The Brasses
70/30 brass also known as cartridge brass contains 70% Cu and 30% Zn. It is used for cartridge cases, condenser tubes, sheet fabrication and for general purposes. Its ultimate tensile strength varies between 350 and 600 N/mm2. It is soft and ductile in and annealed form can withstand severe cold working. 60/40 brass of Muntz metal contains 60% Cu and 40% Zn. Its UTS varies between 400 and 850 N/mm2. It is suitable for hot working operations as well as for casting. Many cast valves and marine fittings are made out of this brass. Addition of 2% Pb improves its machinability.
Small additions of Fe, Al, Sn, Mn and Ni to 60/40 brass improves its strength considerably. Marine propellers and shafts, pump rods, autoclaves, switch gears and high strength fittings are made out of these brasses. Brazing alloys are essentially the brasses of 50/50 composition with small additions of Sn, Mn and Al. These brasses are hard and brittle.