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NIST Reveals How Tiny Rivets Doomed a Titanic Vessel

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.

Photo of the bow of the RMS Titanic on the ocean floor with rust, sea growth
The bow of the RMS Titanic on the ocean floor as seen during a June 2004 expedition.
Credit: National Oceanic and Atmospheric Administration/Institute for Exploration/University of Rhode Island

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. 

Microscopic images of Titanic's iron rivets
Microscopic analysis of iron rivets recovered from Titanic revealed high concentrations of slag residue in the head area (seen as yellow, orange and red) that may have made them brittle in cold temperatures.
Credit: T. Foecke/NIST

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.

Photo of workers installing rivets in the Titanic's hull
Workers installing rivets in the hull of Titanic in 1911 at the Harland & Wolff Shipyard in Belfast, Ireland.

Did You Know...?

  • Experts believe that if Titanic had hit the iceberg head on instead of striking it on the starboard side, the liner likely would have stayed afloat. By turning in a futile attempt to avoid collision, Titanic took the full pressure of the iceberg against its hull, likely resulting in the fatal rivet popping and separation of the hull plates. 
  • Titanic was equipped to carry 64 lifeboats, yet it left Southampton, England, on its maiden (and last) voyage with just 20. Only 28 persons were aboard the first lifeboat launched after the collision with the iceberg, although the craft was designed to seat 65.
  • The Parlour Suites, the most luxurious rooms onboard Titanic, featured a private promenade and cost $4,350 in 1912 U.S. dollars—equivalent to $108,000 in today’s money—for a six-day, one-way transatlantic passage.

– Michael E. Newman

    Created June 20, 2017, Updated February 13, 2019