It really depends on the type of sting you're talking about, here. Car springs are made from steel though, if that's what you're asking! Hope this helps!
Steel
hardened steel
to make it strong
It is because steel has a higher elasticity than copper i.e the opposing force of steel is more than that of copper. Elasticity of steel is more than copper because it has a higher value of Young's Modulus.
Chrome vanadium spring steel
Garden tools and springs
Furniture springs are typically made from steel, which melts at around 2500°F (1371°C). However, the melting temperature may vary depending on the exact composition of the steel used in the springs.
Modern light switches are made from plastic, copper, and (maybe) coiled steel springs.
The automotive industry is the largest consumer of steel springs.
Watch springs are typically made of a form of steel known as spring steel or blue tempered steel. This material is chosen for its flexibility and ability to retain its shape after being wound and unwound thousands of times in a watch movement.
The frame and springs are steel. The bed is a fabric webbing. The springs attach to plastic fittings on the bed. The padding is filled with expanded foam and covered with a plastic-coated fabric.
Alloy, carbon, and stainless steels were the most commonly used spring materials because of their strength. Titanium, however, was gaining popularity in the early 1990s because of its superior strength, light weight, and resistance to corrosion.