Welding of red copper:

The welding methods of red copper (commonly known as 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 red copper

Butt joint is commonly used for welding red copper, and lap joint and T-joint should be used less. 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; the other is the common copper wire and base metal cutting, using gas flux 301 as flux. Neutral flame should be used in gas welding of red copper.

2. Manual arc welding of red copper

In manual arc welding, copper 107 is used as welding rod and red copper (T2, T3) is used as welding core. Before welding, the edge of the weld shall be cleaned. When the thickness of the weldment is greater than 4 mm, it must be preheated before welding, and the preheating temperature is generally about 400 ~ 500 ℃. Copper 107 welding rod is used for welding, and DC reverse connection shall be used for power supply.

Short arc should be used in welding, and welding rod should not swing horizontally. The welding rod can improve the weld forming by reciprocating linear movement. Step back welding method shall be adopted for long welds. The welding speed should be as fast as possible. In multi-layer welding, the slag between layers must be 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 knock the weld to relieve the stress and improve the quality of the weld.

3. Manual argon arc welding of red copper

In manual argon arc welding of red copper, wire 201 (special copper wire) and wire 202 are used, and red 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 the defects such as porosity and slag inclusion. The cleaning methods include mechanical cleaning and chemical cleaning.

When the thickness of butt joint plate is less than 3 mm, no groove shall be made; when the plate thickness is 3-10 mm, V-shaped groove shall be opened, and the angle of groove shall be 60-70?; when the plate thickness is greater than 10 mm, X-shaped groove shall be opened with the groove angle of 60-70?; in order to avoid incomplete penetration, blunt edges are generally not left. According to the plate thickness and groove size, the assembly clearance of butt joint is selected in the range of 0.5 ~ 1.5 mm.

In manual argon arc welding of red copper, DC positive connection is usually adopted, that is, tungsten electrode is connected with negative electrode. In order to eliminate blowholes and reliable fusion and penetration of weld root, it is necessary to increase welding speed, reduce argon consumption and preheat weldments. When the plate thickness is less than 3 mm, the preheating temperature is 150 ~ 300 ℃; when the plate thickness is greater than 3 mm, the preheating temperature is 350 ~ 500 ℃. The preheating temperature should not be too high, otherwise the mechanical properties of welded joints will be reduced.

There are carbon arc welding of red copper. Carbon arc welding uses carbon electrode and graphite electrode. The welding wire used for carbon arc welding of red copper is the same as that for gas welding. The base metal cutting strip can be used, and the flux for gas welding red copper, such as gas flux 301, can be used.

Brass welding method:

Methods are: gas welding, carbon arc welding, manual arc welding and argon arc welding.

1. Gas welding of brass

Because the temperature of gas welding flame is low, the evaporation of zinc in brass is less than that in electric welding, so gas welding is a common method in brass welding.

The welding wires used in brass gas welding include wire 221, wire 222 and wire 224. These welding wires contain silicon, tin, iron and other elements, which can prevent and reduce the evaporation and burning loss of zinc in the molten pool, which is conducive to the performance of the weld and the prevention of porosity. The commonly used fluxes for gas welding brass are solid powder and gas flux. The gas flux is composed of methyl borate and methanol; the flux is such as gas flux 301.

2. Manual arc welding of brass

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

In brass arc welding, the direct current power supply should be used, and the electrode should be connected to the negative electrode. The surface of weldment should be cleaned carefully before welding. Generally, the groove angle should not be less than 60 ~ 70. In order to improve the weld formation, the weldment should be preheated 150 ~ 250 ℃. During operation, short arc welding should be used instead of lateral and forward and backward swing, only linear movement should be made, and welding speed should be high. The brass weldments in contact with seawater, ammonia and other corrosive media must be annealed after welding to eliminate welding stress.

3. Manual argon arc welding of brass

Standard brass welding wires: wire 221, wire 222 and wire 224 can be used for manual argon arc welding of brass, and materials with the same composition as the base metal can be used as filling materials.

Welding can be done by direct current or alternating current. The evaporation of zinc in AC welding is lighter than that in DC welding. Generally, preheating is not necessary before welding, only when the plate thickness difference is large. The welding speed should be as fast as possible. After welding, the weldment should be annealed at 300 ~ 400 ℃ to eliminate the welding stress, so as to prevent the weldment from cracking during use.

4. Brass carbon arc welding

In the process of 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. Gas flux 301 can be used as flux in welding. Welding should be short arc operation to reduce zinc evaporation and burning loss.