Dapeng Town Industrial Park, Tongshan District, Xuzhou City, Jiangsu Province, China
Bolts that made of high-strength steel, or require a large pre tightening, can all be called high-strength bolts. High-strength bolts are generally used for the connection of bridges, steel rails, high-pressure and ultra-high-pressure equipment. The fractures of these bolts are mostly brittle fracture. High-strength bolts for ultra-high-pressure equipment require a large pre-stress to ensure the seal of the container.
Quality use of high-strength bolt:
Nowadays large aircraft, large power generation equipment, automobiles, high-speed trains, large ships, large-scale complete equipment, and so on, as the representative of the advanced manufacturing industry has entered an important development direction. As a result, fasteners also will enter an important development stage. High-strength bolts are used for connections of important machinery, repeated disassembly and assembly or various mounting torque methods require a high standard for high-strength bolts. Therefore, the surface condition and thread accuracy will directly affect the service life and safety of the main engine. In order to improve the friction coefficient and avoid rust, seizure or unsmooth stagnation during use, technical requirements stipulate that the surface should be nickel-phosphorus plating. The thickness of the coating is guaranteed in the range of 0.02 to 0.03mm, the coating is uniform, dense, no pinholes, etc.
Bolt material: 18Cr2Ni4W, 25Cr2MoV steel; Bolt specification: M27～M48. Because this kind of steel is easy to form a passivation film on the surface, and this passivation film will make the bolt cannot obtain chemical nickel-phosphorus layer with good adhesive force, so special pretreatment measures must be taken to remove the film first, and take measures to prevent its regeneration, in order to ensure that the coating after plating and the substrate has a good binding force. Meanwhile, due to the large geometry of the bolt, nickel-phosphorus plating treatment and quality inspection of the process become more difficult.
SAFS devote to the development of space frame for several years, professional manufacture of space frame for diverse projects such as aircraft hangar, bulk storage, warehouse and skylight roof, etc.
For more information please contact us: safs139@safseelstructure.com
