Steel Core Projectiles Research Articles

Ballistic resistance of 7XXX laminate aluminum alloy plates and base alloys subjected to different projectiles

The ballistic impact of two 7XXX aluminum alloys, 7A52-T6 and 7A62-T6, as well as their combination in a 7B52 laminate plate, was simulated and experimentally tested. Three types of projectiles were utilized hard ogival nosed, hard blunt nosed, and 304 steel core projectiles to investigate the ballistic resistance and failure mechanisms of the aluminum alloy targets. Additionally, an existing modified Gurson-Tvergaard-Needleman (GTN) model incorporating shear, void growth, and spalling failure mechanisms, was employed to simulate the ballistic impact process, utilized to analyze energy dissipation during impact. The results reveal that the 7A52 alloy only experiences ductile hole expansion failure, whereas the 7A62 high-strength aluminum alloy undergoes spalling and fragmentation subsequent to penetration, leading to potential impact hazards. Due to its backing layer being the highly ductile 7A52 alloy, the laminate plate will not produce fragments after penetration. The improved GTN model provided better predictions of the impact failure modes of the aluminum alloys. Concerning impact performance, when subjected to hard ogival projectiles, the laminate alloy did not enhance material impact resistance. However, when impacted by blunt-nosed projectiles, the laminate alloy exhibited a 27 % improvement over the 7A52 plate and an 11.9 % increase over the 7A62 plate. Furthermore, when impacted by 304 steel core ogival projectiles, the laminate alloy demonstrated over a 41.3 % improvement compared to the 7A52 plate and over a 15.5 % increase compared to the 7A62 plate. The laminate plate's high ballistic performance was attributed to the increased plastic deformation energy after spalling failure, while ensuring high energy absorption during ductile hole expansion penetration.

Study on the enhancement mechanism of ballistic properties of shear thickening fluid impregnated aramid fabric composite plates

AbstractThis study proposes a process for the preparation of composite laminates using the shear thickening fluid (STF) impregnated aramid fabric and presents some fabric panel configuration strategies. Firstly, this study prepared two kinds of STF using 20 nm and 500 nm silica particles. Then, the STF‐impregnated Kevlar fabrics were laminated and hot‐pressed to form the fabric panels. After that, the ballistic performance of the fabric panels was evaluated by firing the 9 mm steel core projectile using a gas gun. The ballistic tests showed that the ballistic performance of the hybridized configuration panels using STF‐20 treated fabrics as the front panels and STF‐500 treated fabrics as the backing panels was superior, with a reduction of 36.1%–37.6% in the number of perforated layers (4.7–5 layers) compared to a single STF‐treated panel. This study provides a new idea and method for applying STF in protective equipment.Highlights Shear thickening fluid (STF) and aramid fabric are better combined by hot pressing lamination process; The ballistic properties of fabric panels are significantly improved by hybrid configuration; The ballistic performance enhancement mechanism of composite bulletproof plate was revealed.

Influence of projectile physical state on ballistic energy absorption capacity of UHMWPE laminate: Experiment and simulation

This paper presents the influence of projectile physical state on ballistic energy absorption capacity of UHMWPE laminate. Specifically, standard fragment simulating projectile (FSP) and 7.62 mm × 39 mm mild steel core projectile (MSCP) are utilized to perforate two kinds of areal density laminate. Internal damage morphologies of post-impact laminate are characterized via X-ray computer tomography (CT). A sub-laminate discretization approach was used to establish numerical laminate model, and decoupling parametric studies of projectile state were performed. Results of ballistic tests show that ballistic energy absorption capacity of laminate depends on projectile state and laminate areal density. Multi scale damage morphologies analysis indicate that shear fracture and multi-layer delamination failure are the primary failure modes of post-impact laminate, which were in good agreement with simulation results. Results of parametric studies suggest that high-speed spin of projectile will cause torsional deformation of laminate.

The influence of penetration angle on anti-penetration performance and reverse penetration ricochet phenomenon of UHMWPE laminates

Penetration angle refers to the angle between the normal of laminates and the projectile trajectory. In actual battlefield conditions, projectiles may hit Ultra-High Molecular Weight Polyethylene fiber (referred to as UHMWPE) laminates from various angles, resulting in ricochet phenomena and secondary injuries. Currently, research on bullets hitting penetrating laminates at a perpendicular angle is relatively well-developed, while research on the penetration of laminates by bullets at other angles is limited. Therefore, this study combined experiments and numerical calculations to investigate the penetration of 7.62 mm steel core projectiles at different angles on UHMWPE laminates. The study found that UHMWPE laminates enhanced bullet resistance through yawing and bending the penetrating projectiles at different angles. The influence of penetration angle on the impact area of the projectile-facing surface, the height of the bulge on the backside, and the penetration depth, as well as the trajectory and morphology of the projectile, were mastered in this study. Notably, a penetration angle of 50° was the limit condition for projectile to produce reverse penetration ricochet phenomenon of projectiles in UHMWPE laminates with a thickness of 30 mm. These research findings provide a theoretical basis and technical support for the bulletproof design of UHMWPE laminates.

Effect of deep cryogenic treatment on the microstructural, mechanical and ballistic properties of AA7075-T6 aluminum alloy

The study focused on investigating the effect of Deep Cryogenic Treatment (DCT) on the mechanical and ballistic properties of AA7075-T6 aluminum alloy. The microstructure, microhardness, tensile strength, and impact strength of the Base Material (BM) and DCT-treated 7075 samples were analyzed through metallographic analysis and mechanical tests. The microstructure of the DCT-treated 7075 samples revealed fine grains and a distribution of secondary phase particles. The tensile strength, impact strength, and microhardness of DCT-treated samples increased by 7.41%, 4%, and 9.68%, respectively, compared to the BM samples. The fractography analysis of the tensile samples showed cleavage facets, microvoids, and dimples in both the samples. The ballistic behavior of the BM and DCT target plates were studied by impacting hard steel core projectiles at a velocity of 750 ± 10 m/s. The target plates failed due to petaling and ductile hole enlargement, and the depth of penetration (DOP) of the DCT target was less than that of the BM target, indicating a higher ballistic resistance. The post-ballistic microstructure examination of the target plates showed the formation of an Adiabatic Shear Band (ASB) without any cracks. It was concluded that the DCT treatment improved the mechanical and ballistic properties of the aluminum alloy due to grain refinement and high dislocation density.

Effect of Aging on the Ballistic Performance of AA 7017 Alloy


 This study presents the effect of aging on microstructure, texture, mechanical and ballistic properties of AA-7017 aluminium alloy. AA-7017 alloy is subjected to three different aging namely under-aging, peak-aging and over-aging. Significant difference is observed in the mechanical properties after aging. The alloy exhibits maximum strength and hardness in the peak-aged condition. From texture measurements, it is noticed that the overall intensity of orientation distribution function increases from under-aged to peak-aged condition. The AA-7017 aged plates are impacted with 7.62 mm steel core projectiles at 820±10 m/s to evaluate the ballistic performance. It is noticed that AA-7017 alloy displays best ballistic resistance in peak-aged condition. Distorted material flow lines and adiabatic shear band induced cracking is detected in post ballistic microstructure. The ballistic performance of AA-7017 alloy is correlated with the variations in the microstructure and mechanical properties with aging

Damage formations of ramie fiber composites multilayer armour system under high-velocity impacts

Multilayer armour system (MAS) becomes the best choice in reinforcing protection for military officers against projectile attack which has a high velocity of up to 7.62×51 mm NATO ball lead core (projectile level III NIJ standard) or AP 7.62×51 mm hard steel core (projectile level IV NIJ standard). This study aimed to analyze the damage formation of wolfram carbide (WC) ceramic and ramie fiber composites. The frontmost MAS uses WC ceramic and is enveloped by a back layer of ramie fiber composites with epoxy resin reinforcing material as the matrix. Ballistic testing was carried out in this study using a long-barreled rifle to determine the resistance of the MAS from projectile impact. The speed meter in ballistic testing uses a velocity sensor type light screen B 471 and clay witness is used to measure back face signature (BFS). The results show that 7.62 lead core and hard steel core projectiles were unable to penetrate the 3-layer ceramic MAS in the front. The results are marked by a relatively low BFS value of 1.45 and 1.17 mm, so that the energy in the MAS with 3 ceramic layer is absorbed efficiently but with the phenomenon of rupture ceramic failure. Ceramic rupture failure needs to be overcome by bonding several layers of ramie so that MAS can be used in the next stage. MAS with 1 and 2 ceramic layers are unable to withstand projectile level III and level IV NIJ standard. From these results it is known that the MAS limit can withstand the projectile level III and IV NIJ standard, namely MAS with 3 ceramic layers. The damage formation of ceramic was rupturing ceramic failure. Therefore, it is necessary to design a ceramic binder by placing some ramie fibers in front of the ceramic

Study on ballistic impact behavior of Al alloys against two different shapes of steel core projectiles

In this study, a relation between the quasi-static, dynamic compressive and ballistic impact of 7055 and 7075 Al alloys was made. The results showed that the ultimate tensile strength, hardness and absorption capacity were considerably higher in 7055 Al alloy compared to 7075 Al alloy. Consequently, 7055 Al alloy exhibited superior ballistic impact resistance (low depth of penetration) against different shapes of 7.62 mm soft steel core projectiles. The microstructure evolution after ballistic impact revealed gradient variation of strain rate away from the crater which assists in the nucleation of different deformation zones, i.e., fine grain zone (FGZ), high-density deformation zone (HDZ) and low-density deformation zone (LDZ). These zones were confirmed through optical micrographs, hardness, stress-strain and XRD analysis. The strong texture {111} component was changed to the {111} and {200} component in HDZ and LDZ, which also assists in understanding that the deformation was more complex in these regions. Therefore, a model was proposed for the nucleation of fine grains near the crater. In addition, fracture morphology was different under each loading condition and a transitional effect is observed from quasi-static loading to ballistic impact loading. These interesting features can further enhance the understanding and the development of Al alloys in aerospace and military applications.

Ballistic response of ultra-high molecular weight polyethylene laminate impacted by mild steel core projectiles

This paper presents the effect of interlaminar shear property on the ballistic response of ultra-high molecular weight polyethylene (UHMWPE) fiber composite laminate and discusses the detailed progressive ballistic damage process. Specifically, two kinds of UHMWPE fiber composite laminates with different interlaminar shear strength (ILSS) are impacted by a standard projectile (7.62 mm × 39 mm), and their multi-scale internal damage morphologies are characterized. Based on damage patterns, an evaluation model of laminate energy absorption is established to analyze the dissipation mechanism of the kinetic energy of the projectile. Results of ballistic tests indicate that the reduction of ILSS may result in the degradation of anti-penetration performance and in more serious internal damage. Internal damage morphologies show that shear fracture and delamination fracture are the primary failure modes during ballistic impact. The energy absorption by the laminate via tensile deformation, delamination failure and shear failure may account for 56.21%, 17.45%, and 16.49% of the projectile kinetic energy, respectively. Hence, tensile deformation may be the primary energy dissipation mechanism of projectile kinetic energy.

Optimization of target thickness and investigation on the effect of heat treatment on the ballistic performance of aluminium alloy 7075 targets against hard steel core projectile

Optimization of target thickness and influence of heat treatment condition on the high velocity impact response of aluminium alloy 7075 targets have been determined. Both experimental and numerical studies were conducted using a 7.62 mm hard steel core projectile. The numerical simulation used a 7.62 mm Ogival nose shaped projectile with a target thickness ranging from 20 to 26 mm. High velocity impact experiments on T651 and solution treated targets, with rolled plate thicknesses ranging from 21 to 25 mm were carried out to validate the numerical findings. The microhardness of the targets was measured using Vicker's microhardness tester and fractographs were examined using a scanning electron microscope. The projectile penetrated regions were analyzed using light microscopy. A good correlation between the numerical and experimental ballistic behaviour of aluminium alloy 7075 targets was observed and an optimum target thickness of 21 and 24 mm was observed for the T651 and solution treated targets to prevent the projectile's penetration. It was also noted that, after the projectile's impact, solution treated targets had higher microhardness compared to T651 condition targets. This is due to higher work hardening of solution treated targets near the penetration channel. Even though T651 targets have a lower depth of penetration compared to solution treated targets, ‘splintering’ failure of the T651 targets is observed. In contrast, ‘petalling’ and ‘plugging’ kinds of failures were noticed on the solution treated targets. Thus, solution treatment of ballistic targets may enhance the ballistic limit of armoured vehicles.

Evaluation of Steel and Tungsten Carbide Cobalt (WC 8Co) 5.56 x 45 mm Caliber Projectile Penetration into Silicon Carbide (SiC) Experiment and Numerical Simulation

This study aims to evaluate WC-8Co as a substitution material in a standard steel core projectile commercially produced by PT Pindad (Persero). The enhanced performance of 5.56 x 45-millimeter ammunition after the addition of WC-8Co hard metal was evaluated in terms of penetration into a silicon carbide (SiC) target. Numerical simulations and analysis of the ballistic impact of WC-8Co on ceramic targets were verified by experimental data. The results show that front core substitution in SS109 bullets from steel (Pindad standard) to WC-8Co resulted in 1.5 times greater DoP. Although projectiles with steel (Pindad standard) as the front core have a muzzle velocity higher than those using WC-8Co, they have a lower kinetic energy than the latter. In addition, WC-8Co cemented carbides also displayed higher crater and residual velocity on SiC targets; around 1.8 and 1.3 times higher, respectively. These findings demonstrate the potential use of WC-8Co for development as front core material to improve the penetration of projectiles into ceramic armour.

Investigation on ballistic behaviour of friction stir welded rolled AZ31B magnesium alloy

In this paper, an attempt was made to study the ballistic resistance of Friction Stir Welded (FSW) AZ31B magnesium alloy. The base metal AZ31B plates were sliced to required size and FSW was carried out using a non-consumable taper pin tool made up of HCHCr steel. Samples were taken out from the FSW plates to study the microstructure and microhardness. The FSW AZ31B contain refined grains and tiny Mg17Al12 precipitates which were formed because of severe plastic deformation during FSW. The FSW AZ31B targets also showed ∼7.47% increase in microhardness compared to BM target. Further, ballistic test was conducted by impacting Ø7.62 × 39 mm hard steel core projectiles at an initial velocity of 420 m/s. AA6062 material of 25 mm was used as backing plate to measure the Depth of Penetration (DOP) of the projectile. The failure mechanism and the ballistic resistance of BM and FSW AZ31B samples were studied and compared. Finally, post ballistic analysis was made to study the failure modes of the target at microscopic level. Through various experimental results, it was identified that the increase in ballistic resistance of FSW AZ31B target was mainly due to two reasons; the refinement of grain size and small strengthening precipitates.

Normal and Oblique Impact on Polyurea-Coated ASTM1045 Steel Plates by Small-Arms Projectiles

Small-caliber steel core projectiles fired by light weapons pose a great threat to metal structures. Coating with polyurea (PU) is a potential option to improve the anti-penetration performance of metal structures. In this work, we carried out numerical simulations to clarify the dynamic characteristics of PU-coated ASTM1045 steel plates subjected to oblique penetration by 5.8-mm small-caliber steel core projectiles. The failure modes, dynamic response process, energy absorption characteristics, and comprehensive protection effects of target plates with different coating positions and thicknesses during the penetration process were compared and analyzed. The result showed that coating with a certain thickness of PU could enhance the protection ability of the steel plate against the oblique penetration of projectiles. In contrast to the results obtained from experiments in which the projectile penetrated the composite plate normally, when the PU coated both sides, the effect of improving the oblique penetration resistance of the steel plate was the best. The effect was lowest with a PU layer only on the back face. This study provides a reference for strengthening the bulletproof performance of various systems, including steel structures, weapons, and vehicles.

Ballistic evaluation of steel/UHMWPE composite armor system against hardened steel core projectiles

Thin high hardness steel sheets can be an alternative to expensive ceramic armor systems designed to defeat hardened core projectiles. A thin high hardness steel sheet backed with UHMWPE fiber-reinforced composite was ballistically tested against a 7.62 × 39 mm hardened steel core projectile in a single-stage gas gun. Thin steel sheets of 530 BHN hardness were adhesively bonded with UHMWPE fiber-reinforced composite to fabricate armor plates. Armor plates were able to defeat the projectile showing considerable potential. Tensile strength of steel sheet and UHMWPE-fiber reinforced ply was also determined. A detailed numerical simulation of the impact event was also performed to understand the phenomenon of defeat and penetration in greater detail. The numerical model was calibrated from the recovered projectile's core after the ballistic test.

Ballistic Efficiency of Multilayered Armor System Reinforced with Jute-Kevlar Epoxy Composite against High-Energy Steel Core Projectile

Ballistic Efficiency of Multilayered Armor System Reinforced with Jute-Kevlar Epoxy Composite against High-Energy Steel Core Projectile

Microstructure evolution of Mg-Zn-Zr magnesium alloy against soft steel core projectile

The study aimed to shed light on the post deformation and damage behavior of an extruded Mg-Zn-Zr alloy under a ballistic impact. The results revealed that the initial microstructure consisted of both 0001 basal and 101̄0 prismatic fiber texture. After impact, adiabatic shear bands, pronounce different twinning in big grains, <a>, <c>, and <c+a> types of dislocations, and grain refinement through twinning induce recrystallization accommodated the strain, and absorbed ∼65.7 % of the energy during impact carried by a soft steel projectile. Interestingly, the deformation behavior at the top broad sides of the crater was entirely different. The weak basal texture was changed to a strong prismatic texture, which was further proved by typical sigmoidal compressive stress-strain curves. A revised model for the development of the ultra-fine grains adjacent to the crater has been proposed. The microhardness and yield strength was ∼33 % and ∼40 % higher and chiefly ascribed to strain hardening in ultra-fine grained near the surface of the perforation path. The exit of the perforation path was severely damaged and forms onion-shaped concentric rings which were comprised of melted zones, dimples, and cracks. Based on the all interesting findings, this study can be a clue for the development of the lightweight Mg alloy for military and aerospace applications.

The Microstructural Difference and Its Influence on the Ballistic Impact Behavior of a Near β-Type Ti5.1Al2.5Cr0.5Fe4.5Mo1.1Sn1.8Zr2.9Zn Titanium Alloy.

In this work, a near β-type Ti5.1Al2.5Cr0.5Fe4.5Mo1.1Sn1.8Zr2.9Zn alloy was hot-rolled at the temperature of 800–880 °C with a thickness reduction of 87.5% and then heat-treated with the strategy of 880 °C/1 h/air cooling (AC) + 650 °C/3 h/AC. The microstructure difference between the hot-rolled and heat-treated titanium alloys and its influence on the ballistic impact behavior of the hot-rolled and heat-treated titanium alloys were analyzed. The microstructural investigation revealed that the average size of the acicular secondary α phase (αs) dropped from 75 to 42 nm, and the corresponding amount of this phase increased significantly after heat treatment. In addition, the dislocation density of the α and β phases decreased from 0.3340 × 1015/m2 and 4.6746 × 1015/m2 for the hot-rolled titanium alloy plate to 0.2806 × 1015/m2 and 1.8050 × 1015/m2 for the heat-treated one, respectively. The high strength of the heat-treated titanium alloy was maintained, owing to the positive contribution of the acicular secondary α phase. Furthermore, the critical fracture strain increased sharply from 19.9% for the hot-rolled titanium alloy plate to 23.1% for the heat-treated one, thereby overcoming (to some extent) the constraint of the strength–ductility trade-off. This is mainly attributed to the fact that the dislocation density and the difference between the dislocation densities of the α and β phases decreased substantially, and deformation localization was effectively suppressed after heat treatment. Damage to the hot-rolled and heat-treated titanium alloy plates after the penetration of a 7.62 mm ordinary steel core projectile at a distance of 100 m was assessed via industrial computer tomography and microstructure observation. The results revealed that a large crack (volume: 2.55 mm3) occurred on the rear face and propagated toward the interior of the hot-rolled titanium alloy plate. The crack tip was connected to a long adiabatic shear band with a depth of 3 mm along the thickness direction. However, good integrity of the heat-treated titanium alloy plate was maintained, owing to its excellent deformation capability. Ultimately, the failure mechanism of the hot-rolled and heat-treated titanium alloy plates was revealed by determining the crack-forming reasons in these materials.

Development of cost effective personnel armour through structural hybridization

The objective of the present study is to develop cost effective thermoplastic hybrid laminate using Dyneema® HB50 and Tensylon®HSBD 30A through structural hybridization method. Laminates having 20 mm thickness were fabricated and subjected to 7.62 × 39 mm mild steel core projectile with an impact velocity of 730 ± 10 ms−1. Parameters such as energy absorption, back face deformation and rate of back face deformation were measured as a function of hybridization ratio. It was observed that hybrid laminate with 50:50 ratio (w/w) of Tensylon® and Dyneema® with Tensylon® as front face showed 200% more energy absorption when compared to 100% Tensylon® laminate and showed equal energy absorption as that of expensive 100% Dyneema® laminate. Moreover, hybrid laminate with TD50:50 ratio showed 40% lower in terms of final back face deformation than Dyneema® laminate. Rate of back face deformation was also found to be slow for hybrid laminate as compared to Dyneema® laminate. Dynamic mechanical analysis showed that, Tensylon® laminate has got higher stiffness and lower damping factor than Dyneema® and hybrid laminates. The interface between Tensylon® and Dyneema® layers was found to be separating during the penetration process due to the poor interfacial bonding. Failure behaviour of laminates for different hybridization ratios were studied by sectioning the impacted laminates. It was observed that, the Tensylon® laminate has undergone shear cutting of fibers as major failure mode whereas the hybrid laminate showed shear cutting followed by tensile stretching, fiber pull out and delamination. These inputs are highly useful for body armour applications to design cost effective armour with enhanced performance.

Microstructure characteristic of spray formed 7055 Al alloy subjected to ballistic impact by two different steel core projectiles impact

7055 aluminium (Al) alloy was synthesized by spray forming followed by hot extrusion, later subjected to (T6 & T74) aging treatments and its mechanical properties were examined. To investigate the ballistic behavior of the semi-infinite aluminum alloy target material, ballistic test with two different types of projectiles 7.62 mm soft steel core and 7.62 mm armor-piercing hard steel core projectiles were carried out. Excellent mechanical properties such as; higher strength UTS 708 MPa, fracture to elongation 12.8% and hardness 240 HV were achieved in the T6 condition owing to the MgZn2 phase and Al3Zr strengthening particles. Ballistic performance of the 7055-T6 target was superior to the T74 heat treated condition in terms of depth of penetration, crater diameter, strength, ductility and hardness. The target materials were deformed seriously against armor-piercing hard steel projectile impact as compared to soft steel core projectile. The microstructure was modified within the 1–1.5 mm area from the crater wall. The spray formed Al alloy have a good combination of strength and ballistic performance under the T6 heat treatment condition in comparison of T74 and other alloys produced by conventional forming methods.

Experimental Consideration of Projectile Density and Hardness Effect on Its Penetration Ability in Alumina Target

The development of body armour technology must be balanced with the development of ammunition technology. One of the technologies that can be undertaken to improve the performance of ammunition is to use material which is high density and high hardness in the core of the projectile, such as tungsten carbide - cobalt material (WC - 8Co). This research will analyse regarding the effects of material substitution from the Pindad’s standard steel core projectile to WC - 8Co core projectile on the performance of 5.56 × 45 calibre ammunition on ceramic material target, alumina (Al₂O₃). This study used experimental method by performing ballistic tests. The results showed that for Al₂O₃ material target, projectile of WC - 8Co core produced (a) 1.2 times a depth of penetration greater than Pindad’s standard steel core projectile, (b) 2.1 times diameter of the crater bigger than Pindad’s standard steel core projectile, and (c) 1.1 times damage deeper than Pindad’s standard steel core projectile. These results showed that for Al₂O₃ material target, the performance of projectile penetration using WC - 8Co core was better than the performance of projectile penetration using the Pindad’s standard steel core.