Patent ID: 7618503

Claim:
A method of forming a steel structure comprising the steps of: providing a first surface of a hardenable ferrous alloy having a carbon content equal or greater than 0.08% by weight; providing a second surface of a hardenable ferrous alloy having a carbon content equal or greater than 0.08% by weight; positioning said first surface adjacent to said second surface; seam welding said first surface to said second surface by applying a first heat source to said first surface and said second surface at a sufficiently high temperature to said first surface and said second surface above their melting points to form a seam weld; allowing said seam weld to cool to below the martensitic start temperature for said hardenable ferrous alloys; tempering said seam weld subsequent to said step of allowing said seam weld to cool to below the martensitic start temperature for said hardenable ferrous alloys, said tempering including heating said seam weld at a rate of 10° C. per second or greater to above the martensitic start temperature but not to above the lower critical temperature for said hardenable ferrous alloys; and air cooling said seam weld at a rate of 15° C. per minute or greater after said step of tempering said seam weld.