This slide set corresponds to the MaterialsConcepts YouTube video "Muddiest Point- Phase Diagrams III: Fe-Fe3C Phase Diagram Introduction". Here's the link: http://www.youtube.com/watch?v=IUMcbctDNtM To study the vocab used in this video, visit this site: http://quizlet.com/20699470/53-steel-fe-fe3c-phase-diagram-and-microstructures-flash-cards/ This work was supported by NSF Grants #0836041 and #1226325.

1. Muddiest
Points
Phase
Diagrams
III:
Fe
–
Fe3C
Phase
Diagrams
Muddiest
Points:
•
What
is
the
difference
between
eutectoid,
hypoeutectoid,
and
hypereutectoid?
• What
are
ferrite,
austenite,
and
cemenBte?
•
“Reading
the
phase
diagram
was
very
tough.”
• “I
don’t
know
what
1020,
1060,
or
10100
steel
means.”
• “What
does
each
phase
represent?
What
is
gamma?”

2. What Are Characteristics of Important(/#0123-#4526728#
,-.,- Phases on Fe – Fe3C Diagram?
Austenite-­‐
(γ)
Gamma
Iron:
FCC
iron
with
Inters//al
solid
&$""# &)(%B/# &!C(B/#
solu/on
of
C
up
to
2.14
wt.
%
C
&!""# !#
D#
&(C!B/# EF#D#
*
@-8:-72>A7-#B/## &'""# &&!+#B/#
2.14
!*(#
EG#HA3>-<5>-#
&"""#
C&'B/#
EF#,-(/#
%""# #I#F#E### +'+#B/#
*
"*+$#
"*"''#
$""# IG#,-775>-#
I#F#,-(/# ,-(/G#/-8-<;>-#
!""#
"# &# '# (# !# )# $# $*+"#
Ferrite-­‐(α)
Alpha
Iron:
BCC
Iron
/98:935;9<.#=>*#?#/#
with
inters//al
solid
solu/on
of
C
up
to
0.022
wt%
carbon
Carbide
(CemenBte)-­‐
Iron
Carbide:
A
hard
and
"#$%&$'()*+%,&-'./*01%.*,*2(.34%*2'4()*51,2%*&''42*(.$'*$6'*)(7%8%.$*2'4()*51
bri@le
stoichiometric
(fixed
composi/on)
compound,
Fe3C.
It
has
an
orthorhombic
crystal
From
Wikimedia
Commons
structure.
Author:
#=Orci
;
*=ARTE
#

3. Fe-­‐Fe3C
Phase
Diagram
&$""# &)(%B/#
&!C(B/#
&!""# !#
D#
&(C!B/# EF#D#
@-8:-72>A7-#B/##
&'""# &&!+#B/#
2.14
!*(#
EG#HA3>-<5>-#
&"""#
C&'B/#
EF#,-(/#
%""# #I#F#E### +'+#B/#
"*+$#
"*"''#
$""# IG#,-775>-# I#F#,-(/# ,-(/G#/-8-<;>-#
!""#
"# &# '# (# !# )# $# $*+"#
/98:935;9<.#=>*#?#/#

4. &'""# &&!+#F/#
9-8?-72CE7-# Fe-­‐Fe3C
Phase
Diagram
Eutectoid
ReacBon-­‐
Steel
IK#LE3C-A5C-#
&"""#
γ
γ+
Fe3C
Temperature
°C
%""#
α
+
γ
727
°C
0.022
0.76
$""#
α
α
+
Fe3C
Fe3C
M#J#,-
!""#
"# CEutectoid
&# '# (#
6.67
Hypoeutectoid
Comp.
Hypereutectoid
Comp.
Composi/on-­‐
Wt.
%
C
/>8?>35@>A

5. &(G!F/# IJ#H#
9-8?-72CE7-#F/##
&'""#
Steel
Terminology
&
Phase
ProperBes
&&!+
()*()+,"-./0)"12/34/5"678)98:2;"<)/9=:>*"?8
IK#LE3C-A5C-#
&"""#
General
Proper/es:
#M#J#I###
"*+$#
!" !$"()+,"
• Ferrite:
α
-­‐
BCC
Fe
0.022
wt%
C
max.
DucBle.
!"#$"%&'(%")*+))
%""# "#"$"!"""
D'D"F,"
• Austenite:
γ
-­‐
FCC
Fe
2.14%
C
max.
DucBle.
"*"''# %&%''" %&DE"
• CemenBte:
Fe3C
–
Stoichiometric.
Hard
and
bri`le
ceramic.
MK#,-775C-#
$""# "#" #"$"()+,"
()+,"
!""#
"# +5('"6',.7) &# '# (#
8389)
SAE-­‐AISI
Terminology:
YY
XXX
Carbon
Steel
ABC:)78)98:2;",:5C&" ABC)4)78)98:2;",:5C&"
• First
2
or
3
digits
give
steel
alloy
type
+,#$,-./,01)2'3)4)+) />8?>
• 10xx
is
plain
carbon
steel
(no
alloy
elements)
"#$%&$'()*+%,&-'./*01%.*,*2(.34%*2'4()
AISI
Carbon
Steel
ClassificaBon
Chart
• 41xx
is
a
common
alloy
steel
(Cr
0.5-­‐0.95%;
Mo
0.12-­‐0.30%)
• See
h`p://www.keytometals.com/page.aspx? ClassificaBon
%
Carbon
ID=CheckArBcle&site=kts&NM=333
for
more
informaBon
Low
Carbon
<0.30%
C
Medium
Carbon
0.30%-­‐0.60%
• Second
2
or
3
digits
give
%C
content
x
100
High
Carbon
0.60%-­‐1.00%
• YY80
has
0.80
wt%
C
Ultrahigh
Carbon
1.25%-­‐
2.00%
• YY100
has
1.0
wt.%
C

6. ApplicaBons
for
Steel
Types
Low
Carbon
Steel:
Used
for
automobile
body
panels
*
and
low-­‐strength
wires
*
Medium
Carbon
Steel:
Used
for
axles,
gears,
rails,
and
railway
wheels
#
High
Carbon
Steel:
Used
for
springs
and
high-­‐
strength
wires
*
41XX
Alloy
Steels:
Used
for
components
in
fossil
fuel
and
nuclear
power
plants
See
h@p://www.keytometals.com/Ar/cles/Art62.htm
for
more
informa/on
*=
From
Clker.com
#=
Wikimedia
Commons,
author
Rkingsbury-­‐
Background
removed

7. How Does Carbon Content Affect Mechanical Properties?
,-.,-(/#
#&!" #'!"
Yield
a!"#$%&'(%&)#(*"$#&+,-#(.,/&01234& (MPA)
nd
Tensile
Strength
#'!"
,-.,-(/#0123-#452 #)!"
#)!" G&'F/# #!!"
%
ElongaBon
!"#$%&'()%&"
)#(*"$#&+,-#(.,/&
#!!" (!"
&$""# &)(%F/# &$""# &)(%F/#
&!G(F/# &!G(F/#
(!" &!"
&!""# !# &!""# !#
!"#$%&+,-#(.,/&
&!" '!"
*"+,-./01-."
&(G!F/# IJ#H#
&(G!F/#
9-8?-72CE7-#F/##
&'""# '!" &'""#
)!"
&&!+#F/#
IK#LE3C-A5C-# IK#LE3C-A5C-#
!" !$%" #" !" !$%" #"
&"""# 56786*"96(&0:,;&54&& &"""# *%+,%-.)%&"/01!"*2""
I### ComposiBon
(wt%
C)
ComposiBon
(wt%
C)
"*+$#
Temperature
°C
Temperature
°C
%""# %""#
"*"''#
MK#,-775C-#
$""# $""#
M#J
!""# !""#
"# ComposiBon
(wt%
C)
&# "# ComposiBon
(wt%
C)
'# &# (#
/>8?>35@
As
wt%
C
:Yield
and
Tensile
Strength
and
%
ElongaBon

8. Muddiest
Points
Phase
Diagrams
III:
Fe
–
Fe3C
Phase
Diagrams
Muddiest
Points:
•
What
is
the
difference
between
eutectoid,
hypoeutectoid,
and
hypereutectoid?
• What
are
ferrite,
austenite,
and
cemenBte?
•
“Reading
the
phase
diagram
was
very
tough.”
• “I
don’t
know
what
1020,
1060,
or
10100
steel
means.”
• “What
does
each
phase
represent?
What
is
gamma?”