US4040872A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for strengthening of carbon steels
Assignee: Lasalle Steel Co
•
Filing: 1976-04-16
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Granted: 1977-08-09
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Expires: 1996-04-16
Abstract
Abstract A process for the strengthening of carbon steels wherein a hypoeutectoid carbon steel workpiece, preferably in the shape of a rod or a bar, is rapidly heated to a temperature completely within the austenite region at a rate sufficient to minimize grain growth of austenite grains, the resulting austenitized steel workpiece is quenched to transform the steel to a fine mixture of acicular proeutectoid ferrite and a finely divided eutectoid aggregate of ferrite and iron carbide, followed by working at a temperature ranging up to the critical lower temperature to strengthen the steel. The process of the invention provides a drastic increase in both strength and ductility as compared to untreated steels such as those obtained by hot rolling.
Inventors
- 👤 Edeki Mudiare
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 19:05
CPC Classifications
C; C21; C21D; C21D8/00
Claims Analysis
Total Claims: 34
Claim 1
Independent Claim
80 words
A method for the strengthening of a carbon steel comprising the steps of (1) rapidly heating the carbon steel to raise the temperature of the steel into the austenite region at a rate sufficient to minimize grain growth of austenite grains, (2) cooling the austenitized carbon steel to transform the steel to a fine mixture of acicular pro-eutectoid ferrite and a finely divided eutectoid aggregate of ferrite and iron carbide, and (3) working the resulting steel to strengthen the steel.
Claim 2
Independent Claim
80 words
A method for the strengthening of a carbon steel comprising the steps of (1) rapidly heating the carbon steel to raise the temperature of the steel into the austenite region at a rate sufficient to minimize grain growth of austenite grains, (2) cooling the austenitized carbon steel to transform the steel to a fine mixture of acicular pro-eutectoid ferrite and a finely divided eutectoid aggregate of ferrite and iron carbide, and (3) working the resulting steel to strengthen the steel.
Claim 3
Dependent Claim
30 words
A method as defined in claim 1 wherein the carbon steel has a carbon content ranging from 0.1% carbon by weight up to the eutectoid carbon level for the steel.
Claim 4
Dependent Claim
22 words
A method as defined in claim 1 wherein the carbon steel is within the range of 0.1 to 0.5% carbon by weight.
Claim 5
Dependent Claim
25 words
A method is defined in claim 1 wherein the steel is heated into the austenite region at a temperature ranging from 1350° to 2000° F.
Claim 6
Dependent Claim
23 words
A method as defined in claim 1 wherein the steel is heated into the austenite region in a time less than ten minutes.
Claim 7
Dependent Claim
24 words
A method as defined in claim 1 wherein the steel is heated into the austenite region by passing an electrical current through the workpiece.
Claim 8
Dependent Claim
14 words
A method as defined in claim 1 wherein the steel is quenched with water.
Claim 9
Dependent Claim
18 words
A method as defined in claim 1 wherein the steel is worked by extrusion through a reduction die.
Claim 10
Dependent Claim
29 words
A method as defined in claim 8 wherein the extrusion die serves to reduce the cross sectional area of the steel by an amount ranging from 5 to 90%.
Claim 11
Dependent Claim
24 words
A method as defined in claim 1 wherein the working is carried out at a temperature below the lower critical temperature for the steel.
Claim 12
Dependent Claim
32 words
A method as defined in claim 1 which includes the step of stress relieving the steel to produce a steel having high levels of mechanical properties with low levels of residual stress.
Claim 13
Dependent Claim
15 words
A method as defined in claim 1 which includes the step of straightening the steel.
Claim 14
Dependent Claim
16 words
A prestrengthened steel workpiece formed of a carbon steel prepared by the method of claim 1.
Claim 15
Dependent Claim
25 words
A steel as defined in claim 13 wherein the steel has a carbon content from 0.1% carbon by weight up to the eutectoid carbon level.
Claim 16
Dependent Claim
15 words
A steel as defined in claim 13 wherein the steel is an AISI/SAE 1018 steel.
Claim 17
Dependent Claim
18 words
A prestrengthened, stress relieved steel workpiece formed of a carbon steel prepared by the method of claim 11.
Claim 18
Dependent Claim
45 words
A steel as defined in claim 13 wherein the steel contains 0.1 to 0.8% by weight C, 0.50 to 1.65 by weight Mn, 0.01 to 0.50% by weight S, and 0.10 to 0.35% by weight Si, with the remainder being iron and its usual impurities.
Claim 19
Independent Claim
103 words
A method for the strengthening of a hypoeutectoid carbon steel comprising the steps of (1) rapidly heating the steel to a temperature within the austenite region at a rate sufficient to minimize grain growth of austenite grains, (2) quenching the austenite steel to produce a fine mixture of acicular pro-eutectoid ferrite and a finely divided eutectoid aggregate of ferrite and iron carbide, (3) working the resulting steel at a temperature ranging up to the lower critical temperature to strengthen the steel and (4) stress relieving the steel to produce a steel having high levels of mechanical properties with low levels of residual stress.
Claim 20
Independent Claim
103 words
A method for the strengthening of a hypoeutectoid carbon steel comprising the steps of (1) rapidly heating the steel to a temperature within the austenite region at a rate sufficient to minimize grain growth of austenite grains, (2) quenching the austenite steel to produce a fine mixture of acicular pro-eutectoid ferrite and a finely divided eutectoid aggregate of ferrite and iron carbide, (3) working the resulting steel at a temperature ranging up to the lower critical temperature to strengthen the steel and (4) stress relieving the steel to produce a steel having high levels of mechanical properties with low levels of residual stress.
Claim 21
Dependent Claim
22 words
A method as defined in claim 18 wherein the carbon steel is within the range of 0.1 to 0.5% carbon by weight.
Claim 22
Dependent Claim
25 words
A method as defined in claim 18 wherein the steel is heated into the austenite region at a temperature ranging from 1350° to 2000° F.
Claim 23
Dependent Claim
23 words
A method as defined in claim 18 wherein the steel is heated into the austenite region in a time less than ten minutes.
Claim 24
Dependent Claim
24 words
A method as defined in claim 18 wherein the steel is heated into the austenite region by passing an electrical current through the workpiece.
Claim 25
Dependent Claim
14 words
A method as defined in claim 18 wherein the steel is quenched with water.
Claim 26
Dependent Claim
18 words
A method as defined in claim 18 wherein the steel is worked by extrusion through a reduction die.
Claim 27
Dependent Claim
15 words
A method as defined in claim 18 which includes the step of straightening the steel.
Claim 28
Dependent Claim
16 words
A prestrengthened steel workpiece formed of a carbon steel prepared by the method of claim 18.
Claim 29
Independent Claim
105 words
A method for the strengthening of a hypoeutectoid carbon steel comprising the steps of (1) rapidly heating by passing an electrical current through the steel to heat the steel substantially uniformly across the cross section thereof to a temperature within the austenite region, with the rate of heating being sufficient to minimize grain growth of austenite grains, (2) quenching the austenite steel to produce a fine mixture of acicular pro-eutectoid ferrite and a finely divided eutectoid aggregate of ferrite and iron carbide and (3) working the resulting steel at a temperature ranging up to the lower critical temperature for the steel to strengthen the steel.
Claim 30
Independent Claim
105 words
A method for the strengthening of a hypoeutectoid carbon steel comprising the steps of (1) rapidly heating by passing an electrical current through the steel to heat the steel substantially uniformly across the cross section thereof to a temperature within the austenite region, with the rate of heating being sufficient to minimize grain growth of austenite grains, (2) quenching the austenite steel to produce a fine mixture of acicular pro-eutectoid ferrite and a finely divided eutectoid aggregate of ferrite and iron carbide and (3) working the resulting steel at a temperature ranging up to the lower critical temperature for the steel to strengthen the steel.
Claim 31
Dependent Claim
22 words
A method as defined in claim 27 wherein the carbon steel is within the range of 0.1 to 0.5% carbon by weight.
Claim 32
Dependent Claim
23 words
A method as defined in claim 27 wherein the steel is heated into the austenite region in a time less than ten minutes.
Claim 33
Dependent Claim
14 words
A method as defined in claim 27 wherein the steel is quenched with water.
Claim 34
Dependent Claim
32 words
A method as defined in claim 27 which includes the step of stress relieving the steel to produce a steel having high levels of mechanical properties with low levels of residual stress.
References Cited (Backward Citations)
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US3666572A
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US3865636A
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US3855013A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-08-08 | 1981-02-07 | 1981-08-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-08-08 | 1985-02-07 | 1985-08-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-08-08 | 1989-02-07 | 1989-08-09 | $7700.00 | Window Closed / Lapsed |