Patent ID: 6845900

Claim:
A method of welding two pieces of metal to produce a weld joint with a heat-affected-zone having excellent fracture toughness, said method comprising the steps of: (a) positioning said two pieces of metal so as to form a groove; and (b) applying two or more weld pass layers within said groove to produce said weld joint whereby each said weld pass layer is comprised of one primary bead and at least one autogenous bead, and whereby: (i) each said weld pass layer is substantially symmetric about a weld centerline; (ii) each said primary bead has an associated primary A 1 isotherm and an associated primary A 3 isotherm and each of said autogenous beads has an associated autogenous A 1 isotherm and an associated autogenous A 3 isotherm; and (iii) the autogenous A 1 isotherm of each said autogenous bead substantially coincides with (a) the primary A 3 isotherm of the primary bead immediately preceding said autogenous bead or (b) the autogenous A 3 isotherm of the autogenous bead immediately preceding said autogenous bead.