High-Strength Carbon Steel Hex Bolt | Reliable Fastening Solutions for Heavy-Duty Applications
1. Product Overview
Our carbon steel hex bolt is engineered for demanding industrial environments where tensile strength, durability, and precision threading are non-negotiable. Manufactured from premium-grade carbon steel, these bolts provide superior load-bearing capacity and resistance to deformation under extreme torque. Designed in accordance with ISO 898-1 and ASTM A307 standards, each bolt ensures consistent dimensional accuracy and reliable performance across diverse assembly operations. Whether you are securing structural steel frameworks or heavy machinery components, this hex bolt delivers the clamping force required for long-term operational safety.
2. Key Features
- High Tensile Strength: Grade 4.8, 8.8, or 10.9 options available to match your specific load requirements.
- Precision Rolled Threads: Unified Inch (UNC/UNF) or Metric (ISO) threads for smooth engagement and reduced galling.
- Corrosion Resistance Options: Plain finish, zinc-plated, hot-dip galvanized, or black oxide coating for environmental adaptability.
- Chamfered Ends: Facilitates easy nut starting and reduces cross-threading during installation.
- Heat Treatment: Quenched and tempered for enhanced hardness and fatigue resistance in cyclic loading scenarios.
- Full Range of Sizes: Diameters from M6 to M30 (1/4" to 1-1/8") and lengths from 12mm to 300mm, with custom options available.
3. Technical Specifications
| Parameter | Specification |
|---|---|
| Material | Carbon Steel (C1022, C1035, 40Cr) |
| Grade | 4.8 / 8.8 / 10.9 (SAE J429 Grade 2, 5, 8) |
| Thread Standard | ISO 68-1 (Metric) / ASME B1.1 (Unified) |
| Hardness (HRC) | 22–32 (Grade 8.8) / 32–39 (Grade 10.9) |
| Yield Strength (min) | 640 MPa (Grade 8.8) / 940 MPa (Grade 10.9) |
| Surface Finish | Plain, Zinc Plated (Fe/Zn 5–12µm), HDG (55–85µm) |
| Head Type | Hexagon (DIN 933 / DIN 931 / ASME B18.2.1) |
| Tolerance Class | 6g (external thread) |
| Packaging | 25kg cartons, bulk pallets, or OEM packaging |
4. Application Scenarios
The carbon steel hex bolt is a cornerstone component in industries requiring robust mechanical fastening:
- Construction & Structural Steel: Beam-to-column connections, steel trusses, and bridge components.
- Heavy Machinery: Engine mounts, gearbox assemblies, and press frame bolting.
- Oil & Gas Infrastructure: Flange connections, pipeline supports, and drilling equipment.
- Agricultural Equipment: Tractor chassis, harvesting implements, and irrigation systems.
- Automotive Manufacturing: Suspension systems, drivetrain components, and chassis fastening.
5. Advantages
- Cost-Effective Strength: Carbon steel provides an optimal balance between mechanical performance and material cost, outperforming stainless steel in pure tensile applications.
- Wide Availability: Stock sizes and grades ensure quick lead times for urgent procurement needs.
- Easy Installation: Standard hex head geometry allows use with common sockets, wrenches, and impact tools.
- Customizable Coating: Zinc plating offers 72+ hours of salt spray resistance; HDG extends protection to over 1,000 hours for outdoor use.
- Reusability: Grade 8.8 and below bolts can be reused in non-critical applications when not subjected to yield loading.
6. Why Choose Us
As a specialized manufacturer with over 15 years of experience in fastener production, we provide carbon steel hex bolts that meet the exacting demands of global OEMs and distributors. Our advantages include:
- Certified Quality: ISO 9001:2015 and IATF 16949 certified facilities with in-house tensile testing and metallographic analysis.
- Traceability: Each batch is assigned a heat number and material certificate (EN 10204 3.1) for full traceability.
- Flexible MOQs: Low minimum order quantities for sample orders, with volume discounts for container-level purchases.
- Global Logistics: Export packaging compliant with ISPM 15 (wood pallets) and direct shipping to major ports (Shanghai, Ningbo, Hamburg, Los Angeles).
- Engineering Support: Our technical team assists with torque calculations, coating selection, and custom thread specifications.
7. FAQ
Q1: What is the difference between a carbon steel hex bolt and a stainless steel hex bolt?
A: Carbon steel bolts offer higher tensile strength (up to 10.9 grade) and are more economical for structural applications. Stainless steel provides better corrosion resistance but lower strength (typically A2-70 or A4-80).
Q2: Can these bolts be used in outdoor or marine environments?
A: Yes, with proper coating. For outdoor use, we recommend hot-dip galvanized (HDG) or zinc-nickel plated finishes. For direct marine immersion, consider our stainless steel alternatives.
Q3: How do I select the correct grade for my application?
A: Grade 4.8 is suitable for light-duty general assembly. Grade 8.8 is standard for most industrial applications (yield ≈ 640 MPa). Grade 10.9 is recommended for high-stress joints, such as those in heavy equipment or pressure vessels.
Q4: What is the typical lead time?
A: Stock sizes (M8–M20, 20–100mm length) ship within 7–10 working days. Custom sizes or special coatings require 15–25 working days, depending on quantity.
Q5: Do you provide samples for testing?
A: Yes, we offer free samples for qualified B2B buyers. You only pay for shipping. Contact our sales team with your required size, grade, and quantity.
Q6: What packaging options are available?
A: Standard packaging includes 25kg corrugated cartons with inner poly bags. For bulk orders, we offer palletized steel drums or wooden crates. Custom labeling and barcode printing are available upon request.
