Small screws, big safety! In order to make a good bolt, we must first control the purchase of raw materials. Only when we grasp the first pass, can we talk about the quality rejection of the next step. If the quality of the incoming steel materials is problematic, if you can produce it, it is not a qualified bolt.
Bolts or nuts should have relatively high tensile and compressive properties. In addition to the thread accuracy and relevant technical dimensions that should be paid attention to in production, their mechanical properties and fatigue resistance of bolts are determined by materials and subsequent heat treatment processing. Therefore, the quality of materials has a huge impact on the performance of bolts.
After the normal installation of bolts and nuts, there will be some rolling friction movement. Many bolts are thick rods and half teeth, and the part of the thick rod will be treated as a shaft in use. If the material hardness is not enough, the screw will be worn due to this long-term friction, and will break in severe cases. Therefore, the appropriate hardness of the material has a direct bearing on the service time of the bolt, but it is not the higher the hardness, the better. If the hardness is too high, the toughness will decline and fracture will occur.
In a joint connection environment, the bolt also needs to have a certain tensile property, that is, its tensile strength. For example, the connection of two flange plates. If two flange plates need to be stressed at the same time in both directions in application, at this time, if the bolt material does not have a certain tensile property, it will be directly pulled off.
The bolt material also needs to have certain high temperature resistance characteristics. The bolt quality cannot be affected by the temperature change. Whether the bolt can withstand high temperature is determined by the material itself and heat treatment. This is also the stability of materials. After we produce a bolt, its dimensional accuracy is in accordance with the requirements, and these parameters cannot change at any time.
Materials also need to have a certain degree of elasticity. For example, the materials we produce spring washers are completely different from ordinary materials. When you press them to their original positions, they will automatically spring up. Spring washers are also produced using the rebound principle of materials to increase friction.
The bolt material also needs to have anti-corrosion performance. Although we will also carry out some surface treatment on the bolt in the later stage to make it anti-corrosion, this does not mean that the material itself does not need anti-corrosion. Some bolts do not need surface treatment. If the anti-corrosion performance of the material is very poor, the corrosion rate will increase, and this corrosion will always erode to the interior of the material, which is also a very serious quality problem.
Materials also need plasticity, that is to say, they should be easy to produce and shape. You can't make them processed in order to maintain their hardness. Therefore, the plasticity of materials also determines whether the dimensional accuracy of bolts is controllable.
