US3873375A - Method of making steel cartridge cases - Google Patents

Method of making steel cartridge cases Download PDF

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Publication number
US3873375A
US3873375A US352559A US35255973A US3873375A US 3873375 A US3873375 A US 3873375A US 352559 A US352559 A US 352559A US 35255973 A US35255973 A US 35255973A US 3873375 A US3873375 A US 3873375A
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US
United States
Prior art keywords
steel
cartridge case
cartridge
carbon content
cartridge cases
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US352559A
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English (en)
Inventor
Robert J Bolen
Kelley R Chadwick
Richard T Gall
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Remington Arms Co LLC
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Remington Arms Co LLC
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Publication date
Application filed by Remington Arms Co LLC filed Critical Remington Arms Co LLC
Priority to US352559A priority Critical patent/US3873375A/en
Priority to CA196,590A priority patent/CA1026656A/en
Priority to BR3039/74A priority patent/BR7403039D0/pt
Application granted granted Critical
Publication of US3873375A publication Critical patent/US3873375A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/08—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
    • C23C8/20—Carburising
    • C23C8/22—Carburising of ferrous surfaces

Definitions

  • a cartridge case is formed from C1008 steel strip.
  • the cartridge case is heated in a carbon rich atmosphere to increase the carbon content of the steel to approximately 0.55% and is furnace cooled so that it has a ferrite and pearlite structure and exhibits a uniform hardness and has a tensile strength similar to that of a brass cartridge case.
  • This invention relates to the manufacture of ammunition components from steel and more particularly to a method of manufacturing from low carbon steel a rim fire cartridge case which functions in a manner substantially the same as a brass cartridge case.
  • cartridge cases have generally been manufactured from brass because it has been the only metal satisfactorily meeting the requirements of ammunition components in regard to cost, shaping, strength, corrosion resistance and extractibility from a gun.
  • brass has many disadvantages among which are the tendency toward stress corrosion cracking, the tendency to react or cause the primers or powder contained therein to become unstable, and a steadily increasing cost.
  • FIG. 1 is a sectional view of a rim fire cartridge case with an exaggerated clearance between the case and the chamber of the gun. The bulging of the shell due to firing pressures and a split in the body of the case are also exaggerated.
  • FIG. 2 illustrates a flow sheet of the improved method of making steel cartridge cases showing the steps thereof.
  • a cartridge case serves as a container or carrier for the powder and the priming mixture which initiates the combustion of the powder.
  • the projectile is placed in the mouth of the cartridge case and is propelled from the barrel by expanding gas after the primer of the cartridge has been struck by the firing pin to ignite the propellant powder.
  • the shell When in position in the gun, the shell is located in the chamber thereof; the shell must of course be properly sized during manufacture so that it will fit into the chamber. It is obvious, however, that a certain clearance will always be present between the outside of the case and the chamber; also, there is a variation in the snugness of the fit of the case in the chamber and the relative roughness of the chambers in different guns. All of these factors affect the operation of the cartridge and extraction thereof.
  • FIG. 1 in which a conventional rim fire cartridge case is shown, a bolt 10 of a gun is shown closed against the head 11 of the case 12, the case 12 fitting within the chamber 13 of the barrel 14.
  • An extractor 15 of a conventional type engages the rim of the case 12 as it is pushed into the chamber 13.
  • a suitable striker or firing pin 16 is provided to strike the rim of the case 12 wherein the priming mixture is contained.
  • the material of the case have sufficient strength and a sufficiently high yield point so that upon the combustion of the propellant charge and under the high pressure developed thereby it will not be forced a substantial amount beyond this yield point, because this would cause the sides of the shell to permanently expand, producing a bulge, such as is shown in exaggerated form at 17. It is desirable, however, that at the time of firing the shell be resilient enough so that it will spring outwardly and seal the chamber to prevent the escape of gases rearwardly from the chamber of the barrel. In the event that the pressure is such as to exceed the yield point of the metal in the body of the shell and allow too great a permanent deformation to take place, it is obvious that the bulging portion of the shell will tightly engage the side of the chamber 13.
  • the yield point of the metal bears an important relationship to the extraction force necessary to withdraw the shell and also to the sealing of the powder gases and the prevention of the escape thereof through the mechanism of the gun and into the face of the operator. Such leakage of gas is also undesirable inasmuch as it detracts from the power propelling the projectile through the barrel of the gun.
  • M81 C1008 steel strip that is, carbon steel strip having a carbon content of about 0.08%, which has been copper coated, normalized and spheroidized is used, in accordance with this invention, for the manufacture of cartridge cases.
  • This material is sufficiently soft so that tool wear, although greater than experienced in the manufacture of brass cartridge cases, is minimized. It should be noted that while other low carbon steels may be used, C1008 steel is used in the preferred embodiment because of its low cost and commercial availability.
  • the steel strip is blanked and cupped in a manner well known to those skilled in the art.
  • the cups are then washed and dried, to remove any lubricant which may have been applied during blanking and cupping operations, and furnace annealed to eliminate work hardening and put the steel in its softest possible condition for the remaining operations.
  • Each cup is drawn, to extend its length and provide the proper wall thickness, and trimmed, to remove the rough edge formed at its mouth.
  • the drawn and trimmed cup is then headed whereupon it attains the final shape and dimensions of a rim fire cartridge case; the finished steel cartridge cases are degreased, washed and dried.
  • the C1008 steel cartridge cases are, therefore, placed in an oven and heated in a carbonaceous atmosphere at a temperature in the austenite region, preferably about l,650F., for about ninety minutes.
  • This carburization of the cartridge cases causes carbon diffusion to occur, increasing the carbon content of the steel from 0.08% to an amount preferably not substantially less than 0.47% nor substantially greater than 0.62%, or about 0.55%.
  • the carburizing temperature the steel is in its austenitic state.
  • the cartridge cases After the cartridge cases have been fully carburized, they are moved to a cooling chamber and cooled in an oxidationpreventive atmosphere at the most rapid rate possible without the formation of martensite.
  • the carburized cartridge cases are cooled in a nitrogen-hydrogen atmosphere to a temperature of about 200F. in one hour to form a ferrite and pearlite structure which has the maximum hardness and strength obtainable with that structure and carbon content.
  • cartridge cases are then brass plated to prevent oxidation and may then be primed and loaded by any desired method.
  • the hardness of the quenched and tempered martensitic structure causes another problem in that it produces excessive wear of gun parts, such as the firing pin and extractor, and reduces the sensitivity of the rim of the cartridge case so that misfires may occur due to the resulting inability of the firing pin to apply sufficient compressive force through the case to explode the primer.
  • gun parts such as the firing pin and extractor
  • the carburized steel cartridge cases are furnace cooled to have a ferrite and pearlite structure. Because of this slower cooling procedure, the distortion which occurs when austenite is quenched to produce a martensitic structure is prevented and the cartridge cases have the same dimensions after carburization as they did when they were formed.
  • Steel cartridge cases made in accordance with this invention have been found to produce only slightly more wear to firing pins and extractors than do brass cartridge cases and significantly less wear than do quenched and tempered steel cartridge cases.
  • the ferrite and pearlite steel cartridge cases have a hardness range of about -200 KHN which is substantially the same as the hardness range exhibited by brass cartridge cases. Because the steel cartridge cases are heat treated during the carburization process, after the completion of all cold working, the hardness tends to be more uniform over the length of these cases than the hardness of brass cartridge cases which are used in their cold worked state.
  • the average tensile strength of the ferrite and pearlite steel cartridge case of this invention is about 90,000 psi, substantially identical to the average tensile strength of a brass cartridge case. It has been found that the tensile strength exhibited by the steel cartridge cases was generally constant in value throughout the 0.47% to 0.62% range of carbon content.
  • a method of manufacturing a cartridge case from low carbon steel comprising the steps of forming the steel into the shape of a cartridge case, carburizing the cartridge case to increase the carbon content of the steel, and cooling the cartridge case in a gaseous medium to give the steel a ferrite and pearlite structure.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
  • Heat Treatment Of Articles (AREA)
US352559A 1973-04-19 1973-04-19 Method of making steel cartridge cases Expired - Lifetime US3873375A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US352559A US3873375A (en) 1973-04-19 1973-04-19 Method of making steel cartridge cases
CA196,590A CA1026656A (en) 1973-04-19 1974-04-02 Steel cartridge cases
BR3039/74A BR7403039D0 (pt) 1973-04-19 1974-04-17 Processo de fabricacao de um estojo de cartucho, e o estojo de cartucho

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US352559A US3873375A (en) 1973-04-19 1973-04-19 Method of making steel cartridge cases

Publications (1)

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US3873375A true US3873375A (en) 1975-03-25

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US352559A Expired - Lifetime US3873375A (en) 1973-04-19 1973-04-19 Method of making steel cartridge cases

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US (1) US3873375A (pt)
BR (1) BR7403039D0 (pt)
CA (1) CA1026656A (pt)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5048162A (en) * 1990-11-13 1991-09-17 Alliant Techsystems Inc. Manufacturing thin wall steel cartridge cases
US5067407A (en) * 1990-05-17 1991-11-26 Honeywell Inc. Cased telescoped ammunition round
US5106431A (en) * 1990-11-13 1992-04-21 Alliant Techsystems Inc. Process for creating high strength tubing with isotropic mechanical properties
US5130207A (en) * 1990-11-13 1992-07-14 Alliant Tech Systems Inc. Thin wall steel cartridge cases
WO2003038134A1 (en) * 2001-10-26 2003-05-08 Exxonmobil Research And Engineering Company Method for forming pearlite in an iron based article.
US7468107B2 (en) * 2002-05-01 2008-12-23 General Motors Corporation Carburizing method
US9939236B2 (en) 2015-07-27 2018-04-10 Shell Shock Technologies, Llc Method of making a casing and cartridge for firearm
US10697743B2 (en) 2016-07-27 2020-06-30 Shell Shock Technologies LLC Fire arm casing for resisting high deflagration pressure
WO2020214136A1 (en) * 2019-04-14 2020-10-22 Shell Shock Technologies LLC Firearm casing for resisting high deflagration pressure

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2207289A (en) * 1937-01-09 1940-07-09 Timken Roller Bearing Co Ferrous bearing member
US2299138A (en) * 1941-10-04 1942-10-20 Westinghouse Electric & Mfg Co Heat treating of steel
US2531731A (en) * 1946-11-29 1950-11-28 Carnegie Illinois Steel Corp Razor blade stock
US2881109A (en) * 1956-10-22 1959-04-07 Lasalle Steel Co Case-hardened, worked steels
US2997774A (en) * 1957-01-24 1961-08-29 Lyon George Albert Method of making steel shells
US3614816A (en) * 1968-07-12 1971-10-26 Oerlikon Buehrle Ag Method of making cartridge cases

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2207289A (en) * 1937-01-09 1940-07-09 Timken Roller Bearing Co Ferrous bearing member
US2299138A (en) * 1941-10-04 1942-10-20 Westinghouse Electric & Mfg Co Heat treating of steel
US2531731A (en) * 1946-11-29 1950-11-28 Carnegie Illinois Steel Corp Razor blade stock
US2881109A (en) * 1956-10-22 1959-04-07 Lasalle Steel Co Case-hardened, worked steels
US2997774A (en) * 1957-01-24 1961-08-29 Lyon George Albert Method of making steel shells
US3614816A (en) * 1968-07-12 1971-10-26 Oerlikon Buehrle Ag Method of making cartridge cases

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5067407A (en) * 1990-05-17 1991-11-26 Honeywell Inc. Cased telescoped ammunition round
US5048162A (en) * 1990-11-13 1991-09-17 Alliant Techsystems Inc. Manufacturing thin wall steel cartridge cases
US5106431A (en) * 1990-11-13 1992-04-21 Alliant Techsystems Inc. Process for creating high strength tubing with isotropic mechanical properties
US5130207A (en) * 1990-11-13 1992-07-14 Alliant Tech Systems Inc. Thin wall steel cartridge cases
WO2003038134A1 (en) * 2001-10-26 2003-05-08 Exxonmobil Research And Engineering Company Method for forming pearlite in an iron based article.
US6942739B2 (en) 2001-10-26 2005-09-13 Exxonmobil Research And Engineering Company Reactive heat treatment to form pearlite from an iron containing article
US7468107B2 (en) * 2002-05-01 2008-12-23 General Motors Corporation Carburizing method
US9939236B2 (en) 2015-07-27 2018-04-10 Shell Shock Technologies, Llc Method of making a casing and cartridge for firearm
US10260847B2 (en) 2015-07-27 2019-04-16 Shell Shock Technologies LLC Fire arm casing and cartridge
US10697743B2 (en) 2016-07-27 2020-06-30 Shell Shock Technologies LLC Fire arm casing for resisting high deflagration pressure
WO2020214136A1 (en) * 2019-04-14 2020-10-22 Shell Shock Technologies LLC Firearm casing for resisting high deflagration pressure

Also Published As

Publication number Publication date
CA1026656A (en) 1978-02-21
BR7403039D0 (pt) 1974-12-03

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