The performance grades of steel structure connecting bolts are divided into more than 10 grades such as 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9, of which the bolts of grade 8.8 and above are made of low-carbon alloy steel or medium-carbon steel, and are heat treated. Quenching and tempering is generally called high-strength bolts, and the rest are generally called ordinary bolts.
The property class for large hex bolts consists of two numbers representing the nominal tensile strength value and yield ratio of the bolt material.
For example, the performance grade of the big hexagon bolt is 4.6, which means:
1. The nominal tensile strength of the large hexagonal bolt material can reach 400MPa; 2. The material yield ratio of the large hexagonal bolt is 0.6; 3. The material nominal yield strength of the large hexagonal bolt is 400×0.6\\u003d240MPa, and the performance grade is 10.9 high-strength bolts.
After heat treatment, the big hexagon bolt can reach: 1. The nominal tensile strength of the big hexagonal bolt material is 1000MPa; 2. The yield ratio of the big hexagonal bolt material is 0.9; 3. The nominal yield strength of the big hexagonal bolt material is 1000
The meaning of ×0.900MPa bolt performance grade is an international standard. For bolts of the same performance level, regardless of the material and origin, their performance is the same. Only performance classes can be selected in the design.
