US3951697A
Expired / Lapsed
US
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Superplastic ultra high carbon steel
Assignee: Leland Stanford Junior University
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Filing: 1975-02-24
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Granted: 1976-04-20
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Expires: 1995-02-24
Abstract
Abstract An ultra high carbon steel with a fine grained iron matrix stabilized by cementite in predominantly spheroidized form at elevated temperatures. A method for treating the steel including heat treatment and mechanical working under sufficient deformation to refine the iron grain and spheroidize the cementite. Mechanical working is preferably performed either in the upper alpha-cementite range or in the gamma-cementite range. Thermal cycling may be substituted for mechanical working. An alternative method is mixing and sintering fine cementite containing-iron alloy powders and iron powders.
Inventors
- 👤 Oleg D. Sherby
- 👤 Conrad M. Young
- 👤 Bruno Walser
- 👤 Eldon M. Cady, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 07:39
CPC Classifications
C; C21; C21D; C21D8/00; B; B22; B22F; B22F3/00; B22F3/24; C22; C22C; C22C33/00; C22C33/02; C22C33/0207; Y; Y10; Y10S; Y10S420/00; Y10S420/902
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
59 words
An ultra high carbon steel having a carbon content in excess of about 1.0% and an iron grain matrix with uniformly dispersed cementite, said iron grain being stabilized in a predominantly equiaxed configuration having an average grain size no greater than about 10 microns, said cementite being in predominantly spheroidized form in a temperature range of 723°C to 900°C.
Claim 2
Dependent Claim
59 words
An ultra high carbon steel having a carbon content in excess of about 1.0% and an iron grain matrix with uniformly dispersed cementite, said iron grain being stabilized in a predominantly equiaxed configuration having an average grain size no greater than about 10 microns, said cementite being in predominantly spheroidized form in a temperature range of 723°C to 900°C.
Claim 3
Dependent Claim
20 words
An ultra high carbon steel as in claim 1 characterized by superplasticity in the temperature range of 723°C to 900°C.
Claim 4
Dependent Claim
16 words
An ultra high carbon steel as in claim 1 having a maximum carbon content of 2.3%.
Claim 5
Dependent Claim
21 words
An ultra high carbon steel as in claim 1 in which said carbon content comprises 1.3% to 1.9% of the steel.
Claim 6
Dependent Claim
22 words
An ultra high carbon steel as in claim 1 characterized by a yield strength of at least 80 ksi at room temperature.
Claim 7
Dependent Claim
21 words
An ultra high carbon steel as in claim 1 characterized by tensile strength of at least 100 ksi at room temperature.
Claim 8
Dependent Claim
17 words
An ultra high carbon steel as in claim 1 having a tensile elongation of at least 4.0%.
Claim 9
Dependent Claim
21 words
An ultra high carbon steel as in claim 1 in which the iron is predominantly in martensite form at room temperature.
Claim 10
Dependent Claim
54 words
An ultra high carbon steel having a carbon content in excess of about 1.0% and an iron grain matrix with uniformly distributed cementite, said iron grain being stabilized in a predominantly equiaxed configuration having an average grain size no greater than about 10 microns, said cementite being in predominantly spheroidized form at room temperature.
Claim 11
Dependent Claim
54 words
An ultra high carbon steel having a carbon content in excess of about 1.0% and an iron grain matrix with uniformly distributed cementite, said iron grain being stabilized in a predominantly equiaxed configuration having an average grain size no greater than about 10 microns, said cementite being in predominantly spheroidized form at room temperature.
Claim 12
Dependent Claim
20 words
An ultra high carbon steel as in claim 9 characterized by superplasticity in a temperature range of 600°C to 900°C.
Claim 13
Dependent Claim
81 words
In a method for treating an ultra high carbon steel having a carbon content of at least 1.0%, the steps of heat treating the steel at a temperature of at least 500°C, and mechanically working the heat-treated steel under sufficient strain deformation to form an iron grain matrix with uniformly dispersed cementite in which said iron grain has an equiaxed configuration and an average grain size no greater than about 10 microns, and the predominant portion of said cementite is spheroidized.
Claim 14
Dependent Claim
81 words
In a method for treating an ultra high carbon steel having a carbon content of at least 1.0%, the steps of heat treating the steel at a temperature of at least 500°C, and mechanically working the heat-treated steel under sufficient strain deformation to form an iron grain matrix with uniformly dispersed cementite in which said iron grain has an equiaxed configuration and an average grain size no greater than about 10 microns, and the predominant portion of said cementite is spheroidized.
Claim 15
Dependent Claim
23 words
A method as in claim 11 in which the steel is mechanically worked in a temperature range from 500°C to the gamma-cementite range.
Claim 16
Dependent Claim
17 words
A method as in claim 11 in which the steel is mechanically worked in the gamma-cementite range.
Claim 17
Dependent Claim
21 words
A method as in claim 11 together with the step of homogenizing the steel at elevated temperatures prior to mechanical working.
Claim 18
Dependent Claim
17 words
A method as in claim 11 in which the homogenizing step is performed in the gamma range.
Claim 19
Dependent Claim
23 words
A method as in claim 11 in which the heat treatment comprises tempering the steel and mechanical working is performed at cold temperatures.
Claim 20
Dependent Claim
97 words
In a method for treating an ultra high carbon steel having a carbon content of at least 1.0%, the steps of a. heating the steel to a temperature in excess of the alpha-gamma transformation line, b. quenching the heated steel to form martensite, c. tempering the martensite steel, and d. mechanically working the steel under sufficient strain deformation to form an iron grain matrix with uniformly dispersed cementite in which said iron grain has an equiaxed configuration and an average grain size no greater than about 10 microns, and the predominant portion of said cementite is spheroidized.
Claim 21
Dependent Claim
97 words
In a method for treating an ultra high carbon steel having a carbon content of at least 1.0%, the steps of a. heating the steel to a temperature in excess of the alpha-gamma transformation line, b. quenching the heated steel to form martensite, c. tempering the martensite steel, and d. mechanically working the steel under sufficient strain deformation to form an iron grain matrix with uniformly dispersed cementite in which said iron grain has an equiaxed configuration and an average grain size no greater than about 10 microns, and the predominant portion of said cementite is spheroidized.
Claim 22
Independent Claim
86 words
A method for treating an ultra high carbon steel having a carbon content of at least 1% comprising the steps of cyclically heating and cooling the steel through the alpha-gamma iron transition line until sufficient strain deformation is imparted to form an iron grain matrix with uniformly dispersed cementite, said iron grain being stabilized in a predominantly equiaxed configuration and having an average grain size no greater than about 10 microns, said cementite being in predominantly spheroidized form in a temperature range of 723°C to 900°C.
Claim 23
Independent Claim
86 words
A method for treating an ultra high carbon steel having a carbon content of at least 1% comprising the steps of cyclically heating and cooling the steel through the alpha-gamma iron transition line until sufficient strain deformation is imparted to form an iron grain matrix with uniformly dispersed cementite, said iron grain being stabilized in a predominantly equiaxed configuration and having an average grain size no greater than about 10 microns, said cementite being in predominantly spheroidized form in a temperature range of 723°C to 900°C.
Claim 24
Independent Claim
91 words
A method for preparing an ultra high carbon steel having a carbon content of at least 1% comprising the steps of intimately mixing iron of a size less than 10 microns with an iron-carbon alloy containing predominantly spheroidized cementite and pressing and sintering the mixture to form an iron grain matrix with uniformly dispersed cementite, said iron being stabilized in a predominantly equiaxed configuration and having an average grain size no greater than about 10 microns, said cementite being in predominantly spheroidized form in a temperature range of 723°C to 900°C.
Claim 25
Independent Claim
91 words
A method for preparing an ultra high carbon steel having a carbon content of at least 1% comprising the steps of intimately mixing iron of a size less than 10 microns with an iron-carbon alloy containing predominantly spheroidized cementite and pressing and sintering the mixture to form an iron grain matrix with uniformly dispersed cementite, said iron being stabilized in a predominantly equiaxed configuration and having an average grain size no greater than about 10 microns, said cementite being in predominantly spheroidized form in a temperature range of 723°C to 900°C.
Claim 26
Dependent Claim
22 words
A method as in claim 19 in which commercial steel impurities including manganese are supplied in either the iron or iron-carbon alloy.
References Cited (Backward Citations)
US3723194A
Cited
US3857741A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-04-20 | 1979-10-20 | 1980-04-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-04-20 | 1983-10-20 | 1984-04-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-04-20 | 1987-10-20 | 1988-04-20 | $7700.00 | Window Closed / Lapsed |