DIN and GOST strength class

The strength class is an important mechanical characteristic of metal fasteners. This indicates the tensile strength of the metal. For fasteners made of carbon steel, it has a designation in the form of two numbers separated by a dot. At the same time, the standard to which the fastener was manufactured is indicated. Bolts, nuts, and studs are divided into 10 strength classes. The first number indicates a hundredfold reduction in the critical tensile strength. It is expressed as N/mm². That is, the effect of tensile force on the cross-sectional area of a metal product. For example, in a value of 8.8, the first digit indicates that the tensile strength is 800 N/mm². The second figure shows the yield strength, after which deformation processes begin. The second number can be written as 800 (N/mm²).

To facilitate the selection of metal products according to their mechanical and other properties, special tables are created that show the DIN and GOST strength classes. This allows customers of fasteners to quickly place orders with absolutely precise parameters, including tensile, shear, and other strengths.

Bolt strength class

The strength of the bolts is labeled and tested for tensile and shear strength. The bolts are tested… if the first number is higher than the second, the bolts are stronger in tensile strength, but less flexible.

4.8

5.8

They are made of steel grades 10 and 20.

They have relatively low tensile strength. Bolts of strength class 5.8 can withstand loads 20% higher than bolts of strength class 4.8.

Widely used in all sectors of the national economy for lightly loaded compounds.

8.8

They are made of steel 35, 20G2R, 40X with subsequent hardening.

They can withstand twice the destructive impact compared to strength class 4.8.

It is recommended for use in critical structures and mechanisms.

10.9

12.9

They are made of 20G2R, 40Kh, 30Kh3MF steel only, depending on the bolt diameter, and are subsequently hardened.

Withstand destructive impact 2.7 times more than strength class 4.8.

The high strength class makes it possible to use smaller fasteners for the same loads; reduce the metal consumption of fasteners and reduce the price by 30-40%. They are indispensable in mechanisms requiring frequent assembly and disassembly, lifting machines and critical structures.

Bolts of strength class 5.8 according to GOST
GOS 7798, GOS 7805, GOS 15589,
GOS 7795, GOS 7796, GOS 7808
GOS 7795, GOS 7796, GOS 7808

Bolts of strength class 5.8 DIN
DIN 931, DIN 933

Bolts of strength class 6.8 according to GOST
GOST 7805

Bolts of strength class 6.8 according to GOST
DIN 931, DIN 933

Bolts of strength class 8.8 according to GOST
GOS 7798, GOS 7805, GOS 7808, GOS 22353-77, GOS 7795, GOS 7796

Bolts of strength class 8.8 according to GOST
DIN 931, DIN 933

Bolts of strength class 10.9, 11.0 ХЛ, according to GOST
GOS R52644, GOS 22353

Bolts of strength class 10.9 DIN
DIN 931, DIN 933

Strength class of nuts

Attention! The strength class of the nuts is marked only from strength class 8!

Nuts of strength class 5.8 GOST
Nut GOST 5915, GOST 5927, GOST 15526 (strength class 6.0)

Nuts strength class 5.8 DIN
DIN934

Nuts of strength class 8.8 according to GOST
GOS 5915, GOS 5927

Nuts strength class 8.0 DIN
DIN 934

Nuts, strength class 10.9, 11.0 ХЛ according to GOST
GOS R52645-2006, GOS 22354-77

Strength class of washers

The washers do not have a strength class. The hardness of the washers is measured in HV units. A standard DIN 125 washer has a standard hardness of 140 HV. The high-strength washer EN 14399 has a hardness of 300 HV.