Brass is composed of copper and zinc alloy. If it is only the copper, zinc composition of the brass called on ordinary brass. If it is from the above two kinds of elements called on the various special brass alloy. If the lead, tin, manganese, nickel, lead, iron, copper alloy composed of silicon. Brass has strong wear resistance. Special Brass special brass called it high strength, hardness, corrosion-resistant chemical. Also cutting the mechanical properties are more prominent. From the brass pull into a seamless brass, soft, strong wear resistance. Brass seamless tube heat exchanger and condenser can be used for low temperature piping, the Cross-Harbour transport tube. Manufacturing sheet metal, beams, rods, tubing, such as casting parts. Copper in 62% ~ 68%, plastic-to create pressure equipment.
According brass alloy elements contained in the different types, brass brass is divided into ordinary and special brass two. Pressure processing brass called deformation brass.
1. Ordinary brass
(1) General Organization ordinary brass at room temperature Cu-Zn binary alloy is brass, zinc variation range, so the room temperature organizations were very different. According Cu-Zn binary state diagram (Figure 6), the brass at room temperature three organizations: 35% zinc volume in the following brass, at room temperature microstructure from single-phase solid solution composed of α, α called brass; zinc in the 36% to 46% within the scope of brass, at room temperature by the microstructure (α + β) two-phase component, known as the (α + β) brass (two-phase Brass) ; zinc content in excess of 46 per cent to 50 per cent of the brass, at room temperature microstructure only by β phase, known as β brass. Brass Fitting
(2) pressure-α
processing performance of brass (from the H96 and H65) has a good plasticity, can withstand the cold processing, but α brass in the single-phase heat processing, forging and other vulnerable emerging temperature brittle, with the specific temperature range volume containing Zn vary, generally between 200 to 700 ℃. Therefore, thermal processing temperature should be higher than 700 ℃. Single-phase α Brass temperature brittle zone is the main reason in the Cu-Zn alloy α phase of the region there is a Cu3Zn and orderly Cu9Zn two compounds, in the low-temperature heating in an orderly change to Alloy addition, Alloy in the amount of lead, bismuth and copper forming harmful impurities low melting point eutectic films distributed in the grain boundary, the thermal processing of a rupture between the crystal. Practice shows that, by adding small amount of cerium can be effectively eliminated in the temperature brittle.
Brass two-phase (from the H63 and H59), in addition to Alloy Plastic good α phase, but also emerged from the electronic CuZn-based compounds β-solid solution. Β-phase high temperature with high plasticity, and temperature of β 'phase (orderly solid solution) hard and brittle nature. Therefore, (α + β) brass should be carried out in the hot forging.brass ball valve
Zinc is greater than 46% to 50% of the β brass because of hard and brittle, not pressure processing.
(3) the mechanical properties of zinc brass because of different mechanical properties are different, Figure 7 is a brass mechanical properties of the zinc vary the curve. For α brass, with the increased volume of zinc, σ b and δ are rising. For (α + β) brass, zinc when volume increased to about 45%, at room temperature strength continues to increase. If further increase the volume of zinc, as Alloy has emerged in the greater fragility of the r (Cu5Zn8 compounds, as the solid solution), the drastic reduction in strength. (Α + β) at room temperature plastic brass were always with the increase in zinc and lower. So zinc in excess of 45% of the copper-zinc alloy no practical value.
2. Special brass fitting
In order to improve the corrosion resistance of brass fitting, strength, hardness and cutting, etc., in the copper - add a small amount of zinc alloy (usually 1% to 2%, the minority of 3% to 4%, and certain individuals of 5% to 6 %) tin, aluminum, manganese, iron, silicon, nickel, lead, elements of a ternary, four or even five yuan alloy, which is complicated brass, also known as special brass.
(1) Zn equivalent coefficient brass complex organizations, according to add elements of brass "zinc equivalent coefficient" to projections. Because in a small number of copper-zinc alloy joined other alloying elements, usually only the Cu-Zn state diagram in the α / (α + β) phase left or right movement. Therefore, the special brass, brass usually equivalent to the general increase or decrease in the zinc content of the organization. For example, in the Cu-Zn alloy by adding 1% after the silicon, which is equivalent to the Cu-Zn alloy 10 per cent increase in zinc alloy. So Silicon "zinc equivalent" to 10. Silicon "zinc equivalent coefficient of the" largest, Cu-Zn in the α / (α + β) phase boundary significant shift copper side, that is strongly reduced α phase. Nickel "zinc equivalent coefficient" is negative, that is, expansion of α-phase region.
(2) special brass in the performance of special brass α-and β-phase solid solution is diverse complex, the effect of strengthening its larger, and ordinary brass in the α and β phase is the simple solution of Cu-Zn, strengthening effect lower. Although zinc is equivalent multi-solid solution with the simple solution of the dual nature is not the same. Therefore, a small number of multi-alloy enhanced performance is to raise a way. Brass Fitting
(3) Several special deformation brass pressure on the organization and processing properties
Lead Brass: Brass do not dissolve in the actual lead, the state was free distribution of particles on the grain boundaries. Lead Brass α and their organizations (α + β) two. Α leaded brass because of the harmful effects of lead greater low temperature plastic, it can only cold deformation or hot extrusion. (Α + β) Lead Brass has good high temperature plastic, can be forged.
Tin brass: adding tin brass, and can significantly increase the heat-resistant alloys, especially to raise the capacity of seawater corrosion resistance, the tin brass "Navy brass," said.
Tin can into copper-based solid solution, from the solid solution strengthening effect. But with the increase of tin alloy appears in the brittleness of the r (CuZnSn compounds), to the detriment of alloy plastic deformation, the tin containing tin brass of the general 0.5% to 1.5% range.
Commonly used tin brass have HSn70-1, HSn62-1, HSn60-1. The former is α alloy, high plasticity, can be cold and hot pressure processing. After the two brands of alloy with (α + β), the two organizations, and often appeared with a small r, not high temperature plastic, the only state in the thermal deformation.
Brass Manganese: Manganese in solid brass in the greater solubility. Brass by adding 1% to 4% of the manganese, can significantly increase the strength and corrosion resistance of the alloy, without reducing its plasticity.
Manganese brass with (α + β), a commonly used HMn58-2, cold, hot under the pressure of processing performance is quite good.
Rail Brass: Brass Rail, Rail to iron-rich phases of particulate precipitation, as a nucleus and the grain refinement, and can stop recrystallization grain growth, thereby enhancing the mechanical properties of alloy technology and performance. Brass Rail in the iron content is usually at 1.5% below their organizations (α + β), a high strength and toughness, good high temperature plastic, may also cold deformation. Popular brands for Hfe59-1 - 1.
Nickel Brass: nickel and copper to form continuous solid solution, a significant expansion α phase. Brass adding nickel brass can be significantly enhanced in the atmosphere and seawater corrosion resistance. Brass Nickel also enhance the re-crystallization temperature, and to develop more small grains.
HNi65 nickel brass-5 with single phase α organizations, has good room temperature plastic, but also in the thermal deformation, but the lead content of impurities must be strictly controlled, and whether the system will be a serious deterioration alloy thermal processing performance.
China first began using brass Zhu Jian Ming Jiajingnianjian. "Brass" first appeared with respect to the Western Han Dongfang Shuo ((() Shen vary by Arakawa in the ":" Palace northwest, the brass wall, and that of the imperial palace to. "This" brass "refers to the copper alloy, Daikao." Xintangshu-food goods "are 'bronze," "Brass" description refers to the respective colors and smelting ore products, is not now the copper-tin alloy and copper Zinc alloy. consultative Hung Song Kui essays "Daye Fu," another "for its brass also, there is not a pit, hilly Public Park," referring to the refining fire of the copper. term Brass refers specifically copper-zinc alloy, began in the Ming Dynasty, and its records found "that will be Code": "Jiajing in the cases, Tongbao money 6000000, and that the sharing of the burden of two fire brass 47,272……. "Based on the analysis of the Ming Dynasty coins ingredients found" that will be Code, "said Zhu Jian real sense of the kind of brass than the emergence of several other copper alloy night many, it is because the brass was in the metal zinc comparison difficulties. zinc oxide in a 1000 ℃ 950 ℃ temperature can be quickly be restored as zinc, and in liquid zinc at 906 ℃ already boiling, so the reduction of zinc metal steam-existence. cooling in response to downturn Steam zinc furnace oxidation to carbon dioxide into zinc oxide, zinc metal to be the condensation must have a special device, which is the use of zinc metal than copper, lead, tin, iron use much later the reason for brass Coining one of the reasons why there late, but in Jiangzhai Yangshao culture sites have been unearthed in a zinc in excess of 20 per cent of the brass-and yellow brass, plastic County, Shandong Sanlihe Longshan Culture in the strata have unearthed two kind of brass cone. Clearly, the emergence of these artifacts brass is not to say that people in the hands of the brass prehistoric smelting technology, but people in the use of Cu-Zn mine at the symbiotic inadvertently obtained. Shang and Zhou dynasties Bronze the volume of zinc are low, usually in the 10 - z order of magnitude. Han dynasty, Xinmang money in the plate of individual Cu-Zn Gan money, and some of the content of zinc in the coin of 7 per cent, but this could not explain the brass and Zhu Jian arising from the Western Han Dynasty Xinmang time because these copper-zinc alloy is very isolated phenomenon, zinc and generally more of the true meaning of brass zinc 15% to 40% of a much smaller, so we think that these zinc is the coins in the Han Dynasty, "Hill Zhuqian that" the use of copper-zinc ore at the symbiotic. According to a survey of the mine found Shandong Changwei, Yantai, Linyi and Hubei, and other places have rich resources of copper Symbiosis zinc mine, which makes the smelting of copper containing a small portion of zinc. to the Tang Dynasty, Zhu Jian materials standardization, Suozhu trip to the coin of the content of zinc are constant.