Application standard and scope of high strength nut

Big hexagon nut specification reference standard
GB / t90-1985 fastener acceptance inspection, marking and packaging (EQV iso3269:1984)
GB/T196-1981 general thread, basic size (diameter 1~600mm)
GB / t197-1981 general thread, tolerances and fits (diameter 1-355mm)
GB / t1237-2000 fastener marking method (EQV ISO 8991:1986)
GB / t3098.2-2000 mechanical properties of fasteners nuts, coarse thread (IDT ISO 898.2:1992) GB / t3103.1-1982 (confirmed in 1988) fastener tolerance bolts, screws and nuts (EQV iso4759-1:1978) GB / t5267-1985 electroplated coating of threaded fasteners
GB / t5276-1985 fastener bolt, screw, stud and nut dimension code and mark (EQC ISO 225:1983) GB / t5779.2-2000 fastener surface defect nut (IDT ISO 6157.2:1995)
GB / t6170-2000 L-type hex nut (EQV ISO 4032:1999)
GB / t6938-1997 fasteners - Bolts, screws, studs and nuts - General specifications (IDT iso8992:1996), iso10683:2000 fasteners - non electrolytic zinc powder coating
So where are the high strength nuts used?

It is used in high-strength bolt pairs. The strength grade (after heat treatment) is grade 10, which is suitable for grade 10.9 bolts.
The mechanical properties and calculation methods of common bolts and high-strength bolts are different. The stress of high-strength bolt is to bear the external load by applying pretension P in its interior, and then producing friction resistance on the contact surface between the connected parts, while the ordinary bolt bears the external load directly.
High strength bolt connection has the advantages of simple construction, good mechanical performance, detachable and replaceable, fatigue resistance, and no looseness under dynamic load. It is a very promising connection method.
The high-strength bolt is to tighten the nut with a special wrench, so that the bolt produces a huge and controlled pretension. Through the nut and the base plate, the same amount of preload is generated on the connected parts. Under the pre pressure, there will be great friction along the surface of the connected parts. Obviously, as long as the axial force is less than this friction, the components will not slide and the connection will not be damaged. This is the principle of high-strength bolt connection.
High strength bolt connection relies on the friction between the contact surfaces of the connectors to prevent them from sliding. In order to make the contact surfaces have enough friction, it is necessary to increase the clamping force and the friction coefficient of the contact surfaces of the components. The clamping force between components is achieved by applying pretension to the bolt, so the bolt must be made of high-strength steel, which is the reason of high-strength bolt connection.