When NaCl dissolves in water

The sodium ion becomes hydrated. when sodium chloride dissolves in water, the sodium and chloride ions and the polar water molecules are strongly attracted to one another by ion-dipole interactions

Answer : Sulfur

Explanation : When a plate of the steel hull of a ship develops a large crack when the ship strikes a reef.

After the Analysis of the steel’s composition some of the components, showed higher-than-normal levels of an element, We could explain why the plate cracked instead of bending. 

The component was Sulfur, as it the only element which has got much lower melting point as compared to the other metals present in the hull, also it has low hardness than others.