Brass is an alloy of copper and zinc, so named for its yellow color. The melting point of brass containing 62% ~ 68% COPPER IS 934 ~ 967 °C. Brass that consists of only copper and zinc is called brass. A variety of alloys consisting of more than two elements is called special brass. Such as lead, tin, manganese, nickel, lead, iron, silicon composed of copper alloy. Brass has strong wear resistance. Special brass is also called special brass, it is high strength, hardness, chemical corrosion resistance. There are also more prominent machining mechanical properties. Seamless copper tubes made of brass are soft and wear-resistant. Brass seamless tube can be used for heat exchanger and condenser, low temperature pipeline, submarine transportation pipe. Manufacture sheet, strip, bar, pipe, casting parts, etc. . Copper in 62% ~ 68% , strong plasticity, manufacture of pressure equipment.

Copper is copper simple substance, because of its color for the purple-red and named. Red Copper is industrial pure copper, its melting point is 1083 °C, no isomeric transformation, relative density is 8.9, five times of magnesium. It's about 15% heavier than normal steel. It has a rose red, oxide film formed on the surface of the purple, it is generally known as copper. It is copper containing a certain amount of oxygen, so it is also known as copper containing oxygen.

1.Welding method of brass

BRASS WELDING METHODS: Gas Welding, Carbon Arc welding, shielded metal arc welding and Argon arc welding.

(1)Gas Welding of brass

Because of the low temperature of gas welding flame, the evaporation of zinc in brass is less than that in electric welding, so gas welding is the most commonly used method in brass welding. Brass gas welding wire used: Wire 221, wire 222 and wire 224, these wire contains silicon, tin, iron and other elements, can prevent and reduce the pool of zinc evaporation and loss, in order to ensure the performance of the weld and prevent the formation of pores. There are two kinds of fluxes for gas welding brass: solid powder and gas fluxes, the gas fluxes consist of methyl borate and methanol, the fluxes such as gas flux 301.

(2)Brass shielded metal arc welding

In addition to copper 227 and copper 237 welding brass, you can also use homemade electrode. When brass arc welding, should adopt the direct current power source direct connection method, welding rod connection negative pole. The surface of welding parts should be carefully cleaned before welding. GROOVE angle should not be less than 60 ~ 70o in general, in order to improve the weld shape, welding parts to preheat 150 ~ 250 °C. Operation should be used short arc welding, no lateral and back swing, only for a straight line movement, high welding speed. After welding, it is necessary to anneal the brass welds which come into contact with seawater, ammonia and other corrosive medium to eliminate the welding stress.

(3)Manual Argon ARC welding of brass

STANDARD BRASS WIRE: Wire 221, wire 222 and wire 224 can be used for the manual argon arc welding of brass, or the same composition as the parent material can be used as filler material. Welding can be done with either direct current or alternating current. When AC welding is used, the evaporation of zinc is lighter than that of direct current welding. Usually do not preheat before welding, only the plate thickness difference is relatively large before preheating. The welding speed should be as fast as possible. After welding, the welding parts should be heated 300 ~ 400 °C for annealing treatment to eliminate the welding stress, in order to prevent welding parts in the use of the process of cracking.

(4)BRASS CARBON ARC welding

In brass carbon arc welding, wire 221, wire 222 and wire 224 are selected according to the composition of base metal, and self-made brass welding wire can also be used. Gas Flux 301 can be used as flux for welding. Welding should be short arc operation to reduce the evaporation and burning of zinc.

2.Welding method of Red Copper

Methods of welding Red Copper (commonly known as industrial copper) include gas welding, Manual Carbon Arc welding, shielded metal arc welding welding and Manual Argon arc welding, and automatic welding for large structures.

(1) Gas Welding of copper

Butt joints are the most commonly used welding copper, lap joints and t-joints as little as possible. Gas Welding can use two kinds of welding wire, one is containing deoxidization elements, such as wire 201,202; the other is the general copper wire and the base metal of the cut, using gas flux 301 as flux. Neutral flame should be used for gas welding of Red Copper.

(2) SHIELDED METAL ARC welding

In the case of shielded metal arc welding, copper 107 with a red copper core (T2, T3) is used. Clean the edges of the weld before welding. When the thickness of the welding piece is more than 4 mm, the preheating temperature should be about 400 ~ 500 °C before welding. With copper 107 electrode welding, power supply should be used DC reverse connection. When welding, short arc should be used, and the electrode should not swing laterally. The welding rod moves back and forth in a straight line, which can improve the weld shape. Step back welding method should be used for long weld. The welding speed should be as fast as possible. During multi-layer welding, the slag between layers must be completely removed. Welding should be carried out in a well-ventilated place to prevent copper poisoning. After welding, the flat head hammer should be used to strike the weld to eliminate the stress and improve the weld quality.

(3)Manual Argon ARC welding of copper

In the MANUAL ARGON ARC welding of Red Copper, wire 201(special red copper wire) and wire 202 are used, as well as red copper wire, such as T2. Before welding, it should clean up the oxide film, Oil and other dirt on the welding edge and wire surface to avoid the defects such as blowhole and slag inclusion. The methods of cleaning include mechanical cleaning and chemical cleaning. When the thickness of the butt joint plate is less than 3 mm, no groove shall be opened; when the thickness of the plate is 3 ~ 10 mm, Open v Groove, the angle of the GROOVE shall be 60 ~ 70o; when the thickness of the plate is more than 10 mm, open x Groove, the angle of the groove shall be 60 ~ 70o; in order to avoid incomplete welding, generally no blunt edge shall be left. According to the thickness of the plate and the size of the Groove, the assembly clearance of the butt joint is selected in the range of 0.5 ~ 1.5 mm. MANUAL ARGON ARC welding of Red Copper is usually done with direct current connection, I. E. Tungsten Connection with negative electrode. In order to eliminate the porosity and guarantee the reliable fusion and Penetration of the weld root, it is necessary to improve the welding speed, reduce the Argon consumption and preheat the welding parts. When the plate thickness is less than 3 mm, the preheating temperature is 150 ~ 300 °C, and when the plate thickness is more than 3 mm, the preheating temperature is 350 ~ 500 °C. The preheating temperature should not be too high, otherwise the mechanical properties of the welded joint will be reduced. There are also copper carbon arc welding, carbon arc welding electrodes used carbon fine electrode and graphite electrode. Red Copper Carbon Arc welding wire and gas welding when the same, but also can use the base bar, can be used gas welding flux of red copper, such as gas flux 301.

Source: Welding and Cutting Union

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