The Class 4.8 Carbon Steel Hex Bolt is one of the most widely used general-purpose industrial fasteners worldwide. Manufactured from premium low carbon steel (Q195 / Q235 grade), this fastener delivers optimal ductility, reliable shear resistance, and excellent cost-efficiency for non-heavy structural assemblies, machinery alignment, light steel framing, and general engineering applications in accordance with international ISO standards.
Technical Specifications of Class 4.8 Carbon Steel Hex Bolt
Class 4.8 property ratings indicate a nominal tensile strength of 400 MPa (N/mm²) and a yield strength ratio of 80% (yielding at approximately 320 MPa). Unlike high-tensile alloy bolts that require quenching and tempering, low carbon steel hex head bolts undergo precise cold heading and cold rolling to achieve consistent dimensional accuracy and uniform thread profiles.
| Parameter | Metric Standard (DIN / ISO) | Imperial Standard (ANSI / ASTM) |
|---|---|---|
| Core Material | Low Carbon Steel (Q195 / Q235 / C1008) | ASTM A307 Grade A / Grade B Steel |
| Execution Standard | DIN 933 (Full Thread) / DIN 931 (Half Thread) | ANSI/ASME B18.2.1 Hex Head Screws |
| Tensile Strength | 400 N/mm² (Nominal) | 60,000 PSI (Minimum) |
| Yield Strength | 320 N/mm² (Nominal) | 36,000 PSI (Approximate) |
| Thread Pitch Tolerance | 6g Metric Thread Tolerance | Class 2A Thread Fit |
Precision Manufacturing Process for Carbon Steel Hex Bolt
Every batch of low carbon steel hex bolts produced at our Handan facility undergoes a strict cold-forging production routine to guarantee zero material defects and high structural stability:
- Wire Rod Spheroidizing & Pickling: High-grade Q195/Q235 steel wire rods are descaled and lubricated for seamless cold heading without surface micro-cracking.
- High-Speed Cold Heading: Multi-station heading machines form the hexagonal head, crisp bevels, and precise shank geometry with clear head markings (such as 4.8 and manufacturer codes).
- Thread Rolling Process: Thread grooves are cold-rolled rather than cut, graining the steel structure continuously to improve thread fatigue life and torque efficiency.
- Surface Finishing: Electro-galvanizing (Blue-white or Yellow Zinc) or Hot-Dip Galvanizing (HDG) is applied to prevent oxidation in atmospheric and indoor environments.
Key Applications and Standards of Carbon Steel Hex Bolt
Class 4.8 carbon steel bolts serve as reliable fastening solutions across diverse industrial sectors due to their excellent workability and cost balance:
- Light Steel Structures & Construction: Used in conjunction with DIN 934 hex nuts and flat washers for light wall framing, bracket installations, and timber structures.
- General Machinery Assembly: Securing non-vibrational mechanical covers, guardrails, and HVAC ducting support systems.
- Pipe Support & Electrical Fittings: Fastening pipe clamps, strut channel fittings, and utility hardware attachments.
Quality Assurance for Carbon Steel Hex Bolt
As a leading China fastener exporter based in Handan, Handan YiHao Fastener enforces comprehensive quality management across every production stage. We perform thread ring gauge inspections, head-to-shank concentricity tests, tensile load verifications, and salt spray corrosion testing (up to 48–96 hours for electro-zinc plated finishes).
For sea freight export, bolts are packed in heavy-duty 25kg inner cartons and securely shrink-wrapped on ISPM 15 compliant fumigated wooden pallets to prevent moisture ingress during shipping.
Request Factory Direct Pricing for Carbon Steel Hex Bolts
Looking for a reliable Class 4.8 carbon steel hex bolt manufacturer in Handan, China? Contact Handan YiHao Fastener today for detailed technical datasheets, full thread/partial thread options, sample shipments, and competitive bulk pricing.
