Gunmetal 903 Bolts manufactured at TorqBolt are wear and cavitation resistant with excellent impact properties.
Dimensional standards as per DIN 931,DIN 933,BS 1768,UNI 5731,UNI 5737,UNI 5739,ISO 4014,ISO 4017,BS 1769,BS 3692 are provided.
The raw material of these fasteners is classified as Non-Ferrous Alloys. Being a PED certified Fasteners Manufacturer by TUV Rheinland,our fasteners are accompanied with EN 10204 3.1/3.2 certification. Gunmetal 903 Bolts are available in hot forged,cold forged and bar stock machined conditions depending upon the order quantity.
Gunmetal 903 Is Hard ,strong, Tough &,wear Resistant & Fine Grained . This Exhibits Good Machinability And Corrosion Resistance To Sea Water. The Addition Of Nickel Increases The Mechanical Strength And Corrosion Resistance. Plain Bearing Shells, Moderately Stressed Slide And Coupling Components. Stern Tubes & Most Often Used For Heavy Loads & Low Speed Bushing.
Gunmetal 903 bolts are externally threaded fasteners with an integral head, manufactured per ASME B18.2.1, ISO 4014/4017, and DIN 933/931. TorqBolt produces Gunmetal 903 bolts in metric (M6–M100) and imperial (1/4"–4") diameters with custom lengths from 10 mm up to 3000 mm.
Head Styles Available
Hex head — ASME B18.2.1, the workhorse for general bolting
Heavy hex head — thicker head for high-load joints, ASTM A325 / A490 patterns
Socket head cap (SHCS) — ASME B18.3 / DIN 912, ideal where space is limited
Gunmetal 903 bolts are supplied with full or partial threading. Full-thread (UNC, UNF, ISO metric coarse/fine) for tension-only joints; partial-thread shank for shear loads where the unthreaded grip carries the load. Thread fits per ASME B1.1 (Class 2A) or ISO 965 (6g) by default; tighter Class 3A / 4h6h fits available on request. Engagement length follows the 1.5×D rule for tapped holes; 1.0×D minimum on through-bolting.
Mechanical Performance
Gunmetal 903 bolts achieve characteristic tensile strength, yield, and elongation per the source-material spec, with proof-load testing and hardness verification per ASTM F606 / ISO 898-1. Torque-tension calibration is published per ASME PCC-1 for critical joints. Each lot ships with EN 10204 3.1 (or 3.2 on request) certificates listing chemistry, mechanicals, hardness, and dimensional inspection.
Custom Configurations
TorqBolt can produce Gunmetal 903 bolts to drawing, with non-standard heads, drilled-shank variants, double-end, captive, or matched-set configurations. Coatings include zinc, PTFE, Xylan, hot-dip galvanized, and electroless nickel. NACE MR0175 / ISO 15156 sour-service certification on request.
Bronze alloys are copper-based alloys with tin, aluminium, silicon, manganese, or phosphorus alloying additions, each tuned for a specific tribological or environmental envelope. Bronzes deliver excellent bearing properties, marine corrosion resistance, and non-sparking + non-magnetic characteristics — specified for marine fasteners, electrical hardware, oil + gas wellhead components, and industries where sparks must be avoided.
Phosphor bronze (Cu-Sn-P, e.g. C51000, C52400) combines high yield strength + fatigue with seawater corrosion resistance — the standard for marine + spring fasteners. Silicon bronze (Cu-Si, e.g. C65500) is the marine-grade weldable alloy popular for boat fasteners and architectural cladding. Aluminium bronze (Cu-Al, e.g. C95400/C95500/C95800) achieves yield ~310-585 MPa with outstanding seawater + cavitation resistance — the workhorse for marine pump impellers and propeller hub bolting. Gunmetal (Cu-Sn-Zn-Pb, e.g. C90500) is the historic naval bronze for valves and trim. Leaded bronze adds Pb for free-machining + bearing applications.
Bronze fasteners ship per ASTM B98 (rod/bar) and B584 (sand cast) with EN 10204 3.1 / 3.2 certificates covering composition, hardness, and ASTM B66 ammonia stress-corrosion testing where service exposure warrants.
