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1. A Brief History of Steel
&
The Mysterious Eutectic
Kenneth Newell Ph.D.

2. Man, Fire & Rocks
Fire Heated Silcrete Stone Weapons
South Africa 75,000 BC
South Africa’s Wonderwerk Cave
Latest findings show humans controlled
fire 1 Million Years Ago
Flint use is well established
by 250,000 BC
Kenneth Newell Ph.D.

3. Limitations of open Fire
• Open air wood fire generally
limited to 600oC.
• By 4500 BC, convection fed
charcoal pottery kilns could
achieve 1100oC to 1150oC
• Copper smelted from malachite
was most likely discovered by
ancient potters using clay firing
kilns
• 4 acres of forest were needed
to smelt a 60 lb ingot of copper.
Kenneth Newell Ph.D.

4. Discovery of Metal Bearing Rocks
Currently there are 86 known metals.
Prior to 13th Century, only 7 metals
were known:
(1) Gold - 6000BC
(2) Copper - 4200BC
(3) Silver - 4000BC
(4) Lead - 3500BC
(5) Tin - 2500BC
(6) Iron - 1500BC
(7) Mercury - 750BC
Malachite (57%Cu) Chalcocite (80%Cu)
Cassiterite (75%Sn)
Kenneth Newell Ph.D.

5. Discovery of the Alloy
• 3000 BC, the Sumarians
make the first bronze alloy
adding crushed cassiterite
to malachite and charcoal
• At only 1000oC in a pottery
kiln, the first molten
(castable) metal alloy was
produced.
• 10%Sn-90%Cu is still the
base Bronze Alloy used
today.
• Tensile Strength 45ksi
• Charcoal, Tin & Copper
become essential trading
commodities.
Kenneth Newell Ph.D.

6. The First Raw Material Shortages
• By 2000 BC, supplies of
alluvial Tin are nearly
exhausted,
• Charcoal production
completely wipes out
Aegean Cyprus forests,
• Bronze production all but
stops for 300+ years.
• By 1500 BC, Phoenicians'
corner the market on Tin
from British Isles and Spain
• Not till 55 BC, Julius Caesar
invades British Isles and
takes control of Tin supply
from Cornwall
The Ancient Tin TradeKenneth Newell Ph.D.

7. Iron, Armament for the Masses
The transition to the Iron age was critical not because of any
property of the metal itself, but rather because iron was
infinitely more abundant than copper and tin. This enabled, for
the first time in history, true mass-production of weapons.
Kenneth Newell Ph.D.

8. Discovery of Solid State Iron Bloomery
• About the time of the bronze shortage,
2000 BC, it is believed that either the
Persians or the Turks smelted the first
Iron ingot from iron ore.
• Using a bellow-driven charcoal kiln fire,
an “Iron bloom” was formed at around
1150oC (400oC below Fe melting point
1538oC)
Magnetite (Fe3O4) 73%FeHematite (Fe2O3) 69% FeGeothite (FeO(OH)) 62% Fe
Kenneth Newell Ph.D.

9. The Critical Role of Charcoal
• Ancient metal smiths were baffled by the
Iron-Charcoal interaction.
• Charcoal appeared to make the fire burn
hotter and therefore the added heat believed
essential for making good iron.
• In reality, hot air and carbon from the
charcoal were producing an exothermic
reaction.
2 C + O 2 → 2 CO
The resulting carbon monoxide reduced iron
oxide to high purity “Wrought Iron”
3 CO + Fe 2 O 3 → 2 Fe + 3 CO 2
• By compacting the bloom into an ingot, metal
smiths unknowingly hammered carbon into
the wrought iron and produced the first
variations of carbon steel.
Kenneth Newell Ph.D.

10. Iron-Carbon Phase Diagram
Body Center Cubic (BCC)
Face Center Cubic (FCC)
Eutectoid
Eutectic
Kenneth Newell Ph.D.

11. Interstitial Carbon likes Octahedral Sites
Stable Unstable
Kenneth Newell Ph.D.

12. Cannons Spark the Industrial Revolution
• In 1543, Henry VIII commissions Cast Iron
Cannons rather than the Bronze to mass
produce cannons for the Tudor navy.
• The commission for mass production was the
first government works program for
modernization.
• Over the next 250 years, The British nearly
perfected a Two Step iron making process.
Kenneth Newell Ph.D.

13. The Two Step Process
Step 1 – The Blast Furnace smelting to make “Pig Iron”
• The blast furnace is used to melt Iron ore at 1350oC
(still 200oC below Fe melting point 1538oC)
• Water power harnessed to drive bellows for forced air.
• Limestone introduced for “slag” removal of silicon
dioxides.
• The molten iron is poured into ingots called “Pig Iron”.
• Resulting Iron contains 3.5 – 4.5% Carbon.
• Production rate of 1 ton of cast iron every two hours is
possible.
• In 1584, Parliament introduces laws restricting the
building of any additional furnaces to slow
deforestation in the making of charcoal.
Kenneth Newell Ph.D.

14. Blast Furnace makes Pig Iron
•Carbon from charcoal is
absorbed by solid state diffusion
into FCC Austenitic iron crystal
structure.
•At approximately 1% Carbon, a
super solidus phase begins and
the absorption of carbon
accelerates with liquid iron
phase.
•Within minutes, without
additional heating, all the iron
melts at 1.75%C
•Carbon continues to be
absorbed at high rate until the
temperature falls below 1130oC
Limestone added to molten iron
to “slag out” Silicon and Oxygen
Kenneth Newell Ph.D.

15. The Two Step Process
Step 2 –Puddling Furnace refining to make “Wrought Iron”
• The Reverberatory Furnace is
introduced in the 1670s to melt Bronze
using “coke” from coal rather than
charcoal.
• By 1768, the Reverberatory furnace is
adapted to iron processing and is
called the Puddling furnace because
the puddling effect of molten iron
becoming semi-solid as it is heated.
Eiffel tower was built using 7,300 tonnes
of Puddled Iron
Kenneth Newell Ph.D.

16. Puddling Furnace makes Wrought Iron
• Using Coke to generate heat
and produce an oxidizing
atmosphere, Pig Iron is melted.
•When the pig iron ingots melt,
iron oxide is added and the
molten iron boils into a sponge-
like puddle as the carbon
content decreases.
•The Puddler removes chunks
of puddled iron sponge and
forges it into a wrought iron
plate.
•The making of steel remains an
art till 1856.
Iron Oxide added
to molten pig iron
Kenneth Newell Ph.D.

17. Bessemer’s Cannon
• At start of Crimean War, Henry
Bessemer invents a spinning
projectile to be fired from smooth
bore cannons.
• The projectile causes cast iron
cannons to explode.
• Henry recognizes that the addition
of iron oxide in the puddle is the
same as driving air through the
molten pig iron.
• Henry invents the Bessemer
Converter which forces air through
the molten pig iron enabling the
controlled removal of carbon.
• By 1867, together with the recently
invented Watts steam engine, the
Bessemer Converter made it
possible to produce steel quickly,
and cheaply
Kenneth Newell Ph.D.

18. Conversion of Pig Iron to Steel
Kenneth Newell Ph.D.

19. Steel Rail Changes the World
• 1867, 460,000 tons of wrought
iron rails were made and sold
for $83/ton, 2550 tons of
Bessemer steel rails were sold
for $170/ton.
• By 1884, 1.5Million tons of
steel rail are sold at $14/ton.
• Rail life increases from 2 yrs to
10 yrs while maximum bearing
strength increases from 8 tons
to 70 tons
• Today there are 3500 different
grades of steel.
• It would now require 1/3 the
amount of steel to build the
Eiffel Tower.
Kenneth Newell Ph.D.

20. The Samurai Martensitic Katana
• Around 900AD, the Japanese develop a
steel heat treating technique that won’t be
fully understood for another 1000 years.
• By rapid quenching a forging from 800oC,
austenite is transformed to martensite and
is then tempered to a precise hardness.
• Use of clay on the blade produces the
wavy “hamon” which focuses the heat
treatment only on the cutting edge.
• The sword curves during the heat
treatment due to the differential strain
between the hard martensite phase and
the tough pearlite phase.
Kenneth Newell Ph.D.

21. Heat Treating Martensite
Rapid Quenching
Tempering
Kenneth Newell Ph.D.

22. Eng Yeap’s 1640 Samurai Katana
http://www.japaneseswordcollector.com/echsek/echsek.html
Kenneth Newell Ph.D.

23. The Mystery of Wootz Steel
• Around 300BC, India starts exporting
unique hockey-puck sized iron ingots
to Syria.
• Damascus blade smiths learned to
forge superior swords with a surface
pattern of alternating dark & light
phases.
• The technology survived over 2000
years and then was lost in the 1800s.
• Only recently using modern analysis
was it determined that Wootz Steel
was a complex hypereutectoid alloy
with an array of alloying elements.
Fe-1.5C-P-Cu-V-Ni-Mn
Wootz Steel Ingots
Bands of cementite Fe3C
Kenneth Newell Ph.D.

24. Wootz Steel & NanoTubes
• 2006, University of Dresden using high-resolution transmission
electron microscopy prove Damascan Blades contained Cementite
Nanowires form in situ with Vanadium during cyclic forging.
Kenneth Newell Ph.D.

25. Damascan Heat Treatment
Kenneth Newell Ph.D.

26. How important is Steel?
Kenneth Newell Ph.D.

27. Steel enables 1 person to feed 1000s
The second agricultural revolution coincided with the
Industrial Revolution; it was a revolution that would move
agriculture beyond subsistence to generate the kinds of
surpluses needed to feed thousands of people working in
factories instead of in agricultural fields.