Effect of Thermal Cycling on High Temperature Creep of Coated CMSX-4

Abstract

Effect of thermal cycling on high temperature creep of thin-walled and coated CMSX-4 single crystal superalloy was evaluated by performing thermal cycling and isothermal creep tests at 1050°C and 140 MPa, 1150°C and 140 MPa and 1150°C and 80 MPa. The deleterious effect of thermal cycling on the creep behavior and lifetime has been confirmed, particularly for the condition at 1150°C and 80 MPa. Furthermore, the number of low temperature incursions has severe detrimental effect on creep resistance on account of the rafted microstructure destabilization induced by these sequences. These results confirm the role of re-precipitation and dissolution of γ' particles during thermal cycling creep. Thermal cycling infers also on destabilization of subcoating zone in the superalloy but this effect seems to be secondary.

Effect of the Prior Microstructure Degradation on the High Temperature/Low Stress Non-isothermal Creep Behavior of CMSX-4® Ni-based Single Crystal Superalloy

“…However, the detrimental effect of thermal cycling cannot be linked only to an increase of the average temperature since other kind of thermal cycling (i.e. cooling in the course of a high temperature creep test) also leads to a decrease in the creep properties [9][10][11][12][13]23]. It is believed that the thermal transitions (i.e.…”