Spring steel is a low alloy, medium carbon steel or high carbon steel with a very high yield strength. This allows objects made of spring

Spring (device)

A spring is an elastic object used to store mechanical energy. Springs are usually made out of spring steel. Small springs can be wound from pre-hardened stock, while larger ones are made from annealed steel and hardened after fabrication...

 steel to return to their original shape despite significant bending or twisting.
Silicon

Silicon

Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...

 is the key component to most spring steel alloys. The most widely used spring steel is ASTM A228 (0.80–0.95% carbon), which is also known as music wire.

Spring steel is also commonly used in the manufacture of metal swords used for stage combat due to its resistance to snapping or shattering.