Step Bolts
Product: roof head square neck bolts din603
Standard: ASME/ANSI B 18.5 - 2008
Raw material: Q235,10B21 10B33 35K 45K 40CR,etc.
Surface: zinc plated,black oxide,H.D.G,etc.
Specification Range: INCH: 1/4”–1 ” LENGTH 1" TO 12"
Property Class:SAE J429 2 5 8
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Product Introduction
Product: roof head square neck bolts
Standard: ANSI B18.5
Raw material: Q235,10B21 10B33 35K 45K 40CR,etc.
Surface: Yellow zinc white zinc plated,black oxide,etc.
Specification Range: INCH: 1/4"–1 1/4"
grade : J429 2 5 8
Mechanical Properties (Typical Grades)
| Characteristic | Grade 2 | Grade 5 | Grade 8 |
|---|---|---|---|
| Standard | SAE J429 | SAE J429 | SAE J429 |
| Bolt Type | Carriage Bolt (Round Head Square Neck) | Carriage Bolt | Carriage Bolt |
| Material | Low carbon steel | Medium carbon steel, Q&T | Alloy steel, Q&T |
| Min. Tensile Strength | ≥ 60,000 psi (414 MPa)¹ | ≥ 120,000 psi (827 MPa) | ≥ 150,000 psi (1034 MPa) |
| Min. Yield Strength | ≥ 36,000 psi (248 MPa)¹ | ≥ 92,000 psi (634 MPa) | ≥ 130,000 psi (896 MPa) |
| Proof Load Stress | 33,000 psi (228 MPa) | 85,000 psi (586 MPa) | 120,000 psi (827 MPa) |
| Hardness Range | B70 – B100 (Rockwell) | C25 – C34 (Rockwell) | C33 – C39 (Rockwell) |
| Head Marking | No mark (unmarked) | 3 radial lines | 6 radial lines |
| Heat Treatment | None (as-rolled / cold forged) | Quenched & tempered | Quenched & tempered |
| Typical Thread | UNC / UNF (inch) | UNC / UNF (inch) | UNC / UNF (inch) |
| Common Sizes | 1/4" – 3/4" (up to 1-1/2") | 1/4" – 1-1/2" | 1/4" – 1-1/2" |
| Typical Application | Wood structures, fencing, light assembly, furniture | General machinery, automotive, medium load | Heavy machinery, high-stress joints, structural |
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Product Overview
Carriage bolts ANSI B 18.5, also known as round head square neck bolts, are specialized fasteners characterized by a smooth, domed head and a square neck beneath the head. Compliant with international standards such as DIN 603, ISO 8673, and ASTM A193, they are designed for secure, flush-mounted connections in wood, metal, and composite materials. The square neck prevents rotation during installation, making them ideal for applications where only one side of the joint is accessible, widely used across construction, furniture, and industrial equipment.
Key Specifications
Category Details
Raw Materials Carbon steel (C1010 C1035 C1045), alloy steel (40Cr, 35CrMo), stainless steel (304/A2, 316/A4), etc.
Finish: Plain, zinc plating (clear/color passivated), black oxide, hot-dip galvanizing (H.D.G), etc.
Specification Range Metric: INCH: 1/4"–1 1/4"
Property Classes Carbon steel: SAE J429 2 5 8
Application Fields
Construction & Decoration:
Wood structures (beams, rafters, decking), fence installations, door/window frames, and exterior cladding.
01
Furniture Manufacturing:
Wooden furniture (tables, chairs, cabinets), bed frames, and outdoor patio furniture.
02
Industrial Equipment:
Agricultural machinery, conveyor systems, electrical enclosures, and metal brackets.
03
Usage Precautions
Installation:
For wood applications, pre-drill a pilot hole slightly smaller than the bolt diameter to prevent wood splitting; ensure the square neck is fully seated in the material to lock the bolt.
Use a wrench to tighten the nut (do not torque the domed head, as it lacks gripping surfaces and may be damaged).
Environmental Adaptation:
In outdoor or humid environments, select stainless steel (316/A4) or hot-dip galvanized carbon steel to resist rust and corrosion.
For high-load or industrial applications, choose 8.8/10.9 grade alloy steel bolts to ensure sufficient strength.
Maintenance:
Regularly inspect for loosening (especially in vibrating equipment) and retighten as needed; replace bolts if corrosion, thread damage, or neck deformation is detected.
Avoid over-tightening, which may strip threads or crack the base material (particularly wood or plastic).
Main Sales Markets
North America, Europe, the Middle East, Southeast Asia, and domestic construction and furniture manufacturing hubs.
Packaging and Logistics
Packaging Options:
Small plastic bags, ply wood boxes, cartons, wooden pallets, and iron drums. Customized packaging is available upon request.
Order Flexibility:
Supports bulk and small-batch orders; transportation terms (FOB, CIF, EXW) and delivery schedules are negotiable to meet project timelines.
Certification and Quality Assurance
Certified to international quality standards including ISO9001:2015 and IATF16949:2016.
All products undergo strict dimensional inspection (thread gauges, calipers) and mechanical performance testing (tensile, hardness) before delivery.
Provide long-term quality guarantees and professional after-sales support, including technical consultation and replacement of defective products.
FAQ: Key Differences Between Carriage Bolts and Standard Hex Bolts
One-stop Solution
Structural Design: Carriage bolts have a smooth domed head and square neck (anti-rotation function), while standard hex bolts have a hexagonal head and no neck, requiring a wrench on both head and nut for installation.
One-stop Solution
Installation Scenarios: Carriage bolts are designed for single-side access (only nut needs tightening) and excel in wood/composite materials; standard hex bolts require dual-side access and are general-purpose for metal/mechanical connections.
One-stop Solution
Function Focus: Carriage bolts prioritize flush mounting, anti-rotation, and ease of installation in non-structural or semi-structural applications; standard hex bolts focus on versatile load-bearing and compatibility with tools.
One-stop Solution
Strength & Application Scope: Carriage bolts typically range from 4.8–10.9 grade, suitable for medium-load, non-critical connections; standard hex bolts include higher grades (up to 12.9) for heavy-load structural or mechanical use.
In summary, carriage bolts are "specialized installation-focused" fasteners, offering unique anti-rotation and single-side assembly advantages for wood and flush-mount applications, complementing rather than replacing standard hex bolts in diverse fastening scenarios.
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