Core Features of Carriage Bolt/Mushroom Head Square Neck Bolt

Mushroom-shaped round head: Smooth surface without sharp edges, ensuring safety and aesthetic appearance, suitable for exposed installation scenarios
Square neck design: Embeds into the workpiece (e.g., wood, metal slots) to prevent bolt rotation during nut tightening, enabling one-handed operation
Full-thread or half-thread options: Full-thread for maximum engagement and load-bearing capacity; half-thread for better shear resistance in thick workpieces
Excellent anti-loosening performance and stable connection, adapting to both indoor and outdoor environments (stainless steel variants offer corrosion resistance)

Product Parameter (Specification)

Standard	DIN,ASTM/ANSI JIS EN ISO,AS	Material	Carbon steel, Stainless Steel,Aluminum,Brass
Surface Treatment	Zinc Plated, Hop Dip Galvanized(HDG) phosphorization, Black Oxide,Geomet,Dacroment,Nickel plated,Zinc-Nickel plated	Shank	Full thread, Half thread
Grade	4.8,5.8,6.8,8.8, 10.9, 12.9,B7,B7M,B8,B8M,304,316,A2,A4	Size	M3-M64
Unite	Piece,KGS,TON	Packing	Bulk cartons with pallet, small boxes in cartons with pallet

Product Application

Carriage bolt is widely used in heavy Industry, mining, water treatment, healthcare, construction, general industry, Oil & Gas, solar system mounting etc.

Carriage Bolt Application Scenario Table

Application Field	Specific Application Scenario	Recommended Standards & Grades	Key Considerations
Wood Structure & Outdoor Construction	Connection of wooden house frames, assembly of garden fences/gates, and installation of outdoor wooden pavilions.	– Standards: ASTM A307, ASTM A193 (stainless steel A2/A4), ISO 8677 – Grades: Carbon steel Grade 4.6, stainless steel A2-70/A4-80	– Core advantage: Square neck prevents bolt rotation during tightening (no need to hold the head), ideal for wood where wrench access is limited. – Surface treatment: Hot-Dip Galvanizing (HDG) for carbon steel; passivation for stainless steel .
Furniture & Indoor Decoration	Assembly of solid wood tables/chairs , fixing of wooden cabinet doors to metal hinges, and installation of bookshelves.	– Standards: DIN 603, ASTM A307 – Grades: Carbon steel Grade 4.6, stainless steel A2-70	– Safety design: Round head avoids scratching hands, suitable for furniture with frequent contact.
Light-Duty Transportation & Storage	Fixing of metal brackets on hand trucks, assembly of bicycle/motorcycle rear racks.	– Standards: ASTM A307, ISO 8677 – Grades: Carbon steel Grade 4.6 (HDG), stainless steel A4-80	– Vibration resistance: Square neck locks into pre-cut slots to prevent loosening from movement .
Agricultural & Garden Equipment	Assembly of wooden planter boxes, and installation of greenhouse wooden frames.	– Standards: ASTM A307, BS 1212 – Grades: Carbon steel Grade 4.6 (HDG), stainless steel A2-70	– Corrosion resistance: HDG coating resists soil moisture and fertilizer corrosion; stainless steel for greenhouse high-humidity environments. – Maintenance: Check annually for rust on carbon steel bolts; replace if thread engagement weakens.
Light Machinery & Equipment Guards	Fixing of safety guards on small machines , and installation of lightweight toolbox lids.	– Standards: ISO 8677, ASTM A307 – Grades: Carbon steel Grade 4.6 (phosphated), stainless steel A2-70	– Installation convenience: Round head fits in tight spaces ; square neck eliminates the need for a second wrench to hold the bolt head. – Compatibility: Use with hex nuts and ensure the square neck fully seats in the mounting hole to prevent spinning.

Click to enlarge

Steel carriage bolt with mushroom head and square neck for secure fastening.

High-quality mushroom head carriage bolt for secure fastening.

Bolt with mushroom head and square neck for secure fastening.

Stainless steel carriage bolt with mushroom head and square neck for secure fastening.

Carriage Bolt/Mushroom Head Square Neck Bolt

Complies with international standards such as ISO 8677, ASTM A307, and DIN 603
Common materials include carbon steel (e.g., Q235, 45#), stainless steel (e.g., 304, 316), and alloy steel
Classified as special-shaped fasteners, featuring a mushroom-shaped round headand a square neck under the head
Strength grades typically range from 4.8 to 8.8

Category: Carriage Bolt

Description

Standard	DIN,ASTM/ANSI JIS EN ISO,AS	Material	Carbon steel, Stainless Steel,Aluminum,Brass
Surface Treatment	Zinc Plated, Hop Dip Galvanized(HDG) phosphorization, Black Oxide,Geomet,Dacroment,Nickel plated,Zinc-Nickel plated	Shank	Full thread, Half thread
Grade	4.8,5.8,6.8,8.8, 10.9, 12.9,B7,B7M,B8,B8M,304,316,A2,A4	Size	M3-M64
Unite	Piece,KGS,TON	Packing	Bulk cartons with pallet, small boxes in cartons with pallet

Application Field	Specific Application Scenario	Recommended Standards & Grades	Key Considerations
Wood Structure & Outdoor Construction	Connection of wooden house frames, assembly of garden fences/gates, and installation of outdoor wooden pavilions.	– Standards: ASTM A307, ASTM A193 (stainless steel A2/A4), ISO 8677 – Grades: Carbon steel Grade 4.6, stainless steel A2-70/A4-80	– Core advantage: Square neck prevents bolt rotation during tightening (no need to hold the head), ideal for wood where wrench access is limited. – Surface treatment: Hot-Dip Galvanizing (HDG) for carbon steel; passivation for stainless steel .
Furniture & Indoor Decoration	Assembly of solid wood tables/chairs , fixing of wooden cabinet doors to metal hinges, and installation of bookshelves.	– Standards: DIN 603, ASTM A307 – Grades: Carbon steel Grade 4.6, stainless steel A2-70	– Safety design: Round head avoids scratching hands, suitable for furniture with frequent contact.
Light-Duty Transportation & Storage	Fixing of metal brackets on hand trucks, assembly of bicycle/motorcycle rear racks.	– Standards: ASTM A307, ISO 8677 – Grades: Carbon steel Grade 4.6 (HDG), stainless steel A4-80	– Vibration resistance: Square neck locks into pre-cut slots to prevent loosening from movement .
Agricultural & Garden Equipment	Assembly of wooden planter boxes, and installation of greenhouse wooden frames.	– Standards: ASTM A307, BS 1212 – Grades: Carbon steel Grade 4.6 (HDG), stainless steel A2-70	– Corrosion resistance: HDG coating resists soil moisture and fertilizer corrosion; stainless steel for greenhouse high-humidity environments. – Maintenance: Check annually for rust on carbon steel bolts; replace if thread engagement weakens.
Light Machinery & Equipment Guards	Fixing of safety guards on small machines , and installation of lightweight toolbox lids.	– Standards: ISO 8677, ASTM A307 – Grades: Carbon steel Grade 4.6 (phosphated), stainless steel A2-70	– Installation convenience: Round head fits in tight spaces ; square neck eliminates the need for a second wrench to hold the bolt head. – Compatibility: Use with hex nuts and ensure the square neck fully seats in the mounting hole to prevent spinning.