Festigkeitsbewertung von Laserstrahlschweißnähten an Feinkornbaustählen

Tensile and fatigue tests were carried out on laser welded butt joints from 6 mm thick structural steel sheets. Tension loaded specimens with sharp notches in the fusion zone exhibit a higher strength than the unnotched weld metal, indicating a sufficiently ductile deformation behaviour. Even on plain strain conditions brittle failure seems not to be expected. Pores don't have a diminishing influence on the strength, provided that the amount of cross section reduction is only small. Fatigue tests of specimens in the as welded condition proved the possibility of fatigue crack formation at edge notches in the weld seam as well as in the neighbouring base material. In this case pores don't have a damaging effect on the fatigue strength. For machine finished laser welded joints the pore size has to be limited in order to ensure the base material fatigue limit.