High-strength bolts are made of high-strength steel and need bolts with large preload. High strength bolts can be divided into compression type and friction type according to their mechanical characteristics. The two methods are different. Minimum specification M12 of high strength bolts, commonly used M16 ~ M30, when super-large bolts are used, their performance is unstable, so they should be carefully used in design.Stainless steel nut

There are some differences between high strength bolts and ordinary bolts. The bearing load of high strength bolts is larger than that of ordinary bolts of the same specification. Common bolts are made of Q235 (A3). High strength bolts are made of 35 # steel or other high quality materials, which are heat treated to improve strength. Generally speaking, the difference between high strength bolts and ordinary bolts is that they have different strength and compressive strength. Therefore, the high strength bolted connection has the advantages of simple construction, good mechanical performance, removable, fatigue resistance, and no loosening under dynamic load. It is a promising connection method.Blind hole nut

Bolts: Mechanical parts, cylindrical fasteners with threads with nuts. A type of fastener consisting of a head and a screw (a cylinder with external threads) is required to be fitted with a nut to fasten and connect two parts with through holes. This connection form is called bolt connection. If the nut is screwed off from the bolt, the two parts can be separated, so the bolt connection belongs to the removable connection.

According to the force mode of connection, it can be divided into ordinary and articulated holes. According to the shape of the head: hexagonal head, round head, square head, countersunk head and so on. Hexagonal head is the most commonly used. Usually the countersunk head is used where the connection is required.

The English name of riding bolt is U-bolt, which is a non-standard part and its shape is U-shaped, so it is also called U-bolt. The two ends have threads which can be combined with nuts. It is mainly used to fix tubular objects such as water pipes or sheet objects such as car leaf springs. Because the way of fixing objects is like riding on a horse, it is called riding bolt. According to thread length, it can be divided into two categories: full thread and non-full thread.

According to the tooth type of thread, it can be divided into two categories: coarse teeth and fine teeth. The coarse teeth are not shown in the sign of bolt. Bolts are classified into 8 grades according to their performance grades, including 3.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9 and 12.9. The bolts above 8.8 grades (including 8.8 grades) are made of low-carbon alloy steel or medium-carbon steel and heat-treated (quenching and tempering). They are generally referred to as high strength bolts, and those below 8.8 grades (excluding 8.8 grades) are generally referred to as ordinary bolts.

Ordinary bolts can be divided into three grades: A, B and C according to their manufacturing accuracy. Class A and B are refined bolts and Class C are rough bolts. For connecting bolts used in steel structures, except as specified in particular, they are generally rough C-class bolts. Different levels of processing methods are different, usually the corresponding processing methods are as follows: 1) A and B bolts are machined by lathe, the surface is smooth, the size is accurate, the material performance grade is 8.8, the production and installation is complex, the price is high, and seldom used; 2) C bolts are made of rough round steel, the size is not precise enough. Indeed, the material performance grade is 4.6 or 4.8. Shear connection has large deformation, but easy installation and low production cost. It is mostly used for temporary fixing of tension connection or installation.