Air hardenable, formable steel

Claim 2

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 × %C, +%Mn, + %Cr, + 2/3 × %Ni, + %Mo; + 2/3 %Cu, + 1/2 %Al, + 1/4 %Si ≧5; ii. heating the steel above its recrystallization temperature but below its A 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 3 temperature of the steel; and vi. thereafter cooling the structure formed.

Claim 3

A process in accordance with claim 1 in which the steel has been cold rolled prior to step (ii).

Claim 4

A process in accordance with claim 1 in which step (i) is carried out within the temperature range of about 1150°F. to 1400°F. for a period of about 1 to 48 hours.

Claim 5

A process in accordance with claim 3 in which the operating condition is about 1200° to 1350°F. for 24 to 48 hours.

Claim 6

A process in accordance with claim 1 in which step (v) is carried out at 1500° to 2000°F. for at least about 5 minutes.

Claim 7

A process in accordance with claim 5 in which a temperature 1550° to 1750°F. is used for at least about 10 minutes.

Claim 8

A process in accordance with claim 1 in which the alloy contains about 2 to about 4% chromium, about 1.25 to 3% nickel, about 0.005 to 0.15% carbon, up to about 0.5% molybdenum, up to about 1.25% copper and up to about 1% silicon.

Claim 9

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 × %C, + %Mn, + Cr, + 2/3 × %Ni, + %Mo, + 2/3 %Cu, + 1/2 %Al, + 1/4 %Si ≧ 3.5 ii. heating the steel above its recrystallization temperature but below its A 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 3 temperature of the steel; and vi. thereafter cooling the structure formed.

Claim 10

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 × %C, + %Mn, + Cr, + 2/3 × %Ni, + %Mo, + 2/3 %Cu, + 1/2 %Al, + 1/4 %Si ≧ 3.5 ii. heating the steel above its recrystallization temperature but below its A 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 3 temperature of the steel; and vi. thereafter cooling the structure formed.

Claim 11

A process in accordance with claim 8 in which BF is at least 4.