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IS 318 HTB3 Aluminium Brass Casting – Grade 3
IS 318 HTB3 Aluminium Brass Casting – Grade 3
IS 318 HTB3 (High Tensile Brass Grade 3) is the Indian standard aluminium brass casting grade, equivalent to C87200 (USA) and CC770S (EN 1982). The aluminium addition (2–5%) creates alpha + kappa phase microstructure that delivers high strength (420 MPa), excellent erosion-corrosion resistance, and improved seawater resistance compared to standard yellow or naval brass. IS 318 HTB3 is used for high-velocity pump impellers, structural marine hardware, and castings requiring higher strength combined with lead-free compliance.
Alloy Overview
IS 318 HTB3 (Cu 65–70%, Zn ~25%, Al 2–5%) gains its high strength through kappa phase (AlCu₃) intermetallic precipitation in the alpha matrix and the strengthening effect of the aluminium solid solution. Erosion-corrosion resistance is markedly better than HTB2 naval brass at high fluid velocities, making HTB3 preferred for pump impellers in abrasive or high-velocity service. The alloy is essentially lead-free (Pb max 0.30%), meeting most lead-reduced specification requirements.
Material Composition – IS 318
| Element | Min % | Max % | Typical % | Role |
|---|---|---|---|---|
| Copper (Cu) | 65.0 | 70.0 | 67.5 | Primary matrix |
| Zinc (Zn) | Balance | Balance | ~25.5 | Strength, castability |
| Aluminium (Al) | 2.0 | 5.0 | 3.5 | Strengthener, kappa phase, corrosion |
| Manganese (Mn) | 0.5 | 3.0 | 1.5 | Strengthener, grain refiner |
| Iron (Fe) | 0.5 | 2.5 | 1.0 | Grain refiner |
| Nickel (Ni) | – | 1.0 | 0.3 | Toughness |
| Lead (Pb) | – | 0.30 | – | Low-lead |
| Tin (Sn) | – | 0.20 | – | Minor |
| Silicon (Si) | – | 0.10 | – | Impurity |
| Phosphorus (P) | – | 0.05 | – | Deoxidant |
Mechanical Properties
| Property | Sand Cast | Die Cast | Standard |
|---|---|---|---|
| Tensile Strength (MPa) | 420 min | 490 min | IS 318 |
| Yield Strength (MPa) | 160 | 200 | IS 1608 |
| Elongation (%) | 18% | 20% | IS 1608 |
| Hardness (HB) | 90–120 | IS 1756 | |
| Density (g/cm³) | 8.42 | – | |
| Electrical Conductivity (%IACS) | 8–12 | – | |
| Melting Range (°C) | 880–1000 | – | |
| Machinability (%) | 30 | CDA scale | |
International Equivalent Grades
| Standard | Designation | Name |
|---|---|---|
| India (IS 318) | HTB3 | Aluminium Brass Grade 3 |
| USA (ASTM B584) | C87200 / CDA 872 | Silicon/Al Brass Casting |
| Europe (EN 1982) | CC770S | CuZn25Al5-C |
| Germany (DIN) | CuZn22Al3-C (nearest) | Al-Sondermessing |
| UK (BS 1400) | HTB3 (nearest) | High Tensile Brass 3 |
| Japan (JIS H5111) | HBsC3 (nearest) | High Strength Brass 3 |
| ISO | CuZn25Al5-C | Aluminium Brass Casting |
Applications
IS 318 HTB3 castings: high-velocity pump impellers (erosion-corrosion resistant); marine propellers for performance vessels; structural marine hardware requiring strength above HTB2 naval brass; desalination plant components; industrial pump and valve bodies for abrasive slurries; offshore structural connectors.
Pricing
US$ 11.50 per kilogram (CIF, indicative). MOQ: sample 1 pc; production 50 pcs.
Quality
IS 318 HTB3; EN 1982 CC770S; C87200 (nearest); ISO 9001:2015; spectrometric analysis; mechanical property certificates; carbide tooling required for machining. ISO 9001:2015. EN 10204 3.1 MTR.
Related IS 318 Grades
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