热处理-铁碳相图-Fe3C-奥氏体,马氏体,铁素体(特选内容)
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But, under certain conditions it is possible to obtain austenite at room temperature.
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Cooling curve for pure iron
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Definition of structures
Various phases that appear on the Iron-Carbon equilibrium phase diagram are as under: •Austenite •Ferrite •Pearlite •Cementite •Martensite* •Ledeburite
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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
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.
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.
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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
The white ferritic background or matrix contains thin plates of cementite (dark).
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Definition of structures
Pearlite
Average properties are:
Tensile strength = 120,000 psi;
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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
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9
Baidu Nhomakorabea
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.
IRON IRON-CARBON DIAGRAM
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IRON IRON-CARBON DIAGRAM
eutectoid
Eutectic
Pearlite and Cementine
Austenite
Ferrite Pearlite
Pearlite and Carbide
Steel
Cast iron
transformation ➢ Nucleation & growth of pearlite ➢ Effect of C %age on the microstructure of steel ➢ Relationship b/w C %age & mechanical
properties of steel
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Microstructure of different phases of steel
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Definition of structures
Ferrite is known as α solid solution. It is an interstitial solid solution of a small
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.
Elongation
= 20 % in 2 in.;
Hardness
= Rockwell C 20, Rockwell B 95-100, or BHN 250-300.
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Definition of structures
Austenite is an interstitial solid solution of
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3
Cooling curve for pure iron
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4
Definition of structures
Various phases that appear on the Iron-Carbon equilibrium phase diagram are as under: •Austenite •Ferrite •Pearlite •Cementite •Martensite* •Ledeburite
优选内容
5
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
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.
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.
优选内容
2
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
The white ferritic background or matrix contains thin plates of cementite (dark).
优选内容
10
Definition of structures
Pearlite
Average properties are:
Tensile strength = 120,000 psi;
优选内容
8
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
优选内容
9
Baidu Nhomakorabea
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.
IRON IRON-CARBON DIAGRAM
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1
IRON IRON-CARBON DIAGRAM
eutectoid
Eutectic
Pearlite and Cementine
Austenite
Ferrite Pearlite
Pearlite and Carbide
Steel
Cast iron
transformation ➢ Nucleation & growth of pearlite ➢ Effect of C %age on the microstructure of steel ➢ Relationship b/w C %age & mechanical
properties of steel
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6
Microstructure of different phases of steel
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7
Definition of structures
Ferrite is known as α solid solution. It is an interstitial solid solution of a small
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.
Elongation
= 20 % in 2 in.;
Hardness
= Rockwell C 20, Rockwell B 95-100, or BHN 250-300.
优选内容
11
Definition of structures
Austenite is an interstitial solid solution of