Experimental study of transverse attachment joints with 40 and 60 mm thick main plates, improved by high-frequency mechanical impact treatment (HFMI)

In recent years, high-frequency mechanical impact (HFMI) treatment has grown in popularity due to its efficiencyin improving the fatigue strength of welded joints. The fatigue performance of HFMI-treated welded steeljoints has, however, not been thoroughly studied for plate thicknesses above 30 mm. In this study, 40 and 60mmthick main plates with non-load-carrying transverse attachments have been fatigue tested under constant amplitudefour-point bending, both in as-welded and HFMI-treated condition to investigate the fatigue performancefor large plate thicknesses, typical for weldments in bridges. Axial fatigue strengths were estimated by a modificationof the experimental results with fracture mechanics calculations. The main conclusions are that HFMItreatment can result in significant fatigue strength improvement even for large main plate thicknesses and thatthe difference in fatigue strength between bending and axial loading is negligible for the specimen geometriesused in this study