DIN603 304 Stainless Steel Large Round Head Square Neck Bolt
DIN603 304 stainless steel large round head square neck bolt is a corrosion-resistant fastening solution designed for secure installation, smooth surface appearance, and reliable anti-rotation performance. The DIN603 304 stainless steel large round head square neck bolt features a wide domed head and a square neck under the head, allowing the bolt to lock into wood, metal, or preformed square holes during tightening.
The DIN603 304 stainless steel large round head square neck bolt is widely used in construction, machinery, furniture, transportation equipment, marine hardware, renewable energy structures, industrial equipment, and OEM fasteners. Made from 304 stainless steel, it provides excellent corrosion resistance, clean appearance, and long service life in demanding environments.

Product Overview
The DIN603 304 stainless steel large round head square neck bolt is engineered for applications requiring a smooth exposed surface and secure mechanical engagement. The large round head distributes pressure over a wider area, while the square neck prevents rotation during installation.
This DIN603 304 stainless steel large round head square neck bolt is especially suitable for timber structures, metal brackets, guardrails, equipment frames, and visible fastening positions. Its smooth head improves safety by reducing sharp exposed edges.
As a practical industrial fastener, it combines strong fastening performance with an attractive finish for structural and decorative assemblies.
Product Specifications
| Item | Description |
|---|---|
| Standard | DIN603 |
| Product Name | DIN603 304 Stainless Steel Large Round Head Square Neck Bolt |
| Material | 304 Stainless Steel |
| Thread Type | Metric Partial Thread / Custom Full Thread |
| Head Type | Large Round Head |
| Drive Type | Square Neck Anti-Rotation |
| Diameter Range | M5–M24 |
| Length Range | 12mm–200mm |
| Surface Finish | Natural Stainless Steel / Polished / Passivated |
| Strength Grade | A2-50 / A2-70 |
| Thread Direction | Right Hand |
| Packaging | Carton, bag, pallet, OEM packaging |
| Customization | Size, thread length, head size, marking, packaging |
Technical Parameters
| Parameter | Value |
|---|---|
| Tensile Strength | ≥500 MPa / ≥700 MPa, depending on grade |
| Yield Strength | ≥210 MPa / ≥450 MPa |
| Hardness | HV 150–250 |
| Density | 7.93 g/cm³ |
| Corrosion Resistance | Excellent in humid and outdoor environments |
| Operating Temperature | -50°C to 400°C |
| Thread Tolerance | 6g |
| Manufacturing Standard | DIN603 / ISO equivalent |
Materials and Manufacturing Process
The DIN603 304 stainless steel large round head square neck bolt is manufactured through controlled forming and finishing processes to ensure dimensional accuracy and consistent performance.
Production starts with premium 304 stainless steel wire rod. After chemical composition verification, the material is cut and cold forged to form the large round head and square neck. For larger sizes, hot forging may be used to improve forming stability.
CNC machining can be applied for custom head geometry or special shank dimensions. Thread rolling forms accurate metric threads and improves fatigue resistance. Surface finishing includes natural stainless finish, polishing, or passivation. Cleaning removes oil and residues before final inspection and packaging.
Each DIN603 304 stainless steel large round head square neck bolt is checked for head profile, square neck accuracy, thread quality, surface finish, and dimensional consistency.
Applications of the Product
DIN603 304 stainless steel large round head square neck bolts are widely used in construction, machinery, automotive equipment, renewable energy systems, petrochemical support structures, marine equipment, food equipment, industrial equipment, and manufacturing systems.
They are common in timber connections, guardrails, fencing systems, furniture frames, agricultural machinery, solar mounting systems, and transport equipment. The square neck improves installation efficiency by preventing rotation, while the large round head provides a smooth and safe exposed surface.
Why Choose This Product
This product offers premium 304 stainless steel raw material, high precision manufacturing, strong corrosion resistance, stable mechanical performance, long service life, bulk supply capability, OEM/ODM support, fast delivery, and export experience.
The DIN603 304 stainless steel large round head square neck bolt is ideal for buyers needing durable stainless steel fasteners with strong anti-rotation performance and clean appearance.
Why Choose Flybear
Flybear provides professional manufacturing and supply services for industrial fasteners.
Flybear offers manufacturing capability, inventory strength, custom production, engineering support, global supply ability, and technical consultation. We support OEM manufacturers, distributors, EPC contractors, and purchasing managers with reliable fastening products based on drawings, samples, or project specifications.
Quality Inspection and Control
Quality control includes chemical composition analysis, tensile testing, hardness testing, salt spray test, thread gauge inspection, dimensional inspection, surface inspection, square neck inspection, head profile inspection, and packaging inspection.
Production follows ISO quality system compliance to ensure stable batch quality and dependable industrial performance.
Selection Guide
When selecting DIN603 304 stainless steel large round head square neck bolts, consider material type, diameter, length, square neck size, load requirements, installation material, indoor or outdoor environment, and corrosion level.
For marine or chloride-rich environments, 316 stainless steel may be recommended. For decorative applications, polished stainless finish can improve appearance.
FAQ
What is DIN603?
DIN603 is a standard for round head square neck bolts, also known as carriage bolts.
What is the function of the square neck?
The square neck prevents the bolt from rotating during tightening.
Is 304 stainless steel rust resistant?
Yes. 304 stainless steel provides strong corrosion resistance in most indoor and outdoor environments.
Can custom sizes be produced?
Yes. Custom diameter, length, head size, thread length, finish, and packaging are available.
How to request quotation?
Send size, material, quantity, surface finish, drawings, and application details.
The DIN603 304 stainless steel large round head square neck bolt provides corrosion resistance, smooth appearance, and secure anti-rotation fastening for industrial applications. For quotation, customization, and technical support, please Contact Us.
We always adhere to the philosophy of quality first and customer first, providing customers with high-quality fastener products and one-stop fastener solutions.




