The lack of adequate knowledge in materials science and engineering, as well as prioritizing other interests, has contributed to some of the greatest technological disasters in history. Iconic examples are the Challenger space shuttle tragedy; the dramatic accidents of the Havilland Comet, the Columbia and the ships Pendleton and Fort Mercer, as well as the collapse of the Hasselt Road bridge in Belgium. Without forgetting the Titanic disaster.
All of these catastrophes would have been avoided with the advances in materials that we know today.
The fragility of the Titanic’s steel
On September 1, 1985, Robert Ballard found the Titanic at 3,700 m at the bottom of the Atlantic Ocean. The ship had been divided into two main sections, separated by about 600 m. The collision had created openings in the hull totaling 1,115 m².
During an expedition to the wreck in the North Atlantic on August 15, 1996, researchers brought back steel from the ship’s hull for metallurgical analysis. Careful analysis revealed that the steel had a high ductile-brittle transition temperature, making it unsuitable for low-temperature service. At the time of the collision, the water temperature was –2° C.
Today, the quality of these steels has multiplied exponentially.
The error remained on the Liberty ships
During World War II, the United States built more than 6,000 Liberty ships to support Great Britain. One of the peculiarities in its manufacture was that the steel plates of the hull were welded and not joined by rivets. When three of these ships literally broke in half, the reason seemed clear at first and the welding of the plates was blamed. However, the real cause was related to the brittleness of steel at low temperatures.
These ships, along with the SS Schenectady and the Pendleton and Fort Mercer, withstood temperatures close to -2⁰ C, such as those suffered by the Titanic when it sank in the North Atlantic in 1912.
At these temperatures, the steel used in the helmets became brittle, breaking easily. The key to the problem lies in the temperature that determines when a material goes from being ductile to brittle (DBTT). This change in behavior was not discovered until years later and has posed a challenge to metallurgical research in the last half century.
Advances in metallurgy in the 20th century have made it possible to modify the composition of steel so that such a sudden transition does not occur and to reduce this risk. Today we know that the relationship between the elements that make up steel is key to optimizing its behavior, and also that this influences its sensitivity to low temperatures and its susceptibility to the formation of cracks.
With some changes in the composition of steel, many disasters would have been avoided. And not just the sinking of ships.
Challenger: the effect of temperature
The Challenger tragedy in 1986 was one of the most shocking disasters of the 20th century. This NASA flight had a special relevance, since on board was Christa McAuliffe, a teacher selected for the Teachers in Space program, promoted by Ronald Reagan’s government.
The launch was expected to revive interest in space travel, showing its growing safety. However, 73 seconds after takeoff, the Challenger disintegrated at an altitude of 14.6 kilometers, causing the death of all seven crew members.
The investigation revealed that the accident was caused by a failure in the O-rings of the solid fuel boosters. These gaskets, manufactured with fluoroelastomers (FKM), had loss of elasticity at low temperatures.
On the morning of launch, the temperature was -3⁰ C, which prevented the joints from sealing properly. This allowed the escape of hot gases that caused the right propeller to rupture, unleashing disaster.
By 1986 he already knew that O-rings were vulnerable to low temperatures, and several experts suggested postponing takeoff. But the pressure for the mission’s success prevailed, ignoring warnings about the material’s behavior in adverse conditions.
Havilland Comet and metal fatigue
The Havilland DH.106 Comet was the first commercial jet aircraft and marked a milestone in aviation when it began operating in 1949. Powered by turbines, it flew at higher altitudes and with less turbulence, improving comfort for passengers. Its aerodynamic design, with swept wings and embedded engines, made it more efficient.
However, between 1953 and 1954 the Comet suffered a series of accidents, including flight G-ALYV, which disintegrated over Calcutta.
Initially, the causes were thought to be climatic. But the investigation revealed a problem in the plane’s structural design: the square windows.
These windows acted as stress concentrators, causing cracks due to pressure cycles during flights. With each cycle, the cracks increased until they caused explosive decompression, causing the plane to disintegrate.
This discovery was key for the aviation industry, which adopted the oval windows we now see on airplanes to prevent stress concentration and reduce the risk of metal fatigue.
Space Shuttle Columbia: Corrosion
On February 1, 2003, the space shuttle Columbia disintegrated during reentry into the atmosphere, killing all seven crew members.
The disaster was due to damage to the left wing, caused by a piece of insulating foam that came loose during the launch, affecting the thermal protection plates. This damage exposed the shuttle’s internal structure to hot gases in the atmosphere, which weakened the ship and caused it to disintegrate.
One of the factors was the corrosion of metallic materials, which is aggravated in space due to exposure to highly reactive elemental oxygen in the upper layers of the atmosphere. Since then, safety inspections have paid greater attention to the corrosion of materials, which is no longer overlooked, preventing future accidents.
The commitment to materials science and engineering
The disasters mentioned highlight the importance of materials science and engineering in the safety and success of modern technologies.
Understanding how materials behave under different conditions is essential to preventing catastrophic failures. Figures such as Elon Musk have highlighted the importance of this discipline, encouraging people to study careers in science and engineering, crucial for the development of the space industry and other fields. And, as we have seen, to avoid terrible accidents in future history.
**This article was originally published onThe Conversation
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