Creep and rupture properties of an austenitic Fe-30Mn-9Al-1C alloy |
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Authors: | S M Zhu S C Tjong |
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Affiliation: | (1) the Department of Physics and Materials Science, City University of Hong Kong, Kowloon, Hong Kong |
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Abstract: | The creep deformation behavior and rupture properties of as-quenched austenitic Fe-30Mn-9Al-1C alloy have been studied at
923, 948, and 973 K under applied stresses ranging from 50 to 350 MPa. The creep curves of the alloy exhibited an extended
tertiary stage prior to failure. The stress and temperature dependencies of the minimum creep rate indicated two regimes of
creep deformation as well as a transition from creep to power-law breakdown. These two regimes of creep deformation were identified
as a low-stress creep regime having an activation energy of 140 kJ/mol and a stress exponent of about 1, and a power-law creep
regime having an activation energy of 350 kJ/mol and a stress exponent of about 6. Transmission electron microscope (TEM)
observations of the deformed specimens revealed that a low density of dislocations, coarse dislocation networks, and profuse
slip bands were developed in the low stress, power law, and power-law breakdown regimes, respectively. Optical microscope
and scanning electron microscope (SEM) observations of the ruptured specimens showed that creep cavitation shifted from round-type
in the low-stress creep regime to wedge-type in the power-law breakdown regime. The observed creep and rupture characteristics
of the alloy are interpreted in terms of creep mechanisms, which involve the Coble creep and dislocation climb creep. |
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