Product Introduction
Bolt Grade 8.8, also known as Grade 8.8 bolt, is a high-strength bolt that undergoes heat treatment to achieve a tensile strength of no less than 800MPa, with a yield strength to tensile strength ratio of approximately 0.8. It is commonly made from stainless steel or alloy steel and conforms to various international standards. Featuring excellent corrosion resistance, fatigue resistance, and high strength, it is widely used in numerous industrial sectors, including automotive manufacturing, bridge construction, rail transportation, chemical equipment, and machinery manufacturing.
Product Applications
Bridge Construction
Bolt Grade 8.8 bolts are extensively used in connecting vital parts of bridges, such as bridge decks, main beams, and piers. Due to their high strength and good toughness, they can withstand huge tensile and shear forces, ensuring stable structural integrity under various complex external forces like vehicle loads, wind loads, and earthquake loads, thus guaranteeing the safe passage of bridges.
Building Structures
In building structures, Bolt Grade 8.8 bolts are often employed to connect large steel structural members, such as the steel frames of high-rise buildings, roof trusses of industrial plants, and net-frame structures of gymnasiums. These structures need to bear significant deadweight and external loads. The 8.8-grade bolts provide reliable connection strength, ensuring the overall integrity and stability of the structures and preventing safety accidents caused by loose or broken connections.
Machinery Manufacturing
For various machinery, such as heavy equipment like cranes, excavators, loaders, as well as precision equipment like machine tools and generators, Bolt Grade 8.8 bolts are indispensable connecting elements. They can withstand strong vibration, impact, and alternating loads during equipment operation, ensuring tight connections of all parts, stable operation, reducing the probability of failures, and prolonging the service life of the equipment.
Automobile Manufacturing
In automobile manufacturing, Bolt Grade 8.8 bolts are widely used in connecting key parts such as engines, chassis, and bodies. For example, cylinder head bolts and connecting rod bolts in engines need to withstand high temperature, high pressure, and high-speed rotation conditions. The 8.8-grade bolts can provide sufficient tightening force, ensuring the sealing and reliability of engines; suspension systems and braking systems of chassis also use 8.8-grade bolts for connections, ensuring the driving safety and stability of vehicles.
Energy Facilities
In the energy field, such as wind turbines and solar power generation devices, Bolt Grade 8.8 bolts also play an important role. Taking wind turbines as an example, the connections between tower tubes, blades, hubs, and other components require high-strength bolts to withstand huge wind loads and rotational torque. The 8.8-grade bolts can meet these requirements, ensuring the long-term stable operation of wind turbines in harsh natural environments.
Product Parameters
HEX BOLT DIN 931/ISO4014 933/ISO4017 GRADE 8.8
Grade 8.8 high tensile steel is often referred to as the structural grade for bolts. It is the most common form of high tensile material and is usually stocked in plain finish or zinc.
|
M 5 x 30 – 100 |
M 6 x 30 – 200 |
|
M 8 x 35 – 300 |
M 10 x 40 – 300 |
|
M 12 x 45 – 300 |
M 14 x 50 – 300 |
|
M 16 x 55 – 300 |
M 18 x 65 – 300 |
|
M 20 x 70 – 300 |
M 22 x 70 – 300 |
|
M 24 x 70 – 300 |
M 27 x 80 – 300 |
|
M 30 x 80 – 300 |
M 33 x 60 – 200 |
|
M 36 x 90 – 300 |
M 42 x 80 – 200 |
|
Class |
Size |
Material |
Tensile strength |
Hardness |
Elongation δ% |
Reduction of cross-sectional area |
|
8.8 |
d ≤ M16 |
35 #, 45 # |
800 |
22~32 |
12 |
52 |
|
8.8 |
M18≤d≤ 24 |
35 #, 45 # |
830 |
23~34 |
12 |
52 |
|
8.8 |
d ≥ M27 |
40 Cr |
830 |
22~34 |
12 |
52 |
|
10.9 |
All Size |
40 Cr, 35CrMoA |
1040 |
32~39 |
9 |
48 |
|
12.9 |
All Size |
35 CrMoA, 42CrMoA |
1220 |
39~44 |
8 |
44 |
Why Choose Us
High Quality
Our products are manufactured to the highest standards, utilizing premium materials and advanced manufacturing processes to ensure exceptional quality.
Rich Experience
With a commitment to strict quality control and attentive customer service, our experienced team is always ready to address your needs and guarantee complete customer satisfaction.
Quality Control
Our professional staff meticulously monitors the production process, conducts thorough product inspections, and ensures that every final product meets the required quality standards, guidelines, and specifications.
24-Hour Online Service
We strive to respond to all inquiries within 24 hours, and our dedicated teams are always available to assist you in case of any emergencies.
FAQs
Q: What is the typical hardness of Bolt Grade 8.8?
A: Bolt Grade 8.8 typically has a hardness range that corresponds to its material and heat treatment process. While the exact hardness value can vary, it is generally sufficient to meet the requirements for high-strength bolting applications.
Q: Can Bolt Grade 8.8 be used in high-temperature environments?
A: Bolt Grade 8.8 is generally not recommended for use in high-temperature environments due to potential material degradation and strength reduction. Consult specific material datasheets or consult with an engineer for suitable bolt options for high-temperature applications.
Q: Is Bolt Grade 8.8 resistant to corrosion?
A: Bolt Grade 8.8, made from stainless steel or alloy steel, offers good corrosion resistance. However, the specific corrosion resistance may vary depending on the environmental conditions and the material's composition. Galvanic corrosion should be considered when pairing with dissimilar metals.
Q: What is the difference between Bolt Grade 8.8 and Grade 10.9?
A: Bolt Grade 10.9 has a higher tensile strength and yield strength compared to Bolt Grade 8.8. Grade 10.9 bolts are typically used in applications requiring even higher mechanical properties and are more expensive due to their superior performance.
Q: How do I know if a bolt is Bolt Grade 8.8?
A: Bolt Grade 8.8 bolts are usually marked with the grade symbol on their surface. You can identify them by checking for the "8.8" marking. Additionally, you can refer to the bolt's specifications or certification provided by the manufacturer.
Q: Can Bolt Grade 8.8 bolts be reused?
A: Bolt Grade 8.8 bolts can potentially be reused if they have not been damaged or excessively stressed during their initial use. However, it is always best to consult with an engineer or the bolt manufacturer to ensure safety and compliance with relevant standards.
Q: What is the maximum torque value for Bolt Grade 8.8?
A: The maximum torque value for Bolt Grade 8.8 depends on factors such as bolt size, material, and lubrication. It is crucial to consult the bolt's specifications or torque tables provided by the manufacturer to determine the appropriate torque value.
Q: Do Bolt Grade 8.8 bolts require special tools for installation?
A: Bolt Grade 8.8 bolts can generally be installed using standard tools such as wrenches or impact drivers. However, for high-precision or critical applications, the use of specialized tools may be recommended to ensure accurate torque application and bolt tension.
Q: How do I inspect Bolt Grade 8.8 bolts for damage?
A: Inspect Bolt Grade 8.8 bolts visually for any signs of cracking, corrosion, or wear. Additionally, perform a thread inspection to ensure that the threads are not damaged or stripped. If any damage is found, replace the bolt immediately.
Q: Can Bolt Grade 8.8 bolts be galvanically coupled with aluminum?
A: Galvanic coupling between Bolt Grade 8.8 bolts and aluminum should be avoided due to the potential for galvanic corrosion. Consult with a corrosion engineer or material scientist to determine suitable corrosion mitigation strategies or alternative materials for your application.
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