In arc welding, the electrode that generates the arc is indispensable, and welding wire is used for semi-automatic and automatic welding, among others. So, what are the criteria for selecting welding wire? Here we introduce the types and features of welding wire.
What is welding wire?
Welding wire is a coiled welding material used in arc welding. It is used for automatic and semi-automatic welding in arc welding, and is set in a welding machine.
To begin with, arc welding is a welding method using arc discharge, a gaseous discharge phenomenon that emits intense light at high temperatures. An arc is generated between the electrode and the base metal when the electrode is brought into contact with the base metal and an electric current is applied and the electrode is then pulled apart.
This is the same phenomenon that you see when you unplug a plug from an electrical outlet while it is still in use. The high heat generated by the arc melts the base material and additive, fusing them together at the molecular level to form a connection, a process known as arc welding.
Various electrodes and additives are used, including welding rods, TIG torches, and welding wire. For example, in TIG welding, which is manual stick welding, non-melting tungsten is used as the electrode, and the welding rod, which is the material to be fused, is prepared separately. In automatic and semi-automatic welding, on the other hand, the wire is both the electrode and the welding additive, making welding more efficient. When the switch is turned on, the wire comes out automatically and welding is performed.
This welding wire must be used differently depending on the material to be welded. Basically, two types of wire are currently used: 'solid wire' and 'flux-cored wire.
Features of Solid Wire
This wire is made of homogeneous materials and has a homogeneous cross-section. Some types are copper plated. This type of wire is utilized at many sites in Japan and is the most major type of wire. Compared to shielded arc welding rods, this wire is more efficient and easier to automate, and is used in robot welding as well as semi-automatic welding.
It has a wide range of possible welding positions and can be used in a variety of situations. Another advantage of flux-cored wire is that it produces relatively fewer fumes than flux-cored wire and is less expensive. Slag is also less likely to form than with flux-cored wire.
Solid wire is mainly used for MIG (Metal Inert Gas welding). MIG welding is a method of welding aluminum and stainless steel. A mixture of argon gas and 2% oxygen is used as the shielding gas (gas that stabilizes the arc and protects it from atmospheric contamination).
Features of flux-cored wire
Flux-cored wire, as the name implies, is a wire that contains flux. There are different types of flux-cored wire, such as 'gas shielded arc welding wire' for MAG or CO2 welding, 'self shielded arc welding wire' that does not require gas shielding, and 'submerged arc welding wire' mainly used for welding overlay. However, flux-cored wire generally refers to 'gas shielded arc welding wire.
Flux consists of various components such as arc stabilizers, deoxidizers, slag formers, and alloying agents. Each wire has different flux ingredients and composition ratios, and each has different characteristics and cross-sectional shapes. The following two types of flux are commonly used.
Slag covers the surface of the bead after welding. This makes it possible to achieve excellent deposition speed and full-posture welding.
This flux contains a large amount of iron powder and almost no slag-forming agent. It is suitable for downward welding because of its low slag generation, low spatter, and high deposition speed.
Flux-cored wire generates less spatter than solid wire and has the advantage of beautifully finished bead shape and appearance. It is also capable of full-posture welding and has a high deposition rate, making it highly efficient. However, the price of wire is rather high.
Flux-cored wire is mainly used for mag welding (MAG: Metal Active Gas welding). MAG welding is a method of welding iron (steel). A mixture of 20% carbon dioxide gas and 80% argon gas is used as the shielding gas.
In recent years, semi-automatic and automatic welding have become more common than manual welding. The welding wire needed for this purpose has its own characteristics. Use the welding wire that best suits your purpose to achieve smooth and beautiful welding.