What is brass?
Brass is an alloy made of copper and zinc, commonly called common brass. If the alloy contains more than two elements, it is called special brass.
Brass is known for its strong wear resistance and is commonly used in the production of valves, water pipes, connecting pipes for air conditioners, radiators and other applications.
Types of Brass
Lead Brass
Lead is almost insoluble in brass and is found at grain boundaries as free particles. There are two types of lead brass: α and (α+β). α Leaded brass can only be cold formed or hot extruded due to its negative impact and low plasticity at high temperatures. Lead brass (α+β) has good plasticity at high temperatures and can be forged.
Tin brass
The addition of tin to brass significantly improves the alloy's heat resistance, especially its resistance to seawater corrosion. This is why tin brass is known as “naval brass”. The tin dissolves in the copper-based solid solution and increases its strength.
However, as the tin content increases, the brittle R phase (CuZnSn compound) will appear in the alloy, which makes its plastic deformation difficult. The tin content in tin-plated brass is typically in the range of 0.5% to 1.5%.
Common tin brass includes HSn70-1, HSn62-1, HSn60-1, etc. HSn70-1 is a high plasticity alloy and can be used for cold and hot pressing, while the latter two types of alloys have an α (α+ β) two-phase structure, with a small amount of r phase often present. They have low plasticity at room temperature and can only be deformed when hot.
Manganese Brass
Manganese has greater solubility in solid brass. Adding 1% to 4% manganese to brass greatly improves the strength and corrosion resistance of the alloy without reducing its plasticity. Manganese brass has a (α+β) structure, and HMn58-2 is commonly used, with good workability under cold and hot pressure.
Iron Brass
In iron yellow copper, iron precipitates as iron-rich particles, which serve as crystal nuclei to refine the grains and prevent the growth of recrystallized grains, improving the mechanical and technological properties of the alloy. The iron content in ferrous brass is generally less than 1.5% and has an (α+β) structure. It has high strength and toughness and good plasticity at high temperatures, and can also be deformed at cold temperatures. The commonly used brand is Hfe59-1-1.
Nickel Brass
Nickel and copper form a continuous solid solution, significantly expanding the α-phase region. The addition of nickel to brass greatly improves its resistance to corrosion in both the atmosphere and seawater.
Nickel also increases the recrystallization temperature of brass and promotes the formation of finer grains. HNi65-5 nickel brass has a single-phase α structure and has good plasticity at room temperature and can also be deformed in the hot state.
However, the content of lead impurities must be strictly controlled, otherwise the hot workability of the alloy will be severely affected.
Brass composition
Purity Measurement
To determine the purity of brass, Archimedes' principle can be used to measure the volume and mass of the sample, after which the proportion of copper in the brass can be calculated based on the density of copper and zinc.
Common Brass
Common brass is an alloy of copper and zinc. When the zinc content is less than 35%, it can dissolve in copper to form a single-phase α structure, known as single-phase brass. This structure has good plasticity and is ideal for cold and hot pressing.
When the zinc content varies from 36% to 46%, there is a single-phase α solid solution and a copper-zinc-based β solid solution, known as two-phase brass. The β phase reduces the plasticity of brass and increases its tensile strength, making it only suitable for hot pressure processing. If the zinc content continues to increase, the tensile strength will decrease, making it useless.
The brass code is represented by “H+number”, where “H” means brass and the “number” represents the mass fraction of copper. For example, H68 represents brass with 68% copper and 32% zinc.
For cast brass, the letter “Z” is added before the code, such as ZH62. For example, ZCuZnZn38 represents a cast brass with a zinc content of 38% and the remainder being copper.
H90 and H80 are made of single-phase brass and are golden yellow in color. H59 is two-phase brass and is widely used in structural parts of household appliances, such as screws, nuts, washers and springs. Typically, single-phase brass is used for cold deformation processing, while two-phase brass is used for hot deformation processing.
Special Brass
An alloy formed by adding other elements to common brass is known as special brass. Commonly added elements include lead, tin, and aluminum, which are called lead brass, tin brass, and aluminum brass, respectively. The purpose of adding these elements is mainly to improve the tensile strength and processability of brass.
The code for special brass is represented as “H+symbol of the main element added (excluding zinc)+mass fraction of copper+mass fraction of the main element added+mass fraction of other elements”. For example, HPb59-1 indicates that the mass fraction of copper is 59%, the mass fraction of lead (the main added element) is 1%, and the remainder is zinc.
Specification for heat treatment of brass
The hot working temperature range is 750 to 830 degrees Celsius. The annealing temperature range is 520 to 650 degrees Celsius, and the low-temperature annealing temperature to relieve internal stress is 260 to 270 degrees Celsius.
Eco-friendly C26000 (C2600) brass has excellent plasticity, high strength, good machinability, good welding properties and strong corrosion resistance. It is widely used in heat exchangers, paper tubes, machines and electronic parts.
Brass specifications include thickness ranging from 0.01 to 2.0 mm and width ranging from 2 to 600 mm. The hardness of brass can be O, 1/2H, 3/4H, H, EH, SH, etc. Applicable standards for brass include GB, JIS, DIN, ASTM and EN.
Brass has excellent cutting performance and is suitable for processing high-precision parts on automatic lathes and CNC lathes.
