Effect of Overheating Temperature on Thermal Cycling Creep Properties of K465 Superalloy

Abstract

Turbine blades in aircraft engines may encounter overheating and suffer serious creep property degradation. In this study, the thermal cycling creep experiments were conducted on K465 superalloy under (900 °C/30 min–1100 °C/3 min)/50 MPa, (900 °C/30 min–1150 °C/3 min)/50 MPa and (1000 °C/30 min–1150 °C/3 min)/50 MPa. The investigated thermal cycling creep properties were dramatically degraded, and increasing the overheating temperatures significantly decreased the thermal cycling creep life. The secondary γ′ precipitates obviously dissolved and the area fraction decreased to around 35.2% under (900 °C/30 min–1150 °C/3 min)/50 MPa and (1000 °C/30 min–1150 °C/3 min)/50 MPa, which was almost half that after the standard solution treatment. The decline of the thermal cycling creep properties was mainly due to the significant dissolution of γ′ precipitates. The creep holes/cracks were mainly distributed at the M6C carbides and γ/γ′ eutectics interfaces, M6C carbides and γ′ film interfaces in the grain boundaries, and resulted in the final intergranular fracture.

Microstructural Degradation and Creep Property Damage of a Second-Generation Single Crystal Superalloy Caused by High Temperature Overheating

“…The studies on overheating in China have gradually received attention, and studies on overheating effect on forged superalloys [ 8 ], equiaxed casted superalloys [ 9 , 10 ], and directionally solidified superalloys [ 11 , 12 ] have been carried out. The results show that overheating, especially the thermal cycling condition [ 13 ], has a significant impact on the creep properties of superalloys. The creep rate of the alloy increases obviously at the overheating stage, resulting in a significant decrease in the creep life [ 11 , 14 ].…”

Tensile Deformation Behavior of a Directionally Solidified Superalloy at Cryogenic Temperatures

“…Generally, the higher the processing stage, the greater the processing difficulty and the better the properties of the alloy [4,5]. So far, most published research on the mechanical properties of Ni-based alloys focuses on the room temperature and high temperature range [6][7][8][9][10][11].…”