Spring steel is a type of high-carbon steel that is specifically formulated to have excellent elasticity and resilience. It is designed to withstand repeated bending or twisting without permanently deforming or breaking. Spring steel is commonly used in the manufacturing of springs, which are widely employed in various applications such as automotive suspensions, industrial machinery, consumer products, and more.

There are different grades and variations of spring steel, but some common types include:

1. High-carbon spring steel (such as AISI 1070 or 1095): These steels have a high carbon content, typically ranging from 0.70% to 0.95%. They offer excellent strength and elasticity, making them suitable for heavy-duty springs and applications that require high load-bearing capacity.
2. Alloy spring steel: This type of spring steel contains additional alloying elements such as silicon, manganese, chromium, or vanadium to enhance specific properties. Alloy spring steels may provide improved strength, fatigue resistance, or corrosion resistance compared to high-carbon spring steel.
3. Stainless steel: While not as common as high-carbon or alloy spring steels, stainless steel is also used for certain spring applications where corrosion resistance is essential. Stainless steel springs are often utilized in environments with exposure to moisture or chemicals.

The choice of spring steel will depend on factors such as the required strength, flexibility, resistance to fatigue, and environmental conditions in which the spring will be used.