Performance grade of Qingdao bolt

Qingdao Haorui Steel Products Co., Ltd. mainly produces and sells standard fasteners and non-standard fasteners of various specifications (such as carriage bolts, automobile standard screws, special-shaped rivets), and also engages in wire drawing processing and sales.boltIt is a type of fastener composed of two parts, a head and a screw (cylinder with external thread). It needs to be matched with a nut to fasten and connect two parts with through holes.

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 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), commonly known as high-strength bolts, and the rest are commonly known as ordinary bolts. The bolt performance grade label consists of two numbers, which respectively indicate the nominal tensile strength value and the yield ratio of the bolt material. For example: a bolt with a performance level of 4.6, its meaning is: 1. The nominal tensile strength of the bolt material is 400MPa; 2. The yield ratio of the bolt material is 0.6; 3. The nominal yield strength of the bolt material is 400×0.6=240MPa level. Performance grade 10.9 high-strength bolts, after heat treatment, the material can reach: 1. The nominal tensile strength of the bolt material is 1000MPa; 2. The yield ratio of the bolt material is 0.9; 3. The nominal yield strength of the bolt material is 1000 ×0.9=900MPa level. The meaning of the bolt performance grade is the international standard. The bolts of the same performance grade, regardless of the difference in material and origin, have the same performance. Only the performance grade can be selected in the design. The so-called 8.8 and 10.9 strength grades refer to the bolts' shear stress resistance grades of 8.8GPa and 10.9GPa. 8.8 Nominal tensile strength 800N/MM2 Nominal yield strength 640N/MM2

General bolts use"XY" to indicate the strength, X*100=the tensile strength of the bolt, X*100*(Y/10)=the yield strength of the bolt (because according to the label: yield strength /Tensile strength=Y/10) Such as 4.8, the tensile strength of this bolt is: 400MPa, and the yield strength is: 400*8/10=320MPa