Engineering Materials
Gun metal contains

70% copper and 30% zinc
85 - 92% copper and rest tin with little lead and nickel
90% copper and 10% tin
70 - 78% copper and rest tin

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Engineering Materials
Aluminium bronze contains

94% aluminium, 4% copper and 0.5% Mn, Mg, Si and Fe
10% aluminium and 90% copper
92.5% aluminium, 4% copper, 2% nickel, and 1.5% Mg
90% magnesium and 9% aluminium with some copper

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Engineering Materials
Ductile cast iron

Is produced by small additions of magnesium (or creium) in the ladle. Graphite is in nodular or spheroidal form and is well dispersed throughout the material
Contains 1.7 to 3.5% carbon in Free State and is obtained by the slow cooling of molten cast iron
Is also known as chilled cast iron and is obtained by cooling rapidly. It is almost unmachinable
Is produced by annealing process. It is soft, tough and easily machined metal

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Engineering Materials
In a hardening process, the hypo-eutectoid steel is

Heated from 30°C to 50°C above the upper critical temperature and then cooled suddenly in a suitable cooling medium
Heated from 30°C to 50°C above the upper critical temperature and then cooled slowly in the furnace
Heated below or closes to the lower critical temperature and then cooled slowly
Heated from 30°C to 50°C above the upper critical temperature and then cooled in still air

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