Ductile iron bolt

Ductile iron bolt: mechanical parts, cylindrical threaded fasteners with nuts. A kind of fastener composed of head and screw (cylinder with external thread), which is used to connect two parts with through hole. This kind of connection is called bolt connection. If the nut is unscrewed from the bolt, the two parts can be separated, so the bolt connection is a detachable connection.
According to the stress mode of connection: common and reamed. According to the head shape: hexagonal head, round head, square head, countersunk head and so on. The hexagonal head is commonly used. Generally, countersunk head is used where connection is required.
The English name of riding bolt is U-bolt. It is a non-standard part, and its shape is U-shaped, so it is also called U-bolt. There are threads at both ends, which can be combined with nuts. It is mainly used to fix tubular objects, such as water pipes or flakes, such as leaf springs of cars. Because its way of fixing objects is like riding on a horse, it is called riding bolt. According to the thread length, it can be divided into full thread and non full thread.
According to the thread profile, it can be divided into coarse thread and fine thread. The coarse thread profile is not shown in the mark of bolt. According to the performance grade, bolts are divided into 8 grades: 3.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9 and 12.9. Bolts above grade 8.8 (including grade 8.8) are made of low carbon alloy steel or medium carbon steel and heat treated (quenching and tempering), which are generally called high strength bolts, while bolts below grade 8.8 (excluding grade 8.8) are generally called ordinary bolts.
According to the manufacturing accuracy, ordinary bolts can be divided into three grades A, B and C. grade A and B are refined bolts, and grade C is rough bolts. For connecting bolts used in steel structure, unless otherwise specified, they are generally common rough C-grade bolts. There are differences in the processing methods of different levels, and the corresponding processing methods are as follows: ① the bolt rod of Grade A and B bolts is processed by lathe, with smooth surface and accurate size. Its material performance grade is 8.8, and its production and installation are complex, and its price is high, so it is rarely used; ② Grade C bolts are made of raw round steel, the size is not accurate enough, and the material property grade is grade 4.6 or 4.8. Shear connection has large deformation, but it is easy to install and has low production cost. It is mostly used for tensile connection or temporary fixation during installation.