Why are springs made of steel and not of copper.

Springs are made of a variety of materials including copper and various forms of steel. The most common is high carbon steel as it is cheap, easy to work and a couple of other important properties.

Copper springs exist as well, but copper is more expensive than steel. However, in an environment where corrosion resistance is important, copper springs are a good alternative.

A good spring will be that in which a large restoring force is developed on being deformed

Explanation:

Since Young's modulus for steel is more than that of copper, therefore the springs made of steel and not of copper.