STEEL - As a Building material:
A 20-minute brief presentation on STEEL for a seminar session.
This presentation covers the areas of :
Origin of Steel, Discovery of STEEL, History of steel making, Classification of STEEL , Properties of steel, Mild Steel , Characteristic tension test curve, Medium Carbon Steel, High Carbon Steel, TOR Steel, Manufacturing processes.
Why STEEL is preferred to concrete?
Disadvantages of STEEL
Some Important Steel Structures
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Steel - As a Building material
1.
2. PROTO-GERMANIC
Which means ‘standing firm’
Definition:
Steel is an alloy of IRON and CARBON and sometimes with other
elements like Mn,Cr,Ni…etc. It is a hard ,strong grey or bluish grey alloy
which is widely used as a structural and fabricating member.
3. Earliest 4000 years old 1800 BC
Noric steel Roman military
Pioneers of modern steel making
process6thcentury BC
“Tamilians of Tamilakam”
Wootz steel Seric IRON Carbon content
from “Avaram Poo”heated
in crucibles
4. The CHINESE of the WARRING
states quenched hardened
steel 403-221 BC
The Chinese of HAN dynasty
created steel by
melting wrought iron with
cast iron 202BC-220AD
Avaram poo – Cassia auriculata
5. Mainly into 4 types , based on it’s
composition:
1) CARBON steel
2)ALLOY steel
3)STAINLESS steel
4)TOOL steel
But providing a wide range of classification
:
PRODUCTION METHOD :
Continuous cast, elastic furnace…etc
Source: www.metasupermarkets.com
6. FINISHING METHOD:
Cold rolled, hot rolled, cold
drawn…etc
FORM OR SHAPE:
Bar, Rod, tube, pipe, plate,
sheet…etc
DE-OXIDATION PROCESS:
Killed and semi killed steel…etc
MICROSTRUCTURE:
Ferritic, Pearlitic, Martensitic…etc
HEAT TREATMENT: Source: www.metasupermarkets.com
7. Properties of STEEL can be varied by
VARYING the CARBON content in it.
Increase in carbon content increases
the SHEAR STRESS and HARDNESS, at
the same time decreases the
DUCTILITY and TOUGHNESS.
Composition : 0.05% - 2.1% of
Carbon
Melting point : 1300-1400 C
Can be hardened and tempered
8. Compressive strength : 4.75 – 25.2
tonnes/sq.m
Ultimate tensile strength : 5.51-11.02
tonnes/sq.m
It rusts easily
It’s TOUGH , Mallaeble and Ductile
It absorbs SHOCKS
It can be rapidly forged or welded
Commonly USED as a REINFORCEMENT for
RCC , in Steel structures, bolts, rivets and
sheets. For making cutlery, files and
9. Based on the carbon content steel is of
the following types:
Dead Mild Steel ( less than 0.15% of C)
Mild Steel (0.05-0.25% of C)
Medium carbon steel (0.30-0.60% of
C)
High carbon steel (0.60 – 1.50% of C)
Cast steel or Carbon steel ( more than
1.50%)
10. Also known as PLAIN CARBON steel
Most common form of steel
Material properties acceptable for many
applications
CARBON CONTENT : 0.05 – 0.25 %
DENSITY : 7850 kg/m3 (or)
7.85 g/cm3
YOUNG’S MODULUS: 210 Gpa or
30,000,000psi
11. Characteristic STRESS-STRAIN curve for MILD
STEEL
As per Indian Standards(IS)
2062, there are 9 mild steel
grades as :
Fe 250
Fe 275
Fe 300
Fe 350
Fe 410
Fe 450
Fe 550
Fe 600
Fe 650
Where NUMBER denotes the
value ofTENSILE STRENGTHS
of the variant.
12. Carbon content : 0.3% - 0.6%
Manganese content : 0.60% -
1.65%
Ductile
Strong
Long wearing properties
USES : Large parts of
machinery, forging
and automotive
13. Carbon content : 0.60% -
1.70%
Manganese content : 0.30% -
0.90%
High CARBON content STRONG
Holds SHAPE MEMORY well
Uses : Springs , swords,
high strength wires
and sheets…etc
14. Cold Twisted Deformed(CTD) Bars
commonly known as TOR steel
named after TORisteg Steel
Corporation of LUXEMBORG – 1975
Thermo Mechanically Treated
(TMT) :
Hard outer surface with a
softer core. ManufacturedHot
rolled steel wires Water
Surface harder and core softer
15. Steel wasn’t made economically till 19th
century
Began in 1855 Introduction of
BESSEMER’S PROCESS
Raw material PIG iron Bessemer
converter
CHEAP and produced LARGE quantities
Bessemer converter - 1855
16. 19th century SIEMENS-MARTIN
process co-melting of bar
iron with pig iron
Open hearth furnace
17. Linz-Donawitz process of BASIC
OXYGEN STEEL (BOS) making
developed in 1950’s superior
to all
SOURCE:
Hyundai steel
corporation
web
19. High Strength and Light weight :
Weight of structure made of steel will
be small
Uniformity :
Properties of Steel does not change as
opposite to concrete.
Elasticity:
Steel follows Hooke’s law accurately
Ductility:
Steel can withstand extensive
deformation without failure under
high tensile stress (ie) it gives WARNING
before failure takes place.
Toughness :
Steel has both STRENGTH and
Burj
Khalifa
,
Dubai
20. Sometimes R/C structures are preferred to steel structures because
sometimes steel structures cannot provide the necessary strength due to
BUCKLING, whereas R/C columns are generally sturdy and massive (ie) no
buckling occurs.
The other disadvantages maybe:
Maintenance Cost : Steel structures
Corrosion Air,water & Humidity
Painted regularly
Fire proofing cost:
SteelIncombustible But at HIGH
temperatures Strength reduced
21. Susceptibility to Buckling :
As the length and slenderness of a
compressive column increases, the
danger of buckling increases.
Fatigue :
Strength of Steel gets reduced due
to cyclic loading(ie) repeated loading in
regular time intervals
Brittle fracture:
Under certain conditions Steel
loses DUCTILITY Fracture Stress
concentrated areas Fatigue type