Carriage Bolt

Carriage Bolt: High-Strength, Corrosion-Resistant Fasteners for Multiple Applications

A carriage bolt, also known as a coach bolt, is a versatile fastener characterized by its smooth domed head and square neck beneath the head . Designed for secure and efficient joining of wood, metal, and composite materials, our carriage bolts combine modern craftsmanship with strict industry standards to meet the demands of various sectors, including construction, furniture manufacturing, automotive, and marine engineering. Whether you needstainless steel carriage bolts for corrosion resistance, high-strength grade 8 carriage bolts for heavy-load applications, or custom-sized carriage bolts for specific projects, we provide reliable solutions that balance performance and durability.

Core Advantages of Our Carriage Bolts

1. Anti-Rotation Square Neck Design for Easy Installation

The unique square neck under the head is the key feature of our carriage bolts. When installed, the square neck locks into a pre-drilled square hole or embeds into soft materials like wood, preventing the bolt from spinning during nut tightening . This design allows for one-handed operation even in confined spaces, significantly improving installation efficiency and reducing labor costs. Unlike ordinary bolts that require tools to fix the head during installation, our carriage bolts simplify the process—just tighten the nut from one side to achieve a firm connection .

2. Superior Corrosion Resistance for Long-Term Use

We offer a variety of surface treatment options to enhance the corrosion resistance of carriage bolts, including blue-white zinc plating, hot-dip galvanizing, and passivation. Our blue-white zinc plated carriage bolts feature a dense oxide film formed by electroplating and blue-white passivation, with a zinc layer thickness of 8-12μm, achieving 72-120 hours of salt spray resistance . For harsh environments such as marine or coastal areas,304/316 stainless steel carriage bolts are available, providing excellent resistance to moisture, salt fog, and chemical corrosion, ensuring long-term service without rusting.

3. High-Strength Materials & Strict Quality Control

Our carriage bolts are manufactured from high-quality materials, including low-carbon steel (Q235), medium-carbon steel (45# steel), and stainless steel (304, 316, 316L) . Through quenching and tempering processes, they achieve strength grades ranging from 4.8 to 8.8, with grade 8 carriage bolts boasting a minimum tensile strength of 150,000 psi and a yield strength of 120,000 psi, meeting SAE J429 and ASME B18.5 standards . Each batch of bolts undergoes strict quality inspection, including thread precision testing (complying with GB/T 3934-2003), hardness testing, and tensile testing, ensuring no sliding or breakage during use .

4. Smooth Domed Head for Safety & Aesthetics

The smooth domed head of our carriage bolts not only provides an elegant appearance but also eliminates sharp edges, reducing the risk of scratches or hooking . This makes them ideal for applications requiring both safety and aesthetics, such as playground equipment, park facilities, furniture, and decorative signs. In historic restorations or rustic-style projects, our hammered or antique-finish carriage bolts can add an authentic vintage touch while maintaining structural integrity .

Complete Specifications to Meet Diverse Needs

We offer a full range of carriage bolt specifications to adapt to different application scenarios, with thread sizes from #10 to 3/4" (metric sizes M4 to M20) and lengths from 5/8" to 24.5" . Common types include:

<!--[if !supportLists]-->• <!--[endif]-->Semi-circular head carriage bolts (complying with GB/T 12-2017, DIN 603)

<!--[if !supportLists]-->• <!--[endif]-->Large semi-circular head carriage bolts (complying with GB/T 14)

<!--[if !supportLists]-->• <!--[endif]-->Full-thread carriage bolts (also known as shaker screen bolts for industrial vibration equipment)

<!--[if !supportLists]-->• <!--[endif]-->Stainless steel carriage bolts (304, 316, 316L)

<!--[if !supportLists]-->• <!--[endif]-->Carbon steel carriage bolts (Q235, 45# steel) with zinc plating, blackening, or chrome plating

Custom specifications (size, material, surface treatment) are available to meet special project requirements. For example, our M12×80 grade 8 carriage bolts are widely used in railway track beds and bridge construction, withstanding 25-ton axle loads and ensuring minimal displacement 

Wide Applications Across Industries

Our carriage bolts are trusted in 10+ key industries due to their versatility and reliability :

<!--[if !supportLists]-->1. <!--[endif]-->Wood Construction: Ideal for decks, fences, timber framing, and garden sheds—their square neck embeds into wood to prevent rotation, and the domed head avoids damaging the wood surface.

<!--[if !supportLists]-->2. <!--[endif]-->Furniture Manufacturing: Used in assembling wooden furniture, cabinets, and beds, providing a smooth appearance without protruding fastener heads.

<!--[if !supportLists]-->3. <!--[endif]-->Marine & Coastal Projects: Stainless steel carriage bolts resist saltwater corrosion, making them suitable for docks, piers, and boat building.

<!--[if !supportLists]-->4. <!--[endif]-->Automotive & Agricultural Equipment: High-strength carriage bolts fix truck beds, trailers, and plow blades, withstanding vibration and heavy loads without loosening 

<!--[if !supportLists]-->5. <!--[endif]-->Public Facilities: Installed in street signs, lamp posts, playground equipment, and park benches—their anti-rotation design and smooth head ensure safety and anti-tampering 

<!--[if !supportLists]-->6. <!--[endif]-->Industrial Machinery: Full-thread carriage bolts (shaker screen bolts) are used in vibration equipment, with grade 8 strength resisting fatigue and impact failures 

Why Choose Our Carriage Bolts?

• Compliance with international standards: GB/T 12-2017, GB/T 14, DIN 603, SAE J429, ASME B18.5 .

• ISO 9001:2008 certified production process, ensuring consistent quality 

• Comprehensive customization: Material, size, surface treatment, and packaging can be tailored to your needs.

• Cost-effective solutions: Bulk supply with competitive prices, reducing your procurement costs.

Whether for large-scale construction projects, industrial machinery assembly, or DIY home renovations, our carriage bolts deliver the strength, durability, and ease of use you need. Contact us today to get a quote for custom carriage bolts or to learn more about which type fits your application best!