ISSN:
1460-2695
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract— An advanced nickel base alloy, MAR MOO2, was subject to creep-fatigue, strain controlled, cycling at temperatures of 750, 850 and 1000°C. Under continuous cycling the alloy exhibited cyclic stability at 750 and 850°C but not at 1000°C. The presence of a tensile or compressive dwell caused softening at 750 and 850°C compared with the pure fatigue case. At 1000°C a tensile dwell caused slight hardening and a compression dwell caused cyclic softening. The stress response for a balanced, tensile plus compressive, dwell was similar to that for continuous cycling. Unbalanced tensile dwells produced significant compressive mean stresses and compressive dwells resulted in large tensile mean stresses at 750 and 850°C. However, at 1000°C no significant mean stresses were produced whatever cycle was used. Stress relaxation behaviour was similar for both tensile-only and compressive-only dwells. In the balanced case the amount of stress relaxation was double that in each dwell of an unbalanced cycle. Reliable predictions of stress relaxation were possible using stress exponents from available creep data and the Gittus equation. Severe ageing (104 h at 1000°C) does not destroy the cyclic stability of the alloy although some softening occurred in the compression-only dwell at 850°C. Tentative explanations for the observed stress response in terms of dislocation-precipitate interactions have been suggested.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1460-2695.1991.tb00669.x
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