Materials Engineering True-false a) Austenite has a FCC crystal structure. b) Th
ID: 908154 • Letter: M
Question
Materials Engineering True-false
a) Austenite has a FCC crystal structure.
b) The chemical composition of Fe3C can be anything between 2.14 and 6.70 wt% C.
c) 1030 steel is hypereutectoid.
d) The Fe-Fe3C system has three important phase reactions: one peritectic, one eutectic, and one eutectoid.
e) A 1030 steel cooled from the austenite phase field to the ferrite + cementite field would have proeutectoid ferrite, eutectoid ferrite, and cementite present in the final microstructure.
f) Eutectic solder alloys are typically stronger than hypo- or hyper-eutectoid solders in the same system.
g) The lines on a temperature-composition phase diagram represent solubility limits.
h) Steel alloys are commonly divided into families such as low-carbon or medium-carbon based on the amount of carbon in the steel.
Explanation / Answer
a) Yes , Austenite has a FCC crystal structure also known as gamma iron (-Fe)
b) True, The chemical composition of Fe3C can be anything between 2.14 and 6.70 wt% C.
Upto 2.14% it is called Austenite
c) We know that
Microstructures for iron-iron carbide alloys that have compositions between 0.76 and 2.14 wt% carbon are hypereutectoid
1030 stell has 0.28 - 0.34% of carbon
so the statement is false
d) False;The phases are cementite, ferrite and austanite