Hex Head Bolts grade strength:

1. The nominal tensile strength of the bolt material reaches 400MPa;

2. The yield strength ratio of the bolt material is 0.6; the nominal yield strength of the bolt material reaches 400×0.6=240MPa.

Performance grade 10.9-grade high-strength bolts, after heat treatment, can reach:

1. The nominal tensile strength of the bolt material reaches 1000MPa;

2. The yield strength ratio of the bolt material is 0.9; the nominal yield strength of the bolt material reaches 1000×0.9=900MPa.

The meaning of the bolt performance grade is the international standard. The bolts of the same performance grade, regardless of the difference in material and origin, have the same performance. Only the performance grade can be selected in the design.