1. High-quality surface condition and exhaustion characteristics:
When the spring is working, the surface layer bears a large in-situ stress, and the fatigue destruction is usually just started with the surface layer of stainless steel wire, for the springs used in key places such as cylinder springs, valve springs and suspension system springs are specified millions of times, millions of times or even longer circulation system service life, which clearly puts forward a high standard for the fatigue characteristics of raw materials.
There are many factors that harm the fatigue characteristics of raw materials, such as the composition and strength of raw materials, the purity level of stainless steel plates, process properties and alloy composition, etc., and the process performance of raw materials is crucial.
The surface defects of raw materials, such as cracks, telescopic scales, rust, dents, scratches and embossing, etc., are prone to stress in the whole process of work. The location of the stress is often the source of exhaustion that leads to exhaustion.
The source of fatigue is also easy to occur first at the location of the surface carburizing, so strict control of the deep layer of the carburized layer is also an important quality standard.
In order to improve the process performance of spring raw materials, the surface of the raw materials can be polished or polished, and a layer of raw material skin is removed by the peeling process before the stainless steel wire is pulled, so that most of the surface defects can be removed. When the spring quenching and tempering treatment is processed, it can be processed by manipulating the atmosphere or heat treatment to avoid surface carburizing and air oxidation.
2. High compressive strength:
In order to improve the working ability of the spring to alleviate fatigue damage and resist relaxation, the spring raw material should have high tensile strength and ductility limits, especially in the high yield ratio. In general, the ductility limit of the raw material is directly proportional to the tensile strength, so spring designers and manufacturers have always expected the raw material to have high tensile strength. The compressive strength and tensile strength of spring raw materials are closer, such as about 90% of the cold-drawn alloy steel wire: because the compressive strength is very easy to measure than the tensile strength, all the compressive strength shown in the supply of raw materials is compressive strength, so the compressive strength is generally used as the basis for the production and manufacturing of the design scheme. However, the compressive strength of raw materials is not as high as possible, and too high compressive strength reduces the plastic deformation and ductility of raw materials, and improves the ductility tendency. The composition of the compressive strength of the raw material, the composition of the alloy, the quenching and tempering treatment, the level of cold drawing (drawing or cold rolling) and the strengthening of the processing technology are related. Compressive strength is also related to fatigue limit, when the raw material is below 1600MPa, its fatigue limit increases with the increase of compressive strength.
3. Excellent plastic deformation and ductility:
In the whole process of spring production and manufacturing, raw materials need to withstand different levels of production and processing deformation, so it is stipulated that raw materials have a certain plastic deformation. For example, the hook and loop and torsion arm of the complicated tension and torsion spring, when the angle is very hour, when the production and processing of the inverted wire machine or the stamping die is bent and formed, the spring raw materials can not appear cracks, wear and other shortcomings. In addition, when the spring bears impact load or variable load, the raw material should have excellent ductility, which is also of great help to improve the service life of the spring.
Fourth, the precision of strict specifications:
A lot of springs are negative to negative
