Carriage Bolt Black

（1）Product Definition

carriage bolt black, also known as cup head bolt or coach bolt, is a type of fastener with a semi-circular top shape (round head) at the head and a square structure at the neck.

（2）Structural Characteristics

Round Head: The head is smooth and shaped like a semi-spherical or flat-top round cap, without external hexagonal or internal hexagonal interfaces.

Square Neck: There is a square or ribbed neck below the head.

Some specifications feature serrations or embossing: These are used to enhance the grip with the wood and prevent loosening.

（3）Core advantage

Single-sided installation: Saves time and effort. No need to use a wrench to fix the bolt head on the other side. One person can complete the operation.

Anti-reverse function is reliable: The square-neck structure provides mechanical anti-reverse function, and it is unlikely to loosen even in a vibrating environment.

Smooth and beautiful surface: The round head design has no sharp edges, making it suitable for use in exposed areas (such as furniture, guardrails).

Multiple materials and surface treatments: You can choose from carbon steel (galvanized/heat-treated galvanized/dacromet), stainless steel (304/316), brass, etc., to suit different environments.

Why choose Xiaoguo® carriage bolt black?

Xiao Guo is an enterprise that has been engaged in the production and sales of fasteners for many years. For each product, it has a clear sales service plan and advantages. If you purchase carriage bolt black, we highly recommend choosing us. Here are some basic reasons:

（1）Full range of standard inventory, with support for non-standard customization (size, material, surface treatment)

（2）Certified to ISO 9001 and IATF 16949 standards

（3）High precision, qualified quality, reliable performance

（4）Provide salt spray test report and related certificates

（5）Direct supply from the factory, stable delivery time, flexible minimum order quantity

The five most common questions

（1）What materials do you offer for carriage bolt black?

We provide carbon steel (4.8/8.8 grade), alloy steel (10.9/12.9 grade), stainless steel (304, 316), brass, etc. We can recommend the most suitable material based on your application environment.

（2）What is the strength of stainless steel?

The performance grade of 304 stainless steel is A2-70, with an ultimate tensile strength of approximately 700 MPa; 316 stainless steel is A4-80, with an ultimate tensile strength of approximately 800 MPa. For higher strength, it is recommended to use alloy steel of grade 10.9/12.9.

（3）Can your carriage bolt black reach grade 8.8? Do you have any test reports?

Yes, we can offer products of grades 8.8, 10.9, and 12.9. Each batch comes with tensile test reports, hardness reports, and material certification (MTC), and is subject to third-party testing.

（4）What surface treatments do you offer?

Electro-galvanizing, hot-dip galvanizing, Dacromet coating, and blackening.

（5）How long is the delivery period? Can you provide customized packaging (such as printing the brand name)?

For stock products, it takes 7-15 days; for customized products, it takes 25-35 days. We can offer branding services such as laser marking logos, customized packaging boxes, stickers, etc.