What is brass?
Brass is an alloy composed of copper and zinc.
Brass composed of copper and zinc is called ordinary brass.
If it is a variety of alloys composed of more than two elements, it is called special brass.
Brass has strong wear resistance.
Brass is often used to make valves, water pipes, connecting pipes of internal and external units of air conditioners, radiators, etc.
Types of Brass
Lead is practically insoluble in brass and distributed on the grain boundary as free particles.
There are two kinds of lead brass: α and (α+β).
α lead brass can only be cold deformed or hot extruded because of its harmful effect and low plasticity at high temperature.
(α+β) lead brass has good plasticity at high temperature and can be forged.
The addition of tin to brass can significantly improve the heat resistance of the alloy, especially the ability to resist seawater corrosion.
Therefore, tin brass is called “naval brass”.
Tin can dissolve into copper based solid solution and play a solid solution strengthening role.
However, with the increase of tin content, brittle r phase (CuZnSn compound) will appear in the alloy, which is not conducive to the plastic deformation of the alloy.
Therefore, the tin content of tin brass is generally within the range of 0.5%~1.5%.
Common tin brass includes HSn70-1, HSn62-1, HSn60-1, etc.
The former is a alloy with high plasticity and can be used for cold and hot pressing.
The latter two grades of alloys have α (α+β) two-phase structure, and a small amount of r phase often appears.
The plasticity at room temperature is not high, and they can only be deformed in hot state.
Manganese has higher solubility in solid brass.
Adding 1%~4% manganese to brass can significantly improve the strength and corrosion resistance of the alloy without reducing its plasticity.
Manganese brass has (α+β) structure, HMn58-2 is commonly used, and the pressure workability under cold and hot conditions is quite good.
In iron yellow copper, iron is precipitated as iron rich particles, which can be used as crystal nucleus to refine grains and prevent recrystallization grains from growing, thus improving the mechanical and technological properties of the alloy.
The iron content in iron brass is usually less than 1.5%, and its structure is (α+β).
It has high strength and toughness.
It has good plasticity at high temperature and can also be deformed at cold state.
The commonly used brand is Hfe59-1-1.
Nickel and copper can form a continuous solid solution, which significantly expands the α-phase region.
The corrosion resistance of brass in atmosphere and sea water can be significantly improved by adding nickel to brass.
Nickel can also increase the recrystallization temperature of brass and promote 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 hot state.
However, the content of lead impurity must be strictly controlled, otherwise the hot workability of the alloy will be seriously deteriorated.
Composition of brass
To measure the purity of brass, Archimedes principle can be used to measure the volume and mass of the sample, and then the proportion of copper in brass can be calculated according to the density of copper and zinc.
It is an alloy of copper and zinc.
When the zinc content is less than 35%, zinc can dissolve in copper to form single-phase α, which is called single-phase brass.
It has good plasticity and is suitable for cold and hot pressing.
When the zinc content is 36%~46%, there is a single phase α and a copper zinc based β solid solution, called two-phase brass.
Phase β reduces the plasticity of brass and increases the tensile strength, which is only suitable for hot pressure processing.
If the mass fraction of zinc continues to increase, the tensile strength will decrease and there is no use value.
The code is represented by “H+number”, H represents brass, and number represents the mass fraction of copper.
For example, H68 represents the brass with 68% copper and 32% zinc content.
For cast brass, add “Z” before the code, such as ZH62.
For example, ZCuZnzn38 represents a cast brass with a zinc content of 38% and a copper margin.
H90 and H80 belong to single-phase brass, golden yellow.
H59 belongs to two-phase brass and is widely used in structural parts of electrical appliances, such as bolts, nuts, washers, springs, etc.
Generally, single-phase brass is used for cold deformation processing and two-phase brass is used for hot deformation processing.
The multi-element alloy formed by adding other alloy elements to ordinary brass is called special brass.
The commonly added elements are lead, tin, aluminum, etc., which can be called lead brass, tin brass, aluminum brass accordingly.
The purpose of adding alloying elements is mainly to improve the tensile strength and improve the processability.
Code: “H+symbol of main plus elements (except zinc)+mass fraction of copper+mass fraction of main plus elements+mass fraction of other elements”.
For example, HPb59-1 indicates that the mass fraction of copper is 59%, the mass fraction of lead containing the main additive element is 1%, and the residual is zinc.
Specification for heat treatment of brass
The hot working temperature is 750 ～ 830 ℃;
Annealing temperature 520-650 ℃;
The low temperature annealing temperature for relieving internal stress is 260 ～ 270 ℃.
Environmentally friendly brass C26000 C2600 has excellent plasticity, high strength, good machinability, good welding and corrosion resistance, heat exchanger, paper pipe, machinery and electronic parts.
Specification (mm): Specification: thickness: 0.01-2.0mm, width: 2-600mm;
Hardness: O, 1/2H, 3/4H, H, EH, SH, etc;
Applicable standards: GB, JISH, DIN, ASTM, EN;
Specialties: excellent cutting performance, applicable to high-precision parts processed by automatic lathes and CNC lathes.