Tell You The Screw Grade Classification.

1. Bolt functional grade, that is, the functional grade of bolts for steel structure connection, which is divided into more than 10 grades such as 3.6, 4.6, 4.8, 5.6, 5.8, 6.8, 8.8, 9.8, 10.9, and 12.9. The functional 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, etc. Among them, the raw materials of bolts of grade 8.8 and above are low-carbon alloy steel or medium-carbon steel and heat-treated (quenching, tempering), collectively referred to as high-strength bolts, and others are collectively referred to as ordinary bolts. The bolt performance grade label consists of two parts of numbers, which respectively indicate the nominal tensile strength value and yield ratio of the bolt material.

2. The functional 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, etc. Among them, the raw materials of bolts of grade 8.8 and above are low-carbon alloy steel or medium-carbon steel. After heat treatment (quenching, tempering), it is generally called high-strength bolts, and others are generally called ordinary bolts. The bolt performance grade label consists of two parts of numbers, which respectively indicate the nominal tensile strength value and yield ratio of the bolt material. For example: a bolt of functional class 4.6, its meaning is:

1. The nominal tensile strength of bolt raw materials reaches 400MPa;

2. The yield-strength ratio of the bolt material is 0.6;

3. The nominal yield strength of the bolt material reaches 4000.6=240MPa

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

1. The nominal tensile strength of bolt raw materials reaches 1000MPa;

2. The yield-strength ratio of the bolt material is 0.9;

3. The nominal yield strength of the bolt material is 10000.9=900MPa.