How high strength bolts are made of high strength steel, or bolts that require greater preload force can be called high strength bolts. High strength bolts are used for bridges, rails, high pressure and ultrahigh pressure equipment So that the breakage of the bolt is mostly brittle fracture.Application of high strength bolts on the ultrahigh pressure equipment, in order to ensure the container seal, the need to impose a large prestress on the high strength of the bolt several concepts 1. According to the provisions of bolts Of the performance level of 8.8 or more, known as high-strength bolts. Now the national standard is only listed to the M39, for large size specifications, especially the length of more than 10 to 15 times the high-strength bolts, domestic production is short- Hexagon Bolt High Strength T Groove Bolt
High strength bolts and ordinary bolts
High-strength bolts can withstand the load than the same specifications of the ordinary bolts to large. Ordinary bolts are made of Q235 (ie A3). High strength bolts 35 # steel or other high quality materials, made after heat treatment, to improve the strength. The difference between the two is the difference in material strength.
From the raw materials to see: high-strengthbolts using high-strength materials. High-strength bolts of the screw, nuts and washers are made of high-strength steel, commonly used 45 steel, 40 boron steel, 20 manganese titanium boron steel, 35CrMoA and so on. Common bolts are commonly made of Q235 (equivalent to the previous A3) steel. From the strength level point of view: high-strength bolts, the use of increasingly widespread. Commonly used 8.8s and 10.9s two strength levels, of which 10.9 mostly. Ordinary bolt strength level is low, generally 4.4, 4.8, 5.6 and 8.8.
From the force characteristics of view: high-strength bolts to apply pre-tension and friction by the transmission of external force. Ordinary bolts are connected to the shear and shear walls to create shear, tighten the nut when the pre-tension is very small, the impact is negligible, and high-strength bolts in addition to its high strength material, the bolt is also applied to a large Pre-tension, so that the connection between the members of the extrusion force, so that the direction perpendicular to the screw has a lot of friction, and pre-tension, anti-slip coefficient and steel types have a direct impact on the bearing capacity of high-strength bolts. According to the characteristics of force sub-pressure and friction type. The two methods are different. High-strength bolts minimum size M12, commonly used M16 ~ M30, large size of the bolt performance is not stable, the design should be used with caution. High-strength bolt friction type and pressure-type connection of the difference: high-strength bolt connection is a large bolt through the tightening of the tension plate to clamp the board plate, enough to produce a lot of friction, thereby enhancing the integrity of the connection And the stiffness, when the shear force, according to the design and stress requirements of different, can be divided into high-strength bolts and high-strength bolts and pressure-type connection of two, the difference between the two is the ultimate state of the difference, although the same Bolts, but in the calculation method, requirements, scope of application and so on are very different. In the shear design, the high-strength bolt friction-type connection is outside the shear force to reach the plate between the contact surface by the bolt tightening force provided by the maximum possible friction as the limit state, that is to ensure that the connection during the entire period of time the external shear does not exceed Maximum friction. The plate does not undergo relative slip deformation (the gap between the screw and the hole always maintains the original void), and the connected plate is subjected to elasticity as a whole. In the shear design, the high-strength bolts in the pressure-type connection to allow the external shear force exceeds the maximum friction, then the connection plate between the relative slip deformation occurs until the bolt and the hole wall contact, then connect the bolt Body shear and hole wall pressure and the friction between the plate surface friction force together, and finally to the shaft shear or wall pressure damage as a connection to the limit of the state. In short, the friction type high strength bolts and pressure type high strength bolts are actually the same kind of bolts, just whether the design is considering slip. Friction type high-strength bolts must not slide, the bolt does not bear the shear force, once the slip, the design that reached the state of destruction, technically more mature; pressure-type high-strength bolts can slide, bolts also bear shear, the ultimate damage is equivalent to ordinary Bolt damage (bolt cut or steel plate crush).
Add: TANGHUI INDUSTRIAL PARK, JIAXING ECONOMIC DEVELOPMENT AREA, JIAXING, ZHEJIANG, CHINA
Contact person: Ms. Nancy Yue