ZUBAIR AHMAD
UNITED GULF STEEL
Rolling
(Hot/Cold)
=
Permanent
Deformation
=
Mechanical
Working
Mechanical Working
Is a permanent deformation to which metal is
subjected to change its shape and/or properties.
Reheating
• > 1200 °C
• Austenitizing
Roughing
• Grain Refinement
• Recrystallization
Finishing
• Grain Refinement
• Precipitation
Cooling
• Austenite
Decomposition
• Accelerated Cooling
Slab Chemistry
Chemistry
(C, Mn, Ni, Cu, MAE)
Thickness & Temperature
Reduction
Coiling
• Precipitation
• Phase
transformation
PSL2:
• YS (min/max)
• UTS (min/max)
• YS/UTS
• CVN
• DWTT
Strength
Ductility
Toughness
Steel
Mechanical
Properties
Weldability
• CEPcm
…etc
Sour Resistance
• HIC
• SSCC
Steel
Mechanical
Properties
Chemistry
Processing
Parameters
5
Basic Metallurgy
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ُ‫َوأن َزلنا ال َحديد فيه َبأسٌ شديد َو َمنافع‬
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ٌ ِ ‫ِللن‬
‫اس‬
1- Meteoric Iron
(5 – 30 % nickel)
Limited
2- Telluric (Native) Iron
(Grains or nodules of Iron in basalt that erupted
through beds of coal)
3- Man-made Ferrous Metals.
(Use charcoal to reduce iron from its oxides)
Fe2O3 + 3CO → 2Fe + 3 CO2
Rare
Basic Metallurgy
Iron is so important that primitive societies are
measured by the point at which they learn how to
refine iron and enter the iron age!
Gold is for the mistress ….
silver for the maid
Copper for the craftsman cunning at his trade.
"But Iron … Cold Iron … is master of them all !“
Rudyard Kipling, 1910
Basic Metallurgy
Iron
• Strong material
• Easy to shape
• Conduct heat and
electricity
• Unique magnetic properties
• Iron is plentiful (5% of the
Earth's crust)
• Relatively easy to refine
Basic Metallurgy
Iron ores are rocks that contain a high concentration of iron
• Hematite - Fe2O3 - 70 % iron
• Magnetite - Fe3O4 - 72 % iron
• Limonite - Fe2O3 + H2O - 50 % to 66 % iron
• Siderite -
FeCO3 - 48 % iron
Hematite
Basic Metallurgy
Grains
Crystal
Structure
Basic Metallurgy
Crystal Structure
(Atomic Arrangement)
Atom
Y
Z
X
Space Lattice: A collection of
points that divided space into
smaller sized segments.
Unit Cell: A subdivision of the
lattice that still retains the overall
characteristics of the entire lattice.
Basic Metallurgy
Formation of Polycrystalline Material
Solid (Unit Cell)
Liquid
a
b
c
d
a) Small crystalline nuclei b) Growth of Crystals
c) Irregular grain shapes d) Final grain structure
formed upon completion
of solidification
Grain Boundary: The zone of
crystalline mismatch between
adjacent grains. The lattice has
different orientation on either
side of the grain boundary
Grain Boundary
Basic Metallurgy
Atomic Packing in Iron (Allotropic)
1540 oC
BCC - Delta Iron (d)
1400 oC
FCC - Gamma Iron (g)
910 oC
BCC - Alpha Iron (a)
Basic Metallurgy
Body Centered Cubic (BCC)
Alpha & Delta Iron (a , d)
Total 2 Atoms/Unit Cell
Squared Packed Layer
α Lattice Parameter (a) = 0.287 nm
δ Lattice Parameter (a) = 0.293 nm
a
Basic Metallurgy
Face Centered Cubic (FCC)
Gamma Iron (g)
Total 4 Atoms/Unit Cell
g Lattice Parameter (a) = 0.359 nm
Close Packed Layer
a
Basic Metallurgy
Effect of the Atomic Packing in Deformation Behavior
Displacement
Slip
Distance
High Dense Atomic Packing
Displacement
Slip
Distance
Low Dense Atomic Packing
Slip occurs easily on closest packed plane (high atomic packing density) along
the closest packed direction where the slip distance is minimum.
Basic Metallurgy
Effect of the Atomic Packing in Deformation Behavior
Smooth Surface
Easy to slip with minimum power
Example of closed Packed planes
Uneven Surface
Relatively high energy is
required for limited slip
Example of squared packed plans
Rough Surface
Extremely hard to slip
Example of squared packed plans
with high inter-atom spaces
Basic Metallurgy
STEEL = IRON + Alloying Elements ( C + Mn, Si, Ni, …)
What is the difference between “STEEL” and “CAST IRON” ?
IRON + < 2 % Carbon = STEEL
IRON + > 2 % Carbon = CAST IRON
Iron Carbon Phase Diagram
1600 -
(d+L)
1540
0.5%
1495
Liquid (L)
(d+g )
0.18%
1400 Peritectic
Delta Ferrite 0.1%
(d)
(g+L)
Temperature (oC)
1200 -
1150 °C
Austenite (g )
2.1%
Eutectic
1000 -
( g + Fe3C )
910
800 -
(a+g)
727 °C
Eutectoid
600 Ferrite (a )
400 -
Ferrite + Pearlite
Cementite (Fe3C)+ Pearlite
200 -
0-
0.8%
2.0
1.0
Hypoeutectoid
Hypereutectoid
Steel
4.0 4.3%
3.0
Hypoeutectic
Cast Iron
Weight Percentage Carbon
6.67
Hypereutectic
Basic Metallurgy
Atomic Packing in Iron (Allotropic)
BCC - Delta Iron (d)
FCC - Gamma Iron (g)
BCC - Alpha Iron (a)
Ferrite
Cementite
Basic Metallurgy
(d+L)
1600 -
0. 8% C
1540
Liquid (L)
1495
(d+g )
Temperature (oC)
1400 Delta Ferrite
(d)
1000 -
0.2% C
600 -
~0% C
Peritectic
(g+L)
1200 -
1150 °C
0. 5% C
Austenite (g )
( g + Fe3C )
910
800 -
(a+g)
727 °C
Eutectoid
0. 7% C
Ferrite (a )
400 -
Ferrite + Pearlite
Cementite (Fe3C)+ Pearlite
200 -
0-
0.35% C
0.8%
1.0
2.0
Weight Percentage Carbon
1.2% C
Basic Metallurgy
Fundamental Mechanical Properties
• Strength:
Ability to withstand loads (Tensile & Compressive Strength)
• Ductility:
Ability to deform under tensile loads without rupture
• Bending Ability
Ability to bend without Fracture
• Toughness
Ability to absorb energy in shock loading (Impact Strength)
• Hardness
Resistance to penetration
• Weldability
Ability to be welded without cracking
Basic Metallurgy
Carbon (C):
 Strength & Hardness
Silicon (Si):
De-oxidizer,
Manganese (Mn):
Aluminum (Al):
Sulfur (S):
Effect of Alloying Elements
 Strength, Hardenability & Impact Strength
De-oxidizer,
Strong De-oxidizer,
Harmful
 Ductility, Malleability & Weldability
 Strength & Toughness
 Hardenability
 Grain Refinement 
 Strength & Toughness
 Ductility, Weldability Strength & Impact Strength
MAE (V, Ti & Nb):  Grain Refinement 
 Strength, Hardenability & Toughness
Stress – Vs - Strain
Basic Metallurgy
Stress: Force per unit area
s = F/Ao
Measuring the internal resistance of the body.
Strain: Unit deformation
e = (L1 – Lo)/Lo
Measuring the change in dimensions of the body
Force (F)
F
Lo
L1
L1
Stress – Vs - Strain
Basic Metallurgy
S
Stress
B
Y
P: Elastic Limit
P
Y: Yield Point
S: Max. Load Value
B: Breaking Point
O
Elastic
Def.
Plastic Deformation
Strain
Elastic & Plastic Deformation
Basic Metallurgy
Elastic Deformation:
Deformation of a material that recovered
when the applied load is removed. This
type of deformation involves stretching of
the bonds without permanent atomic
displacement.
Plastic Deformation:
Permanent deformation of a material that
is not recovered when the applied load is
removed. This Type of deformation
involves breaking of a limited number of
atomic bonds.
Basic Metallurgy
Microstructural Defects
Theoretical yield strength predicted for perfect crystals is much
greater than the measured strength. The existence of defects
explains the difference.
Which is easier to cut?
Basic Metallurgy
Braking all atomic bonds at once requires grater
energy in perfect crystal
Basic Metallurgy
Microstructural Defects
1) Point defects: a) vacancies, b) interstitial atoms, c) small substitional
atoms, d) large substitional atoms, … etc.
2) Surface defects: Imperfections, such
as grain boundaries, that form a twodimensional plane within the crystal.
Basic Metallurgy
Microstructural Defects
3) Line defects: dislocations (edge, screw, mixed)
Dislocation: A line imperfection in
the lattice or crystalline material
They are typically introduced into
the lattice during solidification of
the material or when the material is
deformed.
Movement of dislocations helps to
explain how materials deform.
Interface with movement of
dislocations helps explain how
materials are strengthened.
Basic Metallurgy
Motion of Dislocation
When a shear stress is applied to the dislocation in (a), the atoms
displaced, causing the dislocation to move one step (Burger’s vector) in
the slip (b). Continued movement of the dislocation eventually creates a
step (deformation) direction (C)
35