Fracture reason of stirring shaft of reactor

The self-priming stirring shaft of a reactor fractured during operation. The fracture causes were studied by macroscopic observation, chemical composition analysis, shear stress check, metallographic examination, scanning electron microscope analysis, energy spectrum analysis and finite element simulation. The results show that the screw hole deformation, material sensitization at the fillet weld and stress concentration on the structure were the main reasons for fatigue fracture of the stirring shaft.