Hardened Martensitic Steel Having a Low Cobalt Content, Process for Manufacturing a Part from Steel, and Part thus Obtained
AssigneeAubert & Duval
InventorFrançois Roch
Life of this patent
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Abstract
A steel characterized in that its composition is percentages by weight: C=0.18-0.30% Co=1.5-4% Cr=2-5% Al=1-2% Mo+W/2=1-4% V=traces-0.3% Nb=traces-0.1% B=traces-30 ppm Ni=11-16% where Ni≧7+3.5 Al Si=traces-1.0% Mn=traces-4.0% Ca=traces-20 ppm Rare earths=traces-100 ppm if N≦10 ppm, Ti+Zr/2=traces-100 ppm where Ti+Zr/2≦10 N if 10 ppm<N≦20 ppm, Ti+Zr/2=traces-150 ppm O=traces-50 ppm N=traces-20 ppm S=traces-20 ppm Cu=traces-1% P=traces-200 ppm the remainder being iron and inevitable impurities resulting from the smelting. A process for manufacturing a part from this steel, and part thus obtained.
Claims33
1-26. (canceled)
A steel composition comprising, in weight percentages, the following:
- C=0.18 to 0.30%;
- Co=1.5 to 4%;
- Cr=2 to 5%;
- Al=1 to 2%;
- Mo+W/2 I to 4%;
- V=traces to 0.3%;
- Nb=traces to 0.1%;
- B=traces to 30 ppm;
- Ni=11 to 16% where Ni≧7+3.5 Al;
- Si=traces to 1.0%;
- Mn=traces to 2.0%;
- Ca=traces to 20 ppm;
- Rare earths=traces to 100 ppm;
- if N≦10 ppm, Ti+Zr/2=traces to 100 ppm where Ti+Zr/2≦10 N;
- if 10 ppm<N≦20 ppm, Ti+Zr/2=traces to 150 ppm;
- O=traces to 50 ppm;
- N=traces to 20 ppm;
- S=traces to 20 ppm;
- Cu=traces to 1%;
- P=traces to 200 ppm;
- and
- the remainder being iron and inevitable impurities resulting from smelting.
Dependencies are inferred from the claim text.