US3865636A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of processing steel material having high austenitic grain-coarsening temperature
Assignee: Kobe Steel Ltd
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Filing: 1973-07-18
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Granted: 1975-02-11
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Expires: 1993-07-18
Abstract
Abstract A method of processing steel material having a high austenitic grain-coarsening temperature and an abnormal grain growth curve of cold worked austenitic grain, which comprises heating said steel material at a temperature of from the ferrite recrystallization temperature to the A1 transformation point for more than five minutes to cause recrystallization. This technique prevents the formation of mixed grains upon austenitizing and thereby preserves the mechanical properties of the steel material.
Inventors
- 👤 Akira Suzuki
- 👤 Shushi Kinoshita
- 👤 Takeshi Ueda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 05:05
CPC Classifications
C; C21; C21D; C21D8/00
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
116 words
A METHOD OF PROCESSING STEEL MATERIAL WHICH IS CHARACTERIZED BY AN ABNORMAL GRAIN GROWTH CURVE OF AUSTENITIC GRAIN AFTER COLD WORKING AND WHICH HAS A HIGH GRAIN COARSENING TEMPERATURE WHICH COMPRISES: HEATING SAID COLD WORKING STEEL MATERIAL TO A TEMPERATURE OF BETWEEN THE FERRITE RECRYSTALLIZATION TEMPERATURE AND THE A1 TRANSFORMATION TEMPERATURE FOR A PERIOD OF AT LEAST 5 MINUTES SO AS TO EFFECT RECRYSTALLIZATION OF THE FERRITIC STRUCTURE WHICH HAD BECOME DEFINED DURING COLD WORKING, AND THEREBY RESING THE AUSTENITIC GRAIN COARSENING TEMPERATURE, FURTHER HEATING SAID STEEL MATERIAL TO A TEMPERATURE WITHIN THE AUSTENITIC REGION OF FROM THE A1 TRANSFORMATION TEMPERATURE TO THE AUSTENITIC GRAIN COARSENING TEMPERATURE TO EFFECT AUSTENITIZING TO FORM A NON-MIXED GRAIN STRUCTURE.
Claim 2
Independent Claim
116 words
A METHOD OF PROCESSING STEEL MATERIAL WHICH IS CHARACTERIZED BY AN ABNORMAL GRAIN GROWTH CURVE OF AUSTENITIC GRAIN AFTER COLD WORKING AND WHICH HAS A HIGH GRAIN COARSENING TEMPERATURE WHICH COMPRISES: HEATING SAID COLD WORKING STEEL MATERIAL TO A TEMPERATURE OF BETWEEN THE FERRITE RECRYSTALLIZATION TEMPERATURE AND THE A1 TRANSFORMATION TEMPERATURE FOR A PERIOD OF AT LEAST 5 MINUTES SO AS TO EFFECT RECRYSTALLIZATION OF THE FERRITIC STRUCTURE WHICH HAD BECOME DEFINED DURING COLD WORKING, AND THEREBY RESING THE AUSTENITIC GRAIN COARSENING TEMPERATURE, FURTHER HEATING SAID STEEL MATERIAL TO A TEMPERATURE WITHIN THE AUSTENITIC REGION OF FROM THE A1 TRANSFORMATION TEMPERATURE TO THE AUSTENITIC GRAIN COARSENING TEMPERATURE TO EFFECT AUSTENITIZING TO FORM A NON-MIXED GRAIN STRUCTURE.
Claim 3
Independent Claim
136 words
A method of processing steel material which contains a grain refining element which is characterized by an abnormal grain growth curve of austenitic grain after cold working and which has a high grain coarsening temperature which comprises: heating said cold worked steel to a temperature of between the ferrite recrystallization temperature and the A1 transformation temperature for a period of at least 5 minutes so as to effect recrystallization of the ferritic structure which had become deformed during cold working, and thereby raising the austenitic grain coarsening temperature, and to precipitate said grain refining elements in the form of nitride, carbide and/or oxide, further heating said steel material to a temperature within the austenitic region of from the A1 transformation temperature to the austenitic grain coarsening temperature to effect austenitizing to form a non-mixed grain structure.
Claim 4
Independent Claim
136 words
A method of processing steel material which contains a grain refining element which is characterized by an abnormal grain growth curve of austenitic grain after cold working and which has a high grain coarsening temperature which comprises: heating said cold worked steel to a temperature of between the ferrite recrystallization temperature and the A1 transformation temperature for a period of at least 5 minutes so as to effect recrystallization of the ferritic structure which had become deformed during cold working, and thereby raising the austenitic grain coarsening temperature, and to precipitate said grain refining elements in the form of nitride, carbide and/or oxide, further heating said steel material to a temperature within the austenitic region of from the A1 transformation temperature to the austenitic grain coarsening temperature to effect austenitizing to form a non-mixed grain structure.
Claim 5
Dependent Claim
28 words
The method of claim 2, wherein said steel material is hot worked subsequent to the first heating step and prior to cooling in the 900* - 500*C range.
Claim 6
Dependent Claim
40 words
The method of claim 2, wherein cold working is sequentially cycled with intermediate heat treating, between a first cold working operation and each succeeding cold working operation, said intermediate heat treatment being below the temperature of the A1 transformation point.
Claim 7
Dependent Claim
40 words
The method of claim 3, wherein cold working is sequentially cycled with intermediate heat treating, between a first cold working operation and each succeeding cold working operation, said intermediate heat treatment being below the temperature of the A1 transformation point.
Claim 8
Dependent Claim
13 words
The method of claim 2, wherein said steel is cold worked by machining.
Claim 9
Dependent Claim
13 words
The method of claim 3, wherein said steel is cold worked by machining.
Claim 10
Dependent Claim
20 words
The method of claim 1, wherein after recrystallization said steel material is subjected to carburization treatment in the austenitic region.
References Cited (Backward Citations)
US3711342A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-02-10 | 1978-08-12 | 1979-02-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-10 | 1982-08-12 | 1983-02-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-10 | 1986-08-12 | 1987-02-11 | $7700.00 | Window Closed / Lapsed |