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  • Brass rod

    Brass rod


    The earliest use time Ming Jiajing years, thickness 1.0-200mm; width 305-600mm; classification hot forging, cold forging, global brass rod


    The word "brass" was first seen in the "Shen Yi Jing· Zhong Ye Jing" written by the Western Han Dynasty. "There is a palace in the northwest, a wall of brass, and a palace of the Emperor." This "brass" refers to What kind of copper alloy is to be tested. "New Tang Book · Food and Food" has the title of "bronze" and "brass", which refer to the color of ore and smelting products respectively, not the current copper-tin alloy and copper-zinc alloy. Song Renhong consulted "Da Ye Fu" There is also "there is brass, the pit has a name, the mountain is more and more simple", referring to the pure copper refined by the fire method. The term brass refers to the copper-zinc alloy, which began in the Ming Dynasty and its record is found in "Ming Hui Dian": "Jiajingzhong is an example, Tongbao money six million texts, combined with two fire brass forty-seven thousand two hundred and seventy-two pounds.... Through the analysis of the composition of the copper coins of the Ming Dynasty, it is found that the true meaning of brass in the Ming Dynasty is more late than other copper alloys. This is because the comparison of metal zinc in brass is compared. Difficulty. Zinc oxide can be reduced to metal zinc quickly at a high temperature of 950 ° C to 1000 ° C, and liquid zinc has already boiled at 906 ° C, so the metal zinc obtained by reduction exists in the form of a vapor. Vapor zinc is reoxidized to carbon dioxide in the furnace, so a special condensing device is required to obtain metal zinc. This is the reason why the use of metallic zinc is much later than the use of copper, lead, tin and iron. One of the reasons for the late emergence of coinage. However, in the Jiangzhao Yangshao cultural site, there were unearthed brass and brass tubes containing more than 20% zinc. Two layers of the Sanlihe culture in the Jiaoli County of Shandong Province were also unearthed. Brass cones. Obviously, the appearance of these brass objects does not mean that people mastered the smelting technology of brass before the prehistoric times, but people inadvertently obtained the use of copper-zinc symbiotic mines. The copper content of the copper is very low, generally in the order of 10-z. There are individual copper and zinc coins in the money of the Western Han Dynasty and Xinyi, and some of the coins have a zinc content of 7%, but this does not explain Brass coins are produced on the occasion of the new Han Dynasty. Because these copper-zinc alloys are extremely rare, their zinc content is generally much smaller than the true zinc content of brass by 15% to 40%. So we It is believed that these zinc-containing copper coins were produced when the copper and zinc symbiotic mines were used in the “Yishan Casting Money” in the Han Dynasty. According to investigations on the mines, Shandong’s Changyi, Yantai, Linyi and Hubei provinces are rich in resources. The copper-zinc symbiotic ore, which makes the smelted copper contain a small part of zinc. In the Tang Dynasty, due to the standardization of the money-making materials, the zinc content in the coins cast was constant.


    Introduction to brass


    Material: H59, H63, H65, H68, H70, H80, H85, H90, H96, T1, T2, C1100, C5111, C5101, C5191, C5210, TU1, TP1, TP2, TAg0.08, TAg0.1, C1100, C1020, C1201, C1220, C1271, C2100, C2200, C2300, C2400, C2600, C2680, C2700, C2720, C2800, C2801, C3600, C3602, C3603, C3604, and the like. Specifications: thickness: 1.0-200mm, width: 305-600mm. Hardness: O, 1/2H, 3/4H, H, EH, SH, and the like.


    Brass classification


    A brass material is called a special brass if it is a plurality of alloys composed of two or more elements. Such as copper alloy composed of lead, tin, manganese, nickel, iron, silicon. Brass has strong wear resistance. Special brass is also called special brass, which has high strength, high hardness and strong chemical resistance. Also, the mechanical properties of the cutting process are also prominent. The seamless copper tube drawn from brass is soft and wear resistant. Brass seamless tubes are available for heat exchangers and condensers, cryogenic piping, and subsea transportation pipes. Manufacture of sheet, strip, bar, pipe, cast parts, etc. Containing copper in 62% to 68%, strong plasticity, manufacturing pressure-resistant equipment.


    Brass rods are classified into ordinary brass and special brass depending on the type of alloying elements contained in the brass. Brass for press working is called deformed brass.


    Brass characteristics


    Brass is an alloy of copper and zinc. The simplest brass is a copper-zinc binary alloy called simple brass or plain brass. Brass with different mechanical properties can be obtained by changing the zinc content of the brass. The higher the content of zinc in brass, the higher the strength and the lower the plasticity. The brass used in the industry does not contain more than 45% zinc. If the zinc content is high, brittleness will occur and the properties of the alloy will deteriorate. In order to improve the performance of brass, brass with other alloying elements added to the one-piece brass is called special brass. Commonly used alloying elements are silicon, aluminum, tin, lead, manganese, iron and nickel. Adding aluminum to brass improves the yield strength and corrosion resistance of brass and slightly reduces plasticity. Brass containing less than 4% aluminum has good properties such as processing and casting. Adding 1% tin to brass can significantly improve the resistance of brass to seawater and marine atmospheric corrosion, hence the name "Naval Brass". Tin also improves the machinability of brass. The main purpose of brass lead is to improve machinability and improve wear resistance. Lead has little effect on the strength of brass. Manganese brass has good mechanical properties, thermal stability and corrosion resistance; adding aluminum to manganese brass can also improve its performance and obtain a smooth surface casting. Brass can be divided into casting and pressure processing.


    Principle of brass rod manufacturing


    (1) All elements reduce the electrical conductivity and thermal conductivity of the copper rod without exception. Any element is dissolved in the copper rod, causing the lattice distortion of the copper rod, causing wave scattering when the free electrons are directed to flow, so that the resistance The rate increases, on the contrary, there is no solid solubility or little solid solution in the copper rod, which has little effect on the conduction and heat conduction of the copper rod. It should be noted that the solid solubility of some elements in the copper rod decreases with temperature. It is drastically reduced, and the precipitation of elemental and metal compounds can not only solidify and disperse the strengthened copper rod alloy, but also reduce the electrical conductivity. This is an important alloying principle for the study of high-strength and high-conductivity alloys. It is pointed out that the alloy consisting of four elements of iron, silicon, silicon and silicon and copper rod is an extremely important high-strength and high-conductivity alloy; the influence of alloying elements on the performance of copper rods is superimposed, and the CoCr-Zr-based alloy is famous for its high strength and high strength. Guide alloy


    (2) The structure of the copper-based corrosion-resistant alloy should be single-phase, avoiding the occurrence of electrochemical corrosion in the second phase of the alloy. For this reason, the alloying elements should have a large solid solubility in the copper rods, even the infinitely miscible elements, and have excellent corrosion resistance in single-phase brass rods, bronze rods and white copper rods for engineering applications. , is an important heat exchange material.


    (3) There are soft phase and hard phase in the copper-based wear-resistant alloy structure. Therefore, in the alloying, it must be ensured that the added elements should be solid-phase precipitated in addition to solid solution in the copper rod. Typical hard phases are Ni3Si, FeALSi compounds and the like. In the automotive synchronizer gear alloy developed in recent years, the phase a is soft phase, the negative phase is hard phase, and the phase a is not more than 10%.


    (4) Copper rod alloys with polycrystalline transformation in solid state have damping properties, such as Cu-Mn alloys, and alloys with thermoelastic martensitic transformation in solid state have memory properties, such as Cu-Zn-Al, Cu-Al Mn alloy.


    (5) The color of the copper rod can be changed by adding alloying elements, such as adding zinc, aluminum, tin, nickel and other elements. As the content changes, the color also changes red, green, yellow and white. The ground control content will result in imitation gold material and imitation silver alloy.


    (6) The alloying elements of copper rods and alloys should be commonly used, cheap and non-polluting. The added elements should be based on the principle of multiple small amounts. The alloy raw materials can be comprehensively utilized. The alloy should have excellent process properties. Processed into a variety of finished and semi-finished products.


    chemical composition


    Purity measurement


    The purity of the measured brass can be measured by the Archimedes principle, the volume and mass of the sample are measured, and the ratio of copper contained in the brass can be calculated from the density of copper and the density of zinc.


    Ordinary brass


    It is an alloy of copper and zinc. When the zinc content is less than 39%, zinc can be dissolved in copper to form a single phase a, called single-phase brass, which has good plasticity and is suitable for cold and hot press processing. When the zinc content is more than 39%, there is a single phase and a copper-zinc-based b solid solution, called duplex brass, b makes plasticity small and tensile strength rises, and is only suitable for hot pressure processing if it continues to increase zinc. The mass fraction, the tensile strength decreases, the no-use code is expressed by "H + number", H is brass, and the number represents the mass fraction of copper. For example, H68 means copper with a copper content of 68% and a zinc content of 32%. For cast brass, the word "Z" is used before the code name. For example, ZH62 such as Zcuzn38 means that the zinc content is 38% and the balance is copper. Cast brass. H90, H80 single phase, golden yellow, so there is a total of gold, called plating, decorations, medals and so on. H68 and H59 are duplex brass and are widely used in structural parts such as bolts, nuts, washers, springs, etc. In general, duplex stainless steel for cold deformation processing uses duplex stainless steel for hot deformation processing.


    Special brass


    A multi-component alloy consisting of other alloying elements added to ordinary brass is called brass. Commonly added elements are lead, tin, aluminum, etc., which may be referred to as lead brass, tin brass, aluminum brass. The purpose of adding alloying elements. Mainly to improve the tensile strength and improve the processability. Code: “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 with main additive element is 1%, and the balance is lead brass of zinc.


    Lead-free free-cutting brass rod


    Therefore, its content shall not be greater than 0.00002010. Elements such as antimony, bismuth, and sulfur are extremely harmful to other copper alloys, and must be strictly controlled during production to prevent the mixing of raw materials, used materials, furnace lining materials, and auxiliary tools. Because of its high electrical conductivity, it can prevent the switch from sticking, improve its working period and ensure safe operation. 7%~1.0% Bi. The copper switch contact copper may contain 0. 7%~1.0% Bi. Generally used in quenching and processing conditions, no need to temper, so as not to precipitate Cu2 Te along the grain boundary, making the material brittle. . Copper containing 0.06% to 0.7% Te has been practically used in the industry. The alloying elements such as Bi and Te have similar characteristics and forms in copper. They are basically insoluble in copper, and exist in the grain boundary with free particles. They are dispersed and distributed in the copper matrix by post-processing, which acts as lubrication and friction reducing. Make the alloy chips brittle and easy to discharge, and ensure the surface of the product is smooth. In some special applications, such as high-conductivity electrical contacts, high-copper alloy series are used. In terms of processing performance, the processing functions of such alloys are not very good, especially for high-copper alloys, the composition control and processing functions are not easy to guarantee, and in lead-free free-cutting brass rods, zinc is added. The solubility is increased to some extent, and the composition is not disordered and the processing function is improved. Trace (0. 003 010) selenium and tellurium (0.00050/0 to 0.003%) significantly reduce the weldability of the copper rod. Lead-free free-cutting brass rods are replacements for free-cutting lead-brass rods. Because lead is a hazard to humans, lead-free, free-cutting brass rods are replaced by non-toxic third alloying elements, which have been developed. Lead-free brass alloy systems include: Cu-Zn-Bi, Cu-Zn-Te, Cu-Zn-Bi-Te, and high-copper alloys such as Cu-Bi, Cu-Te, Cu-C, and Cu-S. There is also some research on the system, but due to factors such as processability, machinability and cost performance, Cu-Zn-Bi lead-free free-cutting brass rods are mainly used. The solubility of bismuth in solid copper is very small. The presence of Cu2 Te diffused particles has little effect on the electrical conductivity and thermal conductivity of copper, but it can significantly improve the cutting performance of copper. forms a eutectic with copper at 270 ° C, in which ruthenium is distributed in the copper grain boundary, which severely reduces the processing power of copper. 01%。 


    Ordinary 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 binary state diagram of Cu-Zn (Fig. 6), there are three kinds of room temperature microstructure of brass: brass with a zinc content of less than 35%. The microstructure at room temperature consists of a single-phase α solid solution called α yellow. Copper; brass with a zinc content ranging from 36% to 46%, the microstructure at room temperature consists of two phases (α + β), called (α + β) brass (two-phase brass); For brass with a zinc content of more than 46% to 50%, the microstructure at room temperature consists only of the beta phase, called beta brass.


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