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

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.

ɤ-TiAl alloy: On the tensile creep deformation behaviour and creep life at 832 °C

Creep deformation in single-phase ɤ-TiAl alloys manufactured using different processing techniques has been an extensively studied topic owing to the high specific strength and excellent creep properties of these alloys at temperatures between 760 and 1000°C. In addition, these lightweight and creep-resistant alloys are being presently considered as replacements to the comparatively heavier Ni-based superalloys for application in the low-pressure turbine blades of the next-generation gas turbine engines. However, there is limited information on the tensile creep deformation behaviour and creep life of ɤ-TiAl alloys at 832°C where these alloys have been reported not to exhibit steady-state creep. To this end, the present work revisits the work on understanding the tensile creep deformation behaviour of wrought single-phase ɤ-TiAl alloy by Saha [1] and is aimed to develop an understanding of the tensile creep deformation behaviour at 832°C and the influence of creep activation energy on the creep life of wrought single-phase ɤ-TiAl alloy for stress levels of 69.4 and 103.4 MPa at 832°C using Monkman–Grant [2] approach.

ɤ-TiAl Alloy: Tensile Creep Deformation Behaviour and Creep Life at 832 °C

Creep deformation in single phase ɤ-TiAl alloy manufactured using different processing techniques has been an extensively studied topic since the late 1970s. The present work revisits the original work on understanding the tensile creep deformation behaviour of wrought single-phase ɤ-TiAl alloy by Hayes and Martin [1] and is aimed to develop an understanding of steady state creep. Besides, it is also aimed to investigate the creep life for stress levels of 69.4 and 103.4 MPa at 832 ⁰C using Monkman-Grant [2] approach.