In the early part 19th century, the only means of transportation
for travelers and mail between Europe and North America was by passenger
steamship. By 1907, the Cunard Steamship Company introduced the world's largest
and fastest steamers in the North Atlantic service, the Lusitania and
Mauritania. Each had a gross tonnage of 31,000 tons and a maximum speed of 26
knots.
In that year, Lord William James Pirrie, managing director and
controlling chair of the Irish shipbuilding company Harland and Wolff, duly met
with J. Bruce Ismay, (MD) managing director of the Oceanic Steam Navigation
Company, better identified as the White Star Line (a name taken from its
pennant).
During this meeting, the plans were made to construct three giant
new White Star liners to compete with the Lusitania and Mauritania on the North
Atlantic by establishing a three-ship weekly steamship service for passengers
and mail between Southampton, England, and New York City.
Sister
Ships of RMS Titanic Inc.,
This decision required the construction of a trio of luxurious
steamships. The first two built were the RMS Olympic and the RMS Titanic; a
third ship, the RMS Britannic, was built later (the fate of the sister ships is
described as below.
The RMS Olympic made more than 500 round trips between Southampton
and New York before it was retired in 1935 and was finally broken up in 1937.
In 1919, it became the first large ship to be converted from coal to oil. On
May 15, 1934, as the Olympic approached New York, it struck the Nantucket
lightship during a heavy fog, cutting it in half. Of the crew, four were
drowned, three were fatally injured, and three were rescued.
The third ship of the series, the Britannic, had a short life.
While it was being constructed, the Titanic was sunk. Immediately, the design
was changed to provide a double hull and the bulkheads were extended to the
upper deck. Before the Britannic was completed, World War I broke out, and the
vessel was converted into a hospital ship.
On November 21, 1916, it was proceeding north through the Aegean
Sea east of Greece when it struck a mine. Because the weather had been warm,
several of the portholes had been opened, hence rapid flooding of the ship
occurred. The ship sank in just 50 minutes with a small loss of life; one of
the loaded lifeboats was drawn into a rotating propeller.
The
Construction of RMS Titanic
The three White Star Line steamships were 269.1 meters long, 28.2
meters maximum wide, and 18 meters tall from the water line to the boat deck
(or 53 meters from the keel to the top of the funnels), with a gross weight of
46,000 tons. Because of the size of these ships, much of the Harland and Wolff
shipyard in Belfast, Ireland, had to be rebuilt before construction could
begin; two larger ways were built in the space originally occupied by three
smaller ways.
A new gantry system with a larger load-carrying capacity was
designed and installed to facilitate the construction of the larger ships. The
Titanic under construction and designed to provide accommodations superior to
the Cunard ships, but without greater speed. Therefore, the first on board
swimming pools were installed as was a gymnasium that included an electric
horse and an electric camel, a squash court, several rowing machines, and
stationary bicycles, all supervised by a staff of professional instructors.
The public rooms for the first-class passengers were large and
elegantly furnished with wood paneling, stained-glass windows, comfortable
lounge furniture, and expensive carpets. The decor of the first-class cabins,
furthermore to being luxurious, differed in style from cabin to cabin. As an
extra feature on the Titanic, the Café Parisienne offered superb cuisine.
The designed speed for these ships was 21–22 knots, in contrast to
the faster Cunard ships. To achieve this speed, each ship had three propellers;
each outboard propeller was driven by a separate four-cylinder,
triple-expansion, reciprocating steam engine. The center propeller was driven
by a low-pressure steam turbine using the exhaust steam from the two
reciprocating engines.
The power plant was rated at 51,000 I.H.P. To provide the
necessary steam for the power plant, 29 boilers were available, fired by 159
furnaces. In addition to propelling the ship, steam was used to generate
electricity for various purposes, distill freshwater, refrigerate the
perishable food, cook, and heat the living space. Coal was burned as fuel at a
rate of 650 per day when the ship was underway. Stokers moved the coal from the
bunkers into the furnaces by hand.
The bunkers held adequate coal for a ten-day voyage. The remodeled
shipyard at Harland and Wolff was large enough for the construction of two
large ships simultaneously. The keel of the Olympic was laid on December 16,
1908, while the Titanic ‘s keel followed on March 31, 1909. The Olympic was
launched on October 20, 1910, and the Titanic on May 31, 1911.
In the early 20th century, ships were constructed using wrought
iron rivets to attach steel plates to each other or to a steel frame. The frame
itself was held together by similar rivets. Holes were punched at appropriate
sites in the steel-frame members and plates for the insertion of the rivets.
Each rivet was heated well into the austenite temperature region, inserted in
the mated holes of the respective plates or frame members, and hydraulically
squeezed to fill the holes and form ahead.
Three million rivets were used in the construction of the ship.
The construction of the Titanic was delayed due to an accident involving the
Olympic. During its fifth voyage, the Olympic collided with the British
cruiser, HMS Hawke, damaging its hull near the bow on the port. This occurred
in the Solent off Southampton on September 20, 1911.
The Olympic was forced to return to Belfast for repairs. To
accomplish the repairs in record time and to return the ship to service
promptly, workmen were diverted from the Titanic to repair the Olympic.
On April 2, 1912, the Titanic left Belfast for Southampton and its
sea trials conducted in the Irish Sea. After spending two days at sea, the
Titanic, and its crew and officers arrived at Southampton and tied up to Ocean
Dock on April 4, 1912. During the next several days, the gigantic ship was
provisioned and prepared for its maiden voyage aiming to create history.
Titanic
Start the Journey
The Titanic started its maiden voyage to New York just before noon
on April 10, 1912, from Southampton, England. So, two days later at 11:40 P.M.,
Greenland time, it struck an iceberg that was three to six times larger than
its own mass, badly damaging the hull so that the six forward compartments were
ruptured.
The flooding of these compartments was enough to cause the ship to
sink within two hours and 40 minutes, with a loss of more than 1,500 lives. The
scope of the tragedy, coupled with a detailed historical record, has fueled
endless fascination with the ship and debate over the reasons as to why it did
in fact sink.
A frequently cited culprit is the quality of the steel used in the
ship’s construction. A metallurgical analysis of hull steel recovered from the
ship’s wreckage provides a clearer view of the issue.
The
Voyage
On the morning of April 10, 1912, the passengers and remaining
crew members came to Ocean Dock to the board and viewing the ship for its
maiden voyage. However, shortly before noon, the Titanic cast off and scarcely
avoided colliding with a docked passenger ship, the New York (which broke its
mooring cables due to the surge of water as the huge ship passed), before
proceeding down Southampton Water into the Solent and then into the English
Channel.
After stopping at Cherbourg, France, on the evening of 10, April
1912, and a second stop at Queenstown (now Cobh), Ireland, the next morning to
take on more passengers and mail, the Titanic headed west on the Great Circle
Route toward the Nantucket lightship 68 kilometers south of Nantucket Island
off the southeast coast of Massachusetts. The Irish coast was left behind about
dusk on April 11.
During the early afternoon of April 12, the French liner, La
Touraine, sent advice by radio of ice in the steamship lanes, but this was not
uncommon during an April crossing. This advice was sent nearly 60 hours before
the fatal collision. As the voyage continued, the warnings of ice received by
radio from other ships became more frequent. With time, these warnings gave
more accurate information on the location of the ice fields and it became
apparent that a very large ice field lay in the ship’s course.
Based on several reports after the accident, it was estimated that
the ice field was 120 km long on a northeast-southwest axis and 20 km wide;
there is evidence that the Titanic was twice diverted to the south in a vain
effort to avoid the fields. The ship continued at a speed of about 21.5 knots.
On the moonless night of April 14, the ocean was very calm and still. At 11:40
P.M., Greenland time, the lookouts in the crow’s nest sighted an iceberg
immediately ahead of the ship; the bridge was alerted.
The duty officer ordered the ship hard to port and the engines
reversed. In about 40 seconds, as the Titanic was beginning to respond to the
change in course, it collided with an iceberg estimated to have a massive gross
weight of 150,000 – 300,000 tons. The iceberg struck the Titanic near the bow
on the starboard right side about 4 m above the keel.
During the next 10 seconds, the iceberg raked the starboard side
of the ship’s hull for about 100 m. The iceberg damaging the hull plates and
popping rivets, thus opening the first six of the 16 watertight compartments
formed by the transverse bulkheads.
Therefore, inspection shortly after the collision by captain
Edward Smith and Thomas Andrews, a managing director, and chief designer for
Harland and Wolff and chief designer of the Titanic. They revealed that the
Titanic had been fatally damaged and could not survive too long. The sad demise
happened at 2:20 A.M., on April 15, 1912, when the Titanic sank with the loss
of more than 1,500 lives leaves many mysteries.
The
Sinking
Initial studies of the sinking proposed that a continuous gash in
the hull 100 m in length was created by the impact with the iceberg. More
recent studies indicate that discontinuous damage occurred along the 100 m
length of the hull. After the sinking, Edward Wilding, design engineer for
Harland and Wolff, estimated that the collision had created openings in the
hull totaling 1.115 m2, based on the reports of the rate of flooding given by
the survivors.
This damage to the hull was enough to cause the ship to sink. The
computer calculations by Hackett and Bedford using the same survivor’s
information but allocating the damage individually to the first six
compartments. The total damage area of 1.171 m2, which is a slightly larger
area than the estimate by Wilding. At the time of the accident, there was
disagreement among the survivors as to whether the Titanic broke into two parts
as it sank or whether it sank intact.
Titanic
Uncovered
On September 1, 1985, Robert Ballard found the Titanic in 3,700 m
of water on the ocean floor. The ship had broken into two major sections, which
are about 600 m apart. Between these two sections is a debris field containing
broken pieces of the steel hull and bulkhead plates, rivets that had been
pulled out, dining-room cutlery and chinaware, cabin and deck furniture, and
other debris.
The only items to survive at the site are those made of metals or
ceramics. All items made from organic materials have long since been consumed
by scavengers, except for items made from leather such as shoes, suitcases, and
mail sacks; tanning made leather unpalatable for the scavengers. The contents
of the leather suitcases and mail sacks, having been protected, have been
retrieved and restored.
The Steel
Composition
During an expedition to the wreckage in the North Atlantic on
August 15, 1996. The researchers brought back steel from the hull of the ship
for metallurgical analysis. After the steel was received at the University of
Missouri-Rolla, the first step was to determine its composition. The first item
noted is the very low nitrogen content.
This indicates that the steel was not made by the Bessemer
process; such steel would have a high nitrogen content that would have made it
very brittle, particularly at low temperatures. In the early 20th century, the
only other method for making structural steel was the open-hearth process.
The high oxygen and low silicon content mean that the steel has
only been partially deoxidized, yielding semiskilled steel. The phosphorus
content is slightly higher than normal, while the sulfur content is quite high,
accompanied by a low manganese content.
This yielded a very low ratio by modern standards. The presence of
relatively high amounts of phosphorous, oxygen, and sulfur tends to embrittle
the steel at low temperatures. Davies has shown that at the time the Titanic
was constructed about two-thirds of the open-hearth steel produced in the
United Kingdom was done in furnaces having acid linings.
There is a high problem ability that the steel used in the Titanic
was made in an acid-lined open-hearth furnace, which accounts for the high
phosphorus and high sulfur content. The lining of the basic open-hearth furnace
will react with phosphorus and sulfur to help remove these two impurities from
the steel.
It is likely that all or most of the steel came from Glasgow,
Scotland. Including the compositions of two other sheets of steel, that is used
to construct lock gates at the Chittenden Ship Lock between Lake Washington and
Puget Sound at Seattle, Washington. Moreover, the composition of modern steel,
ASTM A36 and ship lock was built around 1912, making the steel about the same
age as the steel from the Titanic.
Metallography
Standard metallographic techniques were used to prepare specimens
taken from the hull plate of the Titanic for optical microscopic examination.
After grinding and polishing, etching was done with 2% Nital. Because the
earlier work by Brigham and severe banding in a specimen of the steel,
specimens were cut from the hull plate in the transverse and longitudinal
directions, the microstructure of the steel.
In both micrographs, it is apparent that the steel is banded,
although the banding is more severe in the longitudinal section. In this
section, there are large masses of MnS particles elongated in the direction of
the banding. The average grain diameter is 60.40 mm for the longitudinal
microstructure and 41.92 mm for the microstructure in the transverse direction.
In neither micrograph can the pearlite be resolved. There is a
micrograph of ASTM A36 steel, which has a mean grain diameter of 26.173 mm. The
scanning electron microscopy (SEM) micrograph of the polished and etched
surface of steel from the Titanic. The pearlite can be resolved in this
micrograph.
The dark gray areas are ferrite. The very dark elliptically shaped
structure is a particle of MnS identified by energy-dispersive x-ray analysis
(EDAX). It is elongated in the direction of the banding, suggesting that
banding is the result of the hot rolling of the steel. There is some evidence
of small nonmetallic inclusions and some of the ferrite grain boundaries are
visible.
Tensile
Testing
The steel plate from the hull of the Titanic was nominally 1.875
cm thick, while the bulkhead plate had a thickness of 1.25 cm. Corrosion in the
saltwater had reduced the thickness of the hull plate so that it was not
possible to machine standard tensile specimens from it.
A smaller tensile specimen with a reduced section of 0.625 cm
diameter and a 2.5 cm gauge length was used.10 The tensile-test results are
given in Table III. These data are compared with tensile-test data for an SAE
1020 steel, which is similar in composition. The steel from the Titanic has a
lower yield strength, probably due to the larger grain size. The elongation
increases as well, again due to larger grain size.
Charpy
Impact Tests
Charpy impact tests were performed over a range of temperatures
from –55°C to 179°C on three series of standard Charpy specimens. A series of
specimens machined with the specimen axis parallel to the longitudinal
direction in the hull plate from the Titanic, a series machined in the
transverse direction, and a series made from modern ASTM A36 steel.
A Tinius Olsen model 84 universal impact tester was used to
determine the impact energy to fracture for several specimens at the selected
test temperatures. A chilling bath or a circulating air laboratory oven was
used to prepare the specimens for testing at specific temperatures. The
specimens could soak in the appropriate apparatus for at least 20 minutes at
the selected temperature.
Pairs of specimens were tested at identical test temperatures. An
SEM micrograph of a freshly fractured surface of a longitudinal Charpy specimen
tested at 0°C. The cleavage planes, in ferrite, are quite apparent. There are
cleavage plane surfaces at different levels that are defined by straight lines.
They were connecting parallel cleavage planes; the edges are parallel to the
direction.
The crystallographic surfaces of the risers are the plane. In
addition, there are curved slip lines on the cleavage planes. Particles of MnS
identified by EDAX can be observed. Some of the MnS particles exist as
protrusions from the surface. These protrusions were pulled out of the
complimentary fracture surface. In addition, there are the intrusions remaining
after the MnS particles have been pulled out of this fracture surface.
One of the pearlite colonies lying in the fracture surface is
oriented so that the ferrite and cementite plates have been resolved. The
fractured lenticular MnS particle that protrudes edge-on from the fractured
surface. There are slip lines radiating away from the MnS particle. The plot of
the impact energy versus temperature for the three series of specimens.
At higher temperatures, the specimens prepared from the hull plate
in the longitudinal direction have substantially better impact properties than
for the transverse specimens. At low temperatures, the impact energy required
to fracture the longitudinal and transverse specimens is essentially the same.
The severe banding is certainly the cause of the differences in
the impact energy to cause fracture at elevated temperatures. The specimens
made from ASTM A36 steel have the best impact properties. The ductile-brittle
transition temperature determined at an impact energy of 20 joules is –27°C for
ASTM A36, 32°C for the longitudinal specimens made from the Titanic hull plate,
and 56°C for the transverse specimens.
It is apparent that the steel used for the hull was not suited for
service at low temperatures. The seawater temperature at the time of the
collision was –2°C. Comparing the composition of the Titanic steel and ASTM A36
steel shows that modern steel has a higher manganese content and lower sulfur
content, yielding a higher MnS ratio that reduced the ductile-brittle
transition temperature substantially.
Furthermore, the ASTM A36 steel has a considerably lower
phosphorus content, which will also lower the ductile-brittle transition
temperature. Though, Jankovic has found that the ductile-brittle transition
temperature for the Chittenden lock gate steel was 33°C.
The longitudinal specimens of the Titanic hull steel made in the
UK and those specimens from the Chittenden lock steel made in the United States
have nearly the same ductile-brittle transition temperature.
Shear
Fracture Percent
At low temperatures where the impact energy required for fracture
is less, a faceted surface of cleaved planes of ferrite is observed, indicating
a brittle fracture. At elevated temperatures, where the energy to cause
fracture is greater, a ductile fracture with a shear structure is observed.
The plot of the shear fracture percent versus temperature. Titanic
steel is better than transverse specimens. However, the bending is more
important in the result of the impact energy experiments as compared to with
sheer fracture percent.
Conclusion
So, the steel used in the construction of RMS Titanic was perhaps
the best plain carbon ship plate available in that period of 1909-1911. But it
would not be acceptable at the present standards for construction purposes and
particularly not for ship construction. Whether a ship constructed of modern
steel would have suffered as much damage as the Titanic in a comparable
accident seems problematic.
Moreover, the exit of the navigational aid now that did not exist
in 1912. Hence iceberg would be sighted at a much greater distance allowing
more time for evasive action. If the titanic had not collided with the iceberg.
It could have had a career of more than 20 years as the Olympic had. It was
built of similar steel in the same shipyard and from the same design. The only
difference was a big iceberg.
