Effects of Structural and Technological Factors on the Fatigue Life of the Centrifugal Compressor Impeller Blade-Disk Joint: Experimental Evaluation

The choice of structural and technological parameters of the one-piece connection of the blade and the impeller disk of a centrifugal compressor was experimentally substantiated. The possibility of increasing the durability of the welded joint by using martensitic steel instead of austenitic-martensitic steel in this design was tested. To solve these problems, we developed a methodology for cyclic bending tests of flat specimens with a rib welded by different methods, which model such a joint (tensile specimens) at operating temperatures. The stresses were determined by the experimental calculation method, and the results of the dynamic thermometry of the specimens determined the temperature. Three batches of specimens made of high-strength martensitic steel with different variants of preparation for welded joints were used in the experimental studies. To compare the obtained fatigue resistance characteristics of the martensitic steel specimens, another batch was made of austenitic-martensitic steel, commonly used for products of the above type. The fatigue tests were performed on an electrodynamic vibration test bench under resonant bending vibrations of a cantilever specimen of the first form and a heating temperature of 200°C. The obtained results make it possible to provide recommendations for preparing and implementing a one-piece connection of the blade with the impeller disk, which can increase its fatigue resistance.