Creep Behaviour of Modified Mar-247 Superalloy

Abstract

The paper presents the results of analysis of creep behaviour in short term creep tests of cast MAR-247 nickel-based superalloy samples made using various modification techniques and heat treatment. The accelerated creep tests were performed under temperature of 982 °C and the axial stresses of σ = 150 MPa (variant I) and 200 MPa (variant II). The creep behaviour was analysed based on: creep durability (creep rupture life), steady-state creep rate and morphological parameters of macro- and microstructure. It was observed that the grain size determines the creep durability in case of test conditions used in variant I, durability of coarse-grained samples was significantly higher.

Creep-damage modelling for micro gas turbine combustion chambers lifetime prediction

“…The creep mechanisms acting in a material can be identified for a range of stresses and temperatures in a deformation map, according to the methods described by Frost and Ashby (1982). A deformation map of Inconel 718 is not available to the authors, but similar Nickel-based superalloys, such as IN738LC Carey et al (1990) or MAR-M-200 Cieśla et al (2016), show the onset of dislocation creep at half of the melting point (about 600 C) and at stresses above 50 MPa. The operative conditions at which MGT combustion chambers are operated (metal temperature and stresses due to thermal strains) lay above these values.…”

Phase composition of Ni-Al-Co-Me-based superalloy modified by deformation

“…After compressive deformation the alloys obtain the polycrystalline structure with non-equilibrium morphology [13][14][15][16][17]. Nevertheless, ' I -phase particles are present in the structure, however, their volume fraction and the size is rather reduced as compared to the original state (directional crystallization) ( Table 3).…”

Role of stress on creep behaviors for MarM247LC DS superalloy

“…Directionally solidified (DS) nickel‐based superalloys are widely applied for high‐temperature components, such as turbine blades owing to the outstanding creep properties 1 . This can be attributed to the strengthening effects by a large volume fraction of coherent γ′ phase and elimination of the transverse grain boundaries perpendicular to stress axis, 2 which were potential crack initiation sites in conventionally cast alloy 3,4 . During service, the complex shape of blades and the thermal gradient have imposed the components to suffer various temperatures and stresses 5 .…”

“…1 This can be attributed to the strengthening effects by a large volume fraction of coherent γ 0 phase and elimination of the transverse grain boundaries perpendicular to stress axis, 2 which were potential crack initiation sites in conventionally cast alloy. 3,4 During service, the complex shape of blades and the thermal gradient have imposed the components to suffer various temperatures and stresses. 5 Therefore, it is necessary to investigate the creep behavior under a wide stress and temperature range, contributing to the evaluation of creep damage and future design of new alloys.…”