Bronze Hex Bolts, Silicon Bronze Hex Bolts – Manufacturer & Exporter to USA

Conex Metals is a leading ISO-certified manufacturer and exporter of Bronze Hex Bolts and Silicon Bronze Hex Bolts, supplying USA-based OEMs, distributors, contractors, and MRO buyers across Marine, Construction, Electrical, Automotive, Plumbing, Chemical, and Architectural sectors. Our Bronze and Silicon Bronze hex bolts are manufactured to ASTM, ASME, ANSI, and SAE standards using cold forging and precision threading processes, ensuring superior corrosion resistance, excellent conductivity, and long service life in harsh environments.

We serve customers across all 50 US states including California, Texas, Florida, New York, Louisiana, Michigan, Washington, and the Gulf Coast marine corridor. Our bolts are available in Unified National Coarse (UNC), Unified National Fine (UNF), and metric thread forms, with sizes from #10-24 through 1½”-6 UNC and beyond.

What Are Bronze Hex Bolts?

Bronze Hex Bolts are externally threaded fasteners with a six-sided (hexagonal) head, manufactured from Copper-Tin alloys (Bronze) or Copper-Tin-Silicon alloys (Silicon Bronze). The hexagonal head allows tightening with standard open-end wrenches, combination wrenches, or socket sets. Bronze hex bolts deliver exceptional corrosion resistance in saltwater, marine, and chemical environments, superior to carbon steel or even 304/316 stainless steel in many aggressive atmospheric and immersed conditions.

They are non-magnetic, non-sparking, and biofouling-resistant, making them the preferred choice for boat building, dock hardware, underwater installations, electrical grounding, architectural metalwork, chemical plant equipment, and HVAC systems throughout the United States.

Silicon Bronze Hex Bolts

Silicon Bronze Hex Bolts are manufactured from a Copper-Silicon-Manganese alloy (C65100 / C65500 per ASTM B99/B98), offering the highest corrosion resistance of any Bronze fastener grade. Silicon Bronze delivers tensile strengths of 60,000–85,000 psi (415–585 MPa), far exceeding standard Bronze, making it suitable for structural and high-load marine fastening applications. Silicon Bronze is the material of choice for wooden boat construction (WoodenBoat standard), dock and pier hardware, coastal architectural cladding, cathodic protection systems, and marine electrical bonding across the US.

Related Parts – Bronze & Silicon Bronze Hex Bolts

Bronze hex bolts, Silicon bronze fasteners, C65100 bolts, C65500 silicon bronze hex bolts, naval brass hex bolts, bronze marine bolts, silicon bronze lag bolts, bronze hex cap screws, silicon bronze hex cap screws, bronze carriage bolts, bronze stove bolts, silicon bronze through bolts, bronze machine bolts, anti-corrosion hex bolts, saltwater resistant bolts, non-magnetic bronze bolts, non-sparking fasteners, copper alloy hex bolts, ASTM B98 silicon bronze bolts, ASTM F468 bronze bolts, boat building bolts, dock hardware bolts, marine grade hex bolts USA.

Material Grades & World Equivalents

Silicon Bronze Grades

Bronze (Tin Bronze / Naval Bronze) Grades

Key Mechanical Properties (Reference)

Manufacturing Process – Cold Forging

Conex Bronze Hex Bolts are manufactured using a cold forging (cold heading) process, which is the industry standard for producing high-volume, precision hex bolts with superior grain structure and mechanical integrity compared to machined bolts.

Cold Forging Process Steps:
1. Wire Drawing: Silicon Bronze or Bronze rod (ASTM B98/B99/B139) is drawn to the exact wire diameter required for each bolt size (e.g., 0.375 in dia for 3/8″ bolt).
2. Cutting to Length: Wire is cut into precise slugs using carbide dies on automated wire-fed cold heading machines.
3. Cold Heading (Extrusion): Slugs are cold-forged in multi-die progressive heading machines (2-die, 3-die, or 4-die) at room temperature, forming the bolt shank and hex head simultaneously. Cold working increases tensile strength by 15–25% through work-hardening, without heat treatment.
4. Hex Head Forming: The six-sided head is formed to ANSI B18.2.1 / ASME B18.2.1 dimensional standards using precision hex dies, ensuring accurate across-flats (AF) width, head height, and bearing surface flatness.
5. Pointing / Chamfering: Thread end is chamfered at 15–30° to facilitate thread engagement.
6. Thread Rolling: See Threading Process below.
7. Inspection: 100% dimensional check with go/no-go gauges (ANSI/ASME B1.2), optical comparator, and CMM inspection for critical dimensions.

Advantages of Cold Forging over Machining:
• Superior grain flow continuity — no interrupted grain lines at the head-shank junction
• 15–25% higher tensile strength due to cold work hardening
• Better dimensional repeatability across large production runs
• Less material waste — near-net-shape forming
• Faster cycle times — ideal for ANSI standard sizes in large volumes

Threading Process

All Bronze and Silicon Bronze Hex Bolts are threaded using the thread rolling process, which is preferred over thread cutting for Bronze alloys due to the following advantages:

Thread Rolling Process:
1. Setup: Cold-forged blank is fed into a thread rolling machine with a pair of hardened thread rolling dies (flat die or cylindrical die).
2. Rolling: Dies press against the blank, plastically deforming the material to form the thread profile without removing metal. Material is displaced radially outward (crest) and inward (root), producing a thread with higher surface hardness, better fatigue resistance, and smoother finish than cut threads.
3. Thread Standards: Threads are rolled to ASME B1.1 (UNC/UNF) for inch fasteners and ASME B1.13M (ISO metric) for metric fasteners.
4. Gauging: All threads are gauged using calibrated go/no-go ring gauges per ASME B1.2 and B1.3M. Thread class 2A tolerance is standard for commercial bolts; Class 3A is available on request for precision applications.

Available Thread Forms (USA Market):
• UNC (Unified National Coarse) – Standard thread for most structural and general-purpose applications
• UNF (Unified National Fine) – Finer pitch; used where vibration resistance or adjustment precision is required
• Metric Coarse (ISO) – Available for international or metric-specified US projects
• Left-Hand Thread – Available on request for special assemblies
• Full Thread (FT) and Partial Thread (PT) both available

Thread Size & Pitch Chart – UNC & UNF (ASME B1.1)

Hex Bolt Dimensions – ANSI/ASME B18.2.1 (Hex Cap Screw)

Hexagon & Head Thickness Chart – DIN 931 / DIN 933 Equivalent (Metric)

DIN 931 = Partially threaded hex bolt; DIN 933 = Fully threaded hex bolt. Both are manufactured in Silicon Bronze C65500 / C65100 and Bronze C46400 Naval Brass grades.

ASTM Standard Specifications (USA)

Industries & US Applications

• Marine & Boat Building – Hull through-bolts, keel bolts, chainplate bolts, mast hardware (Silicon Bronze C65500 per WoodenBoat and ABYC standards)
• Dock & Pier Construction – Pier framing bolts, dock cleat hardware, mooring hardware (corrosion-free in saltwater immersion)
• Electrical & Grounding – Grounding electrode conductor bolts, busbar hardware, switchgear panel hardware (non-magnetic, excellent conductivity)
• Chemical Processing – Pump housing bolts, valve body fasteners, tank hardware (resistant to acids, alkalis, brine)
• Architectural & Facade – Exterior cladding bolts, bronze hardware for historic buildings, decorative hex hardware
• Plumbing & HVAC – Fitting bolts, valve assembly bolts, pressure vessel hardware (NSF 61 / ASTM B88 compliant material)
• Military & Defense – Non-magnetic fastener applications, naval vessel hardware (MIL-SPEC compatible alloys)
• Food & Beverage Processing – Non-contaminating fasteners in wet environments

Similar bronze Parts: Bronze hex bolts, Silicon bronze hex bolts, C65500 silicon bronze bolts, C65100 bronze bolts, ASTM F468 bronze bolts, bronze hex cap screws USA, silicon bronze marine bolts, naval brass hex bolts, bronze fasteners supplier USA, silicon bronze fasteners, bronze bolts ASME B18.2.1, UNC silicon bronze bolts, DIN 931 bronze bolts, DIN 933 bronze bolts, bronze bolts for boat building, marine grade hex bolts, saltwater resistant bolts, non-magnetic bronze bolts, non-sparking bronze fasteners, silicon bronze bolts exporter India to USA, bronze hex bolts manufacturer

Why Choose Conex Metals for Bronze Hex Bolts USA

• Three decades of manufacturing and US export experience
• ASTM F468 / ASME B18.2.1 compliant dimensions and tolerances
• Material Test Reports (MTRs), Certificates of Conformance (CoC), and PPAP Level 3 documentation available
• Available in sizes #10 through 1-1/2″ UNC/UNF and metric M6–M30
• Lengths from 1/4″ to 6″ and beyond in standard and custom specifications
• Cold forged + thread rolled for maximum strength and consistency
• Passivation, light oil coating, or bare finish options available
• USD pricing with FOB / CIF / DDP Incoterms; air (FedEx/UPS/DHL) and sea freight to all US ports
• Custom head markings, special lengths, non-standard diameters available
• RoHS, REACH, and NSF-compatible alloys available

Packaging & Shipping to the USA

• Bulk cartons (plain polybag) or retail/distributor-ready packaging with branded labels
• GS1 / UPC barcodes available for US distributor requirements
• ISPM-15 certified pallet packaging (40×48 in US standard pallets) for sea freight
• Sea freight to Los Angeles, Houston, New York / New Jersey, Savannah, Seattle ports
• Air freight via FedEx International Priority, UPS Worldwide, DHL Express
• Full US CBP export documentation: Commercial Invoice, Packing List, B/L, Certificate of Origin, MTRs

FAQ – Bronze & Silicon Bronze Hex Bolts for US Buyers

1. What is the difference between Bronze and Silicon Bronze hex bolts?
Silicon Bronze (C65500/C65100) has higher tensile strength (85,000 psi vs. 60,000–70,000 psi) and superior corrosion resistance compared to standard Tin Bronze or Naval Brass. Silicon Bronze is the preferred grade for marine and structural applications.

2. Are your bronze hex bolts compliant with ASTM F468?
Yes. Our Bronze and Silicon Bronze hex bolts are manufactured to ASTM F468 chemical and mechanical requirements with full material documentation.

3. Do you supply Silicon Bronze bolts per ASME B18.2.1?
Yes. All dimensions (AF width, head height, thread length) conform to ASME B18.2.1 for hex cap screws and heavy hex bolts.

4. Can you supply fully threaded (DIN 933 equivalent) and partially threaded (DIN 931 equivalent) versions?
Yes. Both fully threaded and partially threaded hex bolts are available in all standard sizes.

5. What thread class do you supply – 2A or 3A?
Standard supply is Class 2A (ASME B1.1). Class 3A precision threads are available on request.

6. Are silicon bronze bolts suitable for saltwater marine use?
Yes. C65500 Silicon Bronze is widely accepted as the premium marine fastener material by WoodenBoat, ABYC, and US Coast Guard-approved boatbuilders.

7. Do you offer non-standard lengths or diameters?
Yes. Custom lengths, special diameters, and non-standard configurations are available with lead times of 4–6 weeks from drawing approval.

8. What is your MOQ for silicon bronze hex bolts?
MOQ is typically 5,000 pieces for standard sizes; lower MOQs available for repeat customers and distributors.

9. Do you provide material test reports?
Yes. Full MTRs (chemical composition + mechanical properties) per ASTM F468 / B98 are provided with every shipment.

10. What is the lead time for delivery to the USA?
Standard sizes: 3–4 weeks. Custom sizes: 4–6 weeks. Air freight: 3–5 business days to any US city.

Related Products

Brass Hex Bolts DIN 933 |
Copper Hex Bolts |
All Hex Bolts |
Bronze & Silicon Bronze Fasteners

Updated: 2026 | ISO-Certified Manufacturer | Exporting Bronze Hex Bolts to the USA since 1990s