Brass alloys are comprised of a combination of Copper and Zinc, and are sometimes referred to as Manganese Bronze. These alloys are used mostly in architectural structures, chains, screws, fittings and valves due to the high tensile strength and resistance to corrosion. Brass alloys are available in two forms, alpha alloys which are comprised of less than 37 per cent Zinc, and alpha/beta alloys which contain up to 45 per cent Zinc and no less than 37 per cent Zinc. The amount of zinc affects the properties of brass alloys, so that the many varieties can be used for different functions.
Properties of Brass Alloys
The properties of brass alloys are broken up into two categories, mechanical properties and physical properties. Mechanical properties refer to factors that pertain to the alloy's function, such as hardness and tensile strength. Physical properties refer to aspects of the alloy's physical characteristics such as density and melting point.
Mechanical Properties-Tensile Strength
Tensile strength is a measure of the force needed to pull something apart until it breaks. Alpha brass alloys have a very high tensile strength in comparison to other metals and metal alloys. Alpha/beta brass alloys have a slightly lower tensile strength.
The elongation of a metal refers to the extent of which the metal can be stretched before breaking (think of pulled taffy). In Alpha brass alloys, where Zinc is lower, the elongation is low, as opposed to alpha/beta alloys which have a considerably higher elongation. In fact, elongation increases with the amount of Zinc in the alloy.
Hardness of a metal alloy refers to the level of resistance it has against being indented or scratched. Brass alloys are generally considered to have a good score for hardness.
Density is the mass per unit volume, or mathematically, density is mass divided by volume. Brass alloys, density=8 g/cm cubed, have a high density compared to many other substances. For example, the density of air is approximately 1.4kg/m cubed.
Physical Properties-Melting Point
The temperature at which point a substance will melt is called the melting point. The melting point for brass alloys is around 916 degrees Celsius, which makes brass alloys fairly resistant to heat.
Physical Properties-Modulus of Elasticity
Modulus of Elasticity refers to the propensity of a metal to stretch and return back to its original shape (think of a rubber band). For brass alloys, the modulus of elasticity is around 103 GPa or 15000000 psi (pressure per square inch). A 103 GPa implies that as a metal, brass alloys have a low modulus of elasticity as opposed to other types of metals.