Questions:
(a) Show that:
(b) What value of ε ss would you expect at 800°C and 16000 psi?
A= 0.0043
Using your Larson-Miller curve, what temperature should you use for a life of 20 years at the lowest stress level?
For the extensive length of time, a temperature of approximately 25 oC which is close to room temperature.
With increasing stress or temperature, what changes will you notice in a typical creep curve? When you increase temperature or stress, the creep curve will increase in terms of creep strain. A larger strain rate is shown which correlates to a shorter curve. This implies that fracture will occur sooner when stress or temperature is increased.
Does chromel have a well-defined secondary creep stage? Explain your answer.
No. When you look at the …show more content…
Creep deformation mechanisms all involve the diffusion of atoms, explaining increased transport at higher temperatures. (a) What is diffusion and how does it occur? (b) Why does it occur most rapidly at grain boundaries?
Diffusion in solid materials occurs because of the movement of atoms through the lattice structure. The smaller atoms push/place themselves in the spaces between larger atoms when in a high heat environment. There are essentially two types; interstitial and vacancy.
Diffusion occurs more rapidly at grain boundaries because there are weaker bonds and more space there. This allows for more dislocation motion.
Primary creep is typified by a continuously decreasing creep rate. Give reasons.
When the stress is applied constantly, elastic deformation occurs then plastic. As this deformation occurs, the dislocation causes the grain boundaries to increase which causes necking and hardening. Grain boundaries make the dislocations harder to transpose which in turn makes the material more brittle and less ductile. Therefore, the strain rate decreases which show a decreasing creep
(a) Show that:
(b) What value of ε ss would you expect at 800°C and 16000 psi?
A= 0.0043
Using your Larson-Miller curve, what temperature should you use for a life of 20 years at the lowest stress level?
For the extensive length of time, a temperature of approximately 25 oC which is close to room temperature.
With increasing stress or temperature, what changes will you notice in a typical creep curve? When you increase temperature or stress, the creep curve will increase in terms of creep strain. A larger strain rate is shown which correlates to a shorter curve. This implies that fracture will occur sooner when stress or temperature is increased.
Does chromel have a well-defined secondary creep stage? Explain your answer.
No. When you look at the …show more content…
Creep deformation mechanisms all involve the diffusion of atoms, explaining increased transport at higher temperatures. (a) What is diffusion and how does it occur? (b) Why does it occur most rapidly at grain boundaries?
Diffusion in solid materials occurs because of the movement of atoms through the lattice structure. The smaller atoms push/place themselves in the spaces between larger atoms when in a high heat environment. There are essentially two types; interstitial and vacancy.
Diffusion occurs more rapidly at grain boundaries because there are weaker bonds and more space there. This allows for more dislocation motion.
Primary creep is typified by a continuously decreasing creep rate. Give reasons.
When the stress is applied constantly, elastic deformation occurs then plastic. As this deformation occurs, the dislocation causes the grain boundaries to increase which causes necking and hardening. Grain boundaries make the dislocations harder to transpose which in turn makes the material more brittle and less ductile. Therefore, the strain rate decreases which show a decreasing creep