Space frame high strength bolt is the most important component of space frame structure. It can turn inside the conic elements to connect pipe member to the node, and resist against the pulling forces occurring in the system.
The maximum tensile strength of the material used for space frame high strength bolt has a lot to do with quenching treatment. After 40Cr quenching treatment, it is generally difficult to meet the material requirements of 10.9S-grade high-strength bolts, to determine the maximum tensile strength of the material. In addition to the different properties in the treatment process, high-strength bolts with different materials have different delayed fracture properties under high stress conditions.
40Cr high-strength bolts are mainly used in bolted ball joint grids. The design strength is generally 390MPa (d>=30mm) or 430MPa (d<30mm), and there is no high pre-tensioning stress in use. When used in situations where a high pretension force is to be applied, care should be taken to understand and ensure delayed fracture properties. The delayed fracture performance of 20MnTiB high-strength bolts is better than that of 40B.