FATIGUE PROPERTIES OF LASER-BEAM WELDMENTS ON HIGH-STRENGTH STEELS

The intention of this investigation is to evaluate the behaviour of laser-beam weldments under cyclic loading. The materials tested are several high-strength steel plates with thicknesses of 7-8 mm differing in chemical composition, delivery state and strength level. A number of S-N curves was established not only for the as-welded condition but also for the stress relieved and dressed state. It was found that the fatigue properties of laser-beam welded joints are considerably better than those of weld seams produced by other methods. The increase in fatigue strength amounts to approximately 50%, neither depending on the material used nor on an additional stress-relief annealing. By using the R1MS notch stress model, the good behaviour of the weld seams can be entirely attributed to the favourable weld geometry.