High-strength bolts and nuts specifications and prices/high-strength bolts and nuts pictures and models

High-strength bolts can withstand greater loads than ordinary bolts of the same specification. Ordinary bolts are made of 3 (i.e. 3) materials. Materials for high-strength bolts: 3. Steel-boron steel, manganese-titanium-boron steel, and other high-quality materials are heat-treated after being made to increase the strength. Ordinary bolts are commonly made of 3 (equivalent to 3 in the past) steel. From the perspective of strength level: high-strength bolts are increasingly used. Two intensity levels are commonly used: . and ., among which . is the most common. The strength grade of ordinary bolts is lower, generally ., ., . and . From the perspective of force characteristics: high-strength bolts exert pre-tension force and transmit external force by friction. Ordinary bolt connections rely on the shear resistance of the bolt rod and the pressure bearing of the hole wall to transmit shear force. The pretension force generated when tightening the nut is very small, and its impact can be ignored. The difference between high-strength bolt friction type and pressure-bearing type connections. High-strength bolt connections are made by bolts. The large tightening pre-tension force in the rod clamps the plates of the connecting plate, which is enough to generate a large friction force, thus improving the integrity and stiffness of the connection. When subjected to shear force, depending on the design and stress requirements, it can It is divided into two types: high-strength bolt friction type connection and high-strength bolt pressure-bearing type connection. The essential difference between the two is that the limit state is different. Although they are the same type of bolt, they are very different in terms of calculation methods, requirements, scope of application, etc. . In the shear design, the high-strength bolt friction type connection is the limit state when the external shear force reaches the friction force within the possible bearing range provided by the bolt tightening force between the plate contact surfaces, that is, the internal and external shear force of the connection is ensured throughout the entire period of use. The friction force does not exceed the tolerable range. The plates will not undergo relative sliding deformation (the original gap between the screw and the hole wall is always maintained), and the connected plates will bear stress as a whole elastically. In the shear design, in high-strength bolt pressure-bearing connections, the external shear force is allowed to exceed the friction force within the tolerable range. At this time, relative sliding deformation occurs between the connected plates until the bolt rod contacts the hole wall, and then the connection The force is transmitted by the shear of the bolt body, the pressure of the hole wall, and the friction between the contact surfaces of the plates. Finally, the shear of the shaft or the pressure failure of the hole wall is the ultimate shear state of the connection. In short, friction-type high-strength bolts and pressure-bearing high-strength bolts are actually the same type of bolts, but the difference is whether slippage is considered in the design. Friction-type high-strength bolts cannot slide, and the bolts do not bear shear force. Once they slip, the design is considered to reach a state of failure. Technically more mature pressure-bearing high-strength bolts can slide, and the bolts also bear shear force. The final damage is equivalent to the damage of ordinary bolts. (Bolts are sheared or steel plates are crushed). Another feature of high-strength bolts is that high-strength bolt connections have the advantages of simple construction, good stress performance, removable, fatigue resistance, and no loosening under dynamic loads. They are a promising connection method.