Specific Aspects of Isothermal and Anisothermal Fatigue of the Monocrystalline Nickel-Base Superalloy CMSX-6

Abstract

Experimental Procedure

Influence of the γ' Fraction on the γ/γ' Topological Inversion during High Temperature Creep of Single Crystal Superalloys

“…On the other hand, the connectivity was observed to remain positive in CMSX-6 during creep at 1050°C [1,8]. We have measured the area fraction of γ' phase on a micrograph of a rafted CMSX-6 microstructure after creep at 1050°C, published in [8]. The resulting value of 47.5% for F A (γ') is coherent with the fact that no topological inversion occurs in CMSX-6 at 1050°C.…”

“…Such a γ/γ' topological inversion was also observed during tensile creep at 1100°C and 120 MPa of <001> CMSX-4 and CMSX-10 single crystals [2]. On the other hand, the connectivity was observed to remain positive in CMSX-6 during creep at 1050°C [1,8]. We have measured the area fraction of γ' phase on a micrograph of a rafted CMSX-6 microstructure after creep at 1050°C, published in [8].…”

“…This topological inversion coincides with the onset of the accelerated creep stage which is linked to a growing activity of the deformation mechanisms in both γ and γ' phases [2][3][4][5]. However, the topological inversion does not occur for instance during creep at 1050°C of Alloy 211 [6] and CMSX-6 [1,8]. The purpose of the present paper is therefore to focus on the evolution and stability of the γ/γ' rafted microstructure through the analysis of experimental results and published data on a series of experimental and commercial alloys and to deduce some indications for alloy selection for suited applications.…”

On the Mechanical Behavior of a New Single-Crystal Superalloy for Industrial Gas Turbine Applications

“…Two distinct forms of mechanical response are studied as a function of the heat treatment applied: first, creep deformation, which is important due to the centrifugal loading experienced by the turbine blades in the engine; [1,2] and, second, thermomechanical fatigue (TMF), which is relevant particularly for smaller (aeroderivative) industrial gas turbines (IGTs) because of the interaction of thermal and mechanical strains arising from engine startup/cooldown. [8,9] As mission requirements become more demanding, it is becoming apparent that the performance of the material under TMF conditions can be life limiting; however, historically, very much more attention has been paid to the provision of creep resistance. [10] This is probably due to the significant extra difficulty imposed by the constraints of TMF testing; nonetheless, this situation needs to be corrected.…”

Thermomechanical fatigue behavior of the third-generation, single-crystal superalloy TMS-75: Deformation structure

“…Extended work has been carried out on the mechanical behavior and microstructure of Ni-based SC superalloys in the past decades. [1][2][3][4][5][6][7][8][9][10][11][12] However, these investigations concern mainly the creep and isothermal low-cycle fatigue (LCF). [1][2][3][4][5][6][7][8] The TMF behavior of Nibased SC superalloys, despite its great importance from the viewpoint of applications, has not been reported as much to date.…”