Cracking Analysis of Generator Casting Fan for Steam Turbine

The early cracks in the generator casting fan for steam turbine imported from Italy were found, which plunged into use for two years. The hot acid experiment, fracture morphology, microstructure and mechanical properties were tested and analyzed, and the stress distribution were computed by FEM soft. The results show that, cracking nature of the fan were fatigue cracking caused by low stress cumulative damage. The main reason were involved in more cracks, microporosity and repairing welding defects in source locations as well as no suitable heat treatment at repairing welding parts.