual velocities of plugs and shattered fragment.

NUMERICAL AND EXPERIMENTAL STUDY OF CERAMIC/STEEL COMPOSITE FOR STRUCTURAL APPLICATIONS

The Terminal ballistics is the study of science that deals with the interaction involved in two impacting bodies. This research focused on the high-impact resistance of layered composite comprising of alumina ceramic and armour steel. The composite was designed to have ceramic as the facial plate with armour steel as its backing plate. For the numerical study, the ceramic thickness was varied (6, 8, 10, 12 mm) while keeping the thickness of backing steel constant (7 mm). The projectile, 7.62 mm armour-piercing (AP), was set with a velocity of 838 m/s and made to impact the different ceramic–steel composite target configurations at zero obliquity. The study captured fracture processes of the ceramic, the deformation of projectile, and backing steel. An effective optimum thickness ratio of 1.4 (ceramic:steel; 10/7) for the ceramic/steel components with less deformation of the backing steel is found. Thereafter, the result of the numerical study was validated by experimental ballistic investigation of the determined optimum ceramic/steel ratio. The experiment corroborated the simulation results as the alumina ceramic provided efficient protection to armour steel component after a severe interaction with the impacting projectile.

Selected Issues of Increasing the Fire Effectiveness of Combat Vehicles

The research paper reviews selected issues associated with the current state of the armoured (tanks) and infantry fighting vehicle technology, with particular emphasis on the operating effectiveness of elongated sub-calibre projectiles fired from tank guns, which enable full perforation of ca. 500 mm thick armour steel plates. Their efficiency is comparable with the impact of shaped heads with armour steel penetration capabilities, and amounts from 6 to 8 calibres – warhead diameters. Furthermore, the paper discusses a numerical analysis, which shows the velocities of elongated projectiles (of tungsten matrix sinters) required to achieve a determined armour steel penetration depth. In addition, it also presents the performance characteristics of two 100 mm calibre shaped warheads, with copper inserts and apex angles of 51º and 60º.

Microstructure, mechanical, ballistic property evaluation of RHA steel produced by continuous-casting route

This paper presents the commercial production of rolled homogeneous armour steel with 5 different thicknesses i.e. 20,30,40,50 and 80 mm through continuous casting route. All the plates display tempered martensitic structure. Tensile and charpy impact properties are obtained for all the different thickness plates. It is observed that the produced steel shows a good combination of strength and impact toughness. For ballistic evaluation 30 mm thick plates are impacted with 30 mm medium caliber armour piercing steel projectiles at a velocity of 460±20 m/s at zero degree angle of impact. Depth of penetration method is used to measure the ballistic performance of the plates. From the post ballistic microstructural observations, an adiabatic shear band induced material removal is detected in the front face of the impacted rolled homogeneous armour steel plates. The microstructure, mechanical and ballistic properties of the continuous cast steel is compared with the steel produced by conventional ingot cast route.

The protective capability of the laser welded armour steel plates

Despite the intensive development of plastics and composite materials in the case of armours employed to protect vehicles, armour steel remains a material commonly and effectively used. This is especially evident in the base armour of armoured vehicles, where the body is made of welded armour steel plates. However, the area of joining both the weld and the heat affected zone are sensitive areas with the reduced protective capability. In the case of laser welding in comparison with methods such as shielded metal arc welding and gas metal arc welding, it is possible to narrow down the above mentioned areas. The paper presents the results of research on the protective capability of welded zone of armour steel plates with a hardness of 500 HB. In the first part of the work, in order to select the proper parameters for the bonding process, different connection variants were made and their microstructure and selected mechanical properties were analysed. After selecting the best variant of the welding process, samples (200 mm × 200 mm) consisting of two welded plates with dimensions 100 mm × 200 mm were made for testing. The thickness of the plates was selected in such a way that in the areas outside the bonding zone, the lack of complete perforation by the projectiles used in the tests is guaranteed. The samples were shot at the weld location and at different distances from the weld to verify, for the chosen method of joining steel plates, if the welded armour loses its protective capability and, possibly, how wide this area may be.