Welding of copper

The methods of welding red copper (that is, the so-called industrial pure copper) 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 the most commonly used for welding copper, and lap joints and T-joints are used as little as possible. Gas welding can use two kinds of welding wires, one is the welding wire containing deoxidizing elements, such as wire 201, 202; the other is the general copper wire and the cut strip of the base metal, using the gas agent 301 as the flux. Neutral flame should be used when gas welding red 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). Weld edges should be cleaned before welding. When the thickness of the weldment is greater than 4 mm, it must be preheated before welding, and the preheating temperature is generally around 400~500 °C. For welding with copper 107 electrode, the power supply should be reversed by DC.

A short arc should be used during welding, and the electrode should not swing laterally. The reciprocating linear motion of the electrode can improve the formation of the weld. For long welds, a gradual de-welding method should be used. The welding speed should be as fast as possible. When 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, use a flat hammer to strike the weld to relieve stress and improve the quality of the weld.

3. Manual argon arc welding of red copper

In the manual argon arc welding of red copper, the wires used are wire 201 (special copper wire) and wire 202, and copper wire, such as T2, is also used.

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 inclusions. The cleaning methods include mechanical cleaning and chemical cleaning.

When the plate thickness of the butt joint is less than 3 mm, the groove shall not be opened; when the plate thickness is 3-10 mm, the V-shaped groove shall be opened, and the groove angle shall be 60-70; when the plate thickness is greater than 10 mm, the X-shaped groove shall be opened, The groove angle is 60~70; in order to avoid incomplete penetration, generally do not leave blunt edges. According to the thickness of the plate and the size of the groove, the assembly clearance of the butt joint is selected within the range of 0.5 to 1.5 mm.

Manual argon arc welding of red copper usually adopts DC positive connection, that is, the tungsten electrode is connected to the 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 the consumption of argon gas, and preheat the weldment. When the plate thickness is less than 3 mm, the preheating temperature is 150~300 °C; when the plate thickness is greater 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 carbon arc welding of copper, and the electrodes used in carbon arc welding include carbon electrodes and graphite electrodes. The welding wire used in carbon arc welding of red copper is the same as that used in gas welding, and the base metal can also be used to cut strips.

Welding of Brass

Brass welding methods are: gas welding, carbon arc welding, manual arc welding and argon arc welding.

1. Brass gas welding

Due to the low temperature of the gas welding flame, the evaporation of zinc in the brass during welding is less than that of electric welding, so gas welding is the most commonly used method in brass welding (thank you for your attention to Dingding automatic welding).

The welding wires used in brass gas welding are: wire 221, wire 222 and wire 224, etc. These welding wires contain elements such as silicon, tin, iron, etc., which can prevent and reduce the evaporation and burning of zinc in the molten pool, which is beneficial to ensure the welding seam. performance and prevent porosity. The commonly used fluxes for gas welding of brass are solid powder and gas flux. The gas flux consists of methyl borate and methanol; the flux such as gas flux 301.

2. Manual arc welding of brass

In addition to copper 227 and copper 237 for welding brass, self-made electrodes can also be used.

When brass arc welding, the positive connection method of the DC power supply should be used, and the electrode should be connected to the negative electrode. The surface of the weldment should be carefully cleaned before welding. The groove angle should generally not be less than 60~70º. In order to improve the weld formation, the weldment should be preheated at 150~250℃. During operation, short arc welding should be used, no lateral and forward and backward swings, only linear movement, and the welding speed should 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 wires: wire 221, wire 222 and wire 224, or use the same composition as the base metal as the filler material.

Welding can be done with direct current or alternating current. When welding with AC, the evaporation of zinc is lighter than when welding with DC. Usually, there is no need to preheat before welding, and it is only preheated when the difference in plate thickness is relatively large. Welding speed should be as fast as possible. After welding, the weldment should be heated at 300~400℃ for annealing treatment to eliminate 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 the self-made brass welding wire can also be used for welding. Welding can use gas agent 301 as flux. Welding should be performed with a short arc to reduce zinc evaporation and burnout.