Silicon Bronze Bolts and Hex Screws

Silicon Bronze Bolts and Hex Screws – High-Strength Corrosion-Resistant Fasteners

Silicon bronze bolts and hex screws are premium-grade fasteners manufactured from copper-silicon alloy (C651, C655, ASTM B98), offering exceptional corrosion resistance, mechanical strength, and non-magnetic properties. Widely used by electrical OEMs, EPC contractors, marine engineers, and power utilities in the USA and globally, these fasteners deliver reliable performance in harsh chemical, marine, and high-humidity environments where standard steel or zinc-plated fasteners fail prematurely.

Product Overview

Brass and Copper Parts manufactures silicon bronze bolts and hex screws to ASME, ASTM, DIN, and ISO standards. These fasteners are ideal for applications requiring a combination of corrosion resistance, electrical conductivity, and mechanical strength. Silicon bronze contains 94–96% copper with silicon (2–4%) and manganese, resulting in tensile strength up to 100 ksi while maintaining excellent ductility and weldability.

Product Types and Variants

Silicon Bronze Bolt Types

• Silicon Bronze Hex Bolts (Full Thread and Partial Thread) – Standard hex head, fully and partially threaded, ASME B18.2.1
• Silicon Bronze Carriage Bolts – Round head with square neck, DIN 603 / ASME B18.5
• Silicon Bronze Stud Bolts – Threaded both ends, for flanged connections
• Silicon Bronze Eye Bolts – Forged eye for lifting and rigging
• Silicon Bronze U-Bolts – For pipe clamps and marine hardware
• Silicon Bronze Lag Bolts (Lag Screws) – For wood and composite structures

Silicon Bronze Hex Screw Types

• Silicon Bronze Hex Cap Screws – Fully threaded hex drive, ASME B18.2.1
• Silicon Bronze Hex Flange Screws – Built-in flange washer under head
• Silicon Bronze Set Screws (Grub Screws) – Cup point, cone point, flat point
• Silicon Bronze Socket Head Cap Screws – Allen drive, high-torque applications

Key Features

• Superior marine-grade corrosion resistance – resists saltwater, acids, and alkalis
• Non-magnetic and non-sparking – safe for hazardous and electrical environments
• High tensile strength: 60,000–100,000 psi depending on temper
• Excellent weldability and brazability
• Electrically conductive – suitable for grounding and bonding applications
• Anti-galling and anti-seizing properties – does not seize under load
• RoHS compliant; lead-free grades available
• Available in UNC, UNF, and metric thread forms

Technical Specifications

Raw Material Grades and International Equivalents

Applications in Industry

• Electrical and Power Utilities: Grounding bolts, busbar fasteners, substation hardware, transformer grounding assemblies
• Marine and Offshore: Deck fittings, hull hardware, seawater pump assemblies, dock fittings
• EPC and Construction: Chemical plant fasteners, process piping flanges, structural bolting in corrosive atmospheres
• Plumbing and Water Treatment: Valve assembly bolts, pipe flange connections, desalination plant hardware
• Oil and Gas: Wellhead components, offshore platform fasteners, subsea connectors
• Food and Pharmaceutical: Sanitary fasteners where copper alloys meet hygiene requirements

Manufacturing Process

Silicon bronze bolts and hex screws at Brass and Copper Parts are manufactured using cold forging and hot forging processes followed by CNC thread rolling and machining. Raw material is sourced as C651/C655 silicon bronze rod conforming to ASTM B98. Hex heads are formed by hot upsetting or cold heading depending on diameter, followed by thread rolling for superior surface finish and thread strength. Final products undergo dimensional inspection, thread gauge checking, and mechanical testing before dispatch.

Quality Standards and Certifications

• ASTM B98 – Silicon Bronze Rod, Bar, and Shapes
• ASME B18.2.1 – Square and Hex Bolts and Screws (Inch)
• DIN 931 / DIN 933 – Hexagon Head Bolts (Metric)
• ISO 4014 / ISO 4017 – Hexagon Head Bolts
• RoHS 2 Directive Compliant
• Material Test Certificates (MTCs) per EN 10204 3.1 available
• ISO 9001:2015 Quality Management System

Why Choose Brass and Copper Parts

• In-house forging, machining, and thread rolling – full manufacturing control
• Export experience to USA, Europe, Middle East, and Southeast Asia
• Dedicated supply to electrical OEMs, EPC contractors, and power utilities
• Custom lengths, diameters, and head configurations on request
• Mill test certificates and third-party inspection support
• Small batch and bulk order capability; reliable lead times

Frequently Asked Questions

What is silicon bronze used for in bolts?

Silicon bronze bolts are used where corrosion resistance is critical – marine hardware, electrical grounding, chemical processing, and water treatment. The copper-silicon alloy resists saltwater, acids, and atmospheric corrosion far better than carbon steel.

What is the tensile strength of silicon bronze bolts?

Silicon bronze bolts (C655) have tensile strength of 60,000–100,000 psi depending on temper (soft to spring). This is adequate for most structural and mechanical fastening applications.

Are silicon bronze bolts magnetic?

No. Silicon bronze bolts are non-magnetic, making them suitable for sensitive electrical equipment, MRI facilities, and explosive environments.

What thread forms are available?

We supply silicon bronze bolts in UNC (Unified Coarse), UNF (Unified Fine), and Metric (ISO) thread forms per ASME B1.1 and DIN 13 standards.

Do silicon bronze bolts require anti-seize compound?

Silicon bronze naturally resists galling and seizure better than stainless steel. In extreme cases, a compatible anti-seize compound can be used, but it is typically not required.

What is the difference between C651 and C655 silicon bronze?

C651 contains approximately 1.5% silicon and offers moderate strength with good conductivity. C655 (High Silicon Bronze A) contains ~3% silicon, providing higher strength and superior corrosion resistance. C655 is most commonly specified for industrial fasteners.

Can silicon bronze bolts be used in saltwater environments?

Yes. Silicon bronze is widely used in marine applications due to its exceptional resistance to seawater corrosion. It is preferred over 316 stainless in many marine fastener applications.

What sizes and lengths are available?

We manufacture silicon bronze bolts from #6 to 2″ diameter (imperial) and M4 to M48 (metric), with lengths from 1/4″ to 12″. Custom sizes are available on request.

Do you supply material test certificates?

Yes. Mill Test Certificates (MTC) per EN 10204 3.1 with full chemical and mechanical analysis are available for all silicon bronze bolt orders.

What is the minimum order quantity for silicon bronze bolts?

We accept orders starting from small batches of 100 pieces for standard sizes. Bulk and repeat orders receive preferential pricing. Contact us for a quotation.

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Request a Quote

Need silicon bronze bolts or hex screws in custom sizes, grades, or quantities? Brass and Copper Parts supplies precision silicon bronze fasteners to electrical OEMs, EPC contractors, power utilities, and industrial distributors across the USA and globally. Contact us today for technical support, datasheets, and competitive pricing.