isothermal Correct Answer: TTT curve is an ____________ transformation
coarse pearlite Correct Answer: occurs at temperatures just below eutectoid
(727°C), consists of thick layers, and has higher diffusion rates and slower cooling
rates
fine pearlite Correct Answer: occurs at temperatures around 540°C, consists of
thin layers, and has lower diffusion rates and moderately rapid cooling rates
longer Correct Answer: coarse pearlite has _______ lamellae
shorter Correct Answer: fine pearlite has _______ lamellae
proeutectoid Correct Answer: above and below the eutectoid temperature, a
_____________ phase occurs
bainite, spheroidite, and martensite Correct Answer: other micro-constituents
besides pearlite
bainite Correct Answer: this micro-constituent forms at temperatures below
pearlite
spheroidite Correct Answer: forms when a pearlitic or bainitic microstructure is
held at temperatures below eutectoid for 18 to 24 hours
carbon diffusion Correct Answer: _________ ___________ occurs with
spheroidite, but no change in composition occurs
martensite Correct Answer: micro-constituent that forms when austenite is rapidly
cooled (quenched) at relatively low temperatures
diffusionless; thermal Correct Answer: martensite formation is a _____________
and __________ transformation
BCT (body-centered tetragonal) Correct Answer: structure of martensite
,critical quenching rate Correct Answer: minimum cooling rate required to produce
a completely martensitic microstructure
bainite Correct Answer: with moderate cooling, austenite forms...
martensite Correct Answer: with rapid cooling (quenching), austenite forms...
tempered martensite Correct Answer: when martensite is reheated, it forms...
hard and brittle Correct Answer: quenched condition of martensite is...
below Correct Answer: heat treatment for tempered martensite is ______ eutectoid
temperature
ductility; toughness Correct Answer: relieving internal stresses in tempered
martensite via heat treatment increases __________ and _____________
250 to 650°C Correct Answer: temperature range for tempered martensite
fine Correct Answer: with larger carbon content, _______ pearlite has a higher
Brinell hardness number
coarse Correct Answer: with larger carbon content, _______ pearlite has larger
ductility
harder; stronger Correct Answer: bainite is __________ and __________ than
pearlite
martensite Correct Answer: ________________ is the hardest, strongest, and most
brittle steel microstructure
annealing, stress relief, normalizing, austenitizing, and spheroidizing Correct
Answer: different types of heat treatments
, annealing Correct Answer: a generic term used to denote heat treatment in which
the microstructure and, consequently, the properties of a material are altered;
previously cold-worked material is softened by recrystallization
annealing Correct Answer: heat treatment where material is exposed to an
elevated temperature for extended period of time then slowly cooled
softness; specific Correct Answer: annealing relieves stress, increases
________________, ductility, and toughness, and can produce a ____________
microstructure
heat to desired temperature, hold (soak) at this temperature, cool to room
temperature Correct Answer: steps of annealing
process annealing Correct Answer: negate the effects of cold work and softened
and increases the ductility of a strain-hardened metal (recovery and
recrystallization)
stress relief Correct Answer: heat treatment to remove residual stress
plastic deformation (i.e. machining), non-uniform cooling after processing at an
elevated temperature (i.e. welding and casting), and phase transformations induced
on cooling (i.e. martensite) Correct Answer: internal stresses can develop with...
stress relief annealing heat treatment Correct Answer: component heated to
recommended low temperature, held at this uniform temperature, and cooled to
room temperature in air
normalizing Correct Answer: refines grains and produces a more uniform and
desirable size distribution (at least 55°C above upper critical temperature),
transformed to austenite, then cooled in air
full annealing Correct Answer: heat treatment in low to medium carbon steels to
produce coarse pearlite in components that will be machined or experience
extensive plastic deformation
spheroidizing Correct Answer: carried out a temperature just below the eutectoid
in which the spheroidite microstructure is produced
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