Texas MMET 207 Assessment 1 Solved 100%
Correct
Types of Hardness Testing (3) - ANS-Rockwell, Brinell, Vickers or Knoop
Rockwell Hardness Testing (process) - ANS-Apply minor load, apply major load,
remove loads, calculate the difference of the indentions
Rockwell Hardness Testing (Indentors) - ANS-1/16" Tungsten Carbide Ball for B&T
120 degree Diamond Cone or Brale for C, A, & N (EX: HRC)
Rockwell Regular loads - ANS-Minor: 10 kg
Major: 60kg, 100kg, 150kg
Rockwell Superficial loads - ANS-Minor: 3kg
Major: 15kg, 30 kg, 45kg
What does a major load mean? - ANS-Load that makes the second indention
Differences between regular and superficial loads - ANS-regular - prefer to use this
superficial - use if material is really thin or soft
Rockwell: difference between Beuler and Wilson? - ANS-They are just different
brands, same type of rockwell hardness test
Brinell Hardness Test - ANS-Uses 10mm ball as indentor
Smash ball into metal surface and measure diameter of the indention
What are the mechanical properties of metals? - ANS-- strength
- formability
- stiffness
- toughness
- durability
Strength - ANS-Material's ability to accommodate stress
Properties of Strength (6) - ANS-- tensile
- yield
- compression
- flexural
- shearc
- creep
Formability - ANS-The easiness to shape a metal; can I bend this w/o breaking it?
, Properties of Formability (3) - ANS-- % elongation
- % reduction in area
- bend radius
Toughness - ANS-The energy required to fracture the volume of a material
(measured in foot pounds)
Properties of Toughness (2) - ANS-- impact strength
- notch sensitivity
Durablilty - ANS-Wear resistance
Properties of Durability - ANS-- Hardness
- Wear resistance
- Fatigue strength
Stress - ANS--A force distributed over an area or object
-Stress = F/Ao
-Units: (lb/in2) or (psi or ksi) or (N/m2)
Strain - ANS--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)
Ultimate tensile strength - ANS-The maximum stress that can be applied to a
material before it breaks
Elastic limit/Yield Point - ANS-point where a material goes from elastic to plastic;
last point on linear part of graph
Break point - ANS-End of plastic behavior; where a material breaks
What is 0.2% offset yield (Engineering yield strength) - ANS-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 - ANS-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?) - ANS-
-A measure of rigidity ( or stiffness)
- Slope of linear line
- delta stress/ delta strain (Es)
- tells a material's stiffness
Correct
Types of Hardness Testing (3) - ANS-Rockwell, Brinell, Vickers or Knoop
Rockwell Hardness Testing (process) - ANS-Apply minor load, apply major load,
remove loads, calculate the difference of the indentions
Rockwell Hardness Testing (Indentors) - ANS-1/16" Tungsten Carbide Ball for B&T
120 degree Diamond Cone or Brale for C, A, & N (EX: HRC)
Rockwell Regular loads - ANS-Minor: 10 kg
Major: 60kg, 100kg, 150kg
Rockwell Superficial loads - ANS-Minor: 3kg
Major: 15kg, 30 kg, 45kg
What does a major load mean? - ANS-Load that makes the second indention
Differences between regular and superficial loads - ANS-regular - prefer to use this
superficial - use if material is really thin or soft
Rockwell: difference between Beuler and Wilson? - ANS-They are just different
brands, same type of rockwell hardness test
Brinell Hardness Test - ANS-Uses 10mm ball as indentor
Smash ball into metal surface and measure diameter of the indention
What are the mechanical properties of metals? - ANS-- strength
- formability
- stiffness
- toughness
- durability
Strength - ANS-Material's ability to accommodate stress
Properties of Strength (6) - ANS-- tensile
- yield
- compression
- flexural
- shearc
- creep
Formability - ANS-The easiness to shape a metal; can I bend this w/o breaking it?
, Properties of Formability (3) - ANS-- % elongation
- % reduction in area
- bend radius
Toughness - ANS-The energy required to fracture the volume of a material
(measured in foot pounds)
Properties of Toughness (2) - ANS-- impact strength
- notch sensitivity
Durablilty - ANS-Wear resistance
Properties of Durability - ANS-- Hardness
- Wear resistance
- Fatigue strength
Stress - ANS--A force distributed over an area or object
-Stress = F/Ao
-Units: (lb/in2) or (psi or ksi) or (N/m2)
Strain - ANS--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)
Ultimate tensile strength - ANS-The maximum stress that can be applied to a
material before it breaks
Elastic limit/Yield Point - ANS-point where a material goes from elastic to plastic;
last point on linear part of graph
Break point - ANS-End of plastic behavior; where a material breaks
What is 0.2% offset yield (Engineering yield strength) - ANS-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 - ANS-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?) - ANS-
-A measure of rigidity ( or stiffness)
- Slope of linear line
- delta stress/ delta strain (Es)
- tells a material's stiffness
