2. IRON AND STEEL MANUFACTURE
TECHNOLOGY RELATED TO THE PRODUCTION OF IRON AND ITS
ALLOYS, PARTICULARLY THOSE CONTAINING A SMALL PERCENTAGE OF
CARBON. THE DIFFERENCES BETWEEN THE VARIOUS TYPES OF IRON
AND STEEL ARE SOMETIMES CONFUSING BECAUSE OF THE
NOMENCLATURE USED. STEEL IN GENERAL IS AN ALLOY OF IRON AND
CARBON, OFTEN WITH AN ADMIXTURE OF OTHER ELEMENTS. SOME
ALLOYS THAT ARE COMMERCIALLY CALLED IRONS CONTAIN MORE
CARBON THAN COMMERCIAL STEELS. OPEN-HEARTH IRON AND
WROUGHT IRON CONTAIN ONLY A FEW HUNDREDTHS OF 1 PERCENT OF
CARBON. STEELS OF VARIOUS TYPES CONTAIN FROM 0.04 PERCENT TO
2.25 PERCENT OF CARBON. CAST IRON, MALLEABLE CAST IRON, AND PIG
IRON CONTAIN AMOUNTS OF CARBON VARYING FROM 2 TO 4 PERCENT. A
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SPECIAL FORM OF MALLEABLE IRON, CONTAINING VIRTUALLY NO
CARBON, IS KNOWN AS WHITE-HEART MALLEABLE IRON. A SPECIAL
GROUP OF IRON ALLOYS, KNOWN AS FERROALLOYS, IS USED IN THE
3. THE EXACT DATE AT WHICH PEOPLE DISCOVERED THE TECHNIQUE OF SMELTING
IRON ORE TO PRODUCE USABLE METAL IS NOT KNOWN. THE EARLIEST IRON
IMPLEMENTS DISCOVERED BY ARCHAEOLOGISTS IN EGYPT DATE FROM ABOUT
3000 BC, AND IRON ORNAMENTS WERE USED EVEN EARLIER; THE COMPARATIVELY
ADVANCED TECHNIQUE OF HARDENING IRON WEAPONS BY HEAT TREATMENT WAS
KNOWN TO THE GREEKS ABOUT 1000 BC.
THE ALLOYS PRODUCED BY EARLY IRON WORKERS, AND, INDEED, ALL THE IRON
ALLOYS MADE UNTIL ABOUT THE 14TH CENTURY AD, WOULD BE CLASSIFIED TODAY
AS WROUGHT IRON. THEY WERE MADE BY HEATING A MASS OF IRON ORE AND
CHARCOAL IN A FORGE OR FURNACE HAVING A FORCED DRAFT. UNDER THIS
TREATMENT THE ORE WAS REDUCED TO THE SPONGE OF METALLIC IRON FILLED
WITH A SLAG COMPOSED OF METALLIC IMPURITIES AND CHARCOAL ASH. THIS
SPONGE OF IRON WAS REMOVED FROM THE FURNACE WHILE STILL
INCANDESCENT AND BEATEN WITH HEAVY SLEDGES TO DRIVE OUT THE SLAG AND
TO WELD AND CONSOLIDATE THE IRON. THE IRON PRODUCED UNDER THESE
CONDITIONS USUALLY CONTAINED ABOUT 3 PERCENT OF SLAG PARTICLES AND 0.1
PERCENT OF OTHER IMPURITIES. OCCASIONALLY THIS TECHNIQUE OF
IRONMAKING PRODUCED, BY ACCIDENT, A TRUE STEEL RATHER THAN WROUGHT
IRON. IRONWORKERS LEARNED TO MAKE STEEL BY HEATING WROUGHT IRON AND
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CHARCOAL IN CLAY BOXES FOR A PERIOD OF SEVERAL DAYS. BY THIS PROCESS
THE IRON ABSORBED ENOUGH CARBON TO BECOME A TRUE STEEL.
4. A fte r the 1 4 th ce ntu ry th e fu rn a ce s u sed in sm e ltin g w e re in cre ased in size , a nd
in cre a se d d raft w a s used to fo rce the co m b u stio n ga se s th ro ug h the ”cha rge ,” th e
m ixtu re of ra w m a te ria ls. In th ese la rg e r fu rn a ce s, the iro n o re in the up pe r pa rt of the
fu rna ce w a s first re du ce d to m e ta llic iron a nd th en to o k on m o re ca rb on as a re su lt of
th e ga se s fo rce d th roug h it b y the b la st. T he p ro d uct of the se fu rn a ce s w a s p ig iron , a n
a llo y th at m e lts a t a lo w e r te m pe ra tu re tha n stee l o r w ro ug h t iro n. P ig iro n (so ca lled
b e ca u se it w a s u sua lly ca st in stub by, rou nd ingo ts kn o w n as p ig s) w a s the n fu rth e r
refin ed to m a ke stee l.
M o d e rn ste e lm akin g e m p lo ys b la st fu rn a ce s tha t a re m e re ly refin e m e n ts of th e
fu rna ce s u se d b y the o ld iron w o rke rs. T he p ro ce ss of refin ing m o lte n iro n w ith b la sts of
a ir w a s a cco m p lish ed b y th e B ritish in ve n to r S ir H en ry B e sse m e r w ho d e ve lop ed th e
B e sse m e r fu rna ce , o r co n ve rte r, in 1 85 5. S in ce th e 1 96 0 s, se ve ra l so -ca lled m in im ills
h a ve be en p ro du cing stee l fro m scra p m e ta l in e le ctric fu rna ce s. S u ch m ills a re an
im p o rtan t co m po ne nt of to ta l U .S . stee l p ro du ctio n . T he g ia nt ste e l m ills re m a in
e ssen tia l fo r th e p ro du ction of ste e l fro m iron o re .
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6. WHAT IS STEEL ?
In the beginning, there was iron...
Then came cast iron...
...and finally steel
7. GENERAL ISSUES ABOUT STEEL
•
Steel has been called the world’s most
useful and inexpensive metal.
•
In recent decades, steel manufacturers
have been forced to take a much closer
look at what their processes have been
doing to the fragile environment around
them.
8. WHAT IS STEEL USED FOR - I
The structure of the Pyramid of the
Louvre, canned food, oil
platforms, catalytic converters, paper
clips, mounts for electronic chips...are all
made of steel.
1.
In the construction of bridges
or buildings...
2.
In the automobile sector...
9. WHAT IS STEEL USED FOR-II
3.
5.
For everyday uses:
cans,pots,containers,etc...
In communications...
6.
In energy...
4.
At the heart of food
preservation...
7.
In health...
