US3676907A - Naturally fragmenting projectiles of aisi 06 steel - Google Patents

Naturally fragmenting projectiles of aisi 06 steel Download PDF

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Publication number
US3676907A
US3676907A US530251A US3676907DA US3676907A US 3676907 A US3676907 A US 3676907A US 530251 A US530251 A US 530251A US 3676907D A US3676907D A US 3676907DA US 3676907 A US3676907 A US 3676907A
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United States
Prior art keywords
steel
approximately
shell casing
shell
article
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US530251A
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Sigfred F Magis
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US Department of Navy
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US Department of Navy
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
    • B21K21/00—Making hollow articles not covered by a single preceding sub-group
    • B21K21/06—Shaping thick-walled hollow articles, e.g. projectiles
    • 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
    • C21D9/16—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for explosive shells
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
    • F42B12/00—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material
    • F42B12/02—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material characterised by the warhead or the intended effect
    • F42B12/20—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material characterised by the warhead or the intended effect of high-explosive type
    • F42B12/22—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material characterised by the warhead or the intended effect of high-explosive type with fragmentation-hull construction
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
    • F42B12/00—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material
    • F42B12/72—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material characterised by the material
    • F42B12/76—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material characterised by the material of the casing

Definitions

  • the present invention relates to the production of fracturable projectiles and mortar shell casings and, more particularly, to the selection of the steel and the subsequent heat treatment of that steel to produce the desired fragmentation.
  • the object of the present invention is to provide a method of heat treating a selected steel to produce a desired fragmentation behavior.
  • Another object of the present invention is to provide a method of heat treating a selected steel to produce a fragmentation behavior which is desirable, without impairing the strength or ductility of the steel.
  • Still another object of the present invention is to provide a method of making projectile shell casings which have a desired fragmentation behavior and which are formed of a metal which can be forged to substantially a finished shape.
  • a further object of the present invention is to provide a method of heat treating AlSl 06 steel to produce a desired fragmentation behavior.
  • M51 06 steel is a steel containing substantially 95.8 percent iron; 1.45 percent carbon; [.0 percent manganese; 1.25 percent silicon; 0.25 percent chromium; and 0.25 percent molybdenum, by weight.)
  • a still further object of the present invention is to provide a method of heat treating AlSl 06 steel in such a manner as to produce a fragmentation behavior of from 4-ll grainsm without impairing its strength or ductility.
  • A151 06 steel used in this invention has not been previously used in naturally fracturable munitions.
  • This steel contains graphite nodules and stringers which serve as crack starters in initiating fragmentation under explosive load and enhance machinability which is important in projectile production.
  • the graphite is precipitated from the total carbon content in the steel during mill processing and remains undisturbed by the heat treatment employed in this invention.
  • the form of graphite coupled with a range of microstructures and mechanical properties developed by the heat treatment produces a 4-! l --m in the AIS] steel.
  • Composition B explosive is substantially a mixture of 60 percent RDX and 40 percent TNT.
  • the ratio of explosive weight to steel cylinder weight, C/M, is 0.27.
  • m is the average fragment mass measured in grains and is equal to the total weight in grains of fragments recovered divided by the total number of fragments recovered in a test.
  • AISI 06 steel is first forged into the desired projectile pattern, such as a mortar shell casing. After forging, the casing is rough machined to within close tolerances of the finished pro uct. It 15 then subjected to heat of l,750 F for a period of 2 hours, after which it is air cooled and tempered at 500 F for 1 hour. After cooling, the shell casing is machined to the finished product.
  • the A151 06 steel hardened and tempered to a martensitic structure with a range of mechanical properties will produce, under explosive force, a fragment size of 4-1 I grainsm. m decreases with increase in strength and hardness and with decrease in ductility and impact strength.
  • the fragment size of 4 grainsm has never been attained before using a forgeable metal for shell casings.
  • This fragment size (4 grainsm) which enhances the effectiveness of naturally fragmenting anti-personnel projectiles is produced from AlSl 06 steel.
  • the natural microstructure of AlSI 06 steel is enhanced by normalizing and tempering A181 06 steel to change this microstructure to produce this average fragment.
  • a method of producing a high capacity explosive shell casing of AlSl 06 steel having a mixed microstructure which upon explosion of the shell will produce fragments of 4ll grainsm comprising the steps of:

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Forging (AREA)

Abstract

A method of making a mortar shell of AISI 06 steel, and the product produced thereby, comprising forging the steel to a rough shape, rough machining the forged article, heat treating said article to approximately 1,750* F for approximately 2 hours, aircooling said article, tempering said article at approximately 500* F for approximately 1 hour and finish machining said article to completion.

Description

Unitefi States Patent Magis [451 July 18, 1972 [54] NATURALLY FRAGMENTING 2,368,418 1/1945 McCarroll et a] ..14s/134 PROJECTILES 0F A181 06 STEEL 2,438,267 3/1948 Bonte ..75/l28.l [72] Inventor: Sigfred F. Magis, Dahlgren, Va. OTHER PUBLICATIONS Assigneel The United, States of America as Roberts et al., "r661 Steels," Third Edition, American represented y the Secretary of the y Society for Metals, Ohio, 1952, T8320 G47, 1962, 02 pp. 22 Filed: Feb. 18, 1966 [21] Appl. No.: 530,251 Primary Examiner-Verlin R. Pendegrass Attorney-E. J. Brower and A. L. Branning [52] US. Cl ..29/l.21 102/56 s 1 161. ct ..B2l k 21/06 7 ABSTRACT [58] Field of Search 148/2, 12, 134; 75/123; A method of making a mortar Shell of 1 1 ()6 Steel, and the 29/121; 102/56 product produced thereby, comprising forging the steel to a rough shape, rough machining the forged article, heat treating [56] References cued said article to approximately 1,750" F for approximately 2 UNITED STATES PATENTS hours, air-cooling said article, tempering said article at approximately 500 F for approximately 1 hour and finish 1,0 l 9 l 2 Potter machining aid article to completion 2,087,764 7/1937 Bonte..... .l48/l34 X Bonte ..75/1 23 1 Claim, N0 Drawings NATURALLY FRAGMENTING PROJECTILES OF A181 06 STEEL The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.
The present invention relates to the production of fracturable projectiles and mortar shell casings and, more particularly, to the selection of the steel and the subsequent heat treatment of that steel to produce the desired fragmentation.
Steel previously used in the making of fracturable projectiles and mortar shell casings has shown a poor fragmentation pattern, and, therefore, the majority of fracturable projectiles and mortar shell casings are made from cast iron. Pearlitic Malleable Cast Iron (PMCl) used in the making of mortar shell casings produces the desirable fragmentation behavior, but has strength and ductility limitations and is not forgeable which makes it inadequate for gun projectiles. Also, PMCI must be cast in halves which are afterward joined together by brazing. This joining often causes premature failure of the projectile during gun firing. Ductile Cast Iron (Modular Cast Iron) is also used and produces a fragmentation efficiency equal to that obtained with Pearlitic Malleable Cast Iron. However, neither of these cast irons can produce a fragment size of 4ll grainsm without impairing both their strength and ductility. Also, the economic production of one-piece forged projectiles of cast iron is yet to be developed.
The object of the present invention is to provide a method of heat treating a selected steel to produce a desired fragmentation behavior.
Another object of the present invention is to provide a method of heat treating a selected steel to produce a fragmentation behavior which is desirable, without impairing the strength or ductility of the steel.
Still another object of the present invention is to provide a method of making projectile shell casings which have a desired fragmentation behavior and which are formed of a metal which can be forged to substantially a finished shape.
A further object of the present invention is to provide a method of heat treating AlSl 06 steel to produce a desired fragmentation behavior. (M51 06 steel is a steel containing substantially 95.8 percent iron; 1.45 percent carbon; [.0 percent manganese; 1.25 percent silicon; 0.25 percent chromium; and 0.25 percent molybdenum, by weight.)
A still further object of the present invention is to provide a method of heat treating AlSl 06 steel in such a manner as to produce a fragmentation behavior of from 4-ll grainsm without impairing its strength or ductility.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention.
A151 06 steel used in this invention has not been previously used in naturally fracturable munitions. This steel contains graphite nodules and stringers which serve as crack starters in initiating fragmentation under explosive load and enhance machinability which is important in projectile production. The graphite is precipitated from the total carbon content in the steel during mill processing and remains undisturbed by the heat treatment employed in this invention. The form of graphite coupled with a range of microstructures and mechanical properties developed by the heat treatment produces a 4-! l --m in the AIS] steel. (The fragment size, -m, used throughout this application is determined from fragmentation tests in which the fragments are collected after exploding a cylinder 5.0 inches O.D. X 7.0 inches long X 0.625 inch wall thickness with Composition B. Composition B explosive is substantially a mixture of 60 percent RDX and 40 percent TNT. The ratio of explosive weight to steel cylinder weight, C/M, is 0.27. m is the average fragment mass measured in grains and is equal to the total weight in grains of fragments recovered divided by the total number of fragments recovered in a test.
AISI 06 steel is first forged into the desired projectile pattern, such as a mortar shell casing. After forging, the casing is rough machined to within close tolerances of the finished pro uct. It 15 then subjected to heat of l,750 F for a period of 2 hours, after which it is air cooled and tempered at 500 F for 1 hour. After cooling, the shell casing is machined to the finished product.
The A151 06 steel hardened and tempered to a martensitic structure with a range of mechanical properties will produce, under explosive force, a fragment size of 4-1 I grainsm. m decreases with increase in strength and hardness and with decrease in ductility and impact strength.
The fragment size of 4 grainsm has never been attained before using a forgeable metal for shell casings. This fragment size (4 grainsm) which enhances the effectiveness of naturally fragmenting anti-personnel projectiles is produced from AlSl 06 steel. The natural microstructure of AlSI 06 steel is enhanced by normalizing and tempering A181 06 steel to change this microstructure to produce this average fragment.
Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.
What is claimed is:
l. A method of producing a high capacity explosive shell casing of AlSl 06 steel having a mixed microstructure which upon explosion of the shell will produce fragments of 4ll grainsm comprising the steps of:
forging said shell easing into a desired rough shape;
rough machining said shell casing to within close tolerances of its desired finished shape;
normalizing said shell casing by heating at approximately 1,750 F for a period of about 2 hours;
air cooling said shell casing;
tempering said shell casing by heating at approximately 500 F for a period of about 1 hour;
whereby said mixed microstructure is produced;
and then finish machining said shell casing.

Claims (1)

1. A method of producing a high capacity explosive shell casing of AISI 06 steel having a mixed microstructure which upon explosion of the shell will produce fragments of 4-11 grains-m comprising the steps of: forging said shell casing into a desired rough shape; rough machining said shell casing to within close tolerances of its desired finished shape; normalizing said shell casing by heating at approximately 1,750* F for a period of about 2 hours; air cooling said shell casing; tempering said shell casing by heating at approximately 500* F for a period of about 1 hour; whereby said mixed microstructure is produced; and then finish machining said shell casing.
US530251A 1966-02-18 1966-02-18 Naturally fragmenting projectiles of aisi 06 steel Expired - Lifetime US3676907A (en)

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3791881A (en) * 1972-03-02 1974-02-12 Us Navy Annealing treatment for controlling warhead fragmentation size distribution
US3994752A (en) * 1972-03-02 1976-11-30 The United States Of America As Represented By The Secretary Of The Navy Annealing treatment for controlling warhead fragmentation size distribution
US4035202A (en) * 1972-03-02 1977-07-12 The United States Of America As Represented By The Secretary Of The Navy Annealing treatment for controlling warhead fragmentation size distribution
US4246844A (en) * 1978-12-14 1981-01-27 United States Of America Method of forming high fragmentation mortar shells
US5305505A (en) * 1990-03-12 1994-04-26 National Forge Company Process of making a multi-section bomb casing
US5542354A (en) * 1995-07-20 1996-08-06 Olin Corporation Segmenting warhead projectile
CN106514160A (en) * 2017-01-04 2017-03-22 成都四威高科技产业园有限公司 High-precision microwave assembly bottom face machining process
CN110919297A (en) * 2019-10-31 2020-03-27 成都四威高科技产业园有限公司 Processing technology of aerospace high-precision microwave box body

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1018366A (en) * 1911-12-18 1912-02-20 Alloy Steel Forging Company Production of machined shapes of manganese steel.
US2087764A (en) * 1933-02-24 1937-07-20 Timken Roller Bearing Co Ferrous alloys and method of manufacture
US2362046A (en) * 1943-10-30 1944-11-07 Timken Roller Bearing Co Graphitic steels
US2368418A (en) * 1942-11-06 1945-01-30 Ford Motor Co Heat treatment for steel alloys
US2438267A (en) * 1942-03-23 1948-03-23 Timken Roller Bearing Co Graphitic steel

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1018366A (en) * 1911-12-18 1912-02-20 Alloy Steel Forging Company Production of machined shapes of manganese steel.
US2087764A (en) * 1933-02-24 1937-07-20 Timken Roller Bearing Co Ferrous alloys and method of manufacture
US2438267A (en) * 1942-03-23 1948-03-23 Timken Roller Bearing Co Graphitic steel
US2368418A (en) * 1942-11-06 1945-01-30 Ford Motor Co Heat treatment for steel alloys
US2362046A (en) * 1943-10-30 1944-11-07 Timken Roller Bearing Co Graphitic steels

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Roberts et al., Tool Steels, Third Edition, American Society for Metals, Ohio, 1952, TS320 G47, 1962, C.2 pp. 449 460. *

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3791881A (en) * 1972-03-02 1974-02-12 Us Navy Annealing treatment for controlling warhead fragmentation size distribution
US3994752A (en) * 1972-03-02 1976-11-30 The United States Of America As Represented By The Secretary Of The Navy Annealing treatment for controlling warhead fragmentation size distribution
US4035202A (en) * 1972-03-02 1977-07-12 The United States Of America As Represented By The Secretary Of The Navy Annealing treatment for controlling warhead fragmentation size distribution
US4246844A (en) * 1978-12-14 1981-01-27 United States Of America Method of forming high fragmentation mortar shells
US5305505A (en) * 1990-03-12 1994-04-26 National Forge Company Process of making a multi-section bomb casing
US5542354A (en) * 1995-07-20 1996-08-06 Olin Corporation Segmenting warhead projectile
CN106514160A (en) * 2017-01-04 2017-03-22 成都四威高科技产业园有限公司 High-precision microwave assembly bottom face machining process
CN110919297A (en) * 2019-10-31 2020-03-27 成都四威高科技产业园有限公司 Processing technology of aerospace high-precision microwave box body

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