Method of introducing residual compressive stresses into a shaft

Abstract

The invention relates to a method of introducing compressive residual stresses into shaft notches of a shaft which is configured as a stepped shaft having successive stages having a different diameter. Diameter transitions or notch regions are located between each two adjacent stages. The diameter transitions or notch regions are quenched in a controlled manner as part of a heat treatment of the shaft.

1 - 6 . (canceled) 
     
     
         7 . A method for introducing a residual compressive stress into a shaft having successive stages of different diameters, comprising:
 arranging a diameter transition between adjacent stages of the successive stages; and   controlled quenching the diameter transition after a final tempering treatment as part of a hardening and tempering heat treatment.   
     
     
         8 . The method as claimed in  claim 7 , wherein the diameter transition is sprayed with a quenching medium for the quenching. 
     
     
         9 . The method as claimed in  claim 7 , wherein the diameter transition is cooled by a dipping operation for the quenching. 
     
     
         10 . The method as claimed in  claim 7 , wherein the diameter transition in a heat-treatment contour of the shaft is produced with an allowance to an ultimate final contour of the shaft. 
     
     
         11 . The method as claimed in  claim 10 , wherein the heat-treatment contour is removed during producing the ultimate final contour of the shaft or after the quenching. 
     
     
         12 . The method as claimed in  claim 10 , wherein the allowance is in a magnitude of at most 10 to 40 mm. 
     
     
         13 . The method as claimed in  claim 11 , wherein the heat-treatment contour of the diameter transition has a radius with a magnitude of 25 to 50 mm. 
     
     
         14 . The method as claimed in  claim 7 , wherein the residual compressive stress is introduced into a shaft notch of the shaft. 
     
     
         15 . The method as claimed in  claim 7 , wherein the shaft is used in a turbomachine. 
     
     
         16 . A method for introducing a residual compressive stress into a shaft notch of a shaft having successive stages of different diameters, comprising:
 arranging a notch region between adjacent stages of the successive stages; and   controlled quenching the notch region after a final tempering treatment as part of a hardening and tempering heat treatment.   
     
     
         17 . A turbomachine, comprising:
 a shaft comprising:
 successive stages of different diameters; 
 a diameter transition arranged between adjacent stages of the successive stages that is controlled quenched after a final tempering treatment as part of a hardening and tempering heat treatment.