US2867554A - Process of making soft iron shot - Google Patents

Process of making soft iron shot Download PDF

Info

Publication number
US2867554A
US2867554A US349612A US34961253A US2867554A US 2867554 A US2867554 A US 2867554A US 349612 A US349612 A US 349612A US 34961253 A US34961253 A US 34961253A US 2867554 A US2867554 A US 2867554A
Authority
US
United States
Prior art keywords
shot
iron
treatment
hardness
furnace
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
US349612A
Other languages
English (en)
Inventor
Lewis P Wilson
Dorothy H Turner
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.)
Olin Corp
Original Assignee
Olin Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Olin Corp filed Critical Olin Corp
Priority to US349612A priority Critical patent/US2867554A/en
Priority to ES0211360A priority patent/ES211360A2/es
Priority to US751817A priority patent/US2974031A/en
Application granted granted Critical
Publication of US2867554A publication Critical patent/US2867554A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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
    • F42B12/74—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material characterised by the material of the core or solid body
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
    • F42B7/00—Shotgun ammunition
    • F42B7/02—Cartridges, i.e. cases with propellant charge and missile
    • F42B7/04—Cartridges, i.e. cases with propellant charge and missile of pellet type
    • F42B7/046—Pellets or shot therefor

Definitions

  • iron shot was suggested as a projectile as early as the beginning of the fifteenth century, and although, as early as the year 1880, the'Winth'erliches, aware of the economic advantage of using for-sporting ammunition a dropped shot of iron" instead of lead, obtained two United States patents, namely, No. 224,858 and No. 236,134, in which disclosure is made of a method of manufacture and the advantages of iron shot, these early developments have not been followed by widespread use of iron shot.
  • the potential advantages of iron shot have never been realized largely because iron shot, as produced heretofore, have been so hard as to damage the gun barrels. Even the hardened gun barrels of the present day erode seriously when used with iron shot of the character heretofore suggested.
  • -It is, therefore, the object of the present invention, generally stated, to produce iron shot suitable for use as the projectile in shot guns, and which will not abrade or otherwise damage the barrel of-the shot gun.
  • Another object of the invention is to provide such shot having physical properties ofa character such as to yield desirable ballistic results.
  • shot which is unabrasive to gun barrels and which has quite satisfactory ballistic characteristics, is cast from substantially pure iron by allowing the globules of the molten metal to fall in air where the globules assume a spherical shape before they fall into a tank of water, while still intensely hot, whereby they become solidified and then (without any mechanical working). heat-treated in a hydrogen atmosphere at a temperature in excess of the A transformation point, but below the A; transformation point, so that the resulting shot have a hardness of less than D. P. H., and whose hardness at their centers is not.sub stantially greater than their surface hardness.
  • substantially pure iron as the expression is used herein, is meant iron which is devoid of deliberate addition of hardening elements, such as chromium, molybdenum, tungsten, nickel, copper, vanadium, etc., and which is as free as practicable from other elements.
  • Such substantially pure iron will usually contain less than a quarter of a percent of impuri- Adaptation of the Tukon Tester and the Knoop Indenter, and as described in the February 1949, Issue of Modern Machine Shop in the article entitled Microhardness Testing of Small Tools by G. E.
  • hard lead for example, has a hardness value of about 35
  • zinc and copper have hardness values of from 50 to 60
  • gun barrels of mild steel have hardness values of from 100 to 130
  • chrome molybdenum gun barrels have a hardness of about 240.
  • the hardness values of the iron shot herein referred to were determined after conditioning the shot as follows:
  • the shot samples were mounted in a methyl methacrylate polymeride plastic, such as Lucite, and the mounting was ground down on an abrasive wheel until approximately one-half the diameter of the mounted shot was removed.
  • the mounting was then polished on abrasive paper having grits 0, 2-0, 3-0, and 4-0.
  • the specimen was then polished on a wheel covered with billiard cloth, while the wheel was kept wet with a liquid abrasive, such as an alumina. After all noticeable scratches were removed, the sample was etched with an acidic solution, such as 2% Nital" solution. repolished on a wheel covered with Selvyt cloth using the liquid abrasive. After this final polishing, the sample was etched once more and was then ready for hardness testing.
  • the micro structure of the finished shot should be coarsegrained and in a single phase.
  • the grain size of the finished shot should be no smaller than ASTM grain size No. 2 (ASTM standards, 1944, p. 1933).
  • the desired properties may be imparted to shot as cast from substantially pure iron by heat treatment in a non-oxidizing hydrogen atmosphere above the A point, and that desirable properties are developed in such shot without prolonged heat treatment.
  • the time period above the A point may be as short as 30 seconds, but in commercial scale operations five minutes provides a more adequate factor of safety to assure that the centers of the shot have reached the A point. It is essential, however, to avoid heating the shot as high as the A; transformation point, and therefore the temperature of heat treatment should not exceed about 2400 F. It is also important that the shot be cooled down to about 1300 F. before they are removed from the hydrogen atmosphere. Indeed, unless other precautions against oxidation and scaling are taken, it is preferable that the shot be cooled to room temperature or nearly so while enveloped in hydrogen.
  • the shot be cast from iron which is substantially pure, so that, when introduced into the heat treatment without previous mechanical working, the iron contains not more than 0.25% of impurities other than carbon and nitrogen.
  • the nitrogen content of the shot, as cast has an important bearing on duration and effect of the heat treatmentas with shot containing .019.020% nitrogen, as cast, the ultimate shot are somewhat harder and their grain structure smaller than shot containing .008.010% nitrogen as cast.
  • the heat treatment is carried out in a hydrogen atmosphere as dry (i. e., free of water or water vapor) as possible (in contradistinction to the known wet hydrogen annealing techniques wherein enough water is introduced to create an oxidizing atmosphere).
  • a hydrogen atmosphere as dry (i. e., free of water or water vapor) as possible (in contradistinction to the known wet hydrogen annealing techniques wherein enough water is introduced to create an oxidizing atmosphere).
  • Some water will inevitably find its way into the heat-treating atmosphere, either as an impurity in the hydrogen supply or as a reaction product from any oxide which may be present on the shot being treated, but so long as the content of water in the treating atmosphere does not exceed about 3%, the atmosphere is considered non-oxidizing and desired results are achieved.
  • the treatment of iron shot according to this invention involves first providing the as-cast shot (near spheres most of whose diameters are between 0.062 and 0.144 inch) having the following typical analysis:
  • the shot are then heated in a hydrogen atmosphere and maintained at a temperature above the A point, but below the A, point, for the time period above-indicated, which may be as short as 30 seconds or longer, depending upon the apparatus employed and otherenvironmental conditions consistent with the rule that the higher the temperature (below the A; point) and the lower the nitrogen content of the as-cast shot, the shorter the time period of treatment above the A point need be.
  • the shot are then quenched in a hydrogen bath and preferably maintained in such hydrogen bath until the temperature of the individual shot descends to 300 F. or less.
  • the treatment may be carried out either as a batch process or as a continuous process.
  • the as-cast shot have lower nitrogen content, being on the order of 0.008-0.010% as indicated, than would be the case when the shot are cast from a melt made in an electric furnace or open hearth.
  • the invention is, however, applicable to the treatment of shot having higher as cast nitrogen contents, such as those on the order of 0.019
  • Figure l is a diagrammatic view of the shaker-hearth type of furnace with quenching attachment to which reference has been made above;
  • Figure 2 is a diagrammatic view of a vertical type furnace suitable for use in accordance with the present invention.
  • Figure 3 is a photomicrograph at 100x magnificatio of the grain structure and individual, as cast, shot before treatment.
  • Figure 4 is a photomicrograph at l magnification of the grain structure of an individual shot after treatment.
  • the structure may consist of concentric tubular shells 1 and 2, between which an electric heating element 3 is disposed.
  • the heating element may be either an electrical resistance or an induction coil, but in either case, must be capable of elevating the temperature of shot pellets within tube 2 to a temperature above 1670 F., and preferably as high as 1850" F. or 2200 F.
  • the inner tube 2 is open at one end 4 and is provided with an opening 5 near its opposite end.
  • the tube 2 is preferably formed of refractory material, and the exterior tube 1 may likewise be formed of refractory material.
  • an oscillatable hearth 6 Extending into the tube 2 through the open end 4 thereof is an oscillatable hearth 6, the inner end of which is mounted upon a suitable cradle 7, and the outer end of which is connected to be driven by suitable shaker mechanism 8.
  • the shaker mechanism is of a character such as to move hearth 6 toward opening 5 of the furnace gradually, and then jerk it in the opposite direction, whereby shot deposited toward the outer end of the hearth 6 are moved step by step toward the inner end of the hearth.
  • a feed hopper 9 Above the outer end of the hearth, a feed hopper 9 is provided for depositing the shot to be treated upon the outer end of the hearth 6.
  • the exterior tube is provided with an opening 11 in radial alignment with opening 5 in the interior tube 2, and a sleeve 12 extends across the space between the openings 5 and 11, thus providing a conduit.
  • a conduit 13 extends downwardly and constitutes the inner wall of a cooling device 14, whose outer wall 15 is spaced from conduit 13 and provided with a coolant inlet 16 and a coolant outlet 17.
  • the conduit 13 projects beyond the cooling element 14 and is provided with a removable gas-tight closure 18. Between the closure 18 and the cooling element 14, the conduit 13 is provided with a hydrogen inlet 19.
  • Water, oil, cold air, or any other heat exchange medium may be utilized as the coolant and circulated through the chamber defined between the inner and outer walls 13 and 15 of cooling element 14.
  • the end thereof may be reduced and left open provided the vol-.
  • ume of hydrogen gas introduced at 19 is sufiicient to prevent the intake of air at the open end of conduit 13. An.
  • cooling element 14 of sufiicient volume to accommodate the product of a relatively long run of the furnace and then periodically discontinuing the feed of shot to the furnace while the treated shot within cooling element 14 are discharged therefrom by removal of cap 18.
  • the shot deposited upon hearth 6 attain a temperature of at least1670 F. before they fall from the inner end of the hearth. When the shot fall from the inner end of the hearth, they are re-;
  • Hydrogen is continand consists essentially of a vertically arranged induction furnace having an interior induction chamber 21 provided with a spiral ramp 22 to retard the descent of shot deposited in the top of the furnace.
  • the inclination of the ramp and the height of the furnace are coordinated with the heating capacity thereof so as to assure that individual shot pellets will be elevated to a temperature of at least 1670 F., and preferably 1850 to 2200 F., as they roll down the spiral ramp 22.
  • the shot are dropped into conduit 13 leading to a cooling element of the character hereinabove described.
  • hydrogen is continuously introduced so as to completely envelop the shot in the cooling element, as well as in conduit 13, and in the heating chamber 21, of the furnace.
  • a ceramic core 23 may be provided to fill the space between the inner edges of the spiral ramp.
  • the apparatus above described provides for the continuous treatment of such shot at any chosen temperature between the A and A points, and within a considerable range of treatment time periods.
  • the essential feature of the invention is the provision of iron shot which will not erode gun barrels, and while we have herein recited the value of D. P. H. as the maximum hardness-which should be tolerated immediately after the heat treatment, it is to be noted that shot, cast from substantially pure iron, age-harden at the rate of about 10% over the first five months, after their treatment according to this invention.
  • No. 9 shot the smallest size used in commercial shotshells
  • a hardness as high as 120 D. P. H. is quite suitable and has no serious deleterious effect upon the barrels of the firearms.
  • No. 4 shot which is the largest of the popular commercial sizes used in shotshells
  • the process comprising providing molten iron containing not more than about 0.25 percent impurities, casting the molten iron into near-spheres having a diameter between about 0.062 and about 0.144 inch, then heating the near-spheres in their as-cast condition above 1670 F. but substantially below the melting point thereof for about minutes, and maintaining a non-oxidizing atmosphere of dry hydrogen containing not more than about 3 percent water about said near-spheres while the same are being elevated to, maintained at, and cooled from said temperature to a temperature not in excess of 1300 F. 2.
  • the process of claim 1 wherein the near-spheres are maintained at said temperature until the carbon content thereof is reduced to 0.008 percent or below and the nitrogen is reduced to 0.010 percent or below.

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
US349612A 1953-04-20 1953-04-20 Process of making soft iron shot Expired - Lifetime US2867554A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US349612A US2867554A (en) 1953-04-20 1953-04-20 Process of making soft iron shot
ES0211360A ES211360A2 (es) 1953-04-20 1953-09-23 UN PROCEDIMIENTO PARA FABRICAR MUNICIoN
US751817A US2974031A (en) 1953-04-20 1958-07-17 Manufacture of iron shot

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US349612A US2867554A (en) 1953-04-20 1953-04-20 Process of making soft iron shot

Publications (1)

Publication Number Publication Date
US2867554A true US2867554A (en) 1959-01-06

Family

ID=23373207

Family Applications (1)

Application Number Title Priority Date Filing Date
US349612A Expired - Lifetime US2867554A (en) 1953-04-20 1953-04-20 Process of making soft iron shot

Country Status (2)

Country Link
US (1) US2867554A (es)
ES (1) ES211360A2 (es)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2974031A (en) * 1953-04-20 1961-03-07 Olin Mathieson Manufacture of iron shot
US3177070A (en) * 1961-04-25 1965-04-06 Metallurg D Esperance Longdoz Steel for drawing, and method of manufacturing this steel
US3201289A (en) * 1962-01-18 1965-08-17 Cleveland Metal Abrasive Co Method of heat treating metal shot
US3245840A (en) * 1960-06-22 1966-04-12 Metal Blast Inc Abrasive material and method of making same
US3259529A (en) * 1963-11-15 1966-07-05 Metal Blast Inc Abrasive material
US3325277A (en) * 1965-02-01 1967-06-13 Smith Corp A O Method of making metal powder
US3965962A (en) * 1968-05-25 1976-06-29 Toyo Kogyo Co., Ltd. Process for producing ductile iron casting
US4023985A (en) * 1975-09-29 1977-05-17 Cleveland Metal Abrasive, Inc. Steel abrasives and method for producing same
US5894644A (en) * 1998-06-05 1999-04-20 Olin Corporation Lead-free projectiles made by liquid metal infiltration
US20020184995A1 (en) * 2001-05-15 2002-12-12 Beal Harold F. In-situ formation of cap for ammunition projectile
US6749662B2 (en) 1999-01-29 2004-06-15 Olin Corporation Steel ballistic shot and production method
US20040211292A1 (en) * 1999-06-10 2004-10-28 Olin Corporation, A Company Of The State Of Illinois. Steel ballistic shot and production method
WO2007143800A1 (fr) * 2006-06-16 2007-12-21 Centre De Recherches Metallurgiques Asbl - Centrum Voor Research In De Metallurgie Vzw Projectile en acier adouci a coeur

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US236134A (en) * 1880-12-28 Drop-shot
US1760241A (en) * 1928-10-15 1930-05-27 Link Belt Co Metal
US1988910A (en) * 1926-10-21 1935-01-22 Int Nickel Co Chill cast iron alloy
US2201181A (en) * 1936-10-19 1940-05-21 Kalling Bo Michael Sture Method of decarbonizing carbonholding iron without melting
US2225968A (en) * 1939-06-12 1940-12-24 Gen Motors Corp Decarburized white iron casting
US2231120A (en) * 1938-01-18 1941-02-11 Herrmann Gerth Process for producing malleable iron castings
US2573935A (en) * 1948-09-10 1951-11-06 Olin Ind Inc Process for making shot

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US236134A (en) * 1880-12-28 Drop-shot
US1988910A (en) * 1926-10-21 1935-01-22 Int Nickel Co Chill cast iron alloy
US1760241A (en) * 1928-10-15 1930-05-27 Link Belt Co Metal
US2201181A (en) * 1936-10-19 1940-05-21 Kalling Bo Michael Sture Method of decarbonizing carbonholding iron without melting
US2231120A (en) * 1938-01-18 1941-02-11 Herrmann Gerth Process for producing malleable iron castings
US2225968A (en) * 1939-06-12 1940-12-24 Gen Motors Corp Decarburized white iron casting
US2573935A (en) * 1948-09-10 1951-11-06 Olin Ind Inc Process for making shot

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2974031A (en) * 1953-04-20 1961-03-07 Olin Mathieson Manufacture of iron shot
US3245840A (en) * 1960-06-22 1966-04-12 Metal Blast Inc Abrasive material and method of making same
US3177070A (en) * 1961-04-25 1965-04-06 Metallurg D Esperance Longdoz Steel for drawing, and method of manufacturing this steel
US3201289A (en) * 1962-01-18 1965-08-17 Cleveland Metal Abrasive Co Method of heat treating metal shot
US3259529A (en) * 1963-11-15 1966-07-05 Metal Blast Inc Abrasive material
US3325277A (en) * 1965-02-01 1967-06-13 Smith Corp A O Method of making metal powder
US3965962A (en) * 1968-05-25 1976-06-29 Toyo Kogyo Co., Ltd. Process for producing ductile iron casting
US4023985A (en) * 1975-09-29 1977-05-17 Cleveland Metal Abrasive, Inc. Steel abrasives and method for producing same
US5894644A (en) * 1998-06-05 1999-04-20 Olin Corporation Lead-free projectiles made by liquid metal infiltration
WO1999063297A2 (en) * 1998-06-05 1999-12-09 Olin Corporation Lead-free projectiles made by liquid metal infiltration
WO1999063297A3 (en) * 1998-06-05 2000-10-12 Olin Corp Lead-free projectiles made by liquid metal infiltration
US6749662B2 (en) 1999-01-29 2004-06-15 Olin Corporation Steel ballistic shot and production method
US20040211292A1 (en) * 1999-06-10 2004-10-28 Olin Corporation, A Company Of The State Of Illinois. Steel ballistic shot and production method
US20020184995A1 (en) * 2001-05-15 2002-12-12 Beal Harold F. In-situ formation of cap for ammunition projectile
US6840149B2 (en) * 2001-05-15 2005-01-11 Doris Nebel Beal Inter Vivos Patent Trust In-situ formation of cap for ammunition projectile
WO2007143800A1 (fr) * 2006-06-16 2007-12-21 Centre De Recherches Metallurgiques Asbl - Centrum Voor Research In De Metallurgie Vzw Projectile en acier adouci a coeur
BE1017170A3 (fr) * 2006-06-16 2008-03-04 Ct Rech Metallurgiques Asbl Projectile en acier adouci a coeur.
US20090301338A1 (en) * 2006-06-16 2009-12-10 Centre De Recherches Metallurgiques Asbl Centrum Voor Research In De Metallurgie Vzw Projectile Made Of Steel Softened To The Core
US8356555B2 (en) 2006-06-16 2013-01-22 Centre de Recherches Metallurgiques asbl—Centrum voor de Research in de Metallurgie vzw Projectile made of steel softened to the core

Also Published As

Publication number Publication date
ES211360A2 (es) 1953-11-16

Similar Documents

Publication Publication Date Title
US2867554A (en) Process of making soft iron shot
US5831188A (en) Composite shots and methods of making
US2828202A (en) Titanium tool steel
US6112669A (en) Projectiles made from tungsten and iron
SE446102B (sv) Notnings- och korrosionsherdigt stal och foremal av detta stal
US2974031A (en) Manufacture of iron shot
US4194906A (en) Wear resistant low alloy white cast iron
JPH05214484A (ja) 高強度ばね用鋼およびその製造方法
US2863790A (en) Method of making steel shot
JPS5554508A (en) Production of metal powder
US8356555B2 (en) Projectile made of steel softened to the core
US3005736A (en) High-toughness cast-iron for relatively thick castings, and method of producing same
KR100790097B1 (ko) 철,크롬,탄소 합금을 기재로 하는, 부식되지 않고모서리가 있는 쇼트 블라스팅연마제를 제조하기 위한 방법
US2796373A (en) Method of forming malleableized iron castings
RU2082530C1 (ru) Способ производства чугунных мелющих шаров
US2895816A (en) Steel grit and method for manufacturing same
EP0497074A1 (en) Industrial process to obtain powdered zinc
US3649370A (en) Process for improving the wear resistance of steel shot
JPH07109541A (ja) 超清浄度軸受用鋼の製造方法および超清浄度軸受用鋼
GB2051858A (en) Low alloy white cast iron
US1304224A (en) Louis fenn vogt
US3392013A (en) Cast iron composition and process for making
US2352408A (en) Method of producing ferrous castings having desired physical properties
US4411713A (en) Shell for a composite roll
JPS60190539A (ja) ブラスト用亜鉛合金の製造法