Seam welding

Abstract

A process is provided for seam welding advanced high strength steel sheets together. Respective end portions of first and second advanced high strength steel sheets are placed in overlapping contact with one another, and subjected to first and second weld passes. In the first weld pass, a seam welder including weld electrodes operate at a first-pass applied current and a first-pass pressure and are moved relative to the overlapping end portions at a first-pass carriage speed to establish a weld seam containing a weld nugget with a martensite phase. In the second weld pass, the weld electrodes operate at a second-pass applied current and a second-pass pressure and move relative to the weld seam at a second-pass carriage speed selected to fuse microcracks, lap openings, and porosity in the seam, relieve the residual stress in the joint, and temper the martensite phase of the weld nugget, and thereby form a weld joint.

1 - 29 . (canceled) 
     
     
         30 . A welded seam of advanced high strength steel sheets, the welding seam having an energy absorption capability measured by a ball-punch test ASTM 643-84 of at least 50% of that absorbed by an unwelded portion of the advanced high strength steel sheets tested under identical conditions. 
     
     
         31 - 32 . (canceled)