High strength bolts are made of high-strength materials, such as 45 steel, 40 boron steel, and 20 manganese titanium boron steel.

The maximum tensile strength of the material used for high-strength bolts is closely related to quenching treatment. After 40Cr quenching treatment, it is generally difficult to meet the material requirements of 10.9S grade high-strength bolts. In less stringent inspections, the maximum tensile strength of the material can be determined based on the surface hardness after quenching treatment. Jinhua high-strength bolts indicate that in addition to the different performance in the treatment process, the delayed fracture performance of high-strength bolts with different materials also varies under high stress conditions.

The material of ordinary bolts is Q235 (i.e. A3) manufactured.