Why is the black box on the airplane hard, can ensure that it will not be destroyed, the aircraft why not use the black box material?

In order to achieve such demanding requirements "black box" is very strong. Shell usually have to choose high strength, good corrosion resistance made of materials. Such as titanium alloy. In order to be able to save the black box in the air crash, usually installed in the rear of the aircraft less impact.

While the aircraft to meet the strength requirements of the use of the case as far as possible to reduce their own weight, the fuselage using a large number of aluminum alloys, a small number of composite materials, and structural parts such as titanium alloys, and rarely use steel. It should be emphasized that the quality control of the aircraft is of great significance. Imagine to make the Boeing 747 such as an airplane like a tank as strong as its weight to reach how much? Moreover, even if a tank were to fall from 10,000 meters, it would become a pair of scrap metal. Therefore it is impossible and not necessary to make the fuselage as strong as a black box.