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US 3,944,442 AGranted
Air hardenable, formable steel
AssigneeThe International Nickel Company, Inc.
InventorStephen James Donachie
Life of this patent
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Abstract
A process for producing a highly formable steel capable of affording yield strengths upwards of 90,000 psi through air hardening and without need of liquid quenching, the steel preferably contains correlated percentages of chromium and nickel among other elements and should be in the martensitic condition prior to the first heat treating step.
Claims9
A process for producing a steel adapted for structural applications which comprises:
- i. providing a steel of correlated composition and of a martensitic structure, the steel containing up to about 0.2% carbon, up to about 4% manganese, up to about 3% nickel, up to about 6% chromium, up to about 4% molybdenum, up to about 1.25% copper, up to about 1% aluminum, up to about 1% silicon, and the balance essentially iron, the constituents being interrelated to satisfy the following Base Factor (BF) relationship:
- 5 .times. %C, +%Mn, + %Cr, + 2/3 .times. %Ni, + %Mo;
- + 2/3 %Cu, + 1/2 %Al, + 1/4 %Si .gtoreq.5;
- ii. heating the steel above its recrystallization temperature but below its A.sub.1 temperature;
- iii. cooling the steel to a temperature desired for forming;
- iv. subjecting the steel to a forming operation to attain the configuration desired;
- v. heating the formed structure at a temperature above the A.sub.3 temperature of the steel;
- and
- vi. thereafter cooling the structure formed.
6 more elements
A process for producing a steel adapted for structural application which comprises:
- i. providing a steel of correlated composition and of a martensitic structure, the steel containing up to about 0.2% carbon, up to about 4% manganese, up to about 3% nickel, up to about 6% chromium, up to about 4% molybdenum, up to about 1.25% copper, up to about 1% aluminum, up to about 1% silicon, and the balance essentially iron, the constituents being interrelated to satisfy the following Base Factor (BF) relationship:
- 5 .times. %C, + %Mn, + Cr, + 2/3 .times. %Ni, + %Mo, + 2/3 %Cu, + 1/2 %Al, + 1/4 %Si .gtoreq. 3.5
- ii. heating the steel above its recrystallization temperature but below its A.sub.1 temperature;
- iii. cooling the steel to a temperature desired for forming;
- iv. subjecting the steel to a forming operation to attain the configuration desired;
- v. heating the formed structure at a temperature above the A.sub.3 temperature of the steel;
- and
- vi. thereafter cooling the structure formed.
5 more elements
Dependencies are inferred from the claim text.