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120 Mm Gun Tube Erosion Including Surface Chemistry Effects
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Book Synopsis 120-mm Gun Tube Erosion Including Surface Chemistry Effects by :
Download or read book 120-mm Gun Tube Erosion Including Surface Chemistry Effects written by and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A theoretical model that addresses thermochemical erosion in gun tubes is presented. The model incorporates two interior ballistics codes-XKTC and IBHVG2-and the thermochemical code BLAKE to provide the necessary state variables and bulk species concentrations of the core flow as input. This erosion model utilizes a Crank-Nicolson integration scheme, with dynamic gridding capability to account for material ablation, as well as the addition of energy sources and heat transfer augmentation due to surface deviations. A mass transport scheme, utilizing the Lennard Jones 6-12 diffusion model, enables individual species to be transported to the surface from the core flow. Also fully coupled is a separate thermochemical routine which incorporates the NASA Lewis database. The code is written modularly, enabling the inclusion and modification of existing submodules. Erosion results comparing a fielded kinetic energy tank round and a candidate next generation tank round are presented. The thermochemical effects at the surface are also shown and discussed.
Book Synopsis Gas Chemistry Effects on Gun Barrel Erosion. A Shock Tube Gun Investigation by :
Download or read book Gas Chemistry Effects on Gun Barrel Erosion. A Shock Tube Gun Investigation written by and published by . This book was released on 1982 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt: The subject program is part of a continuing effort to identify distinct mechanisms that contribute to gun barrel wear and erosion. The thermochemical effects of altering the CO/CO2 ratio of a propellant gas in a gun tube was the main topic for investigation in this program. Experiments were conducted in the Shock Tube Gun (STG), a ballistic compressor, designed and developed by Calspan Corporation. This facility can compress mixtures of pure gases to simulate propellant gas flow conditions and cycle times experienced in large caliber guns. Tests were conducted with mixture ratios of carbon monoxide and carbon dioxide that characterize the normal range of CO/CO2 ratios found in propellant gas, i.e., 2.0 to 8.1. Progressive substitution of carbon monoxide for nitrogen in the mix quantified erosion as a function of increasing Co concentration or CO/CO2 ratio. Subsequent tests were conducted with gas mixtures containing double the amount of carbon monoxide and carbon dioxide but with the same effect CO/CO2 ratio, to measure erosion as a function of absolute reactant concentration for the two gas species. The basic chemical effect was observed to be a shift in the erosion threshold to less severe convective heating conditions in response to increasing the CO/CO2 ratio above a value of 5.6. The magnitude of the shift appeared to be directly proportional to the absolute concentrations of the two reactant gases. Variation of both CO/CO2 ratio and absolute amounts of the two gases resulted in distinct changes in specimen surface characteristics, both at near threshold and above threshold flow conditions.
Book Synopsis The Role of Oxygen in Gun Barrel Erosion and Cracking. A Shock Tube Gun Investigation by :
Download or read book The Role of Oxygen in Gun Barrel Erosion and Cracking. A Shock Tube Gun Investigation written by and published by . This book was released on 1980 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiments to determine the individual contributors to gun barrel erosion in an oxidizing atmosphere were conducted in the Shock Tube Gun (STG), a ballistic compressor, designed and developed by Calspan Corporation. This facility can compress mixtures of pure gases and can generate flow conditions and cycle times similar to those experienced in large caliber guns. Tests were conducted with a mixture of argon and nitrogen to define the threshold erosion for an inert baseline. Small concentration of oxygen were substituted for nitrogen in the mix to quantify the oxidation effect. Subsequently, tests were conducted with various gas mixtures containing carbon dioxide, which dissociates to produce oxygen when compressed to high temperatures. The basic oxidation effect was observed to be nearly linear increase in erosion with oxygen concentration. A corresponding shift in the erosion threshold to less severe convective heating conditions was observed in response to surface chemistry. A similar effect was observed for carbon dioxide mixture where erosion was correlated in terms of the equilibrium concentration of oxygen at peak pressure. Surface cracking was observed and found to be most severe near the erosion threshold where the oxide layer was thickest. A white layer was observed in tests with oxygen in the absence of carbon dioxide.
Book Synopsis The Role of Carburization in Gun Barrel Erosion and Cracking by : C. C. Morphy
Download or read book The Role of Carburization in Gun Barrel Erosion and Cracking written by C. C. Morphy and published by . This book was released on 1981 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt: The subject program is part of a continuing effort to identify distinct mechanisms that contribute to gun barrel wear and erosion. The chemical effect of a carburizing atmosphere in a gun tube was the main topic for investigation in this program. Experiments were conducted in the Shock Tube Gun (STG), a ballistic compressor, designed and developed by Calspan Corporation. This facility can compress mixtures of pure gases to simulate propellant gas flow condtions and cycle time experienced in large caliber guns. Test were conducted with a mixture of argon and nitrogen to delineate the threshold of simple melting erosion which served as a chemical inert baseline. Progressive substitution of carbon monoxide for nitrogen in the mix quantified the carburizing effect as a function of CO concentration. Subsequent tests were conducted with a gas mixture containing carbon monoxide, argon and helium to measure the carburizing effect as a function of cycle time. The basic carburizing effect was observed to be a shift in the erosion threshold to less severe convective heating conditions in response to surface chemistry. The magnitude of the shift appeared to be directly proportional to heating cycle time.
Book Synopsis Shot-By-Shot Erosion Modeling of Retired 120mm M256 Gun Tube #1988 by :
Download or read book Shot-By-Shot Erosion Modeling of Retired 120mm M256 Gun Tube #1988 written by and published by . This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: As our gun erosion database increases for in-service and out-of-service 120-mm M256 tubes with M829Ax series rounds, distinct erosion patterns and mechanisms are emerging. Variability exists for M256 guns with M829Ax series rounds depending on round count, round type, round-conditioning temperature, and their order. Our M256/M829Ax gun system erosion model - with its interior ballistics, thermochemistry, and boundary layer components - is constantly being guided and refined by the erosion and materials analysis data from fired gun tubes. A recent refinement includes the improvement of the gun steel subsurface exposure model due to high quality, difficult to obtain data from in-service M256 tubes. Other recent refinements to the boundary layer heat transfer model are based on thermal data from M256 tubes. These refinements include the improvement/incorporation of case gas cooling effects, turbulent gas mixing/heating effects, and a very minor contribution from forcing cone-induced vena contracta cooling effects. These latter refinements are calibrated away from crack walls by positional thermal wall repacking depth, thermal wall transformation depth, and thermocouple data. A comprehensive gun erosion model is described for the 120-mm M256 gun with its M829Ax series rounds. In addition, a detailed shot-by-shot erosion modeling prediction is escribed for retired 120-mm M256 gun tube serial #1988. For this gun tube, the erosion prediction includes the two types of rounds fired, 829 and M829A2, and their three round-conditioning temperatures, hot, ambient, and cold. The gun erosion mechanism consists of heat checking the inert chromium plate, subsequent interfacial degradation of the subsurface gun steel substrate at the chromium crack bases, then chromium platelet spalling, and subsequent bare gun steel gas wash. This gun erosion model correctly calculates and predicts that the worst eroded region is at 1.2 to 2.4 meters from the rear face of the tube.
Book Synopsis Comprehensive Erosion Model for the 120-MM M256/M829A2 Gun System by :
Download or read book Comprehensive Erosion Model for the 120-MM M256/M829A2 Gun System written by and published by . This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Most 120-mm M256 guns firing the M829 round as their "honest" kinetic energy round have been condemned because of fatigue. Despite this fact, it is still important to determine the erosion life of the M829 round, since M256 guns that have fired the most recent kinetic energy rounds (M829A1, M829A2) rely on the M829 round for baseline dispersion testing of that gun. Today this generally results in M256 guns that having an equal mix of M829 and M829A2 rounds, thus necessitating the consideration of M829 round effects for any erosion analysis. Variability exists for M256 guns with M829 rounds depending on round count, round type, round-conditioning temperature, and their order. Distinctive erosion patterns and mechanisms are emerging as our gun erosion database increases for in-service and out-of-service 120-mm M256 tubes with M829 rounds. Our M256/M829 gun system erosion model-with its interior ballistics, thermochemistry, and boundary layer components-is constantly being guided and refined by the erosion and materials analysis data from fired gun tubes. A recent refinement includes improvement of the gun steel subsurface exposure model due to high quality, difficult to obtain data from in-service M256 tubes. Other recent refinements to the boundary layer heat transfer model are based on thermal data from M256 tubes. These refinements include the improvement/incorporation of case gas cooling effects, turbulent gas mixing/heating effects, and a very minor contribution from forcing cone-induced vena contracta cooling effects. These latter refinements are calibrated away from crack walls by positional thermal wall repacking depth, thermal wall transformation depth, and thermocouple data.
Book Synopsis Erosion Modeling of the 120-MM M256/M829A2 Gun System by :
Download or read book Erosion Modeling of the 120-MM M256/M829A2 Gun System written by and published by . This book was released on 1997 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Benet Laboratories/Software and Engineering Associates, Inc. (SEA) gun barrel erosion modeling and design code predicts wall degradation due to transformations, chemical reactions, and cracking coupled with pure mechanical erosion for the 120-man M256/MS29A2 gun system for ambient temperature-conditioned rounds. The A723 steel and 0.005-inch high contraction (HC) chromium plated/A723 steel wall materials are evaluated for erosion. This complex computer analysis is based on rigorously evaluated scientific theory that has been validated in the rocket community over the last forty years. Our gun erosion analysis includes the standard interior ballistics gun code (XNOVAKTC), the standard nonideal gas-wall thermochemical rocket code modified for guns (CCET). the standard mass addition boundary layer rocket code modified for guns (MABL), and the standard wall material ablation conduction erosion rocket code modified for guns (MACE). In addition, bore subsurface metallographic analysis and projectile-bore finite element analysis (ABAQUS) are considered. Our overall analysis provides wall material erosion predictions and comparisons of ablation, conduction, and erosion profiles as a function of time, travel (customer-selected 27. 61, 86, 130, and 201 inches from the rear face of the tube), and number of rounds to barrel condemnation. The 120-mm M256/M829A2 gun system prediction, with significant numbers of M829A2 rounds, agrees well with the wear and erosion pattern of retired M256 gun barrels.
Book Synopsis Gray Layers and the Erosion of Chromium Plated Gun Bore Surfaces by :
Download or read book Gray Layers and the Erosion of Chromium Plated Gun Bore Surfaces written by and published by . This book was released on 1999 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present report describes observations and analyses in a survey study of erosion damage in chromium plated gun bore surfaces. Sections of three fired chromium plated 120-mm M256 gun tubes and two 155-mm gun tubes (M199 and XM297) were examined by optical microscopy, laser scanning confocal microscopy (LSCM), and electron microprobe analyses. These tubes experienced significant erosion damage and chromium loss. A rifled portion of the 155-mm M199 tube was plated with low contractile (LC) chromium and the 155-mm XM297 and 120-mm M256 tubes were plated with high contractile (HC) chromium. New insights regarding the erosion process and the origin of chromium loss are obtained by investigation of the initial damage to the steel at the tips of the fine cracks in the chromium. Reaction products from gas-metal interactions at the gun bore surface are normally difficult to find because of gas wash effects. Examination of unetched specimens from a variety of fired tubes shows that these products remain in lace in the relatively protected regions beneath the chromium when chromium crack widths are small. The initial damage is manifested as gray layers or gray regions in the steel at the tips of the fine chromium cracks. Electron microprobe analyses indicate that these gray layers are composed of iron sulfide, iron oxide, or mixtures of the two compounds.
Book Synopsis Factors Affecting Chrome Loss in Gun Tubes by :
Download or read book Factors Affecting Chrome Loss in Gun Tubes written by and published by . This book was released on 2003 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of the study was to gain further insights into the origin of chromium loss in tank guns. The present report summarizes the results of a study surveying chromium loss at various critical locations along a 120-mm M256 tank gun tube. Tube no. 6824 was selected because it had fired relatively few rounds (119), while still exhibiting initiation of all the typical chromium damage features in the chamber and bore of a 120-mm tube. Coating stresses were also computed with a finite element model to aid in the analyses. The data reveal a broad range of metallurgical effects related to erosion damage at the bore surface during firing. Establishing the cause of chromium loss in any specific case can be difficult because of the numerous contributing factors. Nevertheless, the present data show that high temperature oxidation at the chromium/steel interface is a common feature in both the chamber and the gun bore, indicating that steel oxidation is an essential factor in chromium loss. The interface oxidation occurs by gas penetration through chromium cracks that extend from the coating surface to the interface. This oxidation undermines the chromium coating and promotes chromium spallation, which then leads to pitting in the chamber and erosion in the bore.
Book Synopsis Physicochemical Aspects of Gun Barrel Erosion and Its Control by :
Download or read book Physicochemical Aspects of Gun Barrel Erosion and Its Control written by and published by . This book was released on 1975 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gun tube erosion can be defined as the bore surface damage and bore enlargement caused by firing, which can lead to loss in accuracy and the effectiveness of the weapon. It is one of the two major factors on the basis of which gun tubes are condemned; the other factor being fatigue life, Erosion is a complex phenomenon resulting from the interaction of propellant gases and the projectile with the surface of the bore. The bore surface is exposed for a short time to temperature approaching the melting point of steel, pressures as high as 50,000 psi, reactive atmosphere composed of CO, CO2, H2O, H2, N2, and numerous other identified and unidentified constituents. Superimposed on these conditions are the high velocity of gases and swaging action of the projectile rotating band. It is the objective of this presentation to review the physicochemical processes involved in erosion and indicate some critical areas which need further investigation. Also, various efforts to control erosion in barrels will be briefly discussed.
Book Synopsis Initial Studies of Gun Tube Erosion Macroscopic Surface Kinetics by :
Download or read book Initial Studies of Gun Tube Erosion Macroscopic Surface Kinetics written by and published by . This book was released on 2001 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt: Current theories concerning gun tube erosion consider that erosion can occur under various conditions. The worst condition occurs when the melting temperature of the gun steel is exceeded for the tube's inner surface. This causes the tube to grossly melt This melt wipe mechanism is not as simple as once thought because the propellant product gases are known to read with the surface, resulting in an altered surface material. This altered material may have a lower melting temperature than that of the gun steel and/or weakened mechanical properties. Previous surface reaction studies by the authors used a generalized equilibrium scheme with a control volume analysis to represent surface reactions occurring during a cannon firing. This led to a postreaction treatment at the interface which incorporated the subsurface diffusion of species to limit the surface reaction. In this study, the surface reactions and rates are specified explicitly with published rates and guidance from fundamental molecular modeling results. The results demonstrate the utility of the surface reaction mechanism presently employed and the incorporation of finite rate surface kinetics in the fundamental physical representation of erosion.
Download or read book Ballistics 2011 written by Ernest Baker and published by DEStech Publications, Inc. This book was released on 2011-09 with total page 2230 pages. Available in PDF, EPUB and Kindle. Book excerpt: Includes papers that were first presented at a September 2011 conference organized by the National Defense Industrial Association and the International Ballistics Society. This title includes a CD-ROM that displays figures and illustrations in articles in full color along with a title screen and main menu screen.
Book Synopsis Erosion Study of 7.62mm CR-MO-V Steel Gun Tubes. Part 1. Erosion Analysis and Characterization. Part 2. Fatigue Behavior in Reactive Environments by :
Download or read book Erosion Study of 7.62mm CR-MO-V Steel Gun Tubes. Part 1. Erosion Analysis and Characterization. Part 2. Fatigue Behavior in Reactive Environments written by and published by . This book was released on 1973 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: The erosion process in 7.62mm steel gun barrels has been chronologically characterized by investigation of the test-fired barrels fired from 1 to 3000 rounds. Both unplated barrels and barrels with hard chromium plated bores were included. Detailed metallurgical analysis, using modern analytical techniques, was conducted on the test-fired gun barrels. Evidence is presented to demonstrate that chemical effects substantially augment the erosion phenomenon caused by thermomechanical factors. Gas-metal reactions and chemical attack involving Pb, S, Cu (Cu-Zn) and Ca comprise the observed chemical effects.
Book Synopsis Shot-by-shot Erosion Modeling of Retired 120mm M256 Gun Tube Number 1988 by : Samuel Sopok
Download or read book Shot-by-shot Erosion Modeling of Retired 120mm M256 Gun Tube Number 1988 written by Samuel Sopok and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Effects of Processing Variables on Erosion of Gun Tubes by : J. Passmore
Download or read book Effects of Processing Variables on Erosion of Gun Tubes written by J. Passmore and published by . This book was released on 1979 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: A reduction in silicon with an associated increase in molybdenum is known to increase the wear life of gun steel when fired under subscale firing conditions. However, when this same material is employed in a full scale firing test utilizing the 105-mm M-68 gun tube, the wear life of the tube, as measured at the origin of rifling (i.e. OR), remains the same regardless of silicon and molybdenum content. A few inches beyond the OR (27 inches from the rear face of the tube and beyond), the results of the full scale firing test agree with the results of the subscale firing tests, in that the low silicon steel exhibits a lower erosion rate than for a normal gun steel composition. (Author).
Book Synopsis First Principles Predictions of Gun Tube Erosion Chemistry and Possible Protective Coatings by :
Download or read book First Principles Predictions of Gun Tube Erosion Chemistry and Possible Protective Coatings written by and published by . This book was released on 2002 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Increasing the service lifetime of military machinery will improve logistics in the field (less down-time due to maintenance or replacement) and will free up resources for other pressing needs. To this end, the Army has a vested interest in enhancing the lifetime of gun barrels, which are limited currently by erosion of the steel from which the gun barrels are made. However, it is exceedingly difficult to determine experimentally in situ the mechanisms of erosion. Therefore, computer simulations can help elucidate those mechanisms and in ultimately extending the lifetime of gun barrels by discovering new ways to inhibit erosion.
Book Synopsis Proceedings of the Heat Transfer and Fluid Mechanics Institute by : Heat Transfer and Fluid Mechanics Institute
Download or read book Proceedings of the Heat Transfer and Fluid Mechanics Institute written by Heat Transfer and Fluid Mechanics Institute and published by . This book was released on 1991 with total page 474 pages. Available in PDF, EPUB and Kindle. Book excerpt:
