16 Questions
What is creep in the context of material science?
Time-dependent deformation under constant stress
At what temperature does creep become significant for a material?
0.4 Tm
What renders a material useless in performing its intended function in the context of creep failure?
Permanent dimensional change
What can result from sufficient strain or creep in a material?
Fracture known as stress rupture or creep fracture
What is the creep mechanism that involves atomic diffusion and elongation of the grain in response to applied stress and temperature?
Diffusion-controlled process
What happens to vacancies in the material’s microstructure during the creep mechanism involving atomic diffusion?
Migrate toward grain boundaries
What is the main purpose of conducting a creep test?
To measure strain as a function of time at a constant stress and temperature
What is the significance of thermal activation of dislocations in the context of creep?
It allows dislocations to move under applied stress at elevated temperatures
Why are turbine engine blades particularly susceptible to creep failure?
They experience sustained stress over time at high temperatures
Which materials are susceptible to creep at relatively high temperatures according to the text?
Nickel-based superalloys
Why is it important to ensure quality material fabrication and processing in order to reduce material defects and voids?
To reduce the susceptibility of the material to creep
In which manner may creep failures appear according to the text?
Both ductile and brittle
What do turbines, gas turbine engines, and ovens have in common according to the text?
They all undergo creep phenomenon
What is the role of grain boundaries in accommodating applied stress in materials experiencing creep?
They allow dislocations to move along them
Why are materials with high melting temperatures often selected for turbine engine blades?
To withstand sustained stress over time at high temperatures
What is the purpose of plotting data from a creep test as strain vs. time?
To visualize how strain changes over time under constant stress and temperature
Explore the concepts of creep failure and design against creep in mechanical engineering, covering topics such as creep test, stress and temperature effects on creep behavior. Prepared by Dr. Reham Reda Abbas.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
