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— The thermal fatigue behaviour of a cast cobalt superalloy was investigated. Wedge type specimens were tested on a rig using flame heating. A standard cycle from 200 to 1100°C was used for most tests and the specimen geometry was changed to investigate a broad range of thermal fatigue lives. The maximum temperature was also varied for a single specimen geometry. The thermal fatigue life to create a 1 mm deep crack ranges from a few tens to one thousand cycles. Crack initiation occurs early in life at oxidised interdendritic carbides as in high-temperature, low-cycle fatigue. Precipitation of small chromium-rich carbides was found to occur in the dendrites during thermal fatigue cycling. An identical precipitate distribution could be induced by a two stage thermal treatment as shown by quantitative metallography. The isothermal stress-strain behaviour at high temperature was so shown to be almost insensitive to the microstructure changes induced by thermal fatigue.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1460-2695.1988.tb01181.x
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