The document discusses the iron-carbon phase diagram, which maps the different crystal structures that iron alloys adopt at various temperatures and carbon concentrations. It defines various structures including ferrite, austenite, cementite, pearlite, and martensite. The diagram shows three important reaction lines - the peritectic, eutectic, and eutectoid reactions. It explains how the microstructure of steels with different carbon levels transforms during heating and cooling, resulting in different microstructures like pearlite or ferrite/cementite mixtures. The phase diagram is important for understanding the properties of steels and their heat treatment.
Iron – Carbon Diagram is also known as Iron – Carbon Phase Diagram or Iron – Carbon Equilibrium diagram or Iron – Iron Carbide diagram or Fe-Fe3C diagram
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Phase diagrams for Different Alloy
By
P.SENTHAMARAIKANNAN,
ASSISTANT PROFESSOR ,
DEPARTMENT OF MECHANICAL ENGINEERING,
KAMARAJ COLLEGE OF ENGINEERING AND TECHNOLOGY,
VIRUDHUNAGAR, TAMILNADU,
INDIA
This presentation gives a brief introduction to chemical heat treatment of steels and surface hardening techniques
Keywords: Carburising, Nitriding, Carbonitriding, Flame hardening, Laser hardening, Induction hardening
In their simplest form, steels are alloys of Iron (Fe) and Carbon (C). The Fe-C phase diagram is a fairly complex one, but we will only consider the steel and cast iron part of the diagram, up to 6.67% Carbon
Introduction to Physical Metallurgy Lecture NotesFellowBuddy.com
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Iron – Carbon Diagram is also known as Iron – Carbon Phase Diagram or Iron – Carbon Equilibrium diagram or Iron – Iron Carbide diagram or Fe-Fe3C diagram
FellowBuddy.com is an innovative platform that brings students together to share notes, exam papers, study guides, project reports and presentation for upcoming exams.
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# Students can catch up on notes they missed because of an absence.
# Underachievers can find peer developed notes that break down lecture and study material in a way that they can understand
# Students can earn better grades, save time and study effectively
Our Vision & Mission – Simplifying Students Life
Our Belief – “The great breakthrough in your life comes when you realize it, that you can learn anything you need to learn; to accomplish any goal that you have set for yourself. This means there are no limits on what you can be, have or do.”
Like Us - https://www.facebook.com/FellowBuddycom
Phase diagrams for Different Alloy
By
P.SENTHAMARAIKANNAN,
ASSISTANT PROFESSOR ,
DEPARTMENT OF MECHANICAL ENGINEERING,
KAMARAJ COLLEGE OF ENGINEERING AND TECHNOLOGY,
VIRUDHUNAGAR, TAMILNADU,
INDIA
This presentation gives a brief introduction to chemical heat treatment of steels and surface hardening techniques
Keywords: Carburising, Nitriding, Carbonitriding, Flame hardening, Laser hardening, Induction hardening
In their simplest form, steels are alloys of Iron (Fe) and Carbon (C). The Fe-C phase diagram is a fairly complex one, but we will only consider the steel and cast iron part of the diagram, up to 6.67% Carbon
Introduction to Physical Metallurgy Lecture NotesFellowBuddy.com
FellowBuddy.com is an innovative platform that brings students together to share notes, exam papers, study guides, project reports and presentation for upcoming exams.
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# Students can catch up on notes they missed because of an absence.
# Underachievers can find peer developed notes that break down lecture and study material in a way that they can understand
# Students can earn better grades, save time and study effectively
Our Vision & Mission – Simplifying Students Life
Our Belief – “The great breakthrough in your life comes when you realize it, that you can learn anything you need to learn; to accomplish any goal that you have set for yourself. This means there are no limits on what you can be, have or do.”
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Mumbai University.
Mechanical Engineering
SEM III
Material Technology
MOdule 2.2
Theory of Alloys& Alloys Diagrams :
Significance of alloying, Definition, Classification and properties of different types of alloys, Solidification of pure metal, Different types of phase diagrams (Isomorphous, Eutectic,
08
University of Mumbai, B. E. (Mechanical Engineering), Rev 2016 19
Peritectic, Eutectoid, Peritectoid) and their analysis, Importance of Iron as engineering material, Allotropic forms of Iron, Influence of carbon in Iron- Carbon alloying Iron-Iron carbide diagram and its analysis
The iron-carbon diagram (also called the iron-carbon phase or equilibrium diagram) is a graphic representation of the respective microstructure states depending on temperature (y axis) and carbon content (x axis).
Part a). Pearlite - Pearlite is a two-phased, lamellar (or l.pdfannaelctronics
>> Part a).
>> Pearlite :- Pearlite is a two-phased, lamellar (or layered) structure composed of alternating
layers of ferrite (88 wt%) and cementite (12 wt%) that occurs in some steels and cast irons. In
fact, the lamellar appearance is misleading since the individual lamellae within a colony are
connected in three dimensions; a single colony is therefore an interpenetrating bicrystal of ferrite
and cementite. In an iron-carbon alloy, during slow cooling pearlite forms by a eutectoid reaction
as austenite cools below 727 °C (1,341 °F) (the eutectoid temperature). Pearlite is a
microstructure occurring in many common grades of steels.
>> Cementite :- Cementite, also known as iron carbide, is an interstitial compound of iron and
carbon, more precisely an intermediate transition metal carbide with the formula Fe3C. By
weight, it is 6.67% carbon and 93.3% iron. It has an orthorhombic crystal structure. It is a hard,
brittle material, normally classified as a ceramic in its pure form, though it is more important in
ferrous metallurgy. While iron carbide is present in most steels and cast irons, it is produced as a
raw material in the Iron Carbide process, which belongs to the family of alternative ironmaking
technologies.
>> Austenite :- Austenite, also known as gamma-phase iron (-Fe), is a metallic, non-magnetic
allotrope of iron or a solid solution of iron, with analloying element. In plain-carbon steel,
austenite exists above the critical eutectoid temperature of 1,000 K (1,340 °F; 730 °C); other
alloys of steel have different eutectoid temperatures. It is Face Centred Cubic Configuration
(FCC).
>> Eutectoid Phase :- When the solution above the transformation point is solid, rather than
liquid, an analogous eutectoid transformation can occur. For instance, in the iron-carbon system,
the austenite phase can undergo a eutectoidtransformation to produce ferrite and cementite, often
in lamellar structures such as pearlite and bainite.
>> Proeutectoid :- When a hot steel with carbon content very close to 0.8%, is cooled down
slowly, there is a temperature (723 deg C) at which a constant-temperature transformation takes
place. This is called eutectoid transformation. And this results in formation of alternate layers of
Ferrite and Iron-Carbide (Fe3C).
But if the carbon content in this hot steel is much less than 0.8%, and it is cooled down slowly,
then till the temperature reduces to 723 deg C, a part of Austenite (also called gamma iron) gets
transformed to Ferrite by rejecting carbon from the solution. This is not a constant-temperature
process and occurs over a range of temperature. The ferrite so formed is called Proeutectoid...At
723 deg C, all the remaining Austenite get converted to Pearlite at this constant temperature -
which is nothing but alternate layers of Ferrite and cementite
>> Martensite :- Martensite, most commonly refers to a very hard form of steel crystalline
structure, but it can also refer to any crystal structure that is form.
Student information management system project report ii.pdfKamal Acharya
Our project explains about the student management. This project mainly explains the various actions related to student details. This project shows some ease in adding, editing and deleting the student details. It also provides a less time consuming process for viewing, adding, editing and deleting the marks of the students.
Industrial Training at Shahjalal Fertilizer Company Limited (SFCL)MdTanvirMahtab2
This presentation is about the working procedure of Shahjalal Fertilizer Company Limited (SFCL). A Govt. owned Company of Bangladesh Chemical Industries Corporation under Ministry of Industries.
About
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Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
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Water scarcity is the lack of fresh water resources to meet the standard water demand. There are two type of water scarcity. One is physical. The other is economic water scarcity.
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
Explore the innovative world of trenchless pipe repair with our comprehensive guide, "The Benefits and Techniques of Trenchless Pipe Repair." This document delves into the modern methods of repairing underground pipes without the need for extensive excavation, highlighting the numerous advantages and the latest techniques used in the industry.
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This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
3. Outline
Introduction
Cooling curve for pure iron
Definition of structures
Iron-Carbon equilibrium phase diagram – Sketch
The Iron-Iron Carbide Diagram - Explanation
The Austenite to ferrite / cementite
transformation
Nucleation & growth of pearlite
Effect of C %age on the microstructure of steel
Relationship b/w C %age & mechanical
properties of steel
5. Definition of structures
Various phases that appear on the
Iron-Carbon equilibrium phase
diagram are as under:
•Austenite
•Ferrite
•Pearlite
•Cementite
•Martensite*
•Ledeburite
6. Unit Cells of Various Metals
FIGURE - The unit cell for (a) austentite, (b) ferrite, and (c) martensite.
The effect of the percentage of carbon (by weight) on the lattice dimensions
for martensite is shown in (d). Note the interstitial position of the carbon
atoms and the increase in dimension c with increasing carbon content.
Thus, the unit cell of martensite is in the shape of a rectangular prism.
8. Definition of structures
Ferrite is known as α solid solution.
It is an interstitial solid solution of a small
amount of carbon dissolved in α (BCC) iron.
stable form of iron below 912 deg.C
The maximum solubility is 0.025 % C at
723C and it dissolves only 0.008 % C at
room temperature.
It is the softest structure that appears on the
diagram.
9. Definition of structures
Ferrite
Average properties are:
Tensile strength = 40,000 psi;
Elongation = 40 % in 2 in;
Hardness > Rockwell C 0 or
> Rockwell B 90
10. Definition of structures
Pearlite is the eutectoid mixture
containing 0.80 % C and is
formed at 723°C on very slow
cooling.
It is a very fine platelike or
lamellar mixture of ferrite and
cementite.
The white ferritic background or
matrix contains thin plates of
cementite (dark).
11. Definition of structures
Pearlite
Average properties are:
Tensile strength = 120,000 psi;
Elongation = 20 % in 2 in.;
Hardness = Rockwell C 20, Rockwell B
95-100, or BHN 250-300.
12. Definition of structures
Austenite is an interstitial solid solution of
Carbon dissolved in (F.C.C.) iron.
Maximum solubility is 2.0 % C at 1130°C.
High formability, most of heat treatments
begin with this single phase.
It is normally not stable at room
temperature. But, under certain conditions it
is possible to obtain austenite at room
temperature.
13. Definition of structures
Austenite
Average properties are:
Tensile strength = 150,000 psi;
Elongation = 10 percent in 2 in.;
Hardness = Rockwell C 40,
approx; and
toughness = high
14. Definition of structures
Cementite or iron carbide, is very hard,
brittle intermetallic compound of iron &
carbon, as Fe3C, contains 6.67 % C.
It is the hardest structure that appears on the
diagram, exact melting point unknown.
Its crystal structure is orthorhombic.
It is has
low tensile strength (approx. 5,000 psi),
but
high compressive strength.
15. Definition of structures
Ledeburite is the eutectic
mixture of austenite and
cementite.
It contains 4.3 percent C and is
formed at 1130°C.
16. Definition of structures
Martensite - a super-saturated solid solution of
carbon in ferrite.
It is formed when steel is cooled so rapidly that
the change from austenite to pearlite is
suppressed.
The interstitial carbon atoms distort the BCC
ferrite into a BC-tetragonal structure (BCT).;
responsible for the hardness of quenched steel
17. The Iron-Iron Carbide Diagram
A map of the temperature at which different
phase changes occur on very slow heating
and cooling in relation to Carbon, is called
Iron- Carbon Diagram.
Iron- Carbon diagram shows
the type of alloys formed under very slow
cooling,
proper heat-treatment temperature and
how the properties of steels and cast irons
can be radically changed by heat-treatment.
18. Various Features of Fe-C diagram
Peritectic L + d =
Eutectic L = + Fe3C
Eutectoid = a + Fe3C
Phases present
L
Reactions
d
BCC structure
Paramagnetic
austenite
FCC structure
Non-magnetic
ductile
a ferrite
BCC structure
Ferromagnetic
Fairly ductile
Fe3C cementite
Orthorhombic
Hard
brittle
Max. solubility of C in ferrite=0.022%
Max. solubility of C in austenite=2.11%
19. Three Phase Reactions
Peritectic, at 1490 deg.C, with low wt% C
alloys (almost no engineering importance).
Eutectic, at 1130 deg.C, with 4.3wt% C,
alloys called cast irons.
Eutectoid, at 723 deg.C with eutectoid
composition of 0.8wt% C, two-phase mixture
(ferrite & cementite). They are steels.
20. How to read the Fe-C phase diagram
Ferrite
Austenite
Steel Cast iron
Pearlite
Pearlite and
Cementine
Pearlite and
Carbide
Eutectic
eutectoid
21. The Iron-Iron Carbide Diagram
The diagram shows three horizontal lines which
indicate isothermal reactions (on cooling /
heating):
First horizontal line is at 1490°C, where peritectic
reaction takes place:
Liquid + d ↔ austenite
Second horizontal line is at 1130°C, where
eutectic reaction takes place:
liquid ↔ austenite + cementite
Third horizontal line is at 723°C, where eutectoid
reaction takes place:
austenite ↔ pearlite (mixture of ferrite &
cementite)
22. Delta region of Fe-Fe carbide diagram
Liquid + d ↔ austenite
25. The Austenite to ferrite / cementite transformation in
relation to Fe-C diagram
26. The Austenite to ferrite / cementite
transformation in relation to Fe-C diagram
In order to understand the transformation
processes, consider a steel of the eutectoid
composition. 0.8% carbon, being slow cooled
along line x-x‘.
At the upper temperatures, only austenite is
present, with the 0.8% carbon being dissolved
in solid solution within the FCC. When the steel
cools through 723°C, several changes occur
simultaneously.
27. The Austenite to ferrite / cementite
transformation in relation to Fe-C diagram
The iron wants to change crystal
structure from the FCC austenite to the
BCC ferrite, but the ferrite can only
contain 0.02% carbon in solid solution.
The excess carbon is rejected and
forms the carbon-rich intermetallic
known as cementite.
28. Pearlitic structure
The net reaction at the
eutectoid is the formation
of pearlitic structure.
Since the chemical
separation occurs entirely
within crystalline solids,
the resultant structure is a
fine mixture of ferrite and
cementite.
29. Schematic picture of the formation and
growth of pearlite
Ferrite
Cementite
Austenite
boundary
31. The Austenite to ferrite / cementite transformation in
relation to Fe-C diagram
Hypo-eutectoid steels: Steels having less than
0.8% carbon are called hypo-eutectoid steels
(hypo means "less than").
Consider the cooling of a typical hypo-eutectoid
alloy along line y-y‘.
At high temperatures the material is entirely
austenite.
Upon cooling it enters a region where the stable
phases are ferrite and austenite.
The low-carbon ferrite nucleates and grows,
leaving the remaining austenite richer in carbon.
32. The Austenite to ferrite / cementite
transformation in relation to Fe-C diagram
Hypo-eutectoid steels-
At 723°C, the remaining
austenite will have assumed
the eutectoid composition
(0.8% carbon), and further
cooling transforms it to
pearlite.
The resulting structure, is a
mixture of primary or pro-
eutectoid ferrite (ferrite that
forms before the eutectoid
reaction) and regions of
pearlite.
33. The Austenite to ferrite / cementite transformation in
relation to Fe-C diagram
Hyper-eutectoid steels (hyper means
"greater than") are those that contain more
than the eutectoid amount of Carbon.
When such a steel cools, as along line z-z' ,
the process is similar to the hypo-eutectoid
steel, except that the primary or pro-eutectoid
phase is now cementite instead of ferrite.
34. The Austenite to ferrite / cementite transformation in
relation to Fe-C diagram
As the carbon-rich phase nucleates and grows,
the remaining austenite decreases in carbon
content, again reaching the eutectoid
composition at 723°C.
This austenite transforms to pearlite upon slow
cooling through the eutectoid temperature.
The resulting structure consists of primary
cementite and pearlite.
The continuous network of primary cementite
will cause the material to be extremely brittle.
35. The Austenite to ferrite / cementite transformation in
relation to Fe-C diagram
Hypo-eutectoid steel showing primary cementite along grain
boundaries pearlite
36. The Austenite to ferrite / cementite
transformation in relation to Fe-C diagram
It should be noted that the transitions
as discussed, are for equilibrium
conditions, as a result of slow cooling.
Upon slow heating the transitions will
occur in the reverse manner.
37. The Austenite to ferrite / cementite transformation in
relation to Fe-C diagram
When the alloys are cooled rapidly, entirely
different results are obtained, since sufficient
time may not be provided for the normal phase
reactions to occur.
In these cases, the equilibrium phase diagram
is no longer a valid tool for engineering
analysis.
Rapid-cool processes are important in the heat
treatment of steels and other metals (to be
discussed later in H/T of steels).
38. Principal phases of steel and their
Characteristics
Phase
Crystal
structure
Characteristics
Ferrite BCC Soft, ductile, magnetic
Austenite FCC
Soft, moderate
strength, non-
magnetic
Cementite
Compound of Iron
& Carbon Fe3C
Hard &brittle
40. Cast Irons
-Iron-Carbon alloys of
2.11%C or more are cast
irons.
-Typical composition: 2.0-
4.0%C,0.5-3.0% Si, less
than 1.0% Mn and less
than 0.2% S.
-Si-substitutes partially for C
and promotes formation of
graphite as the carbon
rich component instead
Fe3C.
41. Applications
It is used tailor properties of steel and to heat
treat them.
It is also used for comparison of crystal
structures for metallurgists in case of rupture
or fatigue