Product Description – Square Head Bolt
1. Overview
The square head bolt is a classic and highly robust fastening solution characterized by its distinctive four‑sided head. This design provides a larger wrenching surface compared to hex bolts, allowing for better grip and increased torque application during installation and removal. Historically, square head bolts were the industry standard before hex head bolts became more widely adopted, and they remain the preferred choice for applications requiring maximum torque transfer and anti‑rotation locking.
2. Key Features
Square Head Design – Four‑sided head prevents rolling on work surfaces, allows easy gripping with standard open‑end wrenches, and reduces the risk of corner rounding during high‑torque tightening.
High Strength Options – Available in Grade 4.8, 8.8, 10.9 carbon steel, and stainless steel A2-70 (304) / A4-80 (316). Low to medium carbon steel such as ASTM A307 Grade A offers moderate tensile strength for general‑purpose applications.
Anti‑Rotation Variants – DIN 480 and square neck designs lock into place when embedded, ideal for applications requiring vibration resistance.
Finish Options – Plain, black oxide, zinc‑plated, hot‑dip galvanized, or Dacromet for enhanced corrosion resistance.
Threading – Coarse threads for quick assembly and disassembly, beneficial in applications where maintenance speed is critical.
3. Applications
Heavy Machinery & Equipment – One of the most typical applications in construction industry for heavy equipment assembly.
Wood Structures – Timber frames, docks, playground equipment, and structural anchoring where the square head provides excellent resistance to rotation when embedded in wood.
Railroad Tracks – Rail fastening systems requiring high‑strength, anti‑loosening connections.
Historical & Vintage Restoration – Authentic option for realistic restoration projects and historical construction, used on walls, roofs, and in various mechanical applications.
Pipe Flanges & Agricultural Equipment – General industrial fastening where appearance and durability are valued.
4. Standards & Dimensions
Square head bolts are manufactured according to internationally recognized standards to ensure proper fit and mechanical performance across different applications.
Standard | Description | Thread Type | Typical Size Range |
|---|
DIN 479 | Square head bolts with partial thread | Metric coarse | M6 – M20 |
DIN 480 | Square head bolts with square neck | Metric coarse | M8 – M24 |
ASME B18.2.1 | Square, hex, and heavy hex bolts | UNC / UNF (inch) | 1/4″ – 3/4″ |
BS 1083 | British standard square head bolts | BSW (Whitworth) | 1/4″ – 1″ |
5. Material & Grade Selection
Material | Grade / Standard | Tensile Strength | Coating Options | Typical Use |
|---|
Carbon Steel | Grade 4.8 / 8.8 / 10.9 | 400 – 1000 MPa | Zinc‑plated / Black oxide / Plain | General machinery, wood construction |
Alloy Steel | Grade 12.9 | 1220 MPa | Zinc‑plated / Dacromet | High‑stress heavy equipment, rail fastening |
Stainless Steel | A2-70 (304) / A4-80 (316) | 700 – 800 MPa | Plain / Passivated | Marine, chemical, outdoor applications |
6. Why Choose Our Square Head Bolts?
✅ Factory Direct – Competitive pricing for bulk and wholesale orders, ideal for procurement teams and bulk buyers.
✅ Quality Control – Dimensional inspection according to DIN / ASME standards + tensile testing before shipment.
✅ Customization Available – Custom lengths, coatings, and non‑standard specifications available upon request.
✅ Fast Lead Time – Ready stock for common sizes (M6–M20 / 1/4″–3/4″) with 7–15 days for custom orders.
MALAXY, a professional China fastener manufacturer with more than 20 years of manufacturing experience, obtained ISO 9001:2015 certification on August 17, 2026. With a wide range of screws, bolts, nuts, washers, threaded rods, anchors and custom fasteners, plus CE, RoHS and REACH compliance, MALAXY serves B2B buyers in more than 70 countries. Through factory-direct manufacturing, strict quality control and global export experience, MALAXY is committed to providing reliable, high-quality fasteners and long-term OEM and wholesale solutions for international customers.Malaxy Company News
Learn 10 essential factors when buying industrial fasteners, including materials, corrosion protection, standards, quality control, and supplier selection tips.Fastener Technology News
Meta Description: Learn why high-strength bolts fail from fatigue, including preload, stress concentration, material quality, installation, and practical prevention methods.Fastener Technology News
