Claims
- 1. A method of producing an air-hardenable bainite-martensite steel having a hardenable diameter of at least about 35 mm and a hardness of at least about R.sub.C 20 and suitable either for casting directly into a useful articles form or, after casting, for hot working in a temperature range from about 800.degree. C. to about 1250.degree. C., said method comprising casting, at a temperature from about 1500.degree. C. to about 1650.degree. C., a molten steel containing, by weight percent:
- ______________________________________carbon 0.1 to 0.7%manganese 2.1 to 3.5%silicon 0.1 to 2%chromium 0.1 to 3.5%boron 0.0005 to 0.005%,______________________________________
- and air-cooling the cast and solidified steel from above the austenitizing temperature, without quenching.
- 2. A method according to claim 1, wherein the steel contains from 0.1 to 0.46% carbon, and wherein the method further comprises the step of tempering the cast and air-cooled steel at a temperature in the range of about 150.degree. C. to about 650.degree. C.
- 3. A method of forming a useful steel article comprising hot forming a precursor steel article of an air-hardenable steel containing, by weight percent:
- ______________________________________carbon 0.1 to 0.7%manganese 2.1 to 3.5%silicon 0.1 to 2%chromium 0.1 to 3.5%boron 0.0005 to 0.005%,______________________________________
- heating the precursor article to a temperature at least equal to the austenitizing temperature of the steel, and working the precursor article to a useful article form within a temperature range from the austenitizing temperature to ambient temperature while air-cooling the steel article.
- 4. A method according to claim 3, wherein the carbon content of the steel is from 0.10 to 0.46% by weight.
- 5. A method of producing an air-hardenable bainite-martensite steel having a hardenable diameter of at least about 35 mm and a hardness of at least about R.sub.c 20 and suitable either for casting directly into a useful article form or, after casting, for hot working in a temperature range from about 800.degree. C. to about 1250.degree. C., said method comprising casting, at a temperature from about 1500.degree. C. to about 1650.degree. C., a molten steel containing, by weight percent:
- ______________________________________carbon 0.1 to 0.7%manganese 2.1 to 3.5%silicon 0.1 to 2%chromium 0.1 to 3.5%boron 0.0005 to 0.005%,______________________________________
- solidifying the cast steel, hot working the cast steel at a temperature from about 850.degree. C. to about 1250.degree. C., finishing the hot working at a temperature over 800.degree. C., air cooling the steel and tempering the steel at a temperature within the range from about 150.degree. C. to about 150.degree. C.
- 6. A method of producing an air-hardenable bainite-martensite steel having a hardenable diameter of at least about 35 mm and a hardness of at least about Rc 20 and suitable either for casting directly into a useful article form or, after casting, for hot working in a temperature range from about800.degree. C. to about 1250.degree. C., said method comprising casting, at a temperature from about 1500.degree. C. to about 1650.degree. C., a molten steel containing, by weight percent:
- ______________________________________carbon 0.1 to 0.46%manganese 2.1 to 3.5%silicon 0.1 to 2%chromium 0.1 to 3.5%boron 0.0005 to 0.005%,______________________________________
- solidifying the cast steel, hot working the cast steel at a temperature from about 850.degree. C. to about 1250.degree. C., finishing the hot working at a temperature over 800.degree. C., and then further warm working the steel at a temperature below the hot working and finishing range.
- 7. A process of working and heat treating a steel article having a composition consisting essentially, by weight percent, of:
- ______________________________________carbon 0.26 to 0.70%manganese 2.1 to 3.5%silicon 0.1 to 2%boron 0.0005 to 0.005%chromium up to 3.5%tungsten up to 1.5%molybdenum up to 1.5%vanadium up to 0.15%sulfur up to 0.2%calcium up to 0.1%titanium up to 0.1%rare earth elements up to 0.2% totaliron balance, except for incidental steelmaking impurities______________________________________
- wherein if the amount of chromium is less than 1%, the steel contains manganese and silicon in combined amount of at least 3%, which process comprises hot working the steel at a temperature above the austenitizing temperature, cooling the steel under retarded cooling conditions to form a microstructure selected from the group consisting of pearlite and pearlite plus ferrite, cold working the steel to a useful articles form, reheating the cold worked article to a temperature above the austenitizing temperature, and then air-cooling the articles to form a hardenable bainite/martensite microstructure.
- 8. A method of producing an air-hardenable bainite-martensite steel having a hardenable diameter of at least about 35 mm and a hardness of at least about R.sub.c 20 and suitable either for casting directly onto a useful article form or, after casting, for hot working in a temperature range from about 800.degree. C. to about 1250.degree. C., said method comprising casting, at a temperature from about 1500.degree. C. to about 1650.degree. C., a molten steel containing, by weight percent:
- ______________________________________carbon 0.1 to 0.34%manganese 2.1 to 3.5%silicon 0.1 to 2%chromium 0.1 to 3.5%boron 0.0005 to 0.005%,______________________________________
- into the form of a final useful casting, reheating the unworked casting to a temperature above the steel austenitizing temperature, and air-cooling the casting.
- 9. A method according to claim 6, comprising air-cooling the hot worked steel to a temperature within the range from below the hot working temperature to room temperature, reheating the steel to a temperature below the hot working temperature and warm working the steel.
- 10. A method of producing an air-hardenable bainite-martensite steel having a hardenable diameter of at least about 35 mm and a hardness of at least about R.sub.c 20 and suitable either for casting directly into a useful article form or, after casting, for hot working, said method comprising casting a molten steel consisting essentially, by weight percent:
- ______________________________________carbon 0.1 to 0.7%manganese 2.1 to 3.5%silicon 0.1 to 2%boron 0.0005 to 0.005%chromium up to 3.5%tungsten up to 1.5%molybdenum up to 1.5%vanadium up to 0.15%sulfur up to 0.2%calcium up to 0.1%titanium up to 0.1%rare earth metals up to 0.2% totaliron balance, except for incidental steelmaking impurities,______________________________________
- which process comprises solidifying the steel, hot working the cast and solidified steel at a temperature from about 850.degree. C. to about 1250.degree. C., finishing the hot working at a temperature over 800.degree. C., and then air-cooling the steel.
Priority Claims (1)
Number |
Date |
Country |
Kind |
88102230.6 |
Apr 1988 |
CNX |
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Parent Case Info
This is a division of application Ser. No. 07/283,491 filed Dec. 12, 1988, now U.S. Pat. No. 4,957,702.
Foreign Referenced Citations (4)
Number |
Date |
Country |
06103008 |
Jun 1987 |
CNX |
2302865 |
Jul 1974 |
DEX |
58-034131 |
Feb 1983 |
JPX |
2163454 |
Feb 1986 |
GBX |
Divisions (1)
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Number |
Date |
Country |
Parent |
283491 |
Dec 1988 |
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