Countersunk Head Square Neck Bolt

Bolt Standards:

• This type of bolt is not defined by a specific standard, but is a specialized fastener design.

Material and Properties:

• Carbon steel

• Plain carbon steel (e.g. C10, C15, C22)

• Alloy steel (e.g. 34CrMo4, 40CrMnMoS8-6) for higher strength

• Stainless steel

• Austenitic (e.g. A2, A4) - Excellent corrosion resistance

• Martensitic (e.g. 1.4006, 1.4021) - Good corrosion resistance and strength

Bolt Design:

• Countersunk (flat) head shape

• Square neck beneath the head

• Threaded shank

Applications:

• Fastening components with limited clearance

• Flush or recessed mounting

• Machinery, equipment, and furniture

• Corrosive environments (stainless steel versions)

Coatings and Finishes:

• Plain (uncoated)

• Zinc plated (for mild corrosion resistance)

• Black oxide (for decorative purposes)

• Stainless steel bolts may have a passivation or polishing finish

The key features of countersunk head square neck bolts are the flat, countersunk head shape and the square neck beneath the head. This design allows the bolt to be installed flush with or slightly recessed into the surface, providing a smooth, low-profile appearance.

The square neck helps prevent the bolt from rotating during installation or use, which is important in applications where the bolt needs to maintain a specific orientation. This makes countersunk head square neck bolts well-suited for fastening components with limited clearance, such as in machinery, equipment, and furniture.

These bolts can be manufactured from carbon steel, alloy steel, or stainless steel, depending on the strength and corrosion resistance 

requirements of the application. Coatings like zinc plating or black oxide can also be applied for additional protection or aesthetic purposes.

The selection of the appropriate countersunk head square neck bolt will depend on factors such as the material, size, load-bearing requirements, and the specific application where the bolt will be used.