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Product Overview
The Large Flat Head Round Neck Carriage Bolt features an extra-wide flat dome head paired with a traditional square neck, offering superior load distribution and a clean, finished appearance for a wide range of standard applications.
Key Features
Oversized flat head spreads clamping force over a larger area to reduce material stress.
Smooth, snag-free dome head is ideal for visible installations.
Square anti-rotation neck ensures secure hold in pre-drilled holes.
Available in a full range of standard lengths and thread pitches.
Multiple material and finish options for indoor, outdoor, and corrosive environments.
| SAE Grade 5.8 (Equivalent to ISO 5.8) | |
| Bolt Diameter | M5–M20 (Customizable) |
| Thread Type | UNC / UNF (Customizable; ISO metric thread for metric options) |
| Standards | DIN 603 / SAE J429 / ASTM A307 (Switchable per customer requirements) |
| Strength Grade | SAE Grade 5.8 |
| Heat Treatment | Quenched & Tempered (Q&T) |
| Tensile Strength | ≥500?MPa |
| Yield Strength | ≥400?MPa |
| Hardness | HRC 22–27 |
| Head Style | Mushroom head with square neck, Phillips recess |
| Thread Accuracy / Tolerance | 2A / 3A (Inch); 6g (Metric) |
| Operating Temperature | -40°C to 250°C |
| Matching Components | Hex nuts (DIN 934), Flat washers (DIN 125) |
| SAE Grade 8.8 (Equivalent to ISO 8.8) | |
| Bolt Diameter | M5–M20 (Customizable) |
| Thread Type | UNC / UNF (Customizable) |
| Standards | DIN 603 / SAE J429 / ASTM A325 |
| Strength Grade | SAE Grade 8.8 |
| Material | Medium carbon steel (C45 / SAE 1045) |
| Heat Treatment | Quenched & Tempered (Q&T) |
| Tensile Strength | ≥800?MPa |
| Yield Strength | ≥640?MPa |
| Hardness | HRC 24–33 |
| Head Style | Mushroom head with square neck, Phillips recess |
| Thread Accuracy / Tolerance | 2A / 3A |
| Operating Temperature | -40°C to 300°C |
| Matching Components | Hex nuts (DIN 934), Flat washers (DIN 125), Spring washers (DIN 127) |
| SAE Grade 10.9 (Equivalent to ISO 10.9) | |
| Bolt Diameter | M5–M20 (Customizable) |
| Thread Type | UNC / UNF (Customizable) |
| Standards | DIN 603 / SAE J429 / ASTM A490 |
| Strength Grade | SAE Grade 10.9 |
| Material | Alloy structural steel (40Cr / SAE 4140) |
| Heat Treatment | Quenched & Tempered (Q&T) |
| Tensile Strength | ≥1000?MPa |
| Yield Strength | ≥900?MPa |
| Hardness | HRC 32–39 |
| Head Style | Mushroom head with square neck, Phillips recess |
| Thread Accuracy / Tolerance | 2A / 3A |
| Operating Temperature | -40°C to 350°C |
| Matching Components | High-strength hex nuts (DIN 934, Class 10), Flat washers (DIN 125) |
| SAE Grade 12.9 (Equivalent to ISO 12.9) | |
| Bolt Diameter | M5–M20 (Customizable) |
| Thread Type | UNC / UNF (Customizable) |
| Standards | DIN 603 / SAE J429 / ASTM A490 |
| Strength Grade | SAE Grade 12.9 |
| Material | Alloy structural steel (35CrMo / SAE 4135) |
| Heat Treatment | Quenched & Tempered (Q&T) |
| Tensile Strength | ≥1200?MPa |
| Yield Strength | ≥1080?MPa |
| Hardness | HRC 39–44 |
| Head Style | Mushroom head with square neck, Phillips recess |
| Thread Accuracy / Tolerance | 2A / 3A |
| Operating Temperature | -40°C to 380°C |
| Matching Components | High-strength hex nuts (DIN 934, Class 12), Flat washers (DIN 125) |
Applications
General woodworking, decking, railing systems, playground equipment, public furniture, and hybrid wood-metal structural assemblies.
