The difference between brass and copper
Brass is an alloy of copper and zinc, named for its yellow color.
Brass containing 62% ~ 68% copper has a melting point of 934 ~ 967 degrees.
If only brass composed of copper and zinc is called ordinary brass.
If it is a variety of alloys composed of more than two elements, it is called special brass. Such as copper alloy composed of lead, tin, manganese, nickel, lead, iron and silicon.
Brass has strong wear resistance.
Special brass is also called special brass. It has high strength, high hardness and strong chemical corrosion resistance.
In addition, the mechanical properties of cutting are also prominent. The seamless copper pipe made of brass is soft and has strong wear resistance.
Brass seamless pipes can be used in heat exchangers and condensers, low-temperature pipelines and submarine transportation pipes.
Manufacturing sheet, bar, bar, pipe, casting parts, etc.
Copper content is 62% ~ 68%, strong plasticity, manufacturing pressure equipment, etc.
Red copper is a simple substance of copper, which is named because its color is purplish red.
Red copper is industrial pure copper. Its melting point is 1083 ℃, there is no isomeric transformation, and its relative density is 8.9, five times that of magnesium.
About 15% heavier than ordinary steel. It is rose red and purple after the formation of oxide film on the surface, so it is generally called red copper.
It is copper containing certain oxygen, so it is also called oxygen containing copper.
Brass welding method
Brass welding methods include: gas welding, carbon arc welding, manual arc welding and argon arc welding.
1. Gas welding of brass
Due to the low temperature of 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 wires used for Brass gas welding include wire 221, wire 222 and wire 224.
These welding wires contain elements such as silicon, tin and iron, which can prevent and reduce the evaporation and burning loss of zinc in the molten pool, and help to ensure the performance of the weld and prevent the generation of pores.
The flux commonly used in gas welding brass includes solid powder and gas flux.
The gas flux is composed of methyl borate and methanol; Flux such as gas agent 301.
2. Manual arc welding of brass
In addition to copper 227 and copper 237, self-made electrodes can also be used for welding brass. During brass arc welding, the positive connection method of DC power supply shall be adopted, and the electrode shall be connected to the negative electrode.
The surface of weldment shall be carefully cleaned before welding.
Generally, the groove angle shall not be less than 60 ~ 70O.
In order to improve the weld formation, the weldment shall be preheated at 150 ~ 250 ℃. During operation, short arc welding shall be used, without transverse and back and forth swing, but only linear movement, and the welding speed shall 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
Standard brass welding wires: wire 221, wire 222 and wire 224 can be used for Brass manual argon arc welding, or materials with the same composition as the base metal can be used as filling materials.
Welding can be DC positive connection or AC.
When AC welding is used, the evaporation of zinc is lighter than that when DC positive connection is used.
Generally, preheating is not required before welding. Preheating is only available when the plate thickness difference is relatively large.
The welding speed shall be as fast as possible.
After welding, the weldment shall be heated to 300 ~ 400 ℃ for annealing treatment to eliminate the welding stress and prevent cracks during use.
4. Brass carbon arc welding
During brass carbon arc welding, wires such as wire 221, wire 222 and wire 224 can be selected according to the composition of base metal, or self-made brass welding wire can be used for welding.
Gas flux 301 can be used as flux for welding.
Short arc welding shall be carried out to reduce evaporation and burning loss of zinc.
Red copper welding method
The methods of welding red copper (commonly known as industrial pure copper) include gas welding, manual carbon arc welding, manual electric arc welding and manual argon arc welding. Automatic welding can also be used for large structures.
1. Gas welding of red copper
Butt joints are the most commonly used for welding red copper, and lap joints and T-joints shall be 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 wires 201 and 202;
The other is the cutting strip of general copper wire and base metal, using gas agent 301 as flux. Neutral flame shall be used for gas welding of red copper.
2. Manual arc welding of red copper
In manual arc welding, red copper welding rod copper 107 is used, and the welding core is red copper (T2, T3).
Before welding, the edge of the welding joint shall be cleaned.
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 ℃.
Copper 107 electrode shall be used for welding, and DC reverse connection shall be adopted for power supply.
Short arc shall be used during welding, and the welding rod shall not swing laterally.
The welding rod makes reciprocating linear motion, which can improve the weld formation.
The step-by-step back welding method shall be adopted for long welds.
The welding speed should be as fast as possible.
During multi-layer welding, the slag between layers must be completely removed.
Welding shall be carried out in a well ventilated place to prevent copper poisoning.
After welding, flat hammer shall be used to knock the weld to eliminate stress and improve weld quality.
3. Manual argon arc welding of red copper
In the manual argon arc welding of red copper, the welding wires used include wire 201 (special red copper welding wire) and wire 202, as well as 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. The cleaning methods include mechanical cleaning method and chemical cleaning method.
When the thickness of butt joint plate is less than 3mm, no groove shall be made;
When the plate thickness is 3 ~ 10mm, V-groove shall be opened, and the groove angle is 60 ~ 70O;
When the plate thickness is greater than 10mm, open an x-groove with a groove angle of 60 ~ 70O;
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 shall be selected within the range of 0.5 ~ 1.5mm.
Manual argon arc welding of red copper usually adopts DC positive connection, that is, tungsten electrode is connected to negative electrode.
In order to eliminate pores and ensure reliable fusion and penetration of weld root, it is necessary to improve 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 are also carbon arc welding of red copper.
The electrodes used in carbon arc welding include carbon electrode and graphite electrode.
The welding wire used for carbon arc welding of red copper is the same as that used for gas welding.
The base metal can also be cut, and the flux for gas welding of red copper can be used, such as gas flux 301.