US3901739A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of making light gage members of unalloyed low carbon steel sheets
Assignee: CENTROPA GmbH
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Filing: 1972-10-30
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Granted: 1975-08-26
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Expires: 1992-10-30
Abstract
Abstract Thermal hardening is applied to the material of light gage coldformed members made of unalloyed low carbon steel sheets having a carbon content not greater than 0.50 percent and a thickness not greater than 7 millimetres. Thermal hardening consists in quenching such steels from a temperature in the austenitizing range below the Ms temperature of starting martensite formation, holding the steel at such temperature until transformation is completed and then cooling it down to room temperature. By such method, an increase by 100 to 200 percent of the yield point may be obtained without distortion of the member. This seems to be due to the nose of the TTT-curve of beginning martensite formation being cut by the cooling curve so that softer crystal structures such as pearlite and bainite are formed which provide for absorbing residual stresses during martensite formation.
Inventors
- 👤 Andor Mandoki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 19:51
CPC Classifications
C; C21; C21D; C21D1/00; C21D1/18; C21D1/19; C21D1/22
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
87 words
IN A METHOD OF MAKING LIGHT GAGE MEMBERS OF UNALLOYED LOW CARBON STEEL SHEETS HAVING A CARBON CONTENT NOT GREATER THAN 0.05%, THE STEPS OF HEATING A SAID MEMBER ABOVE THE CRITICAL TEMPERATURE THEREBY TO FORM AUSTENITE, THERMALLY HARDENING THE MEMBER BY QUENCHING THE SAME FROM A TEMPERATURE ABOVE THE CRITICAL TEMPERATURE TO AN INTERMEDIATE TEMPERATURE OF SUBSTANTIALLY 150* TO 470* CENTIGRADE ALONG A COOLING LINE THAT CROSSES THE NOSE OF THE TIME-TEMPERATURE TRANSFORMATION CURVE, TO CONVERT ONLY A PORTION OF SAID AUSTENITE TO PEARLITE AND BAINITE,
Claim 2
Dependent Claim
87 words
IN A METHOD OF MAKING LIGHT GAGE MEMBERS OF UNALLOYED LOW CARBON STEEL SHEETS HAVING A CARBON CONTENT NOT GREATER THAN 0.05%, THE STEPS OF HEATING A SAID MEMBER ABOVE THE CRITICAL TEMPERATURE THEREBY TO FORM AUSTENITE, THERMALLY HARDENING THE MEMBER BY QUENCHING THE SAME FROM A TEMPERATURE ABOVE THE CRITICAL TEMPERATURE TO AN INTERMEDIATE TEMPERATURE OF SUBSTANTIALLY 150* TO 470* CENTIGRADE ALONG A COOLING LINE THAT CROSSES THE NOSE OF THE TIME-TEMPERATURE TRANSFORMATION CURVE, TO CONVERT ONLY A PORTION OF SAID AUSTENITE TO PEARLITE AND BAINITE,
Claim 3
Dependent Claim
48 words
In a method of making members as claimed in claim 1 including the step of cold-forming the cross-sectional area of work material the further improvement of applying the heating, quenching and cooling to the work material prior to cold-forming of the cross-sectional area thereof in a continuous operation.
Claim 4
Dependent Claim
42 words
In a method of making members as claimed in claim 1 including the step of cold-forming the cross-sectional area of work material the further improvement of applying the heating, quenching and cooling to the work material groupwise after cold-forming its cross-sectional area.
Claim 5
Dependent Claim
29 words
In a method of making members as claimed in claim 1 the further improvement of employing steel sheets of a thickness of 1.5 to 4 millimetres for work material.
Claim 6
Dependent Claim
30 words
In a method of making members as claimed in claim 1 the further improvement of employing steel sheets having a carbon content not less than 0.15 percent for work material.
Claim 7
Dependent Claim
31 words
In a method of making members as claimed in claim 1 the further improvement of employing steels for work material the manganese content of which is 0.5 to 1.0% by weight.
Claim 8
Dependent Claim
36 words
In a method of making members as claimed in claim 1 the further improvement of carrying out quenching from a temperature by 30* to 90* centigrade higher than the lowermost temperature limit of the austenitizing range.
Claim 9
Dependent Claim
21 words
In a method of making members as claimed in claim 1 the further improvement of effecting the final cooling in water.
Claim 10
Dependent Claim
22 words
In a method of making members as claimed in claim 1, the further improvement of performing said quenching in a salt bath.
Claim 11
Dependent Claim
26 words
In a method of making members as claimed in claim 1, the further improvement of maintaining the thickness of the members not greater than 7 millimeters.
References Cited (Backward Citations)
US3410734A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-08-25 | 1979-02-24 | 1979-08-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-25 | 1983-02-24 | 1983-08-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-25 | 1987-02-24 | 1987-08-26 | $7700.00 | Window Closed / Lapsed |