The invention relates to steel which is characterized by the following composition as expressed in percentages by weight: —C=0.18 0.30%, —Co=5-7%, —Cr=2-5%, —Al=1-2%, —Mo+W/2=1-4%, —V=trace 0.3%, —Nb=trace 0.1%, —B=trace−50 ppm, —Ni=10.5-15% with Ni≧7+3.5 Al, —Si=trace 0.4%, —Mn=trace 0.4%, —Ca=trac
The invention relates to steel which is characterized by the following composition as expressed in percentages by weight: —C=0.18 0.30%, —Co=5-7%, —Cr=2-5%, —Al=1-2%, —Mo+W/2=1-4%, —V=trace 0.3%, —Nb=trace 0.1%, —B=trace−50 ppm, —Ni=10.5-15% with Ni≧7+3.5 Al, —Si=trace 0.4%, —Mn=trace 0.4%, —Ca=trace−500 ppm, —Rare earths=trace−500 ppm, —Ti=trace−500 ppm, —O=trace−200 ppm if the steel is obtained by means of powder metallurgy or trace−50 ppm if the steel is produced in air or under a vacuum from molten metal, —N=trace−100 ppm, —S=trace−50 ppm, —Cu=trace−1%, and —P=trace−200 ppm, the remainder including iron and the inevitable impurities resulting from production. The invention also relates to a method of producing a part from said steel and to the part thus obtained.
대표청구항▼
1. Method for producing a component from steel, characterized in that the method comprises the following steps prior to the finishing of the component which provides the component with its definitive shape: preparing a steel characterized in that the composition thereof is, in percentages by weight:
1. Method for producing a component from steel, characterized in that the method comprises the following steps prior to the finishing of the component which provides the component with its definitive shape: preparing a steel characterized in that the composition thereof is, in percentages by weight: C=0.18-0.30%Co=5-7%Cr=2-5%Al=1-2%Mo+W/2=1-4%V=trace levels−0.3%Nb=trace levels−0.1%B=trace levels−50 ppmNi=10.5-15% with Ni≧7+3.5 AlSi=trace levels−0.4%Mn=trace levels−0.4%Ca=trace levels−500 ppmRare earth elements=trace levels−500 ppmTi=trace levels−500 ppmO=trace levels−200 ppm if the steel is obtained by means of powder metallurgy, or trace levels−50 ppm if the steel is obtained by means of production in air or under vacuum from liquid metalN=trace levels−100 ppmS=trace levels−50 ppmCu=trace levels−1%P=trace levels−200 ppm the remainder being iron and inevitable impurities resulting from the production operation; forging the steel;a softening tempering operation at 600-675° C. for from 4 to 20 hours followed by cooling in air;solution heat treating at 900-1000° C. for at least 1 hour, followed by cooling in oil or air which is sufficiently rapid to prevent the precipitation of intergranular carbides in the austenite matrix; andhardening ageing at 475-600° C. for from 5-20 h; thereby providing steel which has an Rm at ambient temperature between 2200 and 2350 MPa. 2. Method for producing a component from steel according to claim 1, characterized in that it further comprises a cryogenic processing operation at −50° C. or lower in order to convert all the austenite into martensite, the temperature being 200° C. or more lower than Ms, at least one of the processing operations lasting at least 2 hours, wherein the cryogenic processing operation is carried out between the cooling in oil or air and the hardening ageing. 3. Method for producing a component from steel according to claim 2, characterized in that it further comprises a cryogenic processing operation at −80° C. or lower. 4. Method for producing a component from steel according to claim 1, characterized in that it further comprises a processing operation for softening the martensite so obtained carried out at 150° C.-250° C. for from 4-16 hours, followed by cooling in still air. 5. Method for producing a component from steel according to claim 1, characterized in that the component is also subject to a case-hardening or nitriding operation. 6. Method for producing a component from steel according to claim 1, wherein the hardening ageing is from 490-525° C. for from 5-20 h. 7. Method for producing a component from steel according to claim 1, wherein the steel which is provided-has an Rm of about 1800 MPa at 400° C. 8. Method for producing a component from steel according to claim 7, wherein the steel which is provided has an Rp0.2 of from 1959 to 2135 MPa. 9. Method for producing a component from steel according to claim 8, wherein C=0.20-0.25%. 10. Method for producing a component from steel according to claim 7, wherein C=0.20-0.25%. 11. Method for producing a component from steel according to claim 1, wherein the steel which is provided has an Rp0.2 of from 1959 to 2135 MPa. 12. Method for producing a component from steel according to claim 11, wherein C=0.20-0.25%. 13. Method for producing a component from steel according to claim 1, wherein C=0.20-0.25%.
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이 특허에 인용된 특허 (4)
Olson Gregory B. (Riverwoods IL), Fracture-tough, high hardness stainless steel and method of making same.
Rhoads Mark A. (Cincinnati OH) Raymond Edward L. (Maineville OH) Garrison ; Jr. Warren M. (Pittsburgh PA), High strength, high fatigue structural steel.
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