How to find energy stored in a wire

[pvpkillerx]

There are 1000 tonnes of high tensile steel wire stressed to 1000MPa. How much energy is stored in the steel?



$\sigma = P/A$



First I multiplied the 1000 tonnes (1000000kg) by 9.8m/s^2. Then I found the volume by dividing the weight by the original weight. I don't know what to do next. I am not even sure if i am going in the right direction or which equation i should use. Any help is appreciated.

 

[LawrenceC]

If something streaches, its weight does not change. It gets thinner but longer. Hint: Find the volume by using metal properties.