Bolt Strength Grade

Release time：

2023-08-04

The strength grade is divided according to the mechanical properties. According to relevant standards, bolt performance grades 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 and have been heat treated (quenching, tempering), commonly known as high-strength bolts, and the rest are commonly referred to as ordinary bolts. The bolt performance grade label consists of two parts of numbers, which respectively represent the nominal tensile strength value and yield strength ratio of the bolt material. For example:
bolts with performance grade 4.6, the meaning is:
　　1. The nominal tensile strength of the bolt material reaches 400MPa;
　　2. The yield strength ratio of the bolt material is 0.6;
　　3. The nominal yield strength of the bolt material reaches 400×0.6=240MPa Grade
　　Performance grade 10.9 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;
　　3. The nominal yield strength of the bolt material reaches 1000×0.9=900MPa level
　　Bolts: Mechanical parts, cylindrical threaded fasteners with nuts. A type of fastener consisting of a head and a screw (a cylinder with external threads), which needs to be matched with a nut to fasten two parts with through holes.