The company,of , needed to build the ship quickly and at reasonable cost, which may have compromised quality, said co-author Timothy Foecke. That the shipyard was building two other vessels at the same time added to the difficulty of getting the millions of rivets needed, he added.
“Under the pressure to get these ships up, they ramped up the riveters, found materials from additional suppliers, and some was not of quality,” said Foecke, a metallurgist at the U.S. government’s National Institute of Standards and Technology who has been studying the Titanic for a decade.
More than 1,500 people died when the Titanic, advertised as an “unsinkable” luxury liner, struck an iceberg on its maiden voyage in 1912 and went down in the North Atlantic less than three hours later.
“The company knowingly purchased weaker rivets, but I think they did it not knowing they would be purchasing something substandard enough that when they hit an iceberg their ship would sink,” said co-author Jennifer Hooper McCarty, who started researching the Titanic’s rivets while working on her Ph.D. atin 1999.
The company disputes the idea that inferior rivets were at fault. The theory has been around for years, but McCarty and Foecke’s book, “What Really Sank the Titanic,” published last month, outlines their extensive research into the Harland and Wolff archives and surviving rivets from the Titanic.
McCarty spent two years instudying the company’s archives and works on the training and working conditions of shipyard workers. She and Foecke also studied engineering textbooks from the 1890s and early 1900s to learn more about shipbuilding practices and materials.
“I had the opportunity to study the metallurgy of several rivets,” McCarty said. “It was a process of taking thousands of images of the inside of these rivets, finding out what the structure was like, doing chemical testing and computer modeling.
“Seeing the kind of levels we saw in different areas, in different parts of the ship led us to believe they would have ordered from different people,” she said, adding this may have led to the weaker rivets.
The two metallurgists tested 48 rivets from the ship and found that slag concentrations were at 9 percent, when they should have been 2 to 3 percent. The slag is a byproduct of the smelting process.
“You need the slag but you need just a little to take up the load that’s applied so the iron doesn’t stretch,” Foecke said. “The iron becomes weak the more slag there is because the brittleness of the slag takes over and it breaks easily.”
Foecke said the main question was not whether the Titanic would sink after hitting the iceberg, but how fast the ship went down.
He believes the answer is provided by the weak rivets. His analysis showed the builders used stronger steel rivets where they expected the greatestand weaker iron rivets for the stern and the bow, where they thought there would be less pressure, he said. But it was the ship’s bow that struck the iceberg.
“Typically you want a four bar for rivets,” Foecke said, using the measurement for the strongest rivets. “Some of the orders were for three bar.”
spokesman Joris Minne disputed the findings. “We always say there was nothing wrong with the Titanic when it left here,” he said.
When the iceberg hit the Titanic, it scraped alongside the ship. Foecke said this affected a number of seams in the bow and the weak rivets let go, putting more pressure on the strong rivets.
“Six compartments flooded. If the rivets were on average better quality, five compartments may have flooded and the ship would have stayed afloat longer and more people would have been saved,” Foecke said. “If four compartments flooded, the ship may have limped to.” – yahoo