Butt welded plates with different wall thicknesses are often needed in various kinds of constructions to adapt single components to the requirements resulting from different load situations. Thereby a reduction of total weight can be reached while the bearing capacity stays constant at the same time. Another possibility to reduce the weight of a structure without losing load-capacity is the use of highstrength steel. Thereby, material and energy costs and weld volume can be reduced. For structures made of high-strength steels stability and fatigue design mostly is the decisive factor, so that here a fatigue resistant design is of particular importance. One method to increase the fatigue strength of welded structures is the application of high frequency peening methods. In the following, the results of fatigue tests on butt welded plates and methods to increase the fatigue strength of such details are presented.
At the Research Centre for Steel, Timber and Masonry at the University of Karlsruhe extensive fatigue tests on butt welded plates were carried out in the last years. Butt welded plates, 6 mm to 8 mm thick, welded with and without backing strip, with sealing run and with sealing run and grinded root and a special variant, in which the backing was welded with fusion penetration and removed afterwards, have been investigated. For the test specimens steel grades S700MC, S960QL and S1100QL were used. In addition, fatigue tests on 16 mm and 30 mm thick butt welded plates made of S355J2G3, S460M and S690QL were carried out, which have also been treated with high frequency peening methods.
