Carriage Bolt
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Carriage Bolt

Large Flat Round Head Square Neck Carriage Bolt

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.

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Zhejiang Chance & Union Import and Export Co., Ltd.
Zhejiang Chance & Union Import and Export Co., Ltd.
Zhejiang Chance & Union Import and Export Co., Ltd.
Zhejiang Chance & Union Import and Export Co., Ltd.
Zhejiang Chance & Union Import and Export Co., Ltd.
Zhejiang Chance & Union Import and Export Co., Ltd.
Zhejiang Chance & Union Import and Export Co., Ltd.
Zhejiang Chance & Union Import and Export Co., Ltd.
Zhejiang Chance & Union Import and Export Co., Ltd.
Zhejiang Chance & Union Import and Export Co., Ltd.
Zhejiang Chance & Union Import and Export Co., Ltd.
Zhejiang Chance & Union Import and Export Co., Ltd.
Attributes
Zhejiang Chance & Union Import and Export Co., Ltd.

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.

Product Features
Zhejiang Chance & Union Import and Export Co., Ltd.
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
Zhejiang Chance & Union Import and Export Co., Ltd.

Applications
General woodworking, decking, railing systems, playground equipment, public furniture, and hybrid wood-metal structural assemblies.

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Zhejiang Chance & Union Import and Export Co., Ltd.
Zhejiang Chance & Union Import and Export Co., Ltd.
About Us
Fastening Chances,
Strengthening Union
specializes in high-strength fasteners. We offer bolts, nuts, washers, and custom parts made from stainless steel, alloy steel, and more, serving over 200 clients in 25 countries. With 20 years of industry experience, we provide tailored fastening solutions from R&D to mass production.
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Zhejiang Chance & Union Import and Export Co., Ltd.
Certifications & Honors
Zhejiang Chance & Union Import and Export Co., Ltd.
Utility Model Patent Certificate
Utility Model Patent Certificate
Utility Model Patent Certificate
Utility Model Patent Certificate
Utility Model Patent Certificate
Utility Model Patent Certificate
Utility Model Patent Certificate
Utility Model Patent Certificate
Utility Model Patent Certificate
Utility Model Patent Certificate
Utility Model Patent Certificate
Utility Model Patent Certificate
Utility Model Patent Certificate
Utility Model Patent Certificate
Latest News & Updates
Stay informed with the latest industry trends, company news, and product innovations.
Zhejiang Chance & Union Import and Export Co., Ltd.
2026-05-26
Rooted in Manufacturing Heritage, Domestic Fasteners Expand Globally Steadily
With more than 18 years of mature manufacturing experience, China's fastener sector has established a sound technical and service system. Manufacturers provide high-strength bolts, nuts, screws, washers, pins and various non-standard customized parts. A wide range of materials including stainless steel, alloy steel, aluminum alloy, copper and special alloys are adopted, together with advanced technologies such as cold heading, hot forging and precision machining. The products are exported to over 25 countries worldwide and serve more than 200 overseas clients, playing an important role in the global supply chain.
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Zhejiang Chance & Union Import and Export Co., Ltd.
2026-05-26
One-stop Fastener Solutions Connect Chinese Manufacturing with Global Markets
The global industrial sector has raised higher requirements for comprehensive services of supporting components. The fastener industry has upgraded its service model to cover the whole process from R&D and sampling to mass production, delivering one-stop supporting solutions for overseas customers. Supported by solid technical strength and strict quality control, the industry supplies highly stable and adaptable products, responds efficiently to customized demands worldwide, and builds a solid bridge linking Chinese manufacturing to the global market.
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Zhejiang Chance & Union Import and Export Co., Ltd.
2026-05-26
Diversified Materials and Exquisite Craftsmanship Build Core Competitiveness for Export Fasteners
Material selection and processing technology are the core guarantees for fastener quality. Domestic manufacturers keep optimizing material systems, including common metals and special alloys, and improve production techniques such as cold heading, hot forging and machining to ensure product strength, precision and durability. Both standard parts and complex non-standard customized parts comply with international industrial standards. Superior quality helps Chinese fasteners continuously expand influence across the global market.
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Zhejiang Chance & Union Import and Export Co., Ltd.
2026-05-26
Rising Overseas Demand Drives Sound Development of Fastener Foreign Trade
As global manufacturing, infrastructure and machinery industries recover, international demand for industrial fasteners keeps rising. Leveraging long-term industry experience, mature production systems and comprehensive after-sales services, China’s fastener foreign trade sector continues to expand overseas markets. Products are sold to many regions around the world with a growing customer base. The industry maintains steady order growth, fully demonstrating the strong market vitality and comprehensive strength of Chinese industrial products.
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Zhejiang Chance & Union Import and Export Co., Ltd.