The spring is often subjected to variable load or impact load during operation. To ensure that the spring can work reliably and permanently, the material must have high elastic limit and fatigue limit, and should have sufficient toughness and plasticity, as well as good heat treatability.
Spring materials and properties can be found in the relevant manuals, specifications and standards (GB/T129.6-92, GB4357-89). The commonly used spring steels are:
1: carbon spring steel
This type of spring (such as 65,70 steel, etc.) has the advantages of cheap price and convenient source of raw materials. The disadvantage is that the elastic limit is low, the elasticity is easily lost after repeated deformation, and it can not work normally at a temperature of 130 degrees.
2: Low manganese spring steel
This spring steel (such as 65Mn) compared with carbon spring steel has the advantages of better hardenability and higher strength; the disadvantage is that cracks and hot brittleness tend to occur after quenching. However, due to its low cost, it is generally used mechanically to make springs that do not hit a size, such as clutch springs.
3: Si-Mn spring steel
Since silicon is added to this steel (for example, 60Si2Mn), the elastic limit can be significantly increased and the tempering stability can be improved, so that the steel can be tempered at a higher temperature, and thus good mechanical properties can be obtained. Silicon-manganese spring steel has been widely used in the industry, and is generally used for manufacturing coil springs for automobiles and tractors.
4: Chrome vanadium steel
The purpose of adding vanadium to this type of steel (eg, 50CrVA) is to refine the structure and increase the strength and toughness of the steel. This material has good milk fatigue and impact resistance, and can work reliably at temperatures of -40 degrees to 210 degrees, but it is more expensive. Used in more demanding applications, such as springs used in aeroengine adjustment systems.
In addition, some stainless steels and bronzes are resistant to corrosion. Bronze is also magnetic and conductive. It is commonly used in the manufacture of chemical equipment or springs that work in corrosive media. The disadvantage is that it is not easily heat-treated and its mechanical properties are poor, so it is rarely used in general machinery.
The selection of materials should take into account the use of the spring, the degree of importance, the conditions of use (including load properties, size and cycle characteristics, working duration, operating temperature and surrounding medium conditions, etc.), processing, heat treatment, and economy. At the same time, it is necessary to refer to the springs used in existing equipment and choose to make more compatible materials.