What do the 8.8 and 10.9 grades of high-strength bolts mean?
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Update time : 2020-08-27 11:26:25
1. 10.9 represents the mechanical performance level of the bolt, 10 represents the tensile strength of 1000 MPa, and .9 represents the yield ratio of the bolt, which is the ratio of the yield strength to the tensile strength. There is a clear standard in GB/T 3098.1, and the hardness value of the bolt can be found at night. In other words, as long as the performance level of the bolt is provided, the strength of the bolt is defined.
2. The performance grades of bolts for steel structure connection 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, among which the bolts of grade 8.8 and above are made of low-carbon alloy steel or medium-carbon steel. After heat treatment (quenching and tempering), they are generally called high-strength bolts, and the rest are generally called ordinary bolts. The bolt performance grade label consists of two numbers, which represent the nominal tensile strength value and yield ratio of the bolt material.
The meaning of bolt performance grade is an international standard. For bolts of the same performance grade, regardless of the difference in material and origin, the performance is the same. Only the performance grade can be choosed for design. The so-called 8.8 grade and 10.9 grade of strength refers to the bolt's shear stress resistance grade of 8.8 GPa and 10.9 Gpa.