Matse 259 Final Exam Prep UPDATED ACTUAL Questions and CORRECT Answers
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Course
Matse 259
Institution
Matse 259
Matse 259 Final Exam Prep UPDATED
ACTUAL Questions and CORRECT
Answers
What is important in the Austenite --> Pearlite Transformation - CORRECT ANSWER-
Temperature, Rate of transformation (S-Curve)
for a eutectoid alloy_______temp (decreased supercooling), _______ the rate of
transform...
Matse 259 Final Exam Prep UPDATED
ACTUAL Questions and CORRECT
Answers
What is important in the Austenite --> Pearlite Transformation - CORRECT ANSWER✔✔-
Temperature, Rate of transformation (S-Curve)
for a eutectoid alloy_______temp (decreased supercooling), _______ the rate of
transformation - CORRECT ANSWER✔✔- for a eutectoid alloy increasing temp (decreased
supercooling), slows down the rate of transformation
Austenite --> Pearlite transformation occurs only if an alloy is _______to a temp ______ the
eutectoid. - CORRECT ANSWER✔✔- Austenite --> Pearlite transformation occurs only if
an alloy is supercooled to a temp below the eutectoid.
Austenite --> Pearlite transformation at temps ______ the eutectoid, it takes a ______ time to
reach 50% transformation. - CORRECT ANSWER✔✔- Austenite --> Pearlite
transformation at temps just below the eutectoid, it takes a longtime to reach 50%
transformation.
Austenite --> Pearlite transformation at higher levels of undercooling, the transformation
occurs much more _______. - CORRECT ANSWER✔✔- Austenite --> Pearlite
transformation at higher levels of undercooling, the transformation occurs much more
Rapidly.
Coarse Pearlite at a temp just below the eutectoid, thick layers of ferrite and cementite form,
and _____ diffusion allows C atoms to diffuse ______ distances and creates a _______
Lamellae. - CORRECT ANSWER✔✔- Coarse Pearlite at a temp just below the eutectoid,
thick layers of ferrite and cementite form, and high diffusion allows C atoms to diffuse long
distances and creates a thick Lamellae.
Pic
Fine Pearlite at a temp just below the eutectoid, thin layers of ferrite and cementite form, and
_____ diffusion allows C atoms to diffuse ______ distances and creates a _______ Lamellae.
,Forms at 540 degrees Celsius - CORRECT ANSWER✔✔- Fine Pearlite at a temp just below
the eutectoid, thin layers of ferrite and cementite form, and lower diffusion rates allows C
atoms to diffuse short distances and creates a thin Lamellae.
Forms at 540 degrees Celsius
Pic
In addition to pearlite, other microconstituents are formed during the transformation from the
austenite phase. Those include ________, _________, __________. - CORRECT
ANSWER✔✔- In addition to pearlite, other microconstituents are formed during the
transformation from the austenite phase, those include Bainite, Spheroidite, Martensite .
Bainite consists of __________and _________ phases and is formed by diffusional
processes. - CORRECT ANSWER✔✔- Bainite consists of ferrite and cementite phases and
is formed by diffusional processes.
Bainite forms as ________ or ________, depending on the temperature of the transformation.
Fine microstructure--> electron microscope needed. - CORRECT ANSWER✔✔- Bainite
forms as needles or plates, depending on the temperature of the transformation. Fine
microstructure--> electron microscope needed.
If a _____ or _____ microstructure is held at a temperature below the eutectoid for 18 to 24
h, a _______microstructure will form. - CORRECT ANSWER✔✔- If a pearlitic or bainitic
microstructure is held at a temperature below the eutectoid for 18 to 24 h, a spheroidite
microstructure will form.
Cementite appears as _____-like particles embedded in a ferrite matrix. - CORRECT
ANSWER✔✔- Cementite appears as sphere-like particles embedded in a ferrite matrix.
Transformation occurs by additional _____ diffusion with no change in composition -
CORRECT ANSWER✔✔- Transformation occurs by additional carbon diffusion with no
change in composition
Martensite forms when ______ is _______ cooled (quenched) to a relatively low
temperature. - CORRECT ANSWER✔✔- Martensite forms when austenite is rapidly cooled
(quenched) to a relatively low temperature.
, It is a _____ single phase structure that results from a diffusion-less transformation of _____.
Quenching rate is rapid enough to ______ carbon diffusion. - CORRECT ANSWER✔✔- It
is a non-equilibrium single phase structure that results from a diffusion-less transformation of
austenite. Quenching rate is rapid enough to prevent carbon diffusion.
Martensite has what type of crystal structure? - CORRECT ANSWER✔✔- BCT
Martensitic transformation is _____ of time and is only a function of the _____ to which the
alloy is quenched (athermal transformation) - CORRECT ANSWER✔✔- Martensitic
transformation is independent of time and is only a function of the temperature to which the
alloy is quenched (athermal transformation).
Most heat treatments for steels involve the ____ of a specimen to ______ temperature. -
CORRECT ANSWER✔✔- Most heat treatments for steels involve the continuous cooling of
a specimen to room temperature.
An isothermal transformation diagram is valid only for conditions of _______ temperature -
CORRECT ANSWER✔✔- An isothermal transformation diagram is valid only for
conditions of constant temperature
Normally, bainite _____ form at the eutectoid composition - CORRECT ANSWER✔✔-
Normally, bainite will not form at the eutectoid composition
For any cooling curve that passes through Austenite to Pearlite trans. region, the pearlite
transformation ceases and with continued cooling, the remaining austenite is transformed to
martensite. - CORRECT ANSWER✔✔- For any cooling curve that passes through Austenite
to Pearlite trans. region, the pearlite transformation ceases and with continued cooling, the
remaining austenite is transformed to martensite.
At the ______, 100% martensite will form. - CORRECT ANSWER✔✔- At the ______,
100% martensite will form.
Only martensite will exist at quenching rates greater than the critical. - CORRECT
ANSWER✔✔- Only martensite will exist at quenching rates greater than the critical.
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