MMET 207 EXAM 1 QUESTIONS AND
ANSWERS ALL CORRECT
Difference between interstitial and substitutional atoms - Answer- Interstitial atoms are
stronger
How do interstitial and substitutional atoms affect the crystal lattice - Answer-
Substitutional replaces the existing atoms with a bigger one while interstitial adds a lot
of atoms that are smaller
- Carbon interstitially strengthens iron latitce structure
Where are interstitial and lattice sites located in lattice structure - Answer- interstitial - in
between lattice sites
lattice sites - on corners of lattice structure
Difference between cooling curve of alloys and pure metals - Answer- Pure metals have
an actual liquid and solid line while alloys have a freezing range
*Notes
Mushy Zone - Answer- Area of liquid and solid
Coarse vs fine grains - Answer- coarse grains - less ductile, less slip
fine grains- more ductility, more slip
Types of Hardness Testing (3) - Answer- Rockwell, Brinell, Vickers or Knoop
Rockwell Hardness Testing (process) - Answer- Apply minor load, apply major load,
remove loads, calculate the difference of the indentions
Rockwell Hardness Testing (Indentors) - Answer- 1/16" Tungsten Carbide Ball for B&T
120 degree Diamond Cone or Brale for C, A, & N (EX: HRC)
Rockwell Regular loads - Answer- Minor: 10 kg
Major: 60kg, 100kg, 150kg
Rockwell Superficial loads - Answer- Minor: 3kg
Major: 15kg, 30 kg, 45kg
What does a major load mean? - Answer- Load that makes the second indention
, Differences between regular and superficial loads - Answer- regular - prefer to use this
superficial - use if material is really thin or soft
Rockwell: difference between Beuler and Wilson? - Answer- They are just different
brands, same type of rockwell hardness test
Brinell Hardness Test - Answer- Uses 10mm ball as indentor
Smash ball into metal surface and measure diameter of the indention
What are the mechanical properties of metals? - Answer- - strength
- formability
- stiffness
- toughness
- durability
Strength - Answer- Material's ability to accommodate stress
Properties of Strength (6) - Answer- - tensile
- yield
- compression
- flexural
- shearc
- creep
Formability - Answer- The easiness to shape a metal; can I bend this w/o breaking it?
Properties of Formability (3) - Answer- - % elongation
- % reduction in area
- bend radius
Toughness - Answer- The energy required to fracture the volume of a material
(measured in foot pounds)
Properties of Toughness (2) - Answer- - impact strength
- notch sensitivity
Durablilty - Answer- Wear resistance
Properties of Durability - Answer- - Hardness
- Wear resistance
- Fatigue strength
Stress - Answer- -A force distributed over an area or object
-Stress = F/Ao
-Units: (lb/in2) or (psi or ksi) or (N/m2)
ANSWERS ALL CORRECT
Difference between interstitial and substitutional atoms - Answer- Interstitial atoms are
stronger
How do interstitial and substitutional atoms affect the crystal lattice - Answer-
Substitutional replaces the existing atoms with a bigger one while interstitial adds a lot
of atoms that are smaller
- Carbon interstitially strengthens iron latitce structure
Where are interstitial and lattice sites located in lattice structure - Answer- interstitial - in
between lattice sites
lattice sites - on corners of lattice structure
Difference between cooling curve of alloys and pure metals - Answer- Pure metals have
an actual liquid and solid line while alloys have a freezing range
*Notes
Mushy Zone - Answer- Area of liquid and solid
Coarse vs fine grains - Answer- coarse grains - less ductile, less slip
fine grains- more ductility, more slip
Types of Hardness Testing (3) - Answer- Rockwell, Brinell, Vickers or Knoop
Rockwell Hardness Testing (process) - Answer- Apply minor load, apply major load,
remove loads, calculate the difference of the indentions
Rockwell Hardness Testing (Indentors) - Answer- 1/16" Tungsten Carbide Ball for B&T
120 degree Diamond Cone or Brale for C, A, & N (EX: HRC)
Rockwell Regular loads - Answer- Minor: 10 kg
Major: 60kg, 100kg, 150kg
Rockwell Superficial loads - Answer- Minor: 3kg
Major: 15kg, 30 kg, 45kg
What does a major load mean? - Answer- Load that makes the second indention
, Differences between regular and superficial loads - Answer- regular - prefer to use this
superficial - use if material is really thin or soft
Rockwell: difference between Beuler and Wilson? - Answer- They are just different
brands, same type of rockwell hardness test
Brinell Hardness Test - Answer- Uses 10mm ball as indentor
Smash ball into metal surface and measure diameter of the indention
What are the mechanical properties of metals? - Answer- - strength
- formability
- stiffness
- toughness
- durability
Strength - Answer- Material's ability to accommodate stress
Properties of Strength (6) - Answer- - tensile
- yield
- compression
- flexural
- shearc
- creep
Formability - Answer- The easiness to shape a metal; can I bend this w/o breaking it?
Properties of Formability (3) - Answer- - % elongation
- % reduction in area
- bend radius
Toughness - Answer- The energy required to fracture the volume of a material
(measured in foot pounds)
Properties of Toughness (2) - Answer- - impact strength
- notch sensitivity
Durablilty - Answer- Wear resistance
Properties of Durability - Answer- - Hardness
- Wear resistance
- Fatigue strength
Stress - Answer- -A force distributed over an area or object
-Stress = F/Ao
-Units: (lb/in2) or (psi or ksi) or (N/m2)
