When the remains of RMS Titanic were discovered more than 3,800 meters (12,500 feet) beneath the surface of the North Atlantic in 1985, the story of the great liner once dubbed “unsinkable” by the press began moving from legend into scientific fact.
Numerous research investigations since that time have pieced together the details of what occurred on April 14-15, 1912, after Titanic struck an iceberg, broke in half and carried more than 1,500 people to their deaths. One of the most elusive questions—Why did the 41,730-metric ton (46,000-short ton) ship sink in less than three hours?—was answered in 1998 by National Institute of Standards and Technology (NIST) metallurgist Tim Foecke. The suspected culprit was one of Titanic’s smallest components—the 3 million wrought iron rivets used to hold the hull sections together.
Foecke performed metallurgical and mechanical analyses on steel and rivet samples recovered from the Titanic debris field at the bottom of the ocean. His examinations determined that the wrought iron in the rivets contained three times today’s allowable amount of slag (the glassy residue left behind after the smelting of the iron ore). The slag made the rivets less ductile and more brittle than they should have been when exposed to very cold temperatures—like those typically found in the icy seawater of the North Atlantic. This finding strongly suggested that Titanic’s collision with the iceberg caused the rivet heads to break off, popped the fasteners from their holes and allowed water to rush in between the separated hull plates.
Helping support the rivet theory are two bits of supporting evidence. First, sonar mapping of Titanic’s starboard hull buried in the ocean floor revealed only six thin tears from the iceberg with a total area open to the sea of only one square meter (12 square feet), or less than that of two sidewalk squares. This dispelled the long-believed myth that the iceberg ripped a 90-meter (300-foot) gash in the side of the ship. The actual damage could not have resulted in the flooding that overwhelmed Titanic’s watertight compartments.
Secondly, photographs of Titanic’s sister ship, the RMS Olympic, taken after it collided with another vessel in 1911, clearly show dozens of vacant holes in the hull from which rivets popped.
– Michael E. Newman