| Abstract |
| Creep properties and carbide reaction of a nickel base superalloy Mar-M247 at above 900℃ were investigated in this study. Creep and thermal exposure tests were carried out. Activation energy for creep deformation of Mar-M247 was calculated at 530.2 kJ/mol and the stress exponent was calculated at five (5). Two morphological types of MC carbide were observed in heat treated specimen. Tungsten was abundant in the script type MC carbide and hafnium in the blocky type one. Film-like M6C carbide as well as globular-like M23C6 carbide precipitated along the grain boundary during thermal exposure at 982℃/1000 hours. Globular M23C6 carbide also precipitated near blocky type MC carbide and needle-like M6C carbide precipitated near script type MC carbide in the interdendritic region. Thermo-Calc predicted that M23C6 carbide was stable and M6C carbide was unstable at 982℃. However, M6C carbide precipitation was accelerated during creep deformation. |
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| Key Words |
| Ni-base superalloy, Mar-M247, Creep, Fhermal exposure, Carbide reaction |
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