Martensite (non equilibrium BCT phase from quench of γ) BCC Orthorhombic Iron/Carbon Phase Diagram Iron shows a eutectic with Carbon allowing for a
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[PDF] IRON –CARBON PHASE DIAGRAM
Definition of structures: Various phases that appear on the Iron- Carbon equilibrium phase diagram are as under: • Austenite • Ferrite • Pearlite • Cementite
The C-Fe (carbon-iron) system
Weighk Percent Carbon 1 Assessed Fe-C phase diagram from 0 to 25 aL Fe Stable Fe-C (graphite) and metastable Fe-Fe3C (cementite) equilibria
[PDF] The Iron - Iron Carbide (Fe-Fe C) Phase Diagram - Academic Uprm
Phases in Fe–Fe 3 C Phase Diagram ➢ α-ferrite - solid solution of C in BCC Fe • Stable form of iron at room temperature • Transforms to FCC g-austenite at
[PDF] Iron/Carbon Phase Diagram
Martensite (non equilibrium BCT phase from quench of γ) BCC Orthorhombic Iron/Carbon Phase Diagram Iron shows a eutectic with Carbon allowing for a
[PDF] Iron–Iron Carbide (Fe–Fe3C) Phase Diagram - NIFFT
The Fe-C phase diagram is a fairly complex one, but we will only consider the steel part of the diagram, up to around 7 carbon Page 2 Phases in Fe–Fe3C
[PDF] Iron Carbon Phase diagram Questions - NPTEL
Lecture 23-24 : Iron Carbon Phase diagram Questions: 1 FCC is a more close packed structure yet solubility of carbon in austenite which is FCC is higher
[PDF] Phase Diagrams - NPTEL
3) The iron-carbon system, phase transformations 4) Transformation rate effects and TTT diagrams, Microstructure and property changes in iron- carbon system
[PDF] Iron-Carbon Phase Diagram (a review) see Callister Chapter 9
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 part of the
[PDF] Iron-Carbon Phase Diagram Its defined as:- A map of the
In their simplest form, steels are alloys of Iron (Fe) and Carbon (C) Notes: - This graph, which is known as iron- carbon equilibrium diagram has the following
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Phase Behavior in Iron/Carbon System
Callister P. 252
Chapter 9
2Iron Age
1500 to 1000 BC
Iron Ore is extremely common and was used as a fluxing agent in copper smelting from malachite (Copper carbonate) Making an iron rich slag.Melting point is 1538°C
3 Copper Slag contains some reduced iron as sponge iron.Hammering compacts the sponge producing wrought iron.Iron Ore was used as a fluxing agent in copper smelting from malachite (Copper carbonate)
Making an iron rich porous slag, sponge iron.
Bronze is harder than pure iron
Iron is also subject to corrosion
So pure iron is not an advancement
over Bronze 4 Hittites (Turkey) repeatedly heated bloom in charcoal furnaces at 1200°CFollowed by working with a hammer
CO lead to the diffusion of C into the iron at the surfaceCase Hardened Steel
Even a fraction of a percent of carbon
can have a dramatic effect on hardnessHittites needed to beat bronze
in terms of hardness so their weapons could pierce bronze shieldsQuenching also hardened steel (Martensite)
(followed by tempering (heating)) 5 FCC Martensite (non equilibrium BCT phase from quench of BCCOrthorhombicIron/Carbon Phase Diagram
Iron shows a eutectic with Carbon
allowing for a lower melting alloyBody Centered Tetragonal
6 7 8Carbon content can be reduced
by reaction with oxygen and stirring 9 10Eutectoid Steel Pearlite
11Time-Temperature-Transformation Diagram
12Time-Temperature-Transformation Diagram
Just below 727°C
Thermodynamics drive is low
so time is long 13Time-Temperature-Transformation Diagram
Well below 727°C
Diffusion is slow
so time is long 14Time-Temperature-Transformation Diagram
At very deep quenches
Diffusionless Transformation
Occurs: Martinsitic
Transformation
15Hypoeutectoid Steel
16Hypoeutectoid Steel
17Hypoeutectoid Steel
18Hypoeutectoid Steel
19 20Hypereutectoid Steel
2122
Kinetics of Phase Growth
2324
Heat Treatment of Steel
Spheroidizing
: Spheroidite forms when carbon steel is heated to approximately 700°C for over 30 hours. Spheroidite can form at lower temperatures but the time needed drastically increases, as this is a diffusion-controlled process. The result is a structure of rods or spheres of cementite within primary structure (f errite or pearlite, depending on which side of the eutectoid you are on). The purpose is to soften higher carbon steels and allow more formability. This is the softest and most ductile form of steel.
Process annealing
: A process used to relieve stress in a cold-worked carbon steel with less than 0.3 wt% C. The steel is usually heated up to 550-650°C for 1
hour, but sometimes temperatures as high as 700°C.Quench and tempering
: This is the most common heat treatment encountered, because the final properties can be precisely determined by the temper ature and time of the tempering. Tempering involves reheating quenched steel to a temperature below the eutectoid temperature then cooling. The elevated temperature allows very small amounts of spheroidite to form, which rest ores ductility, but reduces hardness. Actual temperatures and times are carefully chosen for each composition. 25Martensite
Austinite => Martensite Transformation
FCC => BCT
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