Gun Barrel Research Articles

Investigating the thermal-chemical-mechanical coupling effects on the cracking behavior of machine gun barrel: Microstructural insights

The presence of severe cracks at the inner bore of the gun barrel accelerates the erosion failure, whereas the evolution and failure mechanism of crack tips under the thermal-chemical-mechanical coupling effects needs further investigation. Herein, the elemental distribution, phase structure, and strain surrounding the perpendicular and circumferential cracks in a failed gun barrel were investigated in detail by utilizing scanning electron microscopy (SEM), transmission Kikuchi diffraction (TKD), and transmission electron microscopy (TEM). Results indicated that the perpendicular crack was covered by double continuous layers composed of inner FeO oxides and outer Fe0.96S sulfides. Notably, a high-density precipitation of FeO oxides together with severe lattice distortion and localized amorphization was observed at the crack tip, accelerating the growth of the cracks. For the circumferential crack, the presence of fine recrystallized grains alongside coarsened M23C6 carbides was observed at the crack tip. There was a high level of strain concentration along high-angle grain boundaries at the forefront of the circumferential crack tip, resulting in the cracking along grain boundaries. Furthermore, the models for propagation of perpendicular and circumferential cracks under the thermal-chemical-mechanical coupling effects were proposed respectively.

Surface Strain Measurement for Non-Intrusive Internal Pressure Evaluation of a Cannon

Abstract Recent cutting-edge designs for gun barrels, projectiles, and propellants require testing, such as measuring the internal pressure during firing. However, there are concerns with the current drilling method to mount pressure transducers near the breech and chamber of the gun barrel where pressure is highest. To address this challenge, the team hereby presents an alternative, nonintrusive strain measurement method. This method focuses on determining the feasibility and accuracy of relating tangential strain along the sidewall of a gun barrel to the drastic internal pressure rise created during combustion. A transient structural, numerical model of a 155 mm gun barrel was created using ansys. The pressure was derived using the outline in Interior Ballistics of High Velocity Guns, version 2, and the model was validated using published experimental tangential strain testing data from a gun of the same caliber. The model was then used to demonstrate the ideal location for strain measurement along the sidewall of the chamber. Furthermore, three different pressure ranges were simulated in the model. The behavior of the tangential strain in each case indicates a similar trend to the internal pressure rise and oscillation due to a dominant frequency of the barrel. A method to predict internal pressure from external tangential strain was developed. The internal pressure predicted is within 4% of the pressure applied in the model. In the sensitivity study, the thickness and elastic modulus of the gun barrel were found to be the primary factors affecting tangential strain. Overall, this work helps to understand tangential strain behavior on the sidewall of a large-caliber gun barrel and lays the ground for an accurate prediction of internal pressure from external tangential strain.

Cauchy Type Nonlinear Inverse Problem in a Two-Layer Cylindrical Area

Various types of protective coatings, such as ceramics, are used to increase the efficiency of metal parts that are exposed to high heat loads. Maintaining mechanical properties and acceptable thermal stresses requires temperature control for components such as turbine blades, gun barrels or combustion chambers. This paper presents a new method for controlling thermal parameters by solving a non-stationary Cauchy problem for the heat conduction equation. The solution is presented in a cylindrical two-layer area considering the variation of the thermophysical parameters of the metal and ceramic. The non-linear equation was solved by successive approximation method using differential quotients for the space and time variable. In order to regularize the ill-conditioned inverse problem, a quasi-regularization method was applied by performing an energy balance for the ceramic. Numerical calculations were carried out for different thicknesses of the ceramic layer. The temperature, heat flux density and heat transfer coefficient for the protective layer were calculated. For the same values of the heat transfer coefficient for 0.1 and 0.3 mm thick protective layers, the difference in permissible gas temperature differs by 10.5 °C.

Heat Treatment Optimization and Nitriding Effects on Mechanical Properties of 32CrMoV12-10 Steel

32CrMoV12-10 steel is widely utilized in industries where high strength and toughness are crucial. This alloy is commonly used in manufacturing components like gun barrels, gears, and bearings, which demand exceptional mechanical properties. These parts typically undergo heat treatments, including hardening and surface enhancement techniques such as nitriding, to extend their fatigue life significantly. It is crucial to identify optimal heat treatment conditions to achieve desired material performance. In this study, commercial 32CrMoV12-10 steel was selected to investigate the impact of heat treatment parameters (temperature, duration time, and quenching media) on its mechanical properties. To analyse the effect of these parameters, the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) and the Taguchi Method were employed, facilitating a systematic examination of the process stages and subsequent mechanical testing outcomes, including Charpy V-notch impact, hardness, and tensile strength assessments. An optimal heat treatment protocol was established based on these analyses, and the nitriding depth of the optimally treated sample was examined using a micro-Vickers hardness tester. For comparative analysis, another sample with closely related outcomes was also evaluated. Results indicated that the surface hardness of the optimally treated Sample 10 reached 870 HV, with a core hardness of 417 HV, compared to non-nitrided Sample 3, which showed a surface hardness of 860 HV and a core hardness of 415 HV. Despite the proximity in their values, Sample 10 exhibited slightly higher micro-Vickers hardness than Sample 3. However, while Sample 3 fails to meet the specified tensile stress and hardness criteria, Sample 10, produced through optimization, meets criteria, ranging from 970 to 1040 N/mm², underscoring the efficacy of the optimization process facilitated by TOPSIS. This optimization was notable for its minimal experimental requirements, proving effective in conserving time, energy, and resources while investigating the processed material.

The Construction of a Small-Caliber Barrel Wear Model and a Study of the Barrel Wear Rule

The wear of small-caliber barrels is one of the key factors affecting barrel life. Based on the Archard wear model, a high-temperature pin plate wear experiment was carried out, and wear models of chrome-plated layers and gun barrel materials were established. In addition, a finite element model of the interaction between the bullet and the barrel was established. The movement of the projectile along the barrel was simulated and analyzed, and the force distribution of the spatial geometry structure of the rifling was mastered through simulation. The wear law of the gun barrel along the axial direction was obtained based on the wear model of the chrome-plated layer and gun barrel material. A position 100 mm away from the barrel breech wears very fast; this position is where the cone of the bullet is engraved in the barrel. At the position 150–350 mm away from the barrel breech, the barrel bore wears even faster. The barrel chrome layer is mainly affected by the gunpowder impact and projectile engraving, which is consistent with the actual failure of the coating. When the distance to the barrel breech is 350 m, the wear becomes stable. Through an analysis of the diameter of the barrel, it was found that, when the diameter of the barrel exceeded 12.85 mm, the barrel reached the end of its life.

Characterization of Wear Patterns in Gun Barrel’s Throat Region Using Forensic Microscope: Insights Into Long-Term Effects of High-Pressure Gas Exposure

Objectives: This research aims to explore the damage sustained by the gun barrel's throat region over a long period of use, shedding light on the wear characteristics, and providing valuable insights into the long-term effects of high-pressure gas exposure during firing. Methods: To achieve this objective, the appearance of the gun barrel's throat region was characterized using forensic microscopy techniques. Visual and microscopic examinations were conducted on five (5) gun barrels with ten years or less of service usage and five (5) gun barrels with over ten years of service usage from the Philippine National Police to assess the degree of wear in the barrel’s throat region. Findings: The findings revealed varying degrees of wear in the barrel throat regions. Firearms with 10 years or less of service usage exhibited moderate corrosion, narrow cracks, and minimal soot particle presence while firearms with over 10 years of service usage showed severe corrosion, deep cracks, scattered potholes, superficial scraped surfaces, and heavy soot particle presence. Novelty: This research contributes to the understanding of barrel performance, maintenance, and potential hazards associated with aging firearms, thus providing novel insights into the long-term effects of high-pressure gas exposure during firing. By examining the changes in material properties and surface roughness of the gun barrel’s throat region, this study seeks to improve the understanding of how repeated firing impacts gun barrel performance and longevity. This, in turn, may aid in developing future maintenance practices to enhance firearm durability and safety. Keywords: Gun Barrels, Wear Characteristics, Gun Barrel Throat Region, High-Pressure Gas Exposure, Wear Patterns

Design and development of a novel MR finishing method for hollow cylindrical surfaces

ABSTRACT Hollow cylindrical components of longer length are a crucial necessity in industries catering to products like gun barrels, cylinder liners of ship and locomotive engines, pneumatic and hydraulic cylinders, etc. A highly finished inner surface improves resistance to corrosion, wear, and friction. Conventional magnetorheological (MR) finishing techniques typically use axis-based CNC setups, which are limited in their ability to finish longer components (>30 cm) due to the Z-axis tool restriction. In this work, a novel MR finishing method has been designed and developed that is based on the pneumatic cylinder and has extremely high reach for the length of the hollow cylindrical workpiece thereby successfully mitigating the limitation of conventional CNC-based MR finishing techniques. Using mild steel as the material, the new technique achieved a significant reduction in surface roughness, with a minimum average roughness of 0.059 µm after 150 minutes of finishing.

Preparation and performance studies on organic-inorganic phase change composites based on zeolitic imidazolate and paraffin for reducing gun barrel erosion

With the increasing requirements of tank guns for higher muzzle velocity and faster firing rate, some high energetic additives, such as cyclotrimethylene trinitramine (RDX) and cyclotetramethylene tetranitramine (HMX), have been widely used in high energy gun propellants. Consequently, the gun barrel erosion induced by the burning of high energy gun propellants has been an important issue that affects the lifespan of gun barrels. In order to address this problem, erosion reducing additives, including TiO2, paraffin, polyurethane or a combination of these, were introduced into the gun propellant or propellant charge system to alleviate the gun barrel erosion. In this study, a novel organic-inorganic phase change composite paraffin/ZIF-67 with solid paraffin (SP) as the phase change component and zeolitic imidazolate framework-67 (ZIF-67) as the matrix was designed and prepared as anti-erosion additives. The designed composite has a high thermal storage capacity of 93.88 J/g when the ZIF-67 content is 5 wt%. The erosion reducing effect of paraffin/ZIF-67 was determined by erosion tube test. The results show that the introduction of paraffin/ZIF-67 can improve the erosion-reducing efficiency of gun propellants. Compared with the control sample, the erosion-reducing efficiency of paraffin/ZIF-67 exhibited a faster increase with the increase of their contents, having the maximum erosion-reducing efficiency of 39.2 % when the addition of paraffin/ZIF-67 is 3.2 wt%. The incorporation of paraffin/ZIF-67 in the composites has a cooperative effect of each component on reducing gun barrel erosion. The developed organic-inorganic phase change composites exhibit great potential in the application of reducing gun barrel erosion, providing a new way for the development of erosion reducing additives.

Analytical and numerical studies of gas discharge out of gun barrel tube

Abstract This paper investigates the characteristics of the discharge of gases out of gun barrel tube. The paper gives an insight into the physical principles that govern gas discharge through the presentation of analytical and two different numerical approaches. The analytical model is based on the well-known Bravin’s model, whereas the numerical approaches involve single- and two-phase flow numerical simulations conducted by utilities of Computational Fluid Dynamics (CFD). The differences between analytical and numerical results are analysed, from which the numerical approach is found to be capable of capturing the interacting phenomena due to the discharge of hot and high-pressure gases. The visualisation of flow parameters manifests the complex dynamics evoked by flow patterns and the formation of Mach disc and shock waves. It is found that the analytical Bravin’s model underestimates the pressure decay inside the barrel due to gas discharge compared to both the single- and two-phase flow numerical approaches.

The integration and tests of the shattered pellet injection system on EAST

A SPI system specifically designed for EAST has been integrated and commissioned to carry out plasma rapid shutdown. This system is capable of injecting pellets with quantities ranging from 7 to 14 Pa m3 and at velocities between 150 and 400 m/s, as determined after conducting a series of bench tests. A two-stage differential pumping system designed to remove the propellant gas has had its efficiency assessed through the application of pumping equations and the fourth-order Runge-Kutta routine. For the purpose of facilitating remote control of the SPI system, a control system based on EPICS has been developed. This system enables an automated workflow for pellet formation and launch, which includes stages such as pellet formation, strengthening pellet, awaiting trigger, launching pellet, baking gun barrel, and cooling cold head, with the entire process taking 600 s. Furthermore, rapid shutdown experiments using Ne shattered pellet injection have been conducted, demonstrating the system's high reliability and reproducibility on EAST.

Research on the drainage mechanism of a novel gun barrel and the characteristics of gas–liquid mutual interference

Research on the drainage mechanism of a novel gun barrel and the characteristics of gas–liquid mutual interference

Design, analysis, manufacturing, and testing of a composite gun barrel

AbstractUser expects his weapon to be light and reliable and to perform multiple times firing per unit time at the same time. In today's technology, the maximum number of firings can be made per unit time with steel barreled weapons, but in composite barrels; many problems occur due to overheating, strength and reliability. Meeting these opposite demands is an engineering problem. In this study, the design of a composite‐steel combination light gun barrel is studied. Firstly, pressure distribution through the barrel has been calculated using Vallier‐Heydenreich method. According to the calculations, analysis has been conducted using both steel barrel and composite barrel. After the analysis, a composite barrel has been manufactured and testing has been conducted on an all‐steel barrel and the manufactured composite barrel. Composite is carbon fiber and resin is epoxy resin. In composite material, carbon fiber is preferred at the rates of 50% and 60%, the material of the steel barrel is AISI 416R stainless steel. The manufactured steel barrels have the same outer diameter but different wall thickness ratios, firing tests were conducted in such a way that the number of shots per unit time was the same.Highlights Stress distribution within a gun barrel was calculated using Vallier‐Heydenreich method. Design and finite element analysis analysis for an all‐steel gun barrel and a composite gun barrel was conducted. A composite gun barrel was manufactured; by using composite materials, the barrel was lightened by 24.8%. The manufactured composite gun barrel and an all‐steel gun barrel were tested by firing over 2500 shots.

THE INFLUENCE OF THE CARBURIZING PROCESS ON THE IMPACT-SLIDING WEAR BEHAVIOR OF 14NiCr14 STEEL

Weapons depend largely on the barrel. Gunpowder combustion converts chemical energy into thermal and mechanical energy. Barrels give projectiles initial speed and flight direction, and helical grooves require fast spinning for stability while moving toward the target. Due of barrel exposure to heat, high pressures, gunpowder vapors, and external impacts, this weapon element needs extensive investigation. The study discusses carburizing for surface modification in high-pressure circumstances to improve gun barrel interior line tribology. Carburizing has been detected at a depth of 960 μm from the surface, as revealed by light-optical microscope images. The microhardness test has been performed on the sample's cross section, which has a maximal hardness of 650 ± 10 HV0.05 close to the surface and 250 ± 5 HV0.05 close to the interface. At room temperature (RT), this study looked at how the carburizing process affects the impact-sliding wear performance of 14NiCr14 steel, which is widely used in the barrel extensions of guns under complex loading conditions. A series of impact-sliding wear experiments were conducted on 10 mm-diameter bearing steel balls made of 52100-grade steel, for a total of 4297 loading cycles. A 2-D contact profilometer and a light optical microscope (LOM) then examined the wear tracks that had formed on the samples. The carburized steel caused a decrease in the wear rate at the impact and sliding zones of the wear track.

Experimental and Numerical Study on the Protection Efficiency of a Diamond-Shaped Thermal Jacket for Gun Barrels

Abstract Experimental and numerical investigations on the protection efficiency of a diamond-shaped thermal jacket made of the certain braided composites with anisotropic material properties for gun barrels were carried out to gain an insight into its thermal–structural behavior and performance. The experiments for the gun barrels with and without the thermal jacket subjected to unilateral thermal radiation were conducted on a thermal jacket protection efficiency experimental system. Three-dimensional finite element models were established to perform the thermal–structural analysis and approximate the temperature distribution and thermal deformation of the shrouded gun barrel and bare gun tube. The experimental results validated the numerical models for the study of solar radiation on the thermal–structural characteristics of the gun barrels with and without the thermal jacket. The temperature changes together with their gradients, and the thermal deformation of the gun tube shrouded with the thermal jacket were notably less than that of the bare gun tube. The nonuniform temperature distribution caused by unilateral radiation can be substantially ameliorated by the thermal jacket. The developed diamond-shaped thermal jacket owned satisfactory protection effectiveness. In addition, moderately increasing the thermal jacket's thickness or the air gap between the thermal jacket and gun tube can decrease the muzzle deflection of the shrouded gun barrels. The work is promising in providing both theoretical and practical contributions in design of shrouded tank gun barrels aiming at achieving high first shot accuracy.

High frequent cyclic ablations of AlSi alloy modified C/C-SiC-ZrB2-ZrC at different temperatures

Modified C/C composites are promising candidates to the advanced piston of internal engine, pantograph slide plate and rapid-fire gun barrel. To understand the corrosion in the working conditions of these thermal components, cyclic ablations of C/C-SiC-ZrB2-ZrC (C/C-SZZ) were carried out in high frequent impacted combustions at different temperatures (700–2300 ℃). Parallel study of AlSi alloy modified C/C-SiC-ZrB2-ZrC (C/C-SZZ-AS) which had lower cost was performed synchronously for comparison. Results indicated that the ablation rates of both the composites went down with decreased temperature while C/C-SZZ-AS presented a faster decline. Compared with C/C-SZZ, the pressure infiltrated AlSi alloy matrix of C/C-SZZ-AS raised the conductivity and specific heat capacity but reduced the emissivity, which led to a lower surface temperature and thermal gradient during ablation. And combined with the better plasticity and toughness of the alloy matrix, C/C-SZZ had stronger ablation resistance below 1500 ℃ in the serious thermal shock. At temperature above 1500 ℃, excessive phase transformation of the AlSi alloy matrix caused more defects and strengthened the mechanical erosion. And then the faster consumption of the AlSi alloy resulted in the greatly worsened ablation property of C/C-SZZ at 2300 ℃.

Investigation of heat transfer in cracked gun barrels

Heat transfer process significantly affects the life span of gun barrels as it directly associates to the thermoelastic dynamic responses, erosion, and wears of gun barrels. The previous studies regarding the heat transfer in gun barrels were developed in the realm of local theory that is expressed by partial differential equations with the condition of smoothly distributed physical fields, and have rarely studied the cracked gun barrels. However, on one hand, due to manufacturing errors, there inherently exists fractures in realistic gun barrels; on the other hand, the inner wall of the gun barrel wears due to the high-temperature and -speed burning gas generated during the interior ballistic process, as well as the high-speed friction from projectile’s movement, which severely lead more cracks and damages. Therefore, it is of great importance to investigate the heat transfer in cracked gun barrels. In this paper, a non-local heat transfer model for cracked gun barrels is formulated via the bond-based peridynamics. The governing equation is presented in the manner of integration, such that the heat process with the influence of cracks can be readily captured. Numerical results show that the heat energy severely accumulates on the crack surface and as the size of horizon increases, the non-local characteristics of the heat transfer appear to be more pronounced, resulting in a stiffer thermal response.

Research on the Erosion of Gun Barrel Based on Vented Vessel Tests

The vented vessel test, as an alternation of the firing practice, is implemented to reconstruct the deterioration process of the gun barrel suffering the thermochemical erosion by propellant combustion gas. High pressure of over 300 MPa with a duration exceeding 20 ms is applied on the rifled specimen. A phase transition layer about 136 μm is observed by scanning electron microscopy (SEM) from the cross section of the test specimen. Some residual oxidation products of the iron can be detected by energy dispersive x-ray spectroscopy (EDS) on parts of the inner surface. A comprehensive erosion analysis is conducted, which estimates that the mass loss of the specimen is mainly attributed to the periodical formation and peeling of the chemical reaction layer on the bore surface. The most severely eroded part is located on the corner of the land. On the basis of the examined erosion mechanisms, a proper thermochemical erosion model is employed. The mass dissipation and the geometry evolution under continuous firing are simulated using finite element method (FEM). The simulation phenomenon shows good consistency with results of the experimental tests.

ернативна технологія поверхневого зміцнення внутрішніх поверхонь довгомірних деталей

Barrel survivability is the main indicator of tank guns. In order to ensure the competitiveness of Ukrainian armored vehicles on the foreign arms market, there was a need to ensure the survivability of the barrels of domestic tank guns at the level of the best world samples. Solving the problem of strengthening, restoring and increasing the service life of long-dimension parts is associated with the complexity of preparing and processing the inner surface (bore) along its entire length and eliminating possible residual deformations. The problem of increasing the survivability of tank gun barrels by applying protective coatings is considered. Their brief characteristics and limits of application are given. An alternative technology for surface hardening by electrical contact sintering of powder materials is proposed. This technology makes it possible to apply coatings up to 3 mm thick, with a density approaching that of a compact material and an adhesive strength of up to 220 MPa. Electrocontact sintering refers to impulse technologies and can exclude further mechanical processing of coatings The electrical contact method is the most promising method of strengthening and restoration, as it refers to the methods with the minimum necessary heating, thereby excluding thermal deformation of the parts being strengthened (this technology will allow to eliminate the most characteristic defect of the barrel, such as its swelling and distortion). For cauterization, a specially developed electrode-tool made of a copper alloy, dispersed-reinforced with solid particles, was used, which allows combining in one operation the application of coatings and the finishing treatment by the method of plastic surface deformation to the limit size, surface cleanliness and density.

Friction behavior of 30CrNi2MoVA gun barrel steel after thermo-cyclic treatment: Air and simulated seawater

The influence of gun barrel erosion has been proposed, but the research on the wear behavior of gun steel during the initial extrusion phase remains limited. This study employed an experimental approach to investigate the wear of 30CrNi2MoVA gun steel after untreated (25 °C) and thermal cycling treatments (400 °C and 800 °C) under both air and simulated seawater environments. In the air environment, abrasive wear and adhesive wear mechanisms were prominently observed. In the simulated seawater, abrasive wear mechanism was predominant. In both environments, the surface morphology and wear profiles of the untreated samples were similar, exhibiting a negative interaction phenomenon. After thermal cycling treatment, the corrosion wear resistance of 30CrNi2MoVA steel were significantly reduced. Among them, the material performance is the lowest at 800 °C. Therefore, this study provides theoretical and experimental evidence for improving the friction and wear performance of gun barrel rifling during the bullet extrusion process.

Modern methods and means of technical diagnostics of artillery weapons and prospects for their development

The analysis of full-scale military operations in the east of Ukraine indicates an increase in the variety of firing tasks for artillery weapons and the intensity of their execution. This, in turn, requires the maintenance of artillery weapons and systems that ensure their proper operation in a serviceable and ready-to-use condition, as well as the prevention of sudden breakdowns and failures during combat missions.
 Taking into account the influence of the technical condition on the effectiveness and safety of the combat use of artillery weapons, there is a need to improve the methods and means of its diagnosis.
 This article analyzes the available domestic and foreign studies devoted to the development and improvement of methods for diagnosing the technical condition of artillery weapons. Existing devices for measuring, inspecting, evaluating and controlling the technical condition are considered. The existing systematization was expanded, generalization and addition of known methods and tools was carried out. The main possibilities, advantages and disadvantages of known methods, as well as promising directions for further research are determined.
 It has been established that the majority of studies of possible methods of diagnosing the technical condition of artillery weapons are focused mainly on the analysis of the parameters of only the gun barrel and do not consider the ability of the studied methods to assess the technical condition of artillery weapons comprehensively.
 The analysis also showed that despite the large number of existing techniques for diagnosing the technical condition (determining the degree of wear), most of them are not suitable for use directly in field conditions, morally outdated or very expensive.
 In addition, it was determined that the application of the analysis of acoustic and vibration signals that occur during a shot is a promising direction for diagnosing the technical condition of artillery weapons, which potentially has the ability to detect more malfunctions, breakdowns and deviations of technical parameters.