Weld toe fatigue crack initiation is highly dependent on local geometrical imperfections such as inclusions, undercuts and cold-laps. These features are known to promote initiation early in the fatigue life however understanding their relative influence on propagation of early cracks into dominant cracks is still limited.
In this work short cracks have been initiated and interrupted on small weld toe sections using strain gauges to capture a change in compliance. Both micro-Computed tomography and serial metallography have then been combined to capture high-resolution information on the local weld toe geometry and early crack development. 3D finite element models generated from the micro-Computed tomography scans have been used for local stress analysis and the stress distribution at each toe is linked to the early initiation and crack growth path. Results from this work inform us about the most critical weld toe geometries and how these control the fatigue regime in steel arc welded joints. If these geometries can be avoided at the manufacturing stage it is proposed that the fatigue lives of these joints can be maximised with no post-weld treatment costs.