Introduction to the meaning of performance grade of large hexagon bolt in steel structure

       The performance grade of bolts for steel structure connection is divided into more than 10 grades, including 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9, etc., among which the bolts of grade 8.8 and above are made of low carbon alloy steel or medium carbon steel and are heat treated (quenched and tempered), which are generally called high-strength bolts, and the rest are generally called ordinary bolts.

       There are two parts of numbers in the performance grade mark of large hexagon bolt of steel structure, which respectively represent the nominal tensile strength value and yield strength ratio of bolt material.

       For example, a bolt with a performance grade of 4.6 for a large hexagon bolt means:

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

       2. The yield strength ratio of big hexagon bolt material is 0.6;

       3. The nominal yield strength of large hexagon bolt material is up to 400 × 0.6 = 240mpa performance grade 10.9 steel structure bolt.

       After heat treatment, the bolt material of steel structure can reach:

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

       2. The yield strength ratio of big hexagon bolt material is 0.9;

       3. The nominal yield strength of steel structure bolt material up to 1000 × 0.9 = 900MPa grade bolt performance grade means the international general standard. For bolts of the same performance grade, regardless of the difference between the material and the place of origin, the performance is the same, and only the performance grade can be selected in the design.