Four Common Materials for Springs

Springs are frequently subjected to variable or impact loads during operation. To ensure reliable and continuous service of springs, their materials must feature high elasticity and fatigue limit, sufficient toughness and plasticity, as well as favorable heat treatment performance.

Spring materials and their properties shall comply with relevant handbooks, specifications and standards (GB/T129.6-92, GB4357-89). Commonly used spring steels are listed as follows:

1. Carbon Spring Steel
This type of spring material (such as Grade 65 and Grade 70 steel) boasts advantages of low cost and easy access to raw materials, while its disadvantages include a low elastic limit, susceptibility to permanent set after repeated deformation, and inability to function normally at temperatures above 130°C.

2. Low Manganese Spring Steel
Compared with carbon spring steel, this grade of steel (represented by 65Mn) delivers superior hardenability and higher strength. Its drawbacks lie in the tendency to form cracks and hot brittleness after quenching. Nevertheless, thanks to its low price, it is widely adopted for manufacturing small-sized springs such as clutch springs.

3. Silicon-Manganese Spring Steel
The addition of silicon (exemplified by 60Si2Mn) can drastically raise the elastic limit and tempering stability of steel. Accordingly, tempering can be carried out at relatively high temperatures to achieve excellent mechanical properties. Silicon-manganese spring steel finds extensive industrial applications, and is generally utilized for producing coil springs for automobiles and tractors.

4. Chromium-Vanadium Steel
Vanadium is alloyed into steel (e.g., 50CrVA) to refine the steel microstructure and enhance its strength and toughness. This material exhibits outstanding fatigue resistance and impact resistance, and can operate reliably within a temperature range from -40°C to 210°C, yet it comes at a higher cost. It is primarily applied in high-demand scenarios, such as fabricating springs for aero-engine control systems.

In addition, certain materials including stainless steel and bronze possess corrosion-resistant characteristics. Bronze also features non-magnetic properties and electrical conductivity, making it a frequent choice for manufacturing springs deployed in chemical equipment or corrosive media. However, it suffers from poor heat treatability and inferior mechanical performance, so it is rarely used in general machinery.