MATL 240 Final Exam ACTUAL UPDATED QUESTIONS AND CORRECT
ANSWERS
Three stages of solidification of a metal Nucleation, Growth, and Formation of Grain Boundaries
Three most common crystal structures in metals Face Centered Cubic (FCC), Body Centered Cubic (BCC), and Hexagonal Close
Packed (HCP)
Does crystal structure affect metal properties? True - crystal structure significantly affects mechanical, electrical, and physical
properties
, Definition of a metal grain An area where the atoms have the same orientation
Requirement for work hardening Plastically deforming the alloy below its recrystallization temperature
Effects of work hardening Increased hardness, increased strength, decreased ductility (no change to
modulus)
Annealing/Normalizing temperature requirement Heated to approximately 100°F above the recrystallization temperature
Cooling rate for annealing Very slowly - approximately 100°F/hour (typically furnace cooled)
Cooling method for normalizing Air cooled (faster than annealing)
Effects of annealing on properties Lowest hardness, highest ductility, lowest strength (no change to modulus)
Main advantage of normalizing vs annealing Lower cost (faster air-cool vs slow furnace-cool)
Definition of strength Resistance to plastic strain (permanent deformation)
Maximum stress without plastic deformation (not Elastic Limit
measured in tensile test)
Most common measure of metal strength 0.2% Yield Strength
Definition of Ultimate Tensile Strength (UTS) The maximum stress a material can withstand in tension before necking
Definition of Fatigue Strength The stress where the alloy fractures after a specific number of stress cycles
Definition of Endurance Limit Stress where the alloy will have an infinite fatigue life (no failure regardless of
cycles)
Alloys that have an Endurance Limit Steel and Titanium alloys
ANSWERS
Three stages of solidification of a metal Nucleation, Growth, and Formation of Grain Boundaries
Three most common crystal structures in metals Face Centered Cubic (FCC), Body Centered Cubic (BCC), and Hexagonal Close
Packed (HCP)
Does crystal structure affect metal properties? True - crystal structure significantly affects mechanical, electrical, and physical
properties
, Definition of a metal grain An area where the atoms have the same orientation
Requirement for work hardening Plastically deforming the alloy below its recrystallization temperature
Effects of work hardening Increased hardness, increased strength, decreased ductility (no change to
modulus)
Annealing/Normalizing temperature requirement Heated to approximately 100°F above the recrystallization temperature
Cooling rate for annealing Very slowly - approximately 100°F/hour (typically furnace cooled)
Cooling method for normalizing Air cooled (faster than annealing)
Effects of annealing on properties Lowest hardness, highest ductility, lowest strength (no change to modulus)
Main advantage of normalizing vs annealing Lower cost (faster air-cool vs slow furnace-cool)
Definition of strength Resistance to plastic strain (permanent deformation)
Maximum stress without plastic deformation (not Elastic Limit
measured in tensile test)
Most common measure of metal strength 0.2% Yield Strength
Definition of Ultimate Tensile Strength (UTS) The maximum stress a material can withstand in tension before necking
Definition of Fatigue Strength The stress where the alloy fractures after a specific number of stress cycles
Definition of Endurance Limit Stress where the alloy will have an infinite fatigue life (no failure regardless of
cycles)
Alloys that have an Endurance Limit Steel and Titanium alloys
