DIN931/GB5782 Hexagon Head Bolts

8.8 grade DIN 931 / GB/T 5782 hexagonal head bolts are high-strength semi-threaded (partly threaded) external hexagonal bolts, complying with the German standard DIN 931 or the Chinese standard GB/T 5782. Both have basically the same structure (semi-threaded, with a longer section without thread on the shaft). The product is made of medium carbon steel (such as 35K, 45K) and undergoes quenching and tempering heat treatment to achieve an 8.8 grade strength. The surface is treated with oxidation and blackening, presenting a dark black matte appearance. The specifications cover M6-M36, with a length of 30-200mm, a thread accuracy of 6g, and are used with 8 grade nuts. It is one of the most commonly used high-strength structural bolts in the industrial field.

Product Feature

8.8 grade high strength: After quenching and tempering treatment, the comprehensive mechanical properties are excellent. The tensile strength, shear resistance, and fatigue resistance are much higher than those of 4.8 grade, making it suitable for structural connections that need to withstand large dynamic loads and preload forces; Semi-teeth design (DIN 931 feature): The upper end of the rod has a longer non-threaded section, and after passing through the light hole of the connected component, it is only locked by the nut. The thread does not participate in shearing, and the shear section is the smooth rod, which provides a more reasonable load-bearing capacity and reduces the friction between the threaded section and the hole wall, facilitating assembly alignment; Universal external hexagon drive: Standard hexagonal heads are compatible with open wrenches, sockets, and torque wrenches, suitable for large torque tightening, and no special tools are required at the construction site.

Our Strength

·  Direct from manufacturer to customer, On time delivery

·  Completely fastener products,offers one - stop shopping service.

·  High quality and competitive price, saving your cost.

·  Product complies with iso9001 and ts16949 certification

·  After shippment, we will offer the Material report and Test report.

Product Application

Mechanical equipment and heavy industry: High-strength connections for machine tool bases, reducer housings, pump and valve flanges, and structural components of crushers/sand conveyors.

Automobile and rail transportation: Pre-tightening connections for commercial vehicle chassis, trailer beams, track vehicle bogies, and bridge steel structures (non-exposed parts).

Energy and infrastructure: Friction-type or pressure-type connections for internal components of wind turbine towers, main beams of photovoltaic supports, steel structure factories, and power towers (indoor/dry sections).

Molds and tooling: Template clamping for large injection molds and stamping molds, mold guide columns fixation, withstanding alternating clamping forces.

Agriculture and construction machinery: Structural components of tractors, excavators, and harvesters, for vibration and impact-resistant conditions.

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Q: Are you trading company or manufacturer ?

A: We are factory

Q: How long is your delivery time?

A: Generally it is 2-5 days if the goods are in stock. or it takes around 20 days if the goods are not in stock, certainly,it is according to your quantity.

Q: Do u do Non-standard Fasteners,and How about the OEM/ODM?

A:Yes,we do Non-standard Fasteners,OEM/ODM as well,and we have 20 years more experience in this line.We have complete production line, R&D Center. Pre-sales and after-sales support. Let u no worries about the quality.

Q: Do you provide samples ? is it free or extra ?

A: Yes, we could offer the sample for free,but u need charge the freight at the first time.

Q:Do you sell little quantity,like few hundred and few thousand?

A: It depends on the stock. if we have ,that's ok. if not,it needs MOQ.