IS 291 covers manganese bronze (high tensile brass) — a Cu-Zn alloy with Mn, Fe, Al additions for high strength. Used for marine propellers, heavy-duty bearings, gears, and valve stems where both strength and seawater corrosion resistance are needed.
Specification for manganese bronze (high tensile brass) ingots and castings covering grades, chemical composition, and mechanical properties.
Key Values
HTB1 tensileMin 440 MPa
HTB1 elongationMin 15%
HTB2 tensileMin 490 MPa
Practical Notes
! Manganese bronze is the standard material for ship propellers in India.
! Despite the name, manganese bronze is technically a brass (Cu-Zn base), not a true bronze (Cu-Sn).
! High tensile strength (440-490 MPa) compared to ordinary brass (300-350 MPa).
! Castings should be stress-relieved after machining for critical marine applications.