Final Units Flashcards
What are the four methods of strengthening described in class?
strain hardening (cold working), grain size reduction, solid solution strengthening, precipitate hardening
What property is sacrificed as a result of strengthening
Material ductility is sacrificed and materials are more brittle because the buildup of dislocations leads to cracks
What is the driving force during heat treatment
Heat treatment’s driving force is that heat is decreasing the number of dislocations, thereby reduction in strain energy.
What are the stages in heat treatment
Heat treatment stages are, recovery, recrystallization, and crystal growth respectively.
What does bioinert mean
No toxic/tetrogenic/carcinogenic immune response from the body
What does bioresuable mean?
Undergoes degradation in the body
What does bioactive mean
Produces a targeted biological response
What does xenograph mean
Animal based donor for an organ Advantages: Recovery of lost function and larger donor pool but possibility of immune rejection
What is the characteristic of a ductile fracture
Ductile fractures have a lot of plastic deformation and slow crack propogation - large elasticity and area reduction before fracture
What is the characteristic of a brittle fracture
Brittle fractures have little plastic deformation and fast crack propogation - little ductility and area reduction before fracture
What’s the term for very ductile materials
Elastomers
What’s the term for moderately ductile materials
Alloys
What’s the term for very unductile and not brittle materials
Ceramics
What are the stages of fracture?
Necking, void formation, void growth, crack propogation. Keep in mind that flow acts as stress concentrators.
At a crack, the sharper the crack
The higher stress at the crack tip (considered a stress concentrator)
What does crack propogation depend on
Temperature, strain rate, and microstructure.
Explain all of the variables associated with fatigue graphs
S is the amplitude or stress amplitude determined by the delta between the maximum and minimum.
Explain all of the variables associated with fatigue graphs
S is the amplitude or stress amplitude determined by the delta between the maximum and minimum. N is the number of cycles to failure at a particular stress amplitude S. The range of stress is the maximum - minimum.
Explain all of the variables associated with fatigue graphs
S is the amplitude or stress amplitude determined by the delta between the maximum and minimum. N is the number of cycles to failure at a particular stress amplitude S. The range of stress is the maximum - minimum. While mean stress is the max and min averaged out.
What are some ways you can improve for fatigue
- Impose compressive surface stress 2. Remove stress concentrators by design.
What are some ways you can improve for fatigue
- Impose compressive surface stress 2. Remove stress concentrators by design.
What properties are independent of size and geometry of the system
Resistivity and conductivity are independent of size and geometry.
What does mattheisen’s rule suggest
presence of imperfections will increase resistivity, notably from dislocations, impurity atoms, and vacancies.
Resistivity increases with
temperature, wt% measurement of impurity, and % cold working (thermal)
