Hexagon bolt

Overview of Our Hexagon Bolt Collection

Hexagon bolts are the most widely used fasteners in construction, repair, and automotive industries. Characterized by their six-sided head, they are designed to be tightened with a wrench or socket, allowing for high torque application. Our collection spans the full spectrum of material properties, ensuring we have the right bolt whether you need ductility for a fence post or extreme tensile strength for an engine block.

Material and Grade Guide: Decoding the Numbers

Selecting the right hexagon bolt largely depends on the mechanical stress the joint will endure. Carbon steel bolts are marked with grade numbers (e.g., 8.8), while stainless steel bolts focus on corrosion resistance.

Grade / Material	Material Type	Strength Level	Best Use Case
Grade 4.8	Low Carbon Steel	Low (Ductile).	Non-critical fastening, furniture, temporary structures.
Grade 8.8	Medium Carbon Steel	High (Structural Standard).	General construction, steel framework, automotive suspension.
Grade 10.9 / 12.9	Alloy Steel	Ultra-High Tensile.	Heavy machinery, mining equipment, critical engine components.
Stainless (A2/A4)	Stainless Steel	Moderate (Class 70/80).	Outdoor fixtures, chemical plants, marine environments.

Quality Assurance and Documentation

For structural projects, verifying the grade is non-negotiable. We provide EN 10204 Type 3.1 Material Test Certificates (MTC) free of charge upon request. This documentation proves that a Grade 12.9 bolt truly meets the required yield and tensile strength specifications. Please indicate your need for this certificate when placing your order. Third-party inspections are also available for an additional fee.

Industrial Applications

Grade 8.8 bolts are the workhorse of the construction industry, used universally in steel structures and bridges. Grade 10.9 and 12.9 bolts are reserved for high-stress areas in excavators and hydraulic presses where failure is not an option. Meanwhile, Stainless Steel hexagon bolts are essential for water treatment facilities and petrochemical plants where rust prevention takes precedence over extreme tensile strength.

Frequently Asked Questions

What do the numbers "8.8" or "10.9" on the bolt head mean?

These numbers indicate the material's mechanical properties. The first number represents the ultimate tensile strength (e.g., "8" = 800 N/mm²). The second number represents the yield strength ratio (e.g., ".8" means the bolt yields at 80% of its ultimate strength). Therefore, a 12.9 bolt is significantly stronger and harder than a 4.8 bolt.

What is the difference between A2 and A4 stainless steel bolts?

A2 (304) is the standard "18/8" stainless steel, offering good corrosion resistance for general outdoor and indoor use. A4 (316) contains added Molybdenum, which provides superior resistance to chlorides and acids. For marine environments or coastal areas (within 10km of the sea), A4 bolts are highly recommended to prevent tea-staining or pitting.

Can I replace a Grade 8.8 bolt with a Stainless Steel bolt?

You should be careful. Standard stainless steel (A2-70 or A4-70) has a tensile strength of roughly 700 N/mm², which is lower than a Grade 8.8 bolt (800 N/mm²) and significantly lower in yield strength. For non-structural applications, it may be fine, but for load-bearing structural joints, swapping carbon steel for stainless steel requires an engineering check.