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Key words: welding, rotors, erosion, mechanical stress.
Abstract: The present paper contains information concerning the main causes of the usage of Pelton impellers. Also, the results of the research on the deposed metal with the OK 68.37 electrode are included in the content of the paper.
1. INTRODUCTION
The OK.68.37 electrodes are used for reshuffling the defects that appear on Pelton rotors.
While the rotor is functioning, the metal deposed because of the reshuffle is subjected to mechanical stress, abrasive erosion, cavitational erosion and corrosion. [1]
The impellers of the Pelton turbine are solicited by tangential and centrifugal forces.
The tangential forces act periodically on the cups, with a frequency that is equal with the number of impacts per second.
The centrifugal forces have, at the synchronism speed a constant effort.
The internal tensions overlap the operating tensions, the tension state is particularly complex and with a high degree of triaxiality, so the material is subjected to exhaustion.
The abrasive erosion is due to the presence of a number of erosive particles which, in the working environment, cause the uprooting of some material particles from the surface of the cups.
The caviational erosion is caused by the destruction of the materials through caviatation. [1]
The erosion can take...