Welding steel – a proven and highly modern joining technology
The FOSTA e. V. offers excellent possibilities for steel application research, especially for joining and welding technology. A particularly highlighted aspect is the excellent support of research projects. This begins with the consultation with the industrial companies, most importantly the support from the research institutions, but also for help with the meaningful progression of the project-accompanying committees. The close cooperation with the companies in the project-accompanying committee, starting with the application, and the partial bundling of several research projects ensures maximum benefit, both in the research institutions and in the participating industrial companies and leads to excellent steel application research.
Projects in a wide variety of fields are looked after, whether it be the automated welding of new ultrahigh strength steel grades for the automotive industry or high tensile offshore steels for wind energy. Both long established industrial processes such as resistance and arc welding are used here. Also being further developed and examined for their general applicability is e.g. for welding on longitudinally welded large pipes to increase weld quality and toughness welding processes such as electron beam welding, laserbeam welding under vacuum or various laser hybrid welding processes (with GMAW or SAW). In addition to the secure and automated welding processing, the subsequent mechanical properties of the joined connections clearly play a decisive role. As an example, there are investigations on the fatigue strength of resistance spot welds made of high strength multiphase steels considering production specific boundary conditions or the influence of processing and ambient hydrogen sources on the tendency of high strength steels for hydrogen induced cold cracking. To optimise distortions and residual stresses during welding, the latest simulation methods in the field of welding simulation are being researched (amongst others). Firstly to be able to carry out the processes better and safer but also, for example to be able to execute simplified residual stress calculation of multi-layer welds. In addition, new concepts will be developed in order to include the weakened zones in the welding of Advanced High Strength Steels (AHSS) in the simulation. The evaluation of the sustainability of these compounds is also considered. In addition to the methods and the simulation, new test methods are also being developed or enhanced, in order, for example, to investigate the tendency to liquid/metal embrittlement in AHSS spot welded joints.
Uwe Reisgen, Klaus Dilger, Michael Rethmeier