The effect of laser beam alignment on dilution, weld metal chemistry and weldment quality is reported for EN 82 filler-added, horizontal position butt welds between a nickel base alloy, Inconel 600, and a martensitic stainless steel, AISI Type 403. Weldability was assessed by penetrant and metallographic examination of autogenous laser tack welds which concentrate solidification stresses. Heat affected zones were examined by metallography and by microhardness testing in the as-welded condition. An improved technique is described to terminate the weld for configurations where run-off tabs cannot be used.
Ranges of dilution and alignment are defined which provide defect-free weld metal without sacrificing the assurance of full joint penetration. Laser beam welding is demonstrated to provide control of dilution appropriate for direct joining of dissimilar metals.