ME215 Exam 2 Study Guide With
Complete Solutions
Annealing - ANSWER - Cooling in furnace
- Cost effective and time consuming
- The furnace imposes cooling conditions at all locations
- Result in identical structures and properties
Normalizing - ANSWER - Cooling in air
- Cooling will be different in different locations
- Properties will vary between the surface and interior
Process Anneal - ANSWER - Cooling in air
Recrystallization Anneal - ANSWER - Recrystallization is induced after a
material has been cold worked to reduce strain hardening effects
- Induces a change in size, shape and distribution
Stress-Relief Anneal - ANSWER - Reduces residual stresses
- Materials are heated and then slow cooled
- Microstructures and mechanical properties remain unchanged
Spheroidizing Anneal - ANSWER - Slow cooling
- For high carbon materials
,Heat Treatment - ANSWER - A process of controlled heating and cooling of
materials for the purpose of altering their structures and properties, which
changes in physical and mechanical properties can be introduced with no
change in product shape
Processing heat treatments are used to... - ANSWER - increase strength
- prepare the material for fabrication
- improve machining characteristics
- reduce forming forces
- restore ductility for further processing
Heat Treatments for Nonferrous Metals - ANSWER Three purposes
- Produce a uniform, homogenous structure
- Provide a stress relief
Induce recrystallization
Solid-Solution Strengthening - ANSWER Substitutional solutions or
interstitial solutions
Strain Hardening - ANSWER Increases strength by plastic deformation
Grain Size Refinement - ANSWER Metals with smaller grains tend to be
stronger
Precipitation hardening or Age hardening - ANSWER Strength is obtained
from a nonequilibrium structure
Dispersion Hardening - ANSWER Dispersing second-phase particles
through a base material
Phase transformations - ANSWER Heated to form a single phase at an
elevated temperature and subsequently transform to one or more low
temperature phases upon cooling (austenite -> martensite)
Precipitation Hardening - ANSWER - Most effective mechanism to
strengthen nonferrous metals
- Non-equilibrium heat treatment procedure
Process of Precipitation Hardening - ANSWER Three-step Sequence:
solution treatment -> quench -> aged
,Coherency - A Coherent Precipitate - ANSWER The crystallographic
planes of the parent structure are continuous through the precipitate
cluster, and the solute aggregate tends to distort the lattice to a substantial
surrounding regiong
Non-Coherency (Overage) - ANSWER Second phase particles have their
own crystal structure and distinct interphase boundaries
Overaging - ANSWER The decrease in hardness and strength of
precipitation or age hardened materials
Aging Step - ANSWER Divide precipitation-hardening materials into two
types: natural aging materials (ages at room temperature) and artificial
aging material (requires elevated temperature to produce aging)
Tempering - ANSWER To sacrifice strength and hardness for ductility and
toughness
Age Hardening - ANSWER To sacrifice toughness and ductility for strength
Continuous Cooling Transformations (CCT) - ANSWER The modification of
ttt diagram, shows the phase and composition of steels upon cooling as
functions of temperature and time
Jominy Test - ANSWER The hardenability test - a material is heated and
quenched from one end, then hardness along the material length is
determined
Carbon Content - ANSWER The larger carbon content the higher strength,
the higher hardness
Alloy Additions - ANSWER Related to the amounts and types of alloying
elements; Primary reason to add an alloying element is to increase
hardenability
Quench Media - ANSWER Quenchants are the medium in which a material
is quenched
, Stages of Quenching - ANSWER Formation of the vapor jacket -> Nucleate
boiling phase -> Conduction and convection
Quenchant Consideration - ANSWER - Water is an effective quenching
medium because of its high heat of vaporization and relatively high boiling
point
- Brine is similar to water as a quenchant medium
- Oil is utilized if slower quenching rates are desired
- Water based polymer quenchants have properties between oil and water
and brine
- Other slow cooling quenchants: Molten salt baths, cooling in air, bury the
hot material in sand, etc.
Residue Stress - ANSWER - Exist in a part independent of an applied
stress
- Undesirable residual stresses result in cracking, warping, dimensional
changes
Causes of dimensional changes during heat treatment - ANSWER -
Thermal expansion during heating and thermal contraction during cooling
- Volume expansion and contraction
Ways to prevent quench cracking and residual stresses - ANSWER - More
uniform cross-sectional area
- Generous fillets at interior area
- Radiused exterior corners
- Smooth transitions
- Adding additional holes
Austempering - ANSWER Austenite -> Bainite, rapidly quench into liquid
medium 15 degrees celcius above Martensite start temperature and held
for sufficient time
Ausforming - ANSWER Thermomechanical processes in which deformation
and heat treatment are intimately combined. Material is heated to form
austenite and then quenched to a temperature between pearlite and
bainite; then slowly cooled to produce bainite or rapidly quench to
martensite
Complete Solutions
Annealing - ANSWER - Cooling in furnace
- Cost effective and time consuming
- The furnace imposes cooling conditions at all locations
- Result in identical structures and properties
Normalizing - ANSWER - Cooling in air
- Cooling will be different in different locations
- Properties will vary between the surface and interior
Process Anneal - ANSWER - Cooling in air
Recrystallization Anneal - ANSWER - Recrystallization is induced after a
material has been cold worked to reduce strain hardening effects
- Induces a change in size, shape and distribution
Stress-Relief Anneal - ANSWER - Reduces residual stresses
- Materials are heated and then slow cooled
- Microstructures and mechanical properties remain unchanged
Spheroidizing Anneal - ANSWER - Slow cooling
- For high carbon materials
,Heat Treatment - ANSWER - A process of controlled heating and cooling of
materials for the purpose of altering their structures and properties, which
changes in physical and mechanical properties can be introduced with no
change in product shape
Processing heat treatments are used to... - ANSWER - increase strength
- prepare the material for fabrication
- improve machining characteristics
- reduce forming forces
- restore ductility for further processing
Heat Treatments for Nonferrous Metals - ANSWER Three purposes
- Produce a uniform, homogenous structure
- Provide a stress relief
Induce recrystallization
Solid-Solution Strengthening - ANSWER Substitutional solutions or
interstitial solutions
Strain Hardening - ANSWER Increases strength by plastic deformation
Grain Size Refinement - ANSWER Metals with smaller grains tend to be
stronger
Precipitation hardening or Age hardening - ANSWER Strength is obtained
from a nonequilibrium structure
Dispersion Hardening - ANSWER Dispersing second-phase particles
through a base material
Phase transformations - ANSWER Heated to form a single phase at an
elevated temperature and subsequently transform to one or more low
temperature phases upon cooling (austenite -> martensite)
Precipitation Hardening - ANSWER - Most effective mechanism to
strengthen nonferrous metals
- Non-equilibrium heat treatment procedure
Process of Precipitation Hardening - ANSWER Three-step Sequence:
solution treatment -> quench -> aged
,Coherency - A Coherent Precipitate - ANSWER The crystallographic
planes of the parent structure are continuous through the precipitate
cluster, and the solute aggregate tends to distort the lattice to a substantial
surrounding regiong
Non-Coherency (Overage) - ANSWER Second phase particles have their
own crystal structure and distinct interphase boundaries
Overaging - ANSWER The decrease in hardness and strength of
precipitation or age hardened materials
Aging Step - ANSWER Divide precipitation-hardening materials into two
types: natural aging materials (ages at room temperature) and artificial
aging material (requires elevated temperature to produce aging)
Tempering - ANSWER To sacrifice strength and hardness for ductility and
toughness
Age Hardening - ANSWER To sacrifice toughness and ductility for strength
Continuous Cooling Transformations (CCT) - ANSWER The modification of
ttt diagram, shows the phase and composition of steels upon cooling as
functions of temperature and time
Jominy Test - ANSWER The hardenability test - a material is heated and
quenched from one end, then hardness along the material length is
determined
Carbon Content - ANSWER The larger carbon content the higher strength,
the higher hardness
Alloy Additions - ANSWER Related to the amounts and types of alloying
elements; Primary reason to add an alloying element is to increase
hardenability
Quench Media - ANSWER Quenchants are the medium in which a material
is quenched
, Stages of Quenching - ANSWER Formation of the vapor jacket -> Nucleate
boiling phase -> Conduction and convection
Quenchant Consideration - ANSWER - Water is an effective quenching
medium because of its high heat of vaporization and relatively high boiling
point
- Brine is similar to water as a quenchant medium
- Oil is utilized if slower quenching rates are desired
- Water based polymer quenchants have properties between oil and water
and brine
- Other slow cooling quenchants: Molten salt baths, cooling in air, bury the
hot material in sand, etc.
Residue Stress - ANSWER - Exist in a part independent of an applied
stress
- Undesirable residual stresses result in cracking, warping, dimensional
changes
Causes of dimensional changes during heat treatment - ANSWER -
Thermal expansion during heating and thermal contraction during cooling
- Volume expansion and contraction
Ways to prevent quench cracking and residual stresses - ANSWER - More
uniform cross-sectional area
- Generous fillets at interior area
- Radiused exterior corners
- Smooth transitions
- Adding additional holes
Austempering - ANSWER Austenite -> Bainite, rapidly quench into liquid
medium 15 degrees celcius above Martensite start temperature and held
for sufficient time
Ausforming - ANSWER Thermomechanical processes in which deformation
and heat treatment are intimately combined. Material is heated to form
austenite and then quenched to a temperature between pearlite and
bainite; then slowly cooled to produce bainite or rapidly quench to
martensite
