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Stainless Steel Square Neck Bolts
Square neck bolts manufactured from austenitic (304/316) and martensitic (410) stainless steels through cold heading and thread rolling. The square neck geometry locks into pre-cut square holes or punched slots, eliminating rotation during nut tightening. Thread forms comply with ISO 68-1 metric or ANSI/ASME B1.1 unified standards; passivation per ASTM A967 removes free iron. Dimensional tolerances conform to ISO 965-2 and ANSI B1.2, ensuring reliable engagement with standard nuts and tapped holes. Material certifications are traceable to mill test reports.
www.chance-union.com
Family-owned enterprise · 20 years metal manufacturing heritage · Specializing in high-strength fasteners and custom parts.
Core Characteristics
Product Specifications
| Attribute | Specification |
| Material grades | 304 (A2), 316 (A4), 410 (martensitic) |
| Thread standards | ISO metric M6–M24, UNC 1/4–1 inch |
| Property classes | 70, 80 (austenitic); 100 (martensitic) |
| Surface treatments | Passivation, zinc plating, wax coating, PTFE |
| Head configurations | Hex, hex flange, countersunk, round |
| Drive types | Hex, Torx, Phillips, slotted |
| Diameter range (metric) | M6 – M24 (coarse and fine pitch) |
| Diameter range (inch) | 1/4 – 1 inch (UNC/UNF) |
Mechanical property reference
- Class 70 (304/316): proof load 450 MPa, tensile 500–700 MPa
- Class 80 (304/316): proof load 600 MPa, tensile 700–800 MPa
- Class 100 (410): proof load 830 MPa, tensile 900–1000 MPa
Application Fields
Structural
- Beam splices
- Column base plates
- Bracing systems
Machinery
- Frame assemblies
- Motor mounts
- Gearbox housings
Infrastructure
- Bridge bearings
- Sign structures
- Solar tracker frames
Material Selection Guide
Selecting the appropriate stainless steel grade depends on the service environment and mechanical requirements. Grade 304 (A2) is suitable for general indoor and mild outdoor conditions where chloride exposure is limited. Grade 316 (A4) contains 2–3% molybdenum, offering enhanced resistance to pitting and crevice corrosion in marine, coastal, and chemical processing environments. For high-strength applications requiring wear resistance, martensitic grade 410 provides tensile strength up to 1000 MPa but with lower corrosion resistance than austenitic grades. Chance & Union can assist in material selection based on specific service conditions, including temperature, humidity, and chemical exposure.
Grade 304 (A2)
- 18Cr-8Ni
- General fabrication
- Indoor / dry outdoor
- Cost effective
Grade 316 (A4)
- 16Cr-10Ni-2Mo
- Marine / chemical
- Chloride resistance
- Higher pitting resistance
Grade 410
- 12Cr martensitic
- High strength
- Mild corrosion resistance
- Wear resistant
For joints with gaskets or soft materials, re-torque after 24 hours to compensate for embedment relaxation. Use hardened washers under the nut and bolt head to distribute load and prevent bearing damage.
Frequently Asked Questions
Production & Customization Services
Chance & Union leverages the manufacturing capabilities of Shengzhao Metal to offer custom square neck bolts in non-standard diameters (M5–M30), lengths, and head styles. Custom thread forms, drive recesses, and surface finishes are available upon request. We support low-volume prototyping and high-volume production runs, with strict adherence to ISO 9001 quality management and full material traceability per EN 10204 3.1. Our engineering team can assist with design modifications, including special neck dimensions or undercut geometries for specific applications. For customized solutions, contact our sales team with your technical drawings or performance requirements.
Storage & Handling Practices
- Store in a clean, dry area with relative humidity below 55% to maintain passivation.
- Avoid contact with carbon steel, copper, or graphite to prevent galvanic corrosion or contamination.
- Use plastic or coated trays and bins; separate by grade, size, and length.
- Implement FIFO rotation; recommended shelf life up to 36 months in original packaging.
- Inspect for rust spots or discoloration before use; re-passivate if necessary.
Leveraging the factory's robust R&D and production capabilities, we specialize in high-strength rivets bolts, nuts, washers, pins, screws, and various non-standard custom parts. As experienced Custom Stainless Steel Square Neck Bolts Suppliers, we provide flexible manufacturing solutions for different customer requirements. Our product range covers materials including stainless steel, alloy steel, aluminum alloy, copper, and special alloys, utilizing processes such as cold heading, hot forging, and CNC machining. Our products are exported to over 25 countries, serving more than 200 clients.
Chance & Union is committed to seamlessly connecting "Manufactured in China" with the international market, providing global customers with one-stop fastening solutions from R&D to mass production through professional technology and exceptional quality.
