The tensile strength of a bolt refers to the maximum tensile force that the bolt can withstand before being broken in the axial direction. It is the critical value for the transition from uniform plastic deformation to locally concentrated plastic deformation, and it is also the maximum load under static tensile ability. The yield strength of a bolt refers to the phenomenon that the stress does not increase or fluctuates within a small range during the tensile test of the bolt, but the phenomenon of rapid increase in strain occurs.