The difference between high-strength bolts and ordinary bolts
The difference between high-strength bolts and ordinary bolts
High strength bolts are increasingly widely used. Two strength levels, 8.8s and 10.9s, are commonly used, with 10.9 being the most common. The strength level of ordinary bolts is generally lower, including 4.4, 4.8, 5.6, and 8.8 levels.
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 all made of high-strength steel, commonly used in 45 # steel, 40 boron steel, and 20 manganese titanium boron steel. Ordinary bolts are commonly made of Q235 steel.
2. From the perspective of strength level:
High strength bolts are increasingly widely used. Two strength levels, 8.8s and 10.9s, are commonly used, with 10.9 being the most common. The strength level of ordinary bolts is generally lower, including 4.4, 48, 5.6, and 8.8.
From the perspective of force characteristics:
High strength bolts apply pre tension and transmit external forces through friction, while ordinary bolt connections rely on the shear resistance of the bolt rod and the bearing pressure of the hole wall to transmit shear. When tightening the nut, the pre tension is very small, and its impact can be ignored. In addition to its high material strength, high-strength bolts also apply a large pre tension to the bolt, causing squeezing pressure between the connecting components, resulting in a large amount of friction perpendicular to the screw direction. In addition, the pre tension The anti slip coefficient and the type of steel directly affect the bearing capacity of high-strength bolts. According to the stress characteristics, it is divided into pressure bearing type and friction type, and the calculation methods for the two are different. The minimum specification of high-strength bolts is M12, commonly used between M16 and M30. The performance of oversized bolts is unstable, and they should be used with caution in design.
