You can see the indication of ductile failure with surfaces that looked like they fought to stay together. On the left of this image you can see modern steel that was subjected to the Charpy test alongside the Titanic steel. The specimen recovered from the Titanic exhibited the same type of behavior that we saw in our ME 330 lab. In contrast, you can see the flat surface of brittle failure clearly on the freezing water specimen. You can see our steel specimen to the left, and notice the shear lips on the boiling water specimen. We tested all of the materials at different temperatures, one was ice water, 0° C, another at room temperature, and one more in boiling 100° C water. It’s quite a fun test, we get to press a big button and a heavy pendulum comes down and impacts the specimen. In our lab section of ME 330, which is Engineering Materials, we conducted a Charpy impact test on 1045 Steel, 2024 Aluminum, HDPE, which is a plastic often used in grocery bags, and PMMA, which is a clear thermoplastic that can be used as a glass alternative. We know this because samples were retrieved from the wreck of the Titanic, and a Charpy test was performed on them. This is the idea that metals of a particular crystal structure that were ductile at a higher temperature will become brittle at lower temperatures and fail under lesser loads as a result. The makers of the Titanic may not have considered the effects of temperature change in material behavior, but the steel underwent a ductile-to-brittle transition at this lower temperature in the water. The Titanic sailed through very cold water on the night it sank the temperature was just below freezing. Brittle materials will not experience plastic deformation, and absorb a smaller amount of energy before fracture. Plastic deformation is the idea that the material will change permanently under load before actually failing. Some materials have ductile properties, and this means that they will absorb more energy prior to breaking than materials with brittle properties, and will undergo plastic deformation before finally breaking. But one of the main culprits of the disaster was not highlighted on the silver screen, and that is the catastrophic material failure on the ship.īefore we dive in, here’s some background on the material concepts we’ll need to understand what happened. The stories of many characters, both fictional and real, have been told. And please don’t tell me that this is a movie spoiler, we’ve just rolled past the 21 st anniversary of the release of James Cameron’s Titanic, and the 106 th anniversary of the actual tragedy itself. The sinking of the Titanic is a tragedy that captivated this nation for over a century.
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