Are you interested in learning about the different methods of welding brass and red copper? Look no further!
In this blog post, we will dive into the various techniques used to weld these two metals, including gas welding, manual arc welding, and argon arc welding.
We will also discuss the properties and characteristics of brass and red copper, as well as the best practices for welding them. Whether you’re a professional welder or just curious about the welding process, this article is a must-read for anyone interested in the world of metalworking.
So, grab a cup of coffee and let’s dive into the fascinating world of brass and red copper welding!
The difference between brass and copper
Brass is a yellow-colored alloy composed of copper and zinc. Ordinary brass is made up of only these two elements, while special brass is composed of more than two elements, such as lead, tin, manganese, nickel, iron, and silicon.
Brass with a copper content of 62% to 68% has a melting point ranging from 934 to 967 degrees. It is known for its strong wear resistance and good mechanical properties, making it suitable for use in the manufacturing of pressure equipment.
Special brass is also known for its high strength, hardness, and resistance to chemical corrosion. This makes it a popular choice for the production of seamless pipes, which can be used in applications such as heat exchangers, condensers, low-temperature pipelines, and submarine transportation pipes.
In addition to pipes, brass can also be used to manufacture sheet metal, bars, castings, and other products. With its strong plasticity and high copper content, brass is an ideal material for the manufacturing of pressure equipment.
Red copper is a type of copper that gets its name from its reddish-purple color. It is also known as industrial pure copper and is composed solely of copper.
Red copper has a melting point of 1083°C and does not undergo isomeric transformation. Its relative density is 8.9, which is five times greater than that of magnesium. It is also about 15% heavier than ordinary steel.
When an oxide film forms on its surface, red copper takes on a reddish-purple hue, which is why it is referred to as red copper. This copper also contains a certain amount of oxygen and is sometimes referred to as oxygen-containing copper.
Brass welding method
The methods for welding brass include gas welding, carbon arc welding, manual arc welding, and argon arc welding.
1. Gas welding of brass
Gas welding is the most widely used method in brass welding due to the low temperature of the gas welding flame, which reduces the evaporation of zinc in brass compared to electric welding methods.
The welding wires commonly used for brass gas welding are wire 221, wire 222, and wire 224. These wires contain elements such as silicon, tin, and iron, which help prevent and reduce the evaporation and burning loss of zinc during the welding process, ensuring the quality of the weld and preventing the formation of pores.
Two types of flux are commonly used in gas welding brass: solid powder and gas flux. The gas flux is made up of methyl borate and methanol, such as gas agent 301. This flux helps to improve the quality of the weld and prevent contamination.
2. Manual arc welding of brass
In addition to copper 227 and copper 237, self-made electrodes can also be used for brass welding. During brass arc welding, it is recommended to use a DC power supply with the positive electrode connected to the workpiece and the negative electrode connected to the electrode.
Before welding, it is important to thoroughly clean the surface of the workpiece. The groove angle should be between 60 to 70 degrees to ensure proper weld formation.
To improve the quality of the weld, the workpiece should be preheated to a temperature between 150 to 250°C. During welding, it is recommended to use a short arc and a linear movement without any transverse or back and forth swings. The welding speed should be high for best results.
It is important to note that brass weldments that come into contact with corrosive media, such as seawater and ammonia, should be annealed after welding to relieve any welding stress.
3. Manual argon arc welding of brass
Standard brass welding wires such as wire 221, wire 222, and wire 224 can be used for brass manual argon arc welding. Alternatively, filling materials with the same composition as the base metal can be used.
Both DC positive connection and AC welding can be used for this process. When using AC welding, the evaporation of zinc is less compared to when using DC positive connection.
In most cases, preheating is not necessary before welding. However, if there is a significant difference in plate thickness, preheating may be required.
It is recommended to weld as fast as possible to achieve optimal results. After welding, the weldment should be heated to a temperature between 300 to 400°C for annealing to relieve any welding stress and prevent cracks during use.
4. Brass carbon arc welding
For brass carbon arc welding, wire 221, wire 222, and wire 224 can be selected based on the composition of the base metal. Alternatively, self-made brass welding wire can also be used.
Gas flux 301 can be used as a flux during welding.
It is recommended to use short arc welding to minimize the evaporation and burning loss of zinc.
Red copper welding method
Red copper, also known as industrial pure copper, can be welded using various methods such as gas welding, manual carbon arc welding, manual electric arc welding, manual argon arc welding, and automatic welding for larger structures.
1. Gas welding of red copper
Butt joints are the preferred method for welding red copper, with lap joints and T-joints being used only as needed. There are two options for welding wires in gas welding: welding wires that contain deoxidizing elements, such as wires 201 and 202, or a combination of general copper wire and base metal, using gas agent 301 as flux. A neutral flame should be used during the gas welding of red copper.
2. Manual arc welding of red copper
If the thickness of the workpiece is greater than 4mm, preheating is necessary, with a temperature of approximately 400 to 500°C. The copper 107 electrode should be used for welding and a DC reverse connection power supply should be adopted.
During welding, a short arc should be used and the welding rod should not move laterally. A reciprocating linear motion of the welding rod can improve the formation of the weld. For long welds, the step-by-step back welding method should be used. The welding speed should be as fast as possible.
When welding multiple layers, it is important to remove any slag between the layers. Welding should be carried out in a well-ventilated area to prevent copper poisoning. After welding, the weld should be flattened using a hammer to relieve stress and improve the quality of the weld.
Related reading: How to Choose the Right Welding Rod?
3. Manual argon arc welding of red copper
In manual argon arc welding of red copper, welding wires such as wire 201 (special red copper welding wire), wire 202, and T2 red copper wire can be used. Before welding, it is important to clean the welding edges of the workpiece and the surface of the welding wire of any oxide film, oil, or other contaminants to prevent defects such as pores and slag inclusions. This can be done through mechanical or chemical cleaning methods.
The size of the groove made in the workpiece depends on its thickness. If the thickness is less than 3mm, no groove is needed. For 3 to 10mm thickness, a V-groove should be opened with a 60 to 70 degree angle. If the thickness is greater than 10mm, an X-groove with a 60 to 70 degree angle should be made. It is generally recommended to avoid blunt edges to prevent incomplete penetration. The clearance for butt joints should be between 0.5 to 1.5mm, depending on the plate thickness and groove size.
DC positive connection is usually used for manual argon arc welding of red copper, with the tungsten electrode connected to the positive electrode. To prevent pores and ensure reliable fusion and penetration of the weld root, it is necessary to increase welding speed, reduce argon consumption, and preheat the workpiece. The preheating temperature should be between 150 to 300°C for workpieces less than 3mm thick, and between 350 to 500°C for workpieces thicker than 3mm. The preheating temperature should not be too high, as this may reduce the mechanical properties of the welded joint.
Carbon arc welding can also be used for red copper. Carbon electrodes and graphite electrodes can be used as the welding electrodes, and the welding wire used is the same as that used in gas welding. The base metal can also be cut, and gas flux 301 can be used as the flux.