Product Code: JLA_6_1_14

Authors:
P. C. Wang
K. M. Ewing

An experimental study, augmented by three‐dimensional finite element analysis, was performed to assess the effects of various process parameters such as presence of galvanized coating, welding speed and weld geometry (weld start and stop, metal fit‐up, and weld orientation) on the fatigue resistance of laser beam welds. It was found that the fatigue resistance of laser beam welds depends upon the welding speed used and weld geometry. With a 2.75 kW CO₂ laser and at a welding speed of 38.1 mm s⁻¹, the resultant laser beam welds gave the highest fatigue resistance. For a continuous weld, maintaining good metal fit‐up between the metal sheets and orienting the weld perpendicular to the loading direction increased the fatigue resistance of laser beam welds. These increases are attributed to the decrease in stress‐intensity factors at the weld bead periphery. Minimal fatigue difference was found between laser beam welded bare and galvanized 0.76 mm thick low carbon steel. Microscopic examinations of laser beam welds indicated that fatigue of a stitch laser beam weld is dominated by crack propagation.