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Phone: +86 13679287344
E-mail: [email protected]
Add: Room1102, Land Center T1, Yanzhan Road, No. 1111, Qujiang New District, Xi'an, China.
Common Hexagon Flange Bolts- GB/T 5789 and DIN 6921
Time: 2025-02-05 Source: Author:
GB/T 5789 and DIN 6921 are two very common standards in the field of hexagonal flange head bolts, the two are similar in some specifications, but not exactly the same.
1. Size data Head size: In terms of head side size, although the two standards have formulated corresponding size specifications according to the nominal diameter of the bolt, there are differences in the specific values. For example, for a bolt with a nominal diameter of M10, the size of the head opposite side specified in GB/T 5789 May be 16mm, while the corresponding size in DIN 6921 May be 16.5mm. This subtle difference may seem small, but in actual production and assembly, it will affect the tools used and the compatibility with peripheral parts.
Head thickness data also vary. The standard value for the head thickness of the M12 bolt under GB/T 5789 May be 7.5mm, while DIN 6921 May be set at 7.8mm. This reflects the difference in design philosophy between the two standards, and the German standard DIN 6921 May be more inclined to enhance the bearing capacity of the bolt head under complex forces.
Thread size: In the combination of nominal diameter and pitch, GB/T 5789 and DIN 6921 have a partial overlap, but also have their own unique specifications. For a wide range of domestic industrial applications, GB/T 5789 provides a series of commonly used nominal diameters and pitch combinations to meet the needs of versatility and interchangeability. In addition to some common specifications, DIN 6921 will also have some special pitch options to adapt to the requirements of high-precision fine-tuning in the German precision machinery manufacturing sector.
In terms of thread tolerances, GB/T 5789 divides thread tolerances into several precision levels to adapt to the requirements of thread matching accuracy in different application scenarios. The thread tolerance system of DIN 6921 is more detailed and complex, with more tolerance zones, which means that the German standard has more strict control over the precision of thread manufacturing, and can meet the needs of more high-end and precision equipment.
2. Mechanical property
Tensile strength: The two standards have different ways of dividing bolt performance grades, and the corresponding tensile strength requirements are also different. Taking the common 8.8 class bolt as an example, the minimum tensile strength specified by GB/T 5789 is 800MPa, while the minimum tensile strength of 8.8 class bolts under DIN 6921 May reach 830MPa or even higher. This shows that DIN 6921 is more stringent in the performance of bolts under tensile forces, reflecting the high standards of product quality and safety in the German manufacturing industry.
Hardness : GB/T 5789 and DIN 6921 give the corresponding range on the hardness requirements, but the specific values and test method details are different. GB/T 5789 specifies a Rockwell hardness HRC range of 22-32 for class 8.8 bolts, focusing on ensuring the overall performance of bolts during assembly and use. DIN 6921 not only has different requirements for the hardness range, but also has more precise requirements for the test conditions such as the location of the hardness test, the size of the loading force and the duration of the test, in order to ensure the accuracy and consistency of the hardness test results, and thus ensure the stability of the product quality.
3. Surface treatment
In terms of surface treatment, GB/T 5789 and DIN 6921 both recognize the importance of bolt protection, but there is a significant gap in the specific data requirements. GB/T 5789 requirements for the thickness of the galvanized layer are generally not less than 5μm, and the corresponding salt spray test time is specified to evaluate corrosion resistance, which can meet the basic protection needs of bolts in most domestic industrial environments.
DIN 6921 has more stringent and comprehensive requirements for surface treatment. The thickness of the galvanized layer is usually required to be no less than 8μm, and the salt spray test time will be greatly extended. In addition, it also has detailed data indicators on the chemical composition and microstructure of the film layer to ensure that the bolt can maintain good performance and long service life under harsh conditions with high corrosion risks, such as Marine environment and chemical corrosion.
LONGJOY BOLT is A trusted supplier of hexagon flange head bolts, and we offer a wide range of specifications and sizes to meet the needs of different industries and application scenarios. Whether it's construction, machine building, the automotive industry or home repair, LONGJOY BOLT can provide you with affordable, high-quality products to ensure your project is safe and reliable. If you are looking for a reliable BOLT supplier, LONGJOY BOLT is the way to go. Whether you need standard products or customized solutions, our professional team will be happy to serve you. Contact us today to learn more about our products or get a free quote!
LONGJOY GB/T 5789: High quality GB/T 5789-1986 hexagon flange bolts, large series B, to meet the needs of industrial fastening - Hexagon Flange Bolt
LONGJOY DIN 6921: Hexagon flange bolt standard explanation: specification, use and purchase guide | DIN 6921-1983 - Hexagon Flange Bolt
1. Size data Head size: In terms of head side size, although the two standards have formulated corresponding size specifications according to the nominal diameter of the bolt, there are differences in the specific values. For example, for a bolt with a nominal diameter of M10, the size of the head opposite side specified in GB/T 5789 May be 16mm, while the corresponding size in DIN 6921 May be 16.5mm. This subtle difference may seem small, but in actual production and assembly, it will affect the tools used and the compatibility with peripheral parts.
Head thickness data also vary. The standard value for the head thickness of the M12 bolt under GB/T 5789 May be 7.5mm, while DIN 6921 May be set at 7.8mm. This reflects the difference in design philosophy between the two standards, and the German standard DIN 6921 May be more inclined to enhance the bearing capacity of the bolt head under complex forces.
Thread size: In the combination of nominal diameter and pitch, GB/T 5789 and DIN 6921 have a partial overlap, but also have their own unique specifications. For a wide range of domestic industrial applications, GB/T 5789 provides a series of commonly used nominal diameters and pitch combinations to meet the needs of versatility and interchangeability. In addition to some common specifications, DIN 6921 will also have some special pitch options to adapt to the requirements of high-precision fine-tuning in the German precision machinery manufacturing sector.
In terms of thread tolerances, GB/T 5789 divides thread tolerances into several precision levels to adapt to the requirements of thread matching accuracy in different application scenarios. The thread tolerance system of DIN 6921 is more detailed and complex, with more tolerance zones, which means that the German standard has more strict control over the precision of thread manufacturing, and can meet the needs of more high-end and precision equipment.
2. Mechanical property
Tensile strength: The two standards have different ways of dividing bolt performance grades, and the corresponding tensile strength requirements are also different. Taking the common 8.8 class bolt as an example, the minimum tensile strength specified by GB/T 5789 is 800MPa, while the minimum tensile strength of 8.8 class bolts under DIN 6921 May reach 830MPa or even higher. This shows that DIN 6921 is more stringent in the performance of bolts under tensile forces, reflecting the high standards of product quality and safety in the German manufacturing industry.
Hardness : GB/T 5789 and DIN 6921 give the corresponding range on the hardness requirements, but the specific values and test method details are different. GB/T 5789 specifies a Rockwell hardness HRC range of 22-32 for class 8.8 bolts, focusing on ensuring the overall performance of bolts during assembly and use. DIN 6921 not only has different requirements for the hardness range, but also has more precise requirements for the test conditions such as the location of the hardness test, the size of the loading force and the duration of the test, in order to ensure the accuracy and consistency of the hardness test results, and thus ensure the stability of the product quality.
3. Surface treatment
In terms of surface treatment, GB/T 5789 and DIN 6921 both recognize the importance of bolt protection, but there is a significant gap in the specific data requirements. GB/T 5789 requirements for the thickness of the galvanized layer are generally not less than 5μm, and the corresponding salt spray test time is specified to evaluate corrosion resistance, which can meet the basic protection needs of bolts in most domestic industrial environments.
DIN 6921 has more stringent and comprehensive requirements for surface treatment. The thickness of the galvanized layer is usually required to be no less than 8μm, and the salt spray test time will be greatly extended. In addition, it also has detailed data indicators on the chemical composition and microstructure of the film layer to ensure that the bolt can maintain good performance and long service life under harsh conditions with high corrosion risks, such as Marine environment and chemical corrosion.
LONGJOY BOLT is A trusted supplier of hexagon flange head bolts, and we offer a wide range of specifications and sizes to meet the needs of different industries and application scenarios. Whether it's construction, machine building, the automotive industry or home repair, LONGJOY BOLT can provide you with affordable, high-quality products to ensure your project is safe and reliable. If you are looking for a reliable BOLT supplier, LONGJOY BOLT is the way to go. Whether you need standard products or customized solutions, our professional team will be happy to serve you. Contact us today to learn more about our products or get a free quote!
LONGJOY GB/T 5789: High quality GB/T 5789-1986 hexagon flange bolts, large series B, to meet the needs of industrial fastening - Hexagon Flange Bolt
LONGJOY DIN 6921: Hexagon flange bolt standard explanation: specification, use and purchase guide | DIN 6921-1983 - Hexagon Flange Bolt
