1. The maximum tensile strength of the material used for high-strength bolts has a great relationship with the quenching treatment. It is generally difficult to meet the material requirements of 10.9S grade high-strength bolts after 40Cr quenching treatment. In less strict inspections, it can be based on the surface hardness after quenching treatment. To determine the maximum tensile strength of the material. In addition to different properties in the processing process, high-strength bolts made of different materials also have different delayed fracture properties under high stress conditions. \x0d\2. 40Cr high-strength bolts are mainly used in bolt ball node grids, and their design strength is generally 390MPa (dgt; =30mm) or 430MPa (d