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Speaker:
Speakers: Dr. Shahram Sheybany (Pacific Metallurgical Co.) and
Frauke Hogue (Hogue Metallography)
Speaker
Robert Hayes, Metals Technology Inc.
Topic
Oxygen Embrittlement and Time-Dependent Grain-Boundary Cracking in
Ni-Base Superalloys
Abstract
Embrittlement of grain boundaries by oxygen or other deleterious
species can take place in a wide variety of Nickel – base
superalloys when exposed to an aggressive environment. This leads to
a complete change in failure mode from a ductile transgranular
fracture to a macroscopically brittle intergranular fracture with
very low ductility. It has also recently been shown that moisture
level in the test atmosphere may play a significant role in the
grain boundary embrittlement process. The degree of susceptibility
to time – dependent intergranular cracking is highly dependent upon
microstructure as well as composition. Microstructures which are
susceptible to grain boundary embrittlement will be presented and
discussed. Methods to enhance the materials resistance to brittle
grain boundary fracture will also be discussed. Fracture
characteristics have been studied using SEM. Microstructures are
characterized using optical metallography and TEM.
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May 2011
Meeting
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Speaker
Robert Hayes, Metals Technology Inc.
Topic
Oxygen Embrittlement and Time-Dependent Grain-Boundary
Cracking in Ni-Base Superalloys
Abstract
Embrittlement of grain boundaries by oxygen or other
deleterious species can take place in a wide variety of
Nickel – base superalloys when exposed to an aggressive
environment. This leads to a complete change in failure
mode from a ductile transgranular fracture to a
macroscopically brittle intergranular fracture with very
low ductility. It has also recently been shown that
moisture level in the test atmosphere may play a
significant role in the grain boundary embrittlement
process. The degree of susceptibility to time –
dependent intergranular cracking is highly dependent
upon microstructure as well as composition.
Microstructures which are susceptible to grain boundary
embrittlement will be presented and discussed. Methods
to enhance the materials resistance to brittle grain
boundary fracture will also be discussed. Fracture
characteristics have been studied using SEM.
Microstructures are characterized using optical
metallography and TEM. |
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