IS 6921 FNB

IS 6921 FNB is a type of naval brass known as lead-free naval brass, which contains approximately 60% copper, 39.2% zinc, and around 0.8% tin. This alloy is specially designed to provide excellent corrosion resistance in marine environments without the addition of lead, aligning with environmental and health safety regulations.

Chemical Composition

• Copper (Cu): 59.0 – 62.0%

• Tin (Sn): 0.5 – 1.0%

• Zinc (Zn): Balance (~38%)

• Lead (Pb): Nil or trace (lead-free)

• Iron (Fe): Up to 0.1%

• Other Elements: Up to 0.5%

Physical Properties

• Density: Approximately 8.44 g/cm³

• Melting Points: Solidus ~1630°F (887°C), Liquidus ~1650°F (899°C)

• Electrical Conductivity: 26% IACS

• Thermal Conductivity: 67 BTU/(ft²·hr·°F)

• Coefficient of Thermal Expansion: 11.8 × 10⁻⁶ per °F

• Specific Heat Capacity: 0.09 BTU/lb/°F

• Modulus of Elasticity: 15,000 ksi

• Modulus of Rigidity: 5,600 ksi

Mechanical and Fabrication Properties

• Good machinability despite being lead-free

• Excellent corrosion resistance, including resistance to dezincification

• Suitable for hot forging and machining

• Typical applications include marine hardware, heat exchanger tubes, pump shafts, and various components in seawater environments