US2491238A - Heat-treating iron steel body - Google Patents
Heat-treating iron steel body Download PDFInfo
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- US2491238A US2491238A US700166A US70016646A US2491238A US 2491238 A US2491238 A US 2491238A US 700166 A US700166 A US 700166A US 70016646 A US70016646 A US 70016646A US 2491238 A US2491238 A US 2491238A
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- US
- United States
- Prior art keywords
- iron
- steel
- shell
- band
- heat
- Prior art date
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title description 106
- 229910000831 Steel Inorganic materials 0.000 title description 60
- 239000010959 steel Substances 0.000 title description 60
- 229910052742 iron Inorganic materials 0.000 title description 35
- 238000005245 sintering Methods 0.000 description 20
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 16
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 15
- 238000000034 method Methods 0.000 description 15
- 238000010438 heat treatment Methods 0.000 description 13
- 238000005482 strain hardening Methods 0.000 description 13
- 238000004519 manufacturing process Methods 0.000 description 9
- 229910052799 carbon Inorganic materials 0.000 description 8
- 229910052751 metal Inorganic materials 0.000 description 8
- 239000002184 metal Substances 0.000 description 8
- 238000003825 pressing Methods 0.000 description 8
- 239000007789 gas Substances 0.000 description 7
- 229910002804 graphite Inorganic materials 0.000 description 7
- 239000010439 graphite Substances 0.000 description 7
- 239000000843 powder Substances 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 239000004484 Briquette Substances 0.000 description 6
- 239000001257 hydrogen Substances 0.000 description 6
- 229910052739 hydrogen Inorganic materials 0.000 description 6
- 238000001953 recrystallisation Methods 0.000 description 6
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 5
- 238000001816 cooling Methods 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 238000004663 powder metallurgy Methods 0.000 description 5
- 238000005496 tempering Methods 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 239000003921 oil Substances 0.000 description 3
- 230000000087 stabilizing effect Effects 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- 238000011065 in-situ storage Methods 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
- 238000011282 treatment Methods 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910000881 Cu alloy Inorganic materials 0.000 description 1
- VVNCNSJFMMFHPL-VKHMYHEASA-N D-penicillamine Chemical compound CC(C)(S)[C@@H](N)C(O)=O VVNCNSJFMMFHPL-VKHMYHEASA-N 0.000 description 1
- 229910000640 Fe alloy Inorganic materials 0.000 description 1
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 239000005864 Sulphur Substances 0.000 description 1
- 241000193803 Therea Species 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 238000005219 brazing Methods 0.000 description 1
- 239000012267 brine Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 229940075911 depen Drugs 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 230000000266 injurious effect Effects 0.000 description 1
- 235000000396 iron Nutrition 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229910052756 noble gas Inorganic materials 0.000 description 1
- 150000002835 noble gases Chemical class 0.000 description 1
- 229940037201 oris Drugs 0.000 description 1
- 229910001562 pearlite Inorganic materials 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 239000001294 propane Substances 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000003303 reheating Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Classifications
-
- 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
- B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
- B22F7/06—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools
- B22F7/062—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools involving the connection or repairing of preformed parts
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/49826—Assembling or joining
- Y10T29/49908—Joining by deforming
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/12—All metal or with adjacent metals
- Y10T428/12014—All metal or with adjacent metals having metal particles
- Y10T428/12028—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, etc.]
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/12—All metal or with adjacent metals
- Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
- Y10T428/12771—Transition metal-base component
- Y10T428/12861—Group VIII or IB metal-base component
- Y10T428/12951—Fe-base component
- Y10T428/12958—Next to Fe-base component
Definitions
- This invention relates 1170 (the fabrication .of articles made .of iron .or iron-alloyslbyl pressing rand. sintering startingtmaterial -which optionally has the final ,composition of the fabricated article.
- An object of this-invention is to produce .a
- object ⁇ is to heat-treat objects .of such duplex structure so that the steel .component is hardened, while simultaneously the carbon! free iron component .is-softened oris unchanged in hardness.
- briquette .prza mixtureof irons andoarbonis thus esintered;the.atmosphere maybea dry andoxy en :rfree unixturez of .1hydrogensandz methane .or Luther istabilizing igas, intermixed. in. suitable proportion ito prevent i.-.the .sintering atmosphere from wearurizing .or .decarburizing thesbriguette vduring :ithefsintering.
- Thesinteredbodyz should becooled in the sintering atmosphere, until the .sintered body willnotioxi'dize when-it 11810031286. in therair :or ';in ;o.ther oxidizing *atmosphere. .
- the :sintered band is kept free fromoxidation.
- the upperilin'iit of thesinteringtemperature nnay be. ashigh as 24'00 F.; in sinteringeither iron or steel exceptthat' in sintering steel the sinterling JtemperatureJshould preferably "be kept at least I00 F. below the meltingpoint ofthestel, 3.5 which is being sintered.
- the melting point of the ips'te'el depen'dsiupon its*carbon"-content.
- banded shell may now be cooled at a carefully selected rate as hereinafter disclosed which will restore the steel to its original state of hardness, while the iron band will be found to have been softened to approximately it: pre-swaging hardness.
- the bandeL shell may be quenched in water, brine, oil, or any,
- Such cooling will produce in the steel a high hardness, e. g. Rockwell C 40-60, but the iron band will not be hardened but rather will be restored to its preswaging hardness.
- the hardness of the steel shell may then be lowered to its original value by tempering.
- the band can be annealed after it has been cold-swaged into the groove of the shell.
- banded shell-body can be quenched from above its critical temperature, in water or oil which is ;at'a temperature of 20 C.-25 C. This critical temperature is about 1400" F., in an ordinary shell-body.
- the hardness of the banded steel shell-body is regulated by tempering or drawing in the well- ;known manner, by reheating the banded shellbody to a temperature below its critical range, so that the strength and hardness of the steel shell-body are brought to the proper value.
- tempering does not affect the hardness of the .pure iron shell-band.
- the usual precautions are preferably taken to prevent oxidation of the iron band.
- the shell-body and its attached band are simultaneously and equally heat-treat- .ed.
- the hardness of the final annealed band is about -85 on the Rockwell F scale.
- the hardness of such steel .stock is between 9737-10437 on the Rockwell B scale.
- the ultimate tensile strength of such steel stock is 99,700 lbs. per square to 128,800 lbs.
- the iron powder may be cold- In the finished shell-body with its completed band, the Rockwell B hardness of the steel stock is 96-104, after final heat treatment in the case in which the band and shell-body are heat treated after the band. has been swaged on the shellbody.
- composition of a typical steel shell-body may be 0.30%-0.40% carbon, 1.15%-1.55% manganese, not more than 0.045% phosphorus, 0.075%-0.l50% sulphur, and 0.15%-0.30% silicon, the remainder being iron.
- the loose iron powder is located in the groove of the shell-body, and the first cold-pressing is performed on said loose iron powder while it is so located, so that the first cold-pressed body is formed in situ in the groove.
- This cold-pressing can be done by using a die in which the shell-body is located.
- the pressure which is used in cold-pressing said loose and free-flowing iron powder in situ may be tons per square inch.
- the banded steel shell-body is then heated, as for example at 1600 F.-1800 F. during a heating period of two hours. The higher temperature of 1800 F. is preferred. Since this heattreatment softens thesteel body, its strength and hardness are adjusted by quenching and drawing, as in the first alternative method.
- a duplex article which consists partly of relatively pure iron and partly of steel in which the steel component is made by powder metallurgy methods.
- the powder metallurgy steel component can be hardened by heat treatment while the iron component is simultaneously softened or left unchanged in hardness.
- Such a heat treatment may consist of a heating at a temperature which is usually within the range 1400" F.2000 F. followed by quenching in water or oil and subsequent tempering, or the cooling may be more slowly at a predetermined rate suflicient to result in the desired hardness of the steel component without subsequent tempering.
- the heating it is preferable to surround the duplex body by protective atmosphere in order to prevent oxidation. If the heat treatment is relatively long (e. g. 15 minutes or over), it is preferable to use an inert atmosphere such as dry nitrogen or one of the noble gases.
- the methane can be replaced by propane or other stabilizing gas.
- the proportion of graphite is the desired final proportion of combined carbon in the final steelbody
- the proportion of methane in the sintering atmosphere depends upon the sintering temperature and the final proe portion of combined carbon which it is desired to have in the final steel product.
- the methane acts as a stabilizing gas, so that the graphite combines with the iron, and not with the hydrogen.
- the proportion of methane is selected so that the briquette neither loses nor gains carbon during the sintering, and the proportion of combined carbon in the final steel material is determined by the proportion of graphite in the briquette.
- the briquette After the first sintering when the iron has combined with the graphite the briquette is again cold pressed at a higher pressure to obtain the desired density and then resintered.
- This higher pressure is preferably at least approximately 60 tons per square inch.
- Steel compacts made as described above may be combined with iron bodies made from wrought material or by powder metallurgy methods by any of several methods for example the two may be joined by copper brazing, swaging, by riveting etc. Alternatively they may be joined during the powder metallurgy operations of pressing and sintering.
- a method of making a duplex metal body of ferrous metal parts of different hardenability and wherein the separate or assembled parts in their ultimate shape cannot be assembled or disassembled comprising the steps of preforming one part to its ultimate dimensions, preforming the other part to such dimensions as will permit its assembly with the one part, assembling the parts, deforming the said other part into intimate mechanical engagement with said one part, said deformation of said other part being accompanied by severe internal work hardening, and then withdrawing the work hardening from said deformed other part by heat treating the duplex body at'atemperature which-is above the recrys tallization temperature of the deformed part.
- a method of making a duplex metal body of iron and steel parts wherein the steel part is relatively harder than the iron-part and wherein the separate or assembled-parts in their ultimate shape cannot be assembled or disassembled comprising the steps ofpreforming the steel part to its ultimate dimensions, preforming the soft iron part to such dimensions as will permit its assembly with the steel part, assembling the parts, deforming the iron part into intimate mechanical engagement with the steelpart, said deformation of the iron part being accompanied by severe internal work hardening, and then withdrawing the work hardening from the deformed iron part by heat treating the duplex body at a temperature which is above the recrystallization temperature of the deformed iron part.
- the method of making a duplex metal body of interengageable preformed iron and steel parts of different hardenability comprising the steps of preforming the steel part to its ultimate shape, preforming the iron part to such dimensions as will permit assembling it with the steel part, assembling the parts, deforming the iron part into intimate mechanical engagement with the steel part, said deformation of the iron part being accompanied by severe internal work hardening, then Withdrawing the work hardening from the iron part by heat treating the duplex body at a temperature which is above the recrystallization temperature of the deformed.
- the steel part is: relatively harder than the iron part and wherein. the separate or assembled parts in their ultimate shape cannot be assembled or disassembled, comprising the steps of preforming the steel part to its ultimate dimensions, preforming the soft powder iron part to such dimensions as will permit its assembly with the steel part, assembling the parts, deforming the soft iron part into intimate mechanical engagement with the steel part, said deformation of the iron part being accompanied by severe internal work hardening, and then withdrawing the work hardening from the deformed iron part by heat treating the duplex body at a temperature which is above the recrystallization temperature of the deformed iron part without changing the hardness of the steel part.
- a method of making a duplex metal body of iron and steel parts wherein the steel part is relatively harder than the iron part and wherein the separate or assembled parts in their ultimate shape cannot be assembled or disassembled comprisin the steps of preforming the steel part to its ultimate dimensions, preforming the soft powder iron part to such dimensions as will permit its assembly with the steel part, assembling the parts, deforming the soft iron part into intimate mechanical engagement with the steel part, said deformation of the iron part being accompanied by severe internal work hardening, and then withdrawing the work hardening from the deformed iron part by heat treating the du- 7 piex body at a temperature which is above the recrystallization temperature of the deformed iron part and concomitantly increasing the hardness of the steel part.
- a method of making a duplex metal body of iron and steel parts wherein the steel part is relatively harder than the iron part and wherein the separate or assembled parts in their ultimate shape cannot be assembled or disassembled comprising the steps of preforming the steel part to its ultimate dimensions, preforming the soft powder iron part to such dimensions as will permit its assembly with the steel part, assembling the parts, deforming the soft iron part into intimate mechanical engagement with the steel part, said deformation of the iron part being accompanied by severe internal work hardening, and then withdrawing the work hardening from the deformed iron part by heat treating the du- REFERENCES CITED
- the following references are of record in the file of this patent: 1
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Composite Materials (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Powder Metallurgy (AREA)
Description
Patented Dec. 13, 1949 FATENT OFFICE tWIsthniian Metals,
Inc., lloston; Mass, :ascorponationlof Massachusetts N0 Drawing. Origina pplica't-ion August '16,
1944, Serial-No; 549,807; Divided and this applica'tion September 6 Claims.
'21 This invention relates 1170 (the fabrication .of articles made .of iron .or iron-alloyslbyl pressing rand. sintering startingtmaterial -which optionally has the final ,composition of the fabricated article.
.This-startingmaterial isu in loose powder .form.
An object of this-invention is to produce .a
smetal object of duplex structure such that one :componentlconsists :of substantially carbon-free :iron and another component .consists of steel,
lone orl .bothtof these. components beingproduced thy. powder. metallurgy -methods. A further. object {is to heat-treat objects .of such duplex structure so that the steel .component is hardened, while simultaneously the carbon! free iron component .is-softened oris unchanged in hardness.
-;-Another objectislto fabricate Lby, powder metal- .lurgyemethods a substantially.carbonfree iron :rotatingbandtfor steels artillery jshells, the rotating band being attached to the shell eitherduring fabrication of 'the band, or therea'fter, and heat- .treating the bandedv shell simultaneously to soften .the. iron'band, and leave the. shell ina .hardened condition. 7
Many usefulrmetal lartieles'may consist of'ia duplex iron-steel structure. For .example,""artillery shells normally consist of a hardsteershelb ho'dy and a softrotating band which, uponenter- 'ing the gun barrel'becomes sufliciently deformed lto engage tightly the"rifling"of"thebarrel. "The making of such rotating'orshellbands fromiron powder is one "of the Limportantuses *for the method herein described.
In'order tomake androrrsh'ell-band, the" start- "ing material maybe a"loose"'and freelya-fiowi-ng iron powder.
'iThis charge'of'loose ironpowder subjected to cold-pressingat a*relatively =light3-pressuremf -I5 :40"tons per"square inch.
This first "cold=pressed, body-isjsintered, -without using pressure "during "the F sintering, :at =l600" R-2000 F., during a" sintei'ingperiodof twenty minutesto' one*hour,-and= even up' tothree hours. As'atspecific examplethesmtering temperature may be 1660 R, and 'thesintering period: may be "thirty minutes. another specific -example; :the 'sintering' temperature may be' 1 800" F. and the sinteringyperiod maybe two 'hours.
This'sintering-is done in-an inert-*ornon-oxidiziingatmosphere. Forexample, "dry oxygen iree *hydrogen or dry" craeked -oxygen free ammonia gas provide a satisfactory. sintering atmosphere .for,sinte'ringan ironflcompact. "Whenrammonia .;gas is .crackd, nitrogen :aridjhydrogen aretproslduced. Dry and .oxygengfree nitrogen arid/or argon can also be used. ,Ifla.coldrpressedrsteel 28, 1946, Serial No. 700,166
briquette .prza mixtureof irons andoarbonis thus esintered;the.atmosphere maybea dry andoxy en :rfree unixturez of .1hydrogensandz methane .or Luther istabilizing igas, intermixed. in. suitable proportion ito prevent i.-.the .sintering atmosphere from wearurizing .or .decarburizing thesbriguette vduring :ithefsintering. Thesinteredbodyzshould becooled in the sintering atmosphere, until the .sintered body willnotioxi'dize when-it 11810031286. in therair :or ';in ;o.ther oxidizing *atmosphere. .Hence, the :sintered band is kept free fromoxidation.
.;After the first sintering the compact istagain cold .pressed at-,ahigher pressure to obtain the desired .density. .This ;higher pressure is prefer- ,l5 eablg atl-least-eapproximately .60 tons per square inc Normally; a .second .sinteringloperation' is .use- 5315111 afterqthersecond .coldqpress'ing ;in..order to sel-iminate or; .r,educe the workehardening which .20 -results -,from the second .cold pressing .and..,in
-..order to improve. the -;physical properties of the body. .Thesecondsi'nter'ing isperformed under thersamegeneral. conditions as theifirst sintering.
The temperature. oflthe second 'sintering canbe i155 @1.5Q0.F. 2000'i.F.,the sintering, period can'be -.twenty. minuteswto one hour or more; and the sintered band is.. preferab1y allowed to cool slowly in the sintering atmosphere to 400. F.-=500 'F.," as .previously stated.
The upperilin'iit of thesinteringtemperature nnay be. ashigh as 24'00 F.; in sinteringeither iron or steel exceptthat' in sintering steel the sinterling JtemperatureJshould preferably "be kept at least I00 F. below the meltingpoint ofthestel, 3.5 which is being sintered. The melting point of the ips'te'el depen'dsiupon its*carbon"-content.
Shell-iban'dsmadei rom said iron powder,-'ae- ,cjordingito the multiple-step --method previously fdescribedican be cold-'swaged into the-groove'of .4011the shell or other iprojectile, using the same method andapparatus which-"are'now used for col'd-swaging copper alloy'bands intosaid groove. .Ihis co'ld-swaging causes -considerable work- "hardening-of' the iron band, and it maybe desir- 145 ,able" tosoften iii-"by suitable =heat=treatment For example prior to thecold-swaging the iron -band may "have *a' hardness in e the -range Rockwell Y F $5 75, and after cold swaging a hardness 01 -Rockwell "F*82-96. Atypical steel-shell body has v.50 ,ahardnessof Rockwell' B 98-105. such-ashelltbody containing "a cold=swaged ironband ca-n' be iiheattreated by' heating it above the critical tem- .perature of the steel .(abouti1400 F.) .which' is .alsdabove'theirecrystallizingtemperature or the cold-worked iron" band. Thisheating serves ,si
3 multaneously to austenitize the steel and allow recrystallization and grain growth to take place in the iron. The banded shell may now be cooled at a carefully selected rate as hereinafter disclosed which will restore the steel to its original state of hardness, while the iron band will be found to have been softened to approximately it: pre-swaging hardness. Alternatively, the bandeL shell may be quenched in water, brine, oil, or any,
other suitable medium. Such cooling will produce in the steel a high hardness, e. g. Rockwell C 40-60, but the iron band will not be hardened but rather will be restored to its preswaging hardness. The hardness of the steel shell may then be lowered to its original value by tempering.
First alternative method As an alternative method of making a shellband, the band can be annealed after it has been cold-swaged into the groove of the shell.
pressed in the mamier previously mentioned, at a pressure of -60 tons per square inch to give bodies of substantially uniform densities of from 5.5 to 7.3. After sintering at 1800 F. under the conditions previously stated, such bodies may have a hardness of from 10 to 80 on the Rockwell is preferred. The steel shell-body and its iron shell-band are then rapidly cooled from the annealing temperature, by a blast of non-oxidizing gas, to C.- C. This cooling period may be 5-20 minutes. This rapid cooling converts the steel material of the shell-body from austenite, largely to pearlite, without substantially affecting the pure iron or ferrite of the iron band. This treatment removes or reduces the workhardening of the iron band which has resulted from the cold-swaging. 1
Instead of using gas for said cooling, the
banded shell-body can be quenched from above its critical temperature, in water or oil which is ;at'a temperature of 20 C.-25 C. This critical temperature is about 1400" F., in an ordinary shell-body.
If the banded steel shell-body is thus quenched,
.the hardness of the banded steel shell-body is regulated by tempering or drawing in the well- ;known manner, by reheating the banded shellbody to a temperature below its critical range, so that the strength and hardness of the steel shell-body are brought to the proper value. Such tempering does not affect the hardness of the .pure iron shell-band. In heat-treating the banded steel-body, the usual precautions are preferably taken to prevent oxidation of the iron band.
-In this method, the shell-body and its attached band are simultaneously and equally heat-treat- .ed. The hardness of the final annealed band is about -85 on the Rockwell F scale.
In a typical steel stock which is used for making a shell-body, the hardness of such steel .stock is between 9737-10437 on the Rockwell B scale. The ultimate tensile strength of such steel stock is 99,700 lbs. per square to 128,800 lbs.
per square inch.
In this alternative method, the iron powder may be cold- In the finished shell-body with its completed band, the Rockwell B hardness of the steel stock is 96-104, after final heat treatment in the case in which the band and shell-body are heat treated after the band. has been swaged on the shellbody.
The composition of a typical steel shell-body may be 0.30%-0.40% carbon, 1.15%-1.55% manganese, not more than 0.045% phosphorus, 0.075%-0.l50% sulphur, and 0.15%-0.30% silicon, the remainder being iron.
Second alternative method The loose iron powder is located in the groove of the shell-body, and the first cold-pressing is performed on said loose iron powder while it is so located, so that the first cold-pressed body is formed in situ in the groove. This cold-pressing can be done by using a die in which the shell-body is located. The pressure which is used in cold-pressing said loose and free-flowing iron powder in situ, may be tons per square inch. The banded steel shell-body is then heated, as for example at 1600 F.-1800 F. during a heating period of two hours. The higher temperature of 1800 F. is preferred. Since this heattreatment softens thesteel body, its strength and hardness are adjusted by quenching and drawing, as in the first alternative method. A
single pressing and a single heat-treatment are Third alternatice method It may also be desirable to make a duplex article which consists partly of relatively pure iron and partly of steel in which the steel component is made by powder metallurgy methods. In this case the powder metallurgy steel component can be hardened by heat treatment while the iron component is simultaneously softened or left unchanged in hardness. Such a heat treatment may consist of a heating at a temperature which is usually within the range 1400" F.2000 F. followed by quenching in water or oil and subsequent tempering, or the cooling may be more slowly at a predetermined rate suflicient to result in the desired hardness of the steel component without subsequent tempering. During the heating it is preferable to surround the duplex body by protective atmosphere in order to prevent oxidation. If the heat treatment is relatively long (e. g. 15 minutes or over), it is preferable to use an inert atmosphere such as dry nitrogen or one of the noble gases. The
-more usual protective atmosphere such as partially burned gases, or cracked ammonia. or hydrogen, or mixtures of hydrogen and a hydrocarbon, may be suitable when the heating period is relatively short. However these atmospheres react on iron or steel and during a prolonged heat treatment may either carburize the iron or.decarburize the steel or both since itis impossible for such atmosphere to be simultaneously in equilibrium with iron and steel.
In order to produce by powder metallurgy methods steel compacts suitable for hardening by conventional heat treatments the following "procedure maybe used.
amass According" to one m'ethod'which is within the scope of my-invention'j the iron powder is mixed with the proper proportion of graphite, a briquette is made of this mixture by cold-pressing at -40 tons per square inch, and this briquette is then heated and thus sintered in an atmosphere which prevents any injurious loss of the graphite. during the sinteringoperation. Preferably this sintering operation .is carried out at a temperature of 200Q F. and for a period of from one to three hours, in an atmosphere of methane and hydrogen.
The methane can be replaced by propane or other stabilizing gas.
It is desired to combine all the graphite with the iron powder. Hencethe proportion of graphite isthe desired final proportion of combined carbon in the final steelbody, The proportion of methane in the sintering atmosphere depends upon the sintering temperature and the final proe portion of combined carbon which it is desired to have in the final steel product. The methane acts as a stabilizing gas, so that the graphite combines with the iron, and not with the hydrogen.
The proportion of methane must not be excessive,
or else some of the methane will be decomposed, and the resultant liberated carbon will combine with the iron, to over-carburize the steel beyond the desired limit. Hence the proportion of methane is selected so that the briquette neither loses nor gains carbon during the sintering, and the proportion of combined carbon in the final steel material is determined by the proportion of graphite in the briquette.
As elsewhere explained herein, it is very important to provide a sintering atmosphere during carburization, which is free from water vapor and oxygen. Hence the commercial hydrogen and stabilizing gas mixture is purified by removing the oxygen, and water vapor is also removed, as further explained herein.
After the first sintering when the iron has combined with the graphite the briquette is again cold pressed at a higher pressure to obtain the desired density and then resintered. This higher pressure is preferably at least approximately 60 tons per square inch.
Steel compacts made as described above may be combined with iron bodies made from wrought material or by powder metallurgy methods by any of several methods for example the two may be joined by copper brazing, swaging, by riveting etc. Alternatively they may be joined during the powder metallurgy operations of pressing and sintering.
This application is a division of copending application Ser. No. 549.807, filed August 16, 1944, now Patent No. 2,411,073, for Making products of iron or iron alloys.
I claim:
1. A method of making a duplex metal body of ferrous metal parts of different hardenability and wherein the separate or assembled parts in their ultimate shape cannot be assembled or disassembled, comprising the steps of preforming one part to its ultimate dimensions, preforming the other part to such dimensions as will permit its assembly with the one part, assembling the parts, deforming the said other part into intimate mechanical engagement with said one part, said deformation of said other part being accompanied by severe internal work hardening, and then withdrawing the work hardening from said deformed other part by heat treating the duplex body at'atemperature which-is above the recrys tallization temperature of the deformed part.
2. A method of making a duplex metal body of iron and steel parts wherein the steel part is relatively harder than the iron-part and wherein the separate or assembled-parts in their ultimate shape cannot be assembled or disassembled, comprising the steps ofpreforming the steel part to its ultimate dimensions, preforming the soft iron part to such dimensions as will permit its assembly with the steel part, assembling the parts, deforming the iron part into intimate mechanical engagement with the steelpart, said deformation of the iron part being accompanied by severe internal work hardening, and then withdrawing the work hardening from the deformed iron part by heat treating the duplex body at a temperature which is above the recrystallization temperature of the deformed iron part.-
3. The method of making a duplex metal body of interengageable preformed iron and steel parts of different hardenability, the ultimate shape of the parts being such that prior to assembly at least one part must have dimensions different from its final dimensions to permit interengagement of said part with said other part, and that following assembly and deformation to interengage the parts they cannot be disassembled without destruction of one of the parts, comprising the steps of preforming the steel part to its ultimate shape, preforming the iron part to such dimensions as will permit assembling it with the steel part, assembling the parts, deforming the iron part into intimate mechanical engagement with the steel part, said deformation of the iron part being accompanied by severe internal work hardening, then Withdrawing the work hardening from the iron part by heat treating the duplex body at a temperature which is above the recrystallization temperature of the deformed.
iron part.
4. A method of making a duplex metal body of.
iron and steel parts wherein the steel part is: relatively harder than the iron part and wherein. the separate or assembled parts in their ultimate shape cannot be assembled or disassembled, comprising the steps of preforming the steel part to its ultimate dimensions, preforming the soft powder iron part to such dimensions as will permit its assembly with the steel part, assembling the parts, deforming the soft iron part into intimate mechanical engagement with the steel part, said deformation of the iron part being accompanied by severe internal work hardening, and then withdrawing the work hardening from the deformed iron part by heat treating the duplex body at a temperature which is above the recrystallization temperature of the deformed iron part without changing the hardness of the steel part.
5. A method of making a duplex metal body of iron and steel parts wherein the steel part is relatively harder than the iron part and wherein the separate or assembled parts in their ultimate shape cannot be assembled or disassembled, comprisin the steps of preforming the steel part to its ultimate dimensions, preforming the soft powder iron part to such dimensions as will permit its assembly with the steel part, assembling the parts, deforming the soft iron part into intimate mechanical engagement with the steel part, said deformation of the iron part being accompanied by severe internal work hardening, and then withdrawing the work hardening from the deformed iron part by heat treating the du- 7 piex body at a temperature which is above the recrystallization temperature of the deformed iron part and concomitantly increasing the hardness of the steel part.
6. A method of making a duplex metal body of iron and steel parts wherein the steel part is relatively harder than the iron part and wherein the separate or assembled parts in their ultimate shape cannot be assembled or disassembled, comprising the steps of preforming the steel part to its ultimate dimensions, preforming the soft powder iron part to such dimensions as will permit its assembly with the steel part, assembling the parts, deforming the soft iron part into intimate mechanical engagement with the steel part, said deformation of the iron part being accompanied by severe internal work hardening, and then withdrawing the work hardening from the deformed iron part by heat treating the du- REFERENCES CITED The following references are of record in the file of this patent: 1
UNITED STATES PATENTS Number Name Date 2,209,709 Weatherhead, Jr. July 30, 1940 2,275,420 Clark et a1 Mar. 10, 1942' FOREIGN PATENTS Number Country Date 398,045 Great Britain Sept. 7, 1933
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US700166A US2491238A (en) | 1944-08-16 | 1946-09-28 | Heat-treating iron steel body |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US549807A US2411073A (en) | 1944-08-16 | 1944-08-16 | Making products of iron or iron alloys |
| US700166A US2491238A (en) | 1944-08-16 | 1946-09-28 | Heat-treating iron steel body |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US2491238A true US2491238A (en) | 1949-12-13 |
Family
ID=27069238
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US700166A Expired - Lifetime US2491238A (en) | 1944-08-16 | 1946-09-28 | Heat-treating iron steel body |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US2491238A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2842471A (en) * | 1950-12-22 | 1958-07-08 | August H Schilling | Powder metallurgy and piston rings obtained thereby |
| EP0106929A2 (en) * | 1982-09-27 | 1984-05-02 | Acu-Edge, Inc. | Wear-resistant and shock-resistant tools and method of manufacture thereof |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB398045A (en) * | 1932-10-22 | 1933-09-07 | Bofors Ab | Improvements in and relating to driving bands for projectiles |
| US2209709A (en) * | 1937-12-10 | 1940-07-30 | Weatherhead Co | Method of making valves |
| US2275420A (en) * | 1938-04-30 | 1942-03-10 | Frances H Clark | Metallurgy of ferrous metals |
-
1946
- 1946-09-28 US US700166A patent/US2491238A/en not_active Expired - Lifetime
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB398045A (en) * | 1932-10-22 | 1933-09-07 | Bofors Ab | Improvements in and relating to driving bands for projectiles |
| US2209709A (en) * | 1937-12-10 | 1940-07-30 | Weatherhead Co | Method of making valves |
| US2275420A (en) * | 1938-04-30 | 1942-03-10 | Frances H Clark | Metallurgy of ferrous metals |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2842471A (en) * | 1950-12-22 | 1958-07-08 | August H Schilling | Powder metallurgy and piston rings obtained thereby |
| EP0106929A2 (en) * | 1982-09-27 | 1984-05-02 | Acu-Edge, Inc. | Wear-resistant and shock-resistant tools and method of manufacture thereof |
| EP0106929A3 (en) * | 1982-09-27 | 1985-05-02 | Fred G. Gunzner | Wear-resistant and shock-resistant tools and method of manufacture thereof |
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