Why Springs Are Made of Steel Instead of Copper
When a material is subjected to stress, it undergoes deformation. In engineering terms, this is known as strain. When the stress is released, the material can either return to its original shape or stay in the deformed state. If it returns to the original shape, it is said to be elastic; if it stays deformed, it is plastic. Most materials exhibit both elastic and plastic behaviors, but in varying ratios. Steel, in particular, has an elastic behavior until it reaches its yield point, whereas copper tends to exhibit predominantly plastic behavior. This is why steel is preferred for springs.
Steel is the preferred material for springs due to its superior elastic behavior. Specifically, steel that is used for springs is an alloy known as spring steel, which is formulated for its strength and ability to maintain a longer useful life. Copper, on the other hand, tends to have higher plastic deformation properties, making it less ideal for applications requiring consistent elasticity and durability.
The Role of Elastic Behavior in Springs
The elastic behavior of a material is crucial for the functionality of springs. Steel, particularly medium and high carbon steels sometimes with some manganese, has an extremely high elastic modulus (Young's modulus). This means that steel springs can store and release energy more efficiently, providing the desired resilience and bounce.
Comparison Between Steel and Copper Springs
To illustrate the difference between steel and copper springs, consider a simple experiment. Take a single strand of copper wire and bend it; you will find that it does not spring back to its original shape. Now, take a spring and compress it; when you let it go, it will return to its original shape. This behavior is a result of the spring's high elastic modulus. Compare this with a scenario where you depress your car's suspension; a copper wire would not provide the same consistent rebound as a steel spring.
However, it is important to note that steel and copper are not the only materials used for springs. There are numerous types of springs made from various materials, each with its own set of advantages and applications. For example, in some older vehicles, leaf springs made of stacked flat steel or solid round steel bars twisted to create tension were used.
Cost and Manufacturing Considerations
The decision to use steel over copper for springs is primarily driven by cost and ease of manufacturing. Carbon steel springs can be produced and reset by many companies, making them widely accessible and affordable. Copper alloy springs, while potentially superior in many cases, often face limitations due to the higher costs of raw materials and the more complex manufacturing processes required.
Conclusion
In conclusion, while springs can be made from a variety of materials, steel is preferred for its elastic behavior and durability. The choice of material often depends on specific applications, cost considerations, and manufacturing capabilities. Understanding the properties of steel and copper can help in selecting the right material for different spring applications.