ANSI B18.2.1 bolt manufacturers focus on the performance and quality of their products. no matter in which industry or where the products are used, the products can be accepted as long as their performance is normal. otherwise, they will be rejected. The product performance is also a mark for customers to evaluate the processing capability of an ANSI B18.2.1 bolt manufacturer. Of course, it does not exclude some customers who need to be made.
Rail bolt manufacturers can grasp the product quality from these aspects:
- High strength: In order to improve the capacity of rail bolt damage and anti-relaxation, rail bolt materials should have high yield strength and elasticity, especially high yield ratio. Under normal circumstances, the elasticity of the material is proportional to the yield strength, so rail bolt designers and manufacturers always hope that the material has a high yield strength. However, the tensile strength and yield strength of rail bolt materials are close, such as about 90% of that of cold drawn carbon steel wire.
Because tensile strength is easier to measure than yield strength, and all the tensile strength provided in the delivery of materials, tensile strength is generally used as the basis in design and manufacture. However, the higher the tensile strength of the material, the better. Excessive strength will reduce the plasticity and toughness of the material and increase the brittleness tendency. The tensile strength of the material is related to its chemical composition, metallographic structure, heat treatment, degree of cold working (drawing or rolling) and other strengthening processes. There is also a relationship between tensile strength and fatigue strength. When the material is below 1600MPa, its fatigue strength increases with the increase of tensile strength. During the manufacturing process of rail bolts, the materials need to undergo different degrees of processing deformation, thus requiring the plasticity of the materials produced by rail bolt manufacturers. For example, when the radius of curvature is very small for the shackle and torsion arm of the complicated tensile and torsion rail bolt, the rail bolt material shall not have any defects such as cracks and breakage during processing, winding or punching and bending. At the same time, when the rail bolt bears impact load or variable load, the material should have good toughness, which will be of great benefit to improve the service life of the rail bolt.
Excellent surface condition and fatigue performance: the surface of rail bolts is subject to large stress when working, and fatigue damage usually starts from the surface of steel wire. For rail bolts used in important occasions, such as valve rail bolts, valve rail bolts and suspension rail bolts, it requires millions of times, tens of millions of times or even longer cycle life, which puts forward high requirements on the fatigue performance of materials. There are many factors that affect the fatigue performance of materials, such as the chemical composition, hardness, purity of steel, surface quality and metallographic structure of materials used by Track Boltmanufacturers, and the surface quality of materials is especially important. Surface defects of materials, such as cracks, folds, scales, rust, pits, scratches and indentations, are easy to cause stress concentration in the working process of rail bolts. The place where stress is concentrated is often the fatigue source causing fatigue damage. Fatigue sources are also easy to occur first at the decarburized parts of the surface, so strict control of the depth of decarburized layer is also a very important quality index. In order to improve the surface quality of rail bolt material, the surface of the material can be polished or polished, and a layer of material skin can be stripped by peeling process before steel wire drawing, so that most surface defects can be removed. Control atmosphere or vacuum heat treatment can be used for rail bolt heat treatment to prevent surface decarburization and oxidation.
