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Brass is made of
copper
and
zinc
Composed of
alloy
Brass composed of copper and zinc is called ordinary brass, and if it is composed of more than two kinds of alloys, it is called
Special brass
. Brass has a strong wear resistance, brass is often used in the manufacture of valves, water pipes, air conditioning inside and outside the machine connection pipe and radiator.
- Chinese name
- Orichalcum
- Foreign name
- Brass
- Group into
- Copper and zinc
- categorize
- Common brass, special brass
- nature
- High strength, high hardness, strong chemical resistance
- use
- Manufacture valves, water pipes, etc
- Metal type
- alloy
- Publication in print
- Chemical Terms, Science Press
- Announcement time
- The year 1991 [2]
So far, the earliest copper products found in the world are mainly in Western Asia, such as the Zawai Chami region of Iraq, where copper ornaments were found, dating from about 10,000 to 9,000 BC. Copper ornaments have also been found in the Ali Kashgar region of western Iran, dating from 9,000 to 7,000 BC. Copper needles and cones have been found at the site of Chayoni in southern Turkey, dating from about 8,000 BC. These copper products are natural red copper products, not copper obtained by smelting ore.
From the use of pure copper, to smelting copper ore to obtain pure copper, and then to smelting bronze alloy, human beings have experienced a very long period of exploration, just like the magic world with copper bit by bit to create a sparkling time and space tunnel.
Guo Zi white plate
China's earliest use of brass casting money began in the Ming Jiajing years.
The word "brass" first appeared in the Western Han Dynasty
Eastern New Moon
The "Shen Yi Jing · Zhong Jing" written by: "There is a palace in the northwest, brass walls, the title says the palace of the Earth Emperor."
[1]
What kind of copper alloy this "brass" refers to remains to be seen. "New Tang Shu · Shihuo Zhi" also has the title of "bronze" and "brass", respectively referring to the ore color and smelting products, "pit has a special name, Shan Duozhong Pu" refers to the pure copper refined by fire.
Orichalcum
Zinc oxide
At a high temperature of 950℃-1000℃, it can be quickly reduced to metal zinc, and liquid zinc has been boiled at 906℃, so the reduced metal zinc exists in vapor form. Upon cooling, the reaction is reversed and the vapor zinc is in the furnace
Carbon dioxide
Reoxidize to zinc oxide, so to obtain metal zinc must have a special condensing device. This is the use ratio of metal zinc
copper
,
lead
,
tin
,
iron
The reason for the much later use of brass coins is also one of the reasons for the late appearance of brass coins.
The zinc content of copper ware in Shang and Zhou dynasties is very low. There are very few copper, zinc and sweet coins in the coins of the Western Han Dynasty and Xinmang, and the zinc content of some coins reaches 7%, but this does not mean that the brass coin was produced in the time of Xinmang. Because these copper-zinc alloys are very isolated phenomena, their zinc content is generally much smaller than the real zinc content of 15%-40% of brass. Therefore, we believe that these zinc-containing copper coins were produced in the Han Dynasty when copper-zinc symbiosis was used in the "Jishan Chuqian". According to the investigation of the relevant mines, it was found that Changwei, Yantai, Linyi and Hubei provinces in Shandong Province have rich resources of cop-zinc co-growth deposits, which makes the smelted copper contain a small part of zinc. In the Tang Dynasty, due to the standardization of the casting materials, the zinc content of the coins cast was constant.
Brass products were popular in Europe for about 300 years, from about 1230 AD, because they were much cheaper than large sculptures. The bronze statue of Archbishop Wilp, dating from 1231, is the earliest known bronze statue made of brass. The process of casting brass products is as follows: first crushed zinc ore and charcoal are mixed with copper blocks and heated to bind the zinc and copper together, and then heated to melt the alloy, and then the copper liquid is poured into the casting mold. The earliest brasses in England were imported, mainly from Tourney. A client can order a complete tombstone from Tourne, already mounted in a beautiful base or marble base. The way to make a bronze tombstone is to cast a bronze statue, usually a silhouette of the surrounding canopy, and then place it in a prefabricated stone slab, and use a knife to carve out the details of the person on the bronze statue. Sometimes the hands and face of the bronze statues were used
alabaster
Or other Mosaic materials. When the bronze statue was completely finished, it was fixed to the stone base with a dowel in a lead bolt. The bronze statue itself sits on a layer of asphalt. Large bronze statues were cast in sections and then joined together.
Common brass is a copper zinc binary alloy, and its zinc content varies widely, so its room temperature structure is also very different. According to the Cu-Zn binary state diagram, there are three kinds of room temperature microstructure of brass: brass with zinc content below 35%, and the microstructure at room temperature is single-phase
Alpha.
Solid solution composition, called
Alpha.
Brass; The microstructure of brass with zinc content in the range of 36% to 46% at room temperature is determined by (
Alpha.
+
Beta.
Two-phase composition, called (
Alpha.
+
Beta.
Brass (two-phase brass); The microstructure of brasses containing more than 46% ~ 50% zinc at room temperature is only limited by
Beta.
Phase composition, called
Beta.
Brass.
Alpha single-phase brass (from H96 to H65) has good plasticity and can withstand hot and cold processing, but
Alpha.
Single-phase brass is prone to moderate temperature brittleness during hot processing such as forging, and its specific temperature range varies with the amount of Zn, generally between 200 and 700℃. Therefore, the temperature should be higher than 700℃ during hot processing. The medium temperature brittle zone of single-phase α brass is mainly caused by Cu-Zn alloy system
Alpha.
Cu exists in the phase region
3
Zn and Cu
9
Zn, two ordered compounds, undergo an ordered transformation when heated at low temperature, which makes the alloy brittle; In addition, trace harmful impurities of lead and bismuth in the alloy form a low melting point eutectic film with copper and distribute on the grain boundary, which results in intergranular fracture during hot processing. The practice shows that adding trace amount of cerium can effectively eliminate the medium temperature brittleness.
Two-phase brass (from H63 to H59), the alloy structure in addition to a good plasticity of the α phase, also appeared by
Electron compound
Cuzn-based beta solid solution. The β phase has high plasticity at high temperatures, while the β 'phase at low temperatures (β') has high plasticity at low temperatures.
Ordered solid solution
It is hard and brittle. Therefore (α+β) brass should be forged in a hot state. β brass with zinc content greater than 46% to 50% can not be processed by pressure because of its hard and brittle properties.
Due to the different zinc content in brass, the mechanical properties are not the same, and the mechanical properties of brass change with the different zinc content. For alpha brass, both σb and δ increase with the increase of zinc content. For (α+β) brass, the room temperature strength continues to increase until the zinc content is increased to about 45%. If the zinc content is further increased, the more brittle r phase (Cu) appears in the alloy structure
5
Zn
8
Compound based solid solution), the strength is sharply reduced. The room temperature ductility of (α+β) brass always decreases with the increase of zinc content. Therefore, the copper zinc alloy with zinc content of more than 45% has no practical value.
Common brass is widely used, such as water tank belts, water supply and drainage pipes, MEDALS, bellows, serpentine pipes, condensing pipes, shell casings and various shapes of complex products, hardware and so on. With the increase of zinc content from H63 to H59, they can withstand hot processing well, and are mostly used in various parts of machinery and electrical appliances, stamping parts and Musical Instruments.
In order to improve the corrosion resistance, strength, hardness and workability of brass, a small amount of tin, aluminum, manganese, iron, silicon, nickel, lead and other elements are added to the copper-zinc alloy (generally 1% to 2%, a few up to 3% to 4%, and very individual up to 5% to 6%) to form a ternary, four yuan, or even five yuan alloy, that is, complex brass, also known as special brass.
The organization of complex brass can be determined according to the "elements added to brass".
Zinc equivalent coefficient
"To calculate. Because of the addition of a small amount of other
Alloying element
It is usually just to shift the α/(α+β) phase region in the Cu-Zn state diagram to the left or right. Therefore, the organization of special brass is usually equivalent to that of ordinary brass with increased or reduced zinc content. For example, the microstructure after adding 1% silicon to the Cu-Zn alloy is equivalent to adding 10% zinc to the Cu-Zn alloy. So the "zinc equivalent" of silicon is 10. The "zinc equivalent coefficient" of silicon is the largest, and the α/(α+β) phase boundary in Cu-Zn system moves significantly to the copper side, that is, the α phase region is strongly reduced. The "zinc equivalent coefficient" of nickel is negative, that is, the expansion of the alpha phase region.
The α phase and β phase in special brass are multi-component complex solid solutions, and their strengthening effect is larger, while the α phase and β phase in ordinary brass are simple Cu-Zn solid solutions, and their strengthening effect is lower. Although the zinc equivalent is equivalent, the properties of multicomponent solid solutions and simple binary solid solutions are not the same. Therefore, a small amount of multi-component strengthening is a way to improve the properties of the alloy.
Lead is actually insoluble in brass and distributed on the grain boundary as a free particle. Lead brass has two types, α and (α+β), according to its organization. Alpha lead brass due to the harmful effect of lead,
High temperature plasticity
Very low, so it can only be cold deformation or hot extrusion. (α+β) lead brass has good plasticity at high temperatures and can be forged.
Adding tin to brass can significantly improve the alloy
Heat resistance
In particular, improve the ability to resist seawater corrosion, so
tin-brass
It is called "navy brass".
Tin can dissolve into the copper base solid solution and play the role of solid solution strengthening. However, with the increase of tin content, there will be a brittle r phase (CuZnSn compound) in the alloy, which is not conducive to the plastic deformation of the alloy, so the tin content of tin brass is generally in the range of 0.5% to 1.5%.
Commonly used tin brass are
HSn70-1
,
HSn62-1
, HSn60-1, etc. The former is
Alpha.
Alloy, with high plasticity, can be cold, hot pressure processing. The latter two grades of alloy have (α+β) two-phase structure, and often appear a small amount of r phase, room temperature plasticity is not high, can only be deformed in the hot state.
Manganese has a high solubility in solid brass. Adding 1% to 4% manganese to brass can significantly improve the strength and corrosion resistance of the alloy without reducing its plasticity.
Manganese brass has an (α+β) structure, commonly used HMn58-2, cold and hot pressure processing performance is quite good.
In iron brass, iron is precipitated by iron-rich particles, which is used as a crystal nucleus to refine the grain, and can prevent the recrystallization grain growth, so as to improve the mechanical and technological properties of the alloy. The iron content in iron brass is usually less than 1.5%, and its organization is (α+β), with high strength and toughness, good plasticity at high temperature, and deformation under cold conditions. The common brand is Hfe59-1-1.
Nickel and copper can form
Continuous solid solution
The α phase region is significantly enlarged. The addition of nickel to brass can significantly improve the corrosion resistance of brass in atmosphere and seawater. Nickel also enhances brass
Recrystallization temperature
To promote the formation of finer grains.
HNi65-5
Nickel brass has a single-phase alpha structure that is very good at room temperature
plasticity
It can also be deformed in hot state, but the content of impurity lead must be strictly controlled, which will seriously deteriorate the hot working performance of the alloy.
Measuring the purity of brass can be used
The Archimedes Principle
Measure the volume and mass of the sample, and then calculate the proportion of copper contained in brass 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 a single phase
Alpha.
, say
Single-phase brass
Good plasticity, suitable for hot and cold pressure processing.
When the zinc content is 36% to 46%, there is
Alpha.
Single-phase and copper-zinc-based
Beta.
Solid solution, called biphase brass, β phase 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 decreases and has no use value.
The code is denoted by "H + number", where H stands for brass and the number represents the mass fraction of copper.
For example, H68 indicates brass with a copper content of 68% and zinc content of 32%, and casting brass is preceded by a "Z", such as ZH62.
For example, ZCuZnzn38 indicates cast brass with a zinc content of 38% and a margin of copper.
H90
H80 is single-phase brass, golden yellow.
H59
It belongs to biphase brass and is widely used in structural parts of electrical appliances, such as bolts, nuts, washers, springs, etc.
Under normal circumstances, single-phase brass is used for cold deformation processing, and biphase brass is used for hot deformation processing.
Made of ordinary brass by adding other alloying elements to it
Multicomponent alloy
call
Special brass
. Often added elements are lead, tin, aluminum, etc., can be called accordingly
Lead brass
,
tin-brass
,
Aluminium brass
. The purpose of adding alloying elements. It is mainly to improve the tensile strength to improve the processability.
Code: for "H + main plus element symbol (except zinc) + copper mass fraction + main plus element mass fraction + other element mass fraction".
For example, HPb59-1 means that the mass fraction of copper is 59%, the mass fraction of lead containing the main additive element is 1%, and the margin is zinc lead brass.
Hot working temperature 750 ~ 830℃; Annealing temperature 520 ~ 650℃; Low temperature annealing temperature to eliminate internal stress 260 ~ 270℃.
Environmentally friendly brass C26000 C2600 excellent plasticity, high strength, good machinability, welding, good corrosion resistance, heat exchanger, paper pipe, machinery, electronic parts.
Specifications (mm) : 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;
Advantages: Excellent cutting performance, suitable for automatic lathes, CNC lathes processing high-precision parts.
