MMET 207 FINAL EXAM - TAMU – CRAIG
Types of Hardness Testing (3) - Answers :Rockwell, Brinell, Vickers or Knoop
Can FCC or BCC hold more carbon? - Answers :FCC
Are Hardness Rockwell B (HRB) and Hardness Brinell (HB) the same or different tests?
- Answers :Different
(more/less)
___ grains = ____ ductility = ____ slip - Answers :smaller grains = more ductility = more
slip
vice versa
(higher/lower)
___ temp --> ___ grain size - Answers :higher temp --> larger grins size
(higher/lower)
___ MoE --> ___ deflection - Answers :higher MoE = less deflection (droop)
MoE of: (all x 10^6)
Carbon Steel
Titanium
Aluminum
Plastics - Answers :Carbon Steel: 30
Titanium: 20
Aluminum: 10
Plastics: .5
What is the microstructure of the Delta Iron Triangle? - Answers :BCC
Is grain size a determining factor in if a material is BCC/FCC or
Austenite/Ferrite/Pearlite? - Answers :No, you can have any grain size of the same
material
What motion is used for wear testing? - Answers :Rubbing
What heat treatments soften a material? - Answers :Tempering, annealing, stress
relieving, and normalizing
Rockwell Hardness Testing (process) - Answers :Apply minor load, apply major load,
remove loads, calculate the difference of the indentions
Rockwell Hardness Testing (Indentors) - Answers :1/16" Tungsten Carbide Ball for B&T
120 degree Diamond Cone or Brale for C, A, & N (EX: HRC)
,Rockwell Regular loads - Answers :Minor: 10 kg
Major: 60kg, 100kg, 150kg
Rockwell Superficial loads - Answers :Minor: 3kg
Major: 15kg, 30 kg, 45kg
What does a major load mean? - Answers :Load that makes the second indention
Differences between regular and superficial loads - Answers :regular - prefer to use this
superficial - use if material is really thin or soft
Rockwell: difference between Beuler and Wilson? - Answers :They are just different
brands, same type of rockwell hardness test
Brinell Hardness Test - Answers :Uses 10mm ball as indentor
Smash ball into metal surface and measure diameter of the indention
What are the mechanical properties of metals? - Answers :- strength
- formability
- stiffness
- toughness
- durability
Strength - Answers :The max load a material can take before fracture
Properties of Strength (6) - Answers :- tensile
- yield
- compression
- flexural
- shearc
- creep
Formability - Answers :The easiness to shape a metal; can I bend this w/o breaking it?
Properties of Formability (3) - Answers :- % elongation
- % reduction in area
- bend radius
Toughness - Answers :The energy required to fracture the volume of a material
(measured in foot pounds)
Properties of Toughness (2) - Answers :- impact strength
- notch sensitivity
Durablilty - Answers :Wear resistance
,Properties of Durability - Answers :- Hardness
- Wear resistance
- Fatigue strength
Stress - Answers :-A force distributed over an area or object
-Stress = F/Ao
-Units: (lb/in2) or (psi or ksi) or (N/m2)
Strain - Answers :-Percentage size change of a material in a particular direction when
subjected to a force in that direction
-Strain (Es) = Lf - Lo / Lo
-Units: none or (in/in) or (m/m)
What does the size of the area under the stress-strain curve indicate about a metal? -
Answers :How much energy is absorbed when the material breaks
Draw and label a stress-strain curve - Answers :
What is the difference in stress/strain diagram for ductile and brittle materials? -
Answers :
Ultimate tensile strength - Answers :The maximum stress that can be applied to a
material before it breaks
Elastic limit/Yield Point - Answers :point where a material goes from elastic to plastic;
last point on linear part of graph
Break point - Answers :End of plastic behavior; where a material breaks
What is 0.2% offset yield (Engineering yield strength) - Answers :the stress at which a
material exhibits a specified deviation from proportionality of stress/strain. Also, it hard
to determine precisely so yield point is considered at an offset strain of 0.2%
How to find 0.2% offset yield - Answers :determining .002 strain and traveling parallel to
modulus of elasticity
Modulus of Elasticity
(What is it?, formula, where on stress/strain curve, tell about the material?) - Answers :-
A measure of rigidity ( or stiffness)
- Slope of linear line
- delta stress/ delta strain (Es)
- tells a material's stiffness
Modulus of Elasticity of Steel - Answers :E(steel) = 30x10^6 psi
Standard gauge for tensile specimens - Answers :2 inches
, Elastic Behavior - Answers :returns to original shape
Plastic Behavior - Answers :Does not return to original shape... permanent deformation
Necking - Answers :Tensile deformation where relatively large amounts of strain localize
disproportionately in a small region of the material (post UTS an about to break)
Impact testing (what for) - Answers :Tests toughness; measures a materials ability to
with stand a shock load
- Temperature also has a huge impact on it
Impact Testing (how) - Answers :Take a material that is NOTCHED, whack it with
pendulum or hammer; Charpy Vee or Izod
Charpy Impact Testing - Answers :- Has a notch in it and is facing away from impact
- Done more often, easier, faster
what does the difference between Charpy and Izod impact testing look like - Answers :
Nil Ductility Temp - Answers :the temp at which the toughness of a material drops below
the DBTT
DBTT - Answers :Ductile to Brittle Transition Temperature
Fatigue Strength - Answers :The highest stress that a material can withstand for a given
number of cycles without breaking
Fatigue Strength/ Endurance Test - Answers :Continuously loading (bending back and
forth) a material at given stress levels until it breaks
Endurance Limit/ fatigue strength - Answers :The point where you can bend a metal
back and forth infinite times and it never breaks
Creep Strength - Answers :the resistance of a material to plastic deformation under a
sustained load
Creep units - Answers :% deformation at a given stress
TRUE/FALSE: a Creep testing temperature must be shown - Answers :TRUE
Creep Testing - Answers :Used to rate the resistance of a material to plastic
deformation under a sustained load and temp; a load is put on a material and when load
is taken off, did it retain elasticity
- EX: Fan blade in container
Types of Hardness Testing (3) - Answers :Rockwell, Brinell, Vickers or Knoop
Can FCC or BCC hold more carbon? - Answers :FCC
Are Hardness Rockwell B (HRB) and Hardness Brinell (HB) the same or different tests?
- Answers :Different
(more/less)
___ grains = ____ ductility = ____ slip - Answers :smaller grains = more ductility = more
slip
vice versa
(higher/lower)
___ temp --> ___ grain size - Answers :higher temp --> larger grins size
(higher/lower)
___ MoE --> ___ deflection - Answers :higher MoE = less deflection (droop)
MoE of: (all x 10^6)
Carbon Steel
Titanium
Aluminum
Plastics - Answers :Carbon Steel: 30
Titanium: 20
Aluminum: 10
Plastics: .5
What is the microstructure of the Delta Iron Triangle? - Answers :BCC
Is grain size a determining factor in if a material is BCC/FCC or
Austenite/Ferrite/Pearlite? - Answers :No, you can have any grain size of the same
material
What motion is used for wear testing? - Answers :Rubbing
What heat treatments soften a material? - Answers :Tempering, annealing, stress
relieving, and normalizing
Rockwell Hardness Testing (process) - Answers :Apply minor load, apply major load,
remove loads, calculate the difference of the indentions
Rockwell Hardness Testing (Indentors) - Answers :1/16" Tungsten Carbide Ball for B&T
120 degree Diamond Cone or Brale for C, A, & N (EX: HRC)
,Rockwell Regular loads - Answers :Minor: 10 kg
Major: 60kg, 100kg, 150kg
Rockwell Superficial loads - Answers :Minor: 3kg
Major: 15kg, 30 kg, 45kg
What does a major load mean? - Answers :Load that makes the second indention
Differences between regular and superficial loads - Answers :regular - prefer to use this
superficial - use if material is really thin or soft
Rockwell: difference between Beuler and Wilson? - Answers :They are just different
brands, same type of rockwell hardness test
Brinell Hardness Test - Answers :Uses 10mm ball as indentor
Smash ball into metal surface and measure diameter of the indention
What are the mechanical properties of metals? - Answers :- strength
- formability
- stiffness
- toughness
- durability
Strength - Answers :The max load a material can take before fracture
Properties of Strength (6) - Answers :- tensile
- yield
- compression
- flexural
- shearc
- creep
Formability - Answers :The easiness to shape a metal; can I bend this w/o breaking it?
Properties of Formability (3) - Answers :- % elongation
- % reduction in area
- bend radius
Toughness - Answers :The energy required to fracture the volume of a material
(measured in foot pounds)
Properties of Toughness (2) - Answers :- impact strength
- notch sensitivity
Durablilty - Answers :Wear resistance
,Properties of Durability - Answers :- Hardness
- Wear resistance
- Fatigue strength
Stress - Answers :-A force distributed over an area or object
-Stress = F/Ao
-Units: (lb/in2) or (psi or ksi) or (N/m2)
Strain - Answers :-Percentage size change of a material in a particular direction when
subjected to a force in that direction
-Strain (Es) = Lf - Lo / Lo
-Units: none or (in/in) or (m/m)
What does the size of the area under the stress-strain curve indicate about a metal? -
Answers :How much energy is absorbed when the material breaks
Draw and label a stress-strain curve - Answers :
What is the difference in stress/strain diagram for ductile and brittle materials? -
Answers :
Ultimate tensile strength - Answers :The maximum stress that can be applied to a
material before it breaks
Elastic limit/Yield Point - Answers :point where a material goes from elastic to plastic;
last point on linear part of graph
Break point - Answers :End of plastic behavior; where a material breaks
What is 0.2% offset yield (Engineering yield strength) - Answers :the stress at which a
material exhibits a specified deviation from proportionality of stress/strain. Also, it hard
to determine precisely so yield point is considered at an offset strain of 0.2%
How to find 0.2% offset yield - Answers :determining .002 strain and traveling parallel to
modulus of elasticity
Modulus of Elasticity
(What is it?, formula, where on stress/strain curve, tell about the material?) - Answers :-
A measure of rigidity ( or stiffness)
- Slope of linear line
- delta stress/ delta strain (Es)
- tells a material's stiffness
Modulus of Elasticity of Steel - Answers :E(steel) = 30x10^6 psi
Standard gauge for tensile specimens - Answers :2 inches
, Elastic Behavior - Answers :returns to original shape
Plastic Behavior - Answers :Does not return to original shape... permanent deformation
Necking - Answers :Tensile deformation where relatively large amounts of strain localize
disproportionately in a small region of the material (post UTS an about to break)
Impact testing (what for) - Answers :Tests toughness; measures a materials ability to
with stand a shock load
- Temperature also has a huge impact on it
Impact Testing (how) - Answers :Take a material that is NOTCHED, whack it with
pendulum or hammer; Charpy Vee or Izod
Charpy Impact Testing - Answers :- Has a notch in it and is facing away from impact
- Done more often, easier, faster
what does the difference between Charpy and Izod impact testing look like - Answers :
Nil Ductility Temp - Answers :the temp at which the toughness of a material drops below
the DBTT
DBTT - Answers :Ductile to Brittle Transition Temperature
Fatigue Strength - Answers :The highest stress that a material can withstand for a given
number of cycles without breaking
Fatigue Strength/ Endurance Test - Answers :Continuously loading (bending back and
forth) a material at given stress levels until it breaks
Endurance Limit/ fatigue strength - Answers :The point where you can bend a metal
back and forth infinite times and it never breaks
Creep Strength - Answers :the resistance of a material to plastic deformation under a
sustained load
Creep units - Answers :% deformation at a given stress
TRUE/FALSE: a Creep testing temperature must be shown - Answers :TRUE
Creep Testing - Answers :Used to rate the resistance of a material to plastic
deformation under a sustained load and temp; a load is put on a material and when load
is taken off, did it retain elasticity
- EX: Fan blade in container
