Do you know High Strength Bridge Bolt?

As a High Strength Bridge Bolt Manufacturer, share with you. Bolts made of high-strength steel or requiring a large preload can be called high-strength bolts. High-strength bolts are mostly used for the connection of bridges, rails, high-pressure and ultra-high pressure equipment. The fracture of this kind of bolt is a mostly brittle fracture. The high-strength bolts used in ultra-high pressure equipment needs to be prestressed in order to ensure the sealing of the container.

High Strength Bridge Bolt

Several concepts about High Strength Bridge Bolt 1. The bolts whose performance level is above 8.8 are called high-strength bolts. The current national standard is only listed in M39. For large sizes, especially those with lengths greater than 10 to 15 High-strength bolts, domestic production is still short-term.

The difference between high-strength bolts and ordinary bolts:

High-strength bolts can bear larger loads than ordinary bolts of the same specification.

The material of ordinary bolts is Q235 (namely A3).

The material of high-strength bolts is 35 # steel or other high-quality materials, which are heat-treated after being manufactured to increase the strength.

The difference between the two is the difference in material strength.

From the perspective of raw materials:

High-strength bolts are made of high-strength materials. The screws, nuts and washers of high-strength bolts are made of high-strength steel, commonly used are 45 # steel, 40 boron steel, 20 manganese titanium boron steel, 35CrMoA, etc. Ordinary bolts are usually made of Q235 (equivalent to A3 in the past) steel.

From the strength level: high-strength bolts are increasingly used. Two intensity levels of 8.8s and 10.9s are commonly used, of which the 10.9 level is mostly. The strength level of ordinary bolts is lower, generally 4.4, 4.8, 5.6 and 8.8.

From the point of view of the force characteristics: high-strength bolts apply pre-tension and friction to transmit external forces. The ordinary bolt connection transfers the shear force by the shear resistance of the bolt and the pressure of the hole wall. The preload generated when tightening the nut is very small, and its effect is negligible. In addition to its high material strength, the high-strength bolt also exerts a large amount on the bolt. The pre-pressure causes a squeezing force between the connecting members, so that there is a large friction force perpendicular to the direction of the screw, and the pre-pressure, anti-slip coefficient and steel type directly affect the bearing capacity of high-strength bolts.

According to the characteristics of the force, there are pressure type and friction type. The calculation methods of the two are different. The minimum specifications of high-strength bolts are M12, commonly used M16 ~ M30, the performance of oversized bolts is unstable, and should be used carefully in the design.

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