Common brass welding methods, gas welding, carbon arc welding, manual arc welding and argon arc welding

【Summary Description】 Brass welding methods include gas welding, carbon arc welding, manual arc welding and argon arc welding. (1) Brass gas welding Due to the low flame temperature of gas welding, 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 wires for brass gas welding are No. 221, No. 222, No. 224, etc. These wires contain silicon, tin, iron and other elements, which can prevent and reduce the evaporation and burning of zinc in the molten pool, help to ensure the performance of the weld and prevent the generation of pores. The commonly used flux for welding gas brass is solid powder and gas flux, and the gas flux is composed of methyl borate and methanol. For example, flux 301. (2) Brass manual arc welding In addition to copper 227 and copper 237, homemade welding rods can also be used for brass welding. When brass arc welding, the DC power supply should be connected to the positive pole and the electrode should be connected to the negative pole. Before welding, the surface of the weldment shall be carefully cleaned. In general, the groove angle should not be less than 60 °-70 °. In order to improve the weld formation, the weldment should be preheated 150-250 ℃. The operation should be short arc welding, no horizontal and back and forth swing, only linear motion, 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: No. 221, No. 222, No. 224, or use the same material as the base metal as the filling material. DC connection or AC connection can be used for welding. When AC welding is used, the evaporation of zinc is lighter than when DC welding is used. Usually do not need to preheat before welding, only when the thickness difference is large. The welding speed should be as fast as possible. After welding, the weldment should be heated to 300-400 ℃ for annealing treatment to eliminate welding stress and prevent the weldment from cracking during use. (4) Brass Carbon Arc Welding In the carbon arc welding process of brass, welding wire 221, welding wire 222, welding wire 224, etc. Depending on the composition of the base material, it is also possible to use a self-made brass wire for welding. A gas reagent 301 or the like may be used as a flux for soldering. Short arc welding should be used to reduce zinc evaporation and burning. DC TIG welding process is widely used in the welding of copper and copper alloys. Welding wind forming good, good quality inside and outside. Under the protection of argon, the molten pool is pure, the pores are few, the thermal cracking effect is small, and it is easy to operate. When the thickness is less than or equal to 4mm, preheating before welding is not required and can be directly preheated with argon. When the temperature of the molten pool is close to 600 ℃, filler wire can be added to melt the base metal to realize welding. For copper with a thickness of more than 4mm, pure copper should be preheated at 400-600 ℃. The copper alloy is preheated by welding at 200-300 ℃. 300TSP, 315TX DC TIG welding machine can weld pure copper, silicon bronze, phosphor bronze, brass, cupronickel and other copper alloys. The 300WP5 and 300/500WX4 AC/DC TIG welding machines can use AC TIG to weld aluminum bronze (use AC square wave to remove surface oxide film), and DC TIG to weld the above copper. In recent years, MIG welding of copper and copper alloys has become more and more popular, especially aluminum bronze, silicon bronze and cupronickel with a thickness of ≥ 3mm. MIG welding is almost always used for copper and copper alloys with a thickness of 3~14mm and above because of its high deposition efficiency, large penetration depth and fast welding speed (usually 3~4 times that of TIG welding), which meets the requirements of high efficiency, high quality and low cost. Before welding, all copper materials shall meet the requirements of preheating temperature (pure copper 400~600 ℃, copper alloy 200~300 ℃). The chemical composition of the welding wire is completely similar to that of the base metal, and the purity of argon is ≥ 99.98%.

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