Fatigue behaviour of weathering steels

: Müller, F.; Sonsino, C.M.

Abstract
The fatigue behaviour under constant amplitude loading of several charges of the structural steel St 52-3 and the weathering steel WT St 52-3 was examined in the unwelded state (unnotched flat bar) and in the welded state (butt weld, longitudinal stiffener, transverse stiffener) after an environmental exposure of six years. The following results were observed: The weathering steel did not show a better fatigue performance than the normal structural steel, although the loss of material due to corrosion was lower for the weathering steel. After six years of weathering the endurance limit of the unnotched flat bars was reduced by 40% due to the corrosive attack. The fatigue behaviour was not affected, if the specimens were coated by a protective colour before the exposure. The fatigue behaviour of the welded joints was not affected by the corrosion. Even a tendency towards higher fatigue lifes could be observed, as the sharp notch radii of the welds were smoothed during corrosive attack. The fatigue notch factor was reduced and thus the fatigue behaviour was improved.