Summary of welding methods for brass and copper

【Summary Description】 Brass and copper are widely used in life and production, so what are their differences and their respective welding methods? First of all, let's talk about the difference between brass and copper. Brass is an alloy of copper and zinc, named for its yellow color. Brass with a copper content of 62% to 68% has a melting point of 934 to 967 degrees. If only composed of copper, zinc brass is called ordinary brass. If it is composed of more than two kinds of elements of a variety of alloys called special brass. Such as copper alloy composed of lead, tin, manganese, nickel, lead, iron, silicon. Brass has strong wear resistance. Special brass is also called special brass. It has high strength, high hardness and strong chemical resistance. And the mechanical properties of cutting processing is also more prominent. Seamless copper tube made of brass, soft and strong wear resistance. Brass seamless tubes can be used for heat exchangers and condensers, cryogenic pipelines, and subsea transportation pipes. Manufacture of sheet metal, bars, bars, pipes, cast parts, etc. Copper in 62% ~ 68%, strong plasticity, manufacturing pressure-resistant equipment, etc. Copper is copper simple substance, because of its color is purple red and named. Copper is industrial pure copper, its melting point is 1083 ℃, no isomeric transition, the relative density is 8.9, five times that of magnesium. It is about 15% heavier than ordinary steel. It has a rose red, purple after the formation of oxide film on the surface, so it is generally called copper. It is copper containing a certain amount of oxygen, so it is also called copper containing oxygen. Brass welding method Brass welding methods are: gas welding, carbon arc welding, manual arc welding and argon arc welding. 1. Gas welding of brass Due to the low temperature of the gas welding flame, the evaporation of zinc in brass during welding is less than that during electric welding, so gas welding is the most commonly used method in brass welding. The welding wire used in brass gas welding are: wire 221, wire 222 and wire 224, etc. These welding wires contain silicon, tin, iron and other elements, which can prevent and reduce the evaporation and burning of zinc in the molten pool, which is conducive to ensuring the performance of the weld and preventing pores. Gas welding brass commonly used flux of solid powder and gas flux, gas flux by boric acid methyl ester and methanol composition; flux such as gas agent 301. 2. Manual arc welding of brass In addition to copper 227 and copper 237, self-made welding rods can also be used for welding brass. When brass arc welding, DC power source should be used for positive connection, and the electrode should be connected to the negative electrode. The surface of the weldment shall be cleaned carefully before welding. Generally, the groove angle should not be less than 60 ~ 70o. In order to improve the weld formation, the weldment should be preheated at 150~250 ℃. Short arc welding should be used during operation, not for horizontal and back and forth swing, only for linear movement, welding speed to be high. Brass weldments in contact with corrosive media such as seawater and ammonia must be annealed after welding to eliminate welding stress. 3. Manual argon arc welding of brass Brass manual argon arc welding can use standard brass welding wire: wire 221, wire 222 and wire 224, or materials with the same composition as the base metal as filling materials. Welding can be connected with DC or AC. When welding with AC, the evaporation of zinc is lighter than when DC is connected. Usually do not have to preheat before welding, only plate thickness difference is relatively large before preheating. The welding speed should be as fast as possible. After welding, the weldment should be heated to 300~400 ℃ for annealing treatment to eliminate the welding stress and prevent the weldment from cracking during use. 4. Brass carbon arc welding When brass carbon arc welding, wire 221, wire 222, wire 224 and other welding wires are selected according to the composition of the base metal, and self-made brass welding wires can also be used for welding. Welding can use gas 301, etc. as a flux. Welding should be short arc operation to reduce zinc evaporation and burning loss. red copper welding method Welding copper (commonly known as industrial pure copper) methods include gas welding, manual carbon arc welding, manual arc welding and manual argon arc welding, and automatic welding can also be used for large structures. 1. Gas welding of copper Butt joints are most commonly used for welding copper, and lap joints and T-joints are used as little as possible. Two kinds of welding wires can be used for gas welding, one is the welding wire containing deoxidizing elements, such as wire 201 and 202, and the other is the general copper wire and the cutting strip of the base metal, using the gas agent 301 as the flux. Neutral flame shall be used for gas welding of copper. 2. Manual arc welding of copper In manual arc welding, red copper electrode copper 107 is used, and the welding core is red copper (T2, T3). The edge of the welding place shall be cleaned before welding. When the thickness of the weldment is greater than 4mm, it must be preheated before welding, and the preheating temperature is generally about 400~500 ℃. With copper 107 electrode welding, the power supply should be DC reverse connection. When welding, short arc should be used, and the welding rod should not be swung laterally. The reciprocating linear motion of the welding rod can improve the forming of the weld. Long welds shall be welded by step-back method. The welding speed should be as fast as possible. During multi-layer welding, the slag between the layers must be completely removed. Welding should be carried out in a well-ventilated place to prevent copper poisoning. After welding, flat head hammer should be used to knock the weld to eliminate stress and improve the quality of the weld. 3. Manual argon arc welding of copper When red copper manual argon arc welding, the welding wire used is wire 201 (special red copper welding wire) and wire 202, and red copper wire, such as T2. Before welding, the oxide film, oil and other dirt on the welding edge of the workpiece and the surface of the welding wire must be cleaned to avoid defects such as pores and slag inclusion. Cleaning methods are mechanical cleaning and chemical cleaning method. When the thickness of the butt joint plate is less than 3mm, no groove is opened; When the plate thickness is 3~10mm, open a V-shaped groove with a groove angle of 60 ~ 70o; When the plate thickness is more than 10mm, open an X-shaped groove with a groove angle of 60 ~ 70o; In order to avoid incomplete welding, generally no blunt edge is left. According to the plate thickness and groove size, the assembly clearance of the butt joint is selected in the range of 0.5~1.5mm. Manual argon arc welding of red copper usually adopts DC positive connection, I .e. tungsten electrode is connected to negative electrode. In order to eliminate pores and ensure reliable fusion and penetration at the root of the weld, it is necessary to increase the welding speed, reduce argon consumption, and preheat the weldment. When the plate thickness is less than 3mm, the preheating temperature is 150~300 ℃; when the plate thickness is greater than 3mm, the preheating temperature is 350~500 ℃. The preheating temperature should not be too high, otherwise the mechanical properties of the welded joint will be reduced. There is also carbon arc welding of copper. The electrodes used in carbon arc welding are carbon electrodes and graphite electrodes. The welding wire used for carbon arc welding of red copper is the same as that used for gas welding. It can also be cut from the base metal and flux used for gas welding of red copper, such as gas 301, etc.

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