Fatigue and failure behaviour of friction welded steel joints under normal and shear stresses

Rotary friction welding is a fast and efficient joining process with the possibility to join materials that are not weldable by conventional GMAW-processes. If done properly, the welds have a static and fatigue strength higher than the base material. However, in literature, there exists only sparse information on the design and assessment of these joints in terms of fatigue. The fatigue strength of two material combinations, S355-S355 and S355-1.4301, is investigated based on two specimen conditions, (1) with flash and (2) with flash mechanically removed. In the majority of tests, failure occurred outside the weld zone, in the base material. The derived endurable nominal stresses are compared to the design S-N curve of conventionally welded specimens and show a more than 50% higher fatigue strength.