Process for fusion-welding iron-nickle-cobalt alloy and copper or said

Abstract

In a process for fusion-welding a binary combination of an iron alloy containing 50 % by weight or less of nickel and cobalt combined and copper; or a ternary combination of said iron alloy, copper, and iron, including the steps of bringing members of said binary combination or ternary combination into gapless contact with one another and subjecting the contact zone to a treatment including at least one of electron beam welding, laser beam welding, plasma welding, and TIG welding without use of a filler metal, an improvement which is characterized by supplying welding energy necessary to form in the welding zone molten weld metal having such a width and depth that have been determined from the composition and thickness of said base metals so that the composition of the weld metal may fall within the specified area in a diagram, shown in FIG. 1, representing composition of a three component system, said specified area being enclosed with straight lines connecting successively the point X (97 wt-% Cu, 2 wt-% Fe, 1 wt-% Ni + Co), the point Y (2 wt-% Cu, 49 wt-% Fe, 49 wt-% Ni + Co), the point Z (2 wt-% Cu, 97 wt-% Fe, 1 wt-% Ni + Co), and the point X except for the area enclosed with straight lines connecting successively the point a (35 wt-% Cu, 32.5 wt-% Fe, 32.5 wt-% Ni + Co), the point b (10 wt-% Cu, 45 wt-% Fe, 45 wt-% Ni + Co), the point c (8 wt-% Cu, 91 wt-% Fe, 1 wt-% Ni + Co), the point d (45 wt-% Cu, 54 wt-% Fe, 1 wt-% Ni + Co), and the point a. According to this improved process, development of weld cracking can be prevented.