Titanic was the largest ship ever made at that time, about 275 meters long and 46,000 tons weight. Her builders had claimed that even if two ships collide,Titanic would stay afloat for three long days and thus would provide a time enough to escape the passengers.

image-google.com

But all their claims gone in to water when it struck a huge iceberg and sank in just three hours.

Most argued it did happen due to faulty design, misjudgment in sailing, blah.. blah..

But it is known to very few that the reason behind the tragic scene is Ductile to Brittle Transition. After long and expensive researches, metallurgists found Ductile to Brittle Transition was the main reason behind the incident.

Ductile to Brittle Transition generally means the ductility behaviour of a material changes to brittle behaviour at certain low temperature.Ductile material is one which absorbs impact energy and thus takes more time & energy to get fractured after experiencing plastic deformation. But once a material becomes brittle it will break catastrophically i.e. without deformation and bending.

The water temperature was below freezing point(around -2 deg C),which was responsible for the Ductile to Brittle Transition. So when the hull struck the iceberg it fractured directly without showing prior plastic deformation and bending. Also an evil role played by the steel which was rich in high sulphur content. Sulphur increases the Ductile to Brittle Transition temperature thus made the steel behave as brittle at the water temperature.

In modern steels to counter the effect of sulphur, manganese is added and also nowadays the ship hulls are made up of steel containing high manganese to sulphur ratio.

The below figure shows a impact test : the left is Titanic steel sample which has broken in to pieces shows granular cleavage surface (brittle fracture) and the right shows a modern steel which has shown prior bending rather than breaking directly in to pieces after impact (ductile fracture).

[Gannon, 1995]

This mysterious incident has brought a lot of improvements in materials making, designing and their applications.