Effect of pre-strain treatment on mechanical properties of a Ni-Co base disk superalloy

The effect of pre-strain treatment on mechanical properties of a Ni-Co base disk superalloy was studied. Results show that the pre-strain treatment, creep at 725 degrees C/630 MPa, improves the yield strength of the alloy at 23 degrees C and 760 degrees C. However, the creep life (at 760 degrees C/480 MPa) of the alloy was reduced by pre-strain treatment. The microstructure indicated that a lot of microtwins and Suzuki segregations were introduced by the pre-strain treatment, besides some unfavorable factors on mechanical properties, i.e., ripening of precipitates. The interactions of microtwin and Suzuki segregation with dislocations were discussed in this study, and it was deemed that the impediment of twin boundary and Suzuki segregation to the motion of dislocation may be responsible for the enhancement of the mechanical properties. Meanwhile, the microtwin and the Suzuki segregation have good stability at service temperature. If the problem of reducing the creep properties caused by pre-strain treatment would be solved, the introduction of microtwin and Suzuki segregation appropriately can be considered as a novel strengthening method in designing advanced superalloys.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

The effect of pre-strain treatment on the mechanical properties of a Ni-Co base disk superalloy was investigated. The results showed that pre-strain treatment at 725 degrees C/630 MPa improved the yield strength of the alloy at both 23 degrees C and 760 degrees C. However, the creep life of the alloy at 760 degrees C/480 MPa was reduced by pre-strain treatment. Microstructural analysis revealed the presence of microtwins and Suzuki segregations introduced by the pre-strain treatment, which had both positive and negative effects on the mechanical properties.