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Questions and Answers
The martensite transformation is a diffusion-controlled process.
The martensite transformation is a diffusion-controlled process.
False
The temperature range for the formation of martensite is between 600°C to 400°C.
The temperature range for the formation of martensite is between 600°C to 400°C.
True
The resulting microstructure of martensite transformation is composed of ferrite and cementite.
The resulting microstructure of martensite transformation is composed of ferrite and cementite.
False
The formation of martensite requires a specific percentage of carbon in the alloy.
The formation of martensite requires a specific percentage of carbon in the alloy.
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The austenite to martensite transformation is a slow process that occurs over a long period of time.
The austenite to martensite transformation is a slow process that occurs over a long period of time.
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The microstructure of martensite is characterized by the presence of pearlite.
The microstructure of martensite is characterized by the presence of pearlite.
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Tempering reduces internal stresses caused by quenching in martensite transformation.
Tempering reduces internal stresses caused by quenching in martensite transformation.
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The process of tempering produces extremely large Fe3C particles surrounded by α.
The process of tempering produces extremely large Fe3C particles surrounded by α.
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The increase in C content results in a decrease in TS and YS.
The increase in C content results in a decrease in TS and YS.
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Pearlite is a hard phase in the Fe-C system.
Pearlite is a hard phase in the Fe-C system.
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Hypereutectoid alloys have a C content less than 0.76 wt%.
Hypereutectoid alloys have a C content less than 0.76 wt%.
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Fine pearlite has a larger microstructure than coarse pearlite.
Fine pearlite has a larger microstructure than coarse pearlite.
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Increasing the austenite grain size increases the alloy strength.
Increasing the austenite grain size increases the alloy strength.
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A slower cooling rate produces finer lamellae in the pearlite.
A slower cooling rate produces finer lamellae in the pearlite.
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The transformation temperature of 675°C corresponds to the eutectoid composition of 0.77 wt% C.
The transformation temperature of 675°C corresponds to the eutectoid composition of 0.77 wt% C.
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Austenite is stable at temperatures above 727°C.
Austenite is stable at temperatures above 727°C.
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Rapidly cooling to 625°C and then holding it constant is an example of an isothermal transformation.
Rapidly cooling to 625°C and then holding it constant is an example of an isothermal transformation.
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The rate of transformation of austenite to pearlite increases with increasing ΔT.
The rate of transformation of austenite to pearlite increases with increasing ΔT.
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