Thermomechanical modeling and experimental study of a multi-layer cast iron repair welding for weld-induced crack prediction

Large-scale components such as hubs in wind turbines are often made of cast iron to minimize the production costs. One of the common challenges in the casting process of such large-scale components is manufacturing defects. However, repair welding will induce residual stress which can initiate cracks in the repaired structure, especially since cast iron is not as tough as steel. The current study addresses developing a thermo-mechanical model of the cast iron repair weld validated with experiments to predict thermal and residual stresses and to identify critical locations for crack initiation. A thermo-mechanical weld model is developed, and the predicted temperature and residual stress distribution are validated against experimental data. Two repair weld experiments, one manual and one automated are carried out and are simulated using the developed thermo-mechanical model. The regions with maximum principal residual stresses are calculated by the thermo-mechanical model and the maximum principal stress method is used to predict the location and direction of the developed cracks in the repair weld. A comparison with the repair weld experiments shows good correlation with the observed cracks in the welded specimens. The outcome of this research provides a basis for repair weld optimization of large-scale cast iron components in order to reduce the carbon footprint caused by their reproduction.