Welding is a very famous fabrication process around the world that joins materials by melting them with the help of heat and pressure.
The welding process is most commonly used in many industries, such as automotive, construction, aerospace, oil & gas, and agriculture. Welding also plays a key role in joining the items for domestic purposes.
The final joint in this process is called a weldment, and the elements combined are called the parent material. The filler is the material that is applied to make the weldment.
In this article, the principles of welding, common terms in welding, and different welding methods are explored thoroughly.
Two metals can be joined directly by the process of welding, or the welding effect can be enhanced by the use of welding wires, welding rods, and other welding supplies.
The method of connecting two or more metal pieces or edges by creating a localized joint by heat (fusion) with or without pressure to produce a homogenous connection is known as welding.
Common Welding Terms
Arc
An arc is a flow of electricity that heats up metals and joins them together. Arcs can also be formed using welding gas. It is also considered plasma. Normal gas is not conductive, but the gas between two electrodes becomes ionized, and the gas atoms are broken down into gas ions and free electrons. At this point, the gas is conductive and will generate sparks, resulting in an arc. Arc discharge generates a significant amount of heat. Arc welding makes advantage of this heat to weld.
Shielding Gas
Shielding gas plays an important role in preventing the surrounding atmosphere from contaminating the welded region. In this process, metal heated in the air will oxidize to generate a black oxide scale and inert or semi-inert gas is typically employed.
The oxide scale acts as an impurity that influences the performance of welded metal. You must isolate the air during heating if you do not want the oxide scale to form. In welding, shielding gas is very important because shielding gas is released during the welding process.
Molten Pool
The molten pool is defined as the region of metal that melts while welding. Since only a little portion of the metal is heated during welding, the majority of the metal remains solid and only the heated portion becomes liquid. The molten pool produces a section where the metals are united after solidification.
Slag
One of the wastes that is produced during the welding process is called slag. Slag is a non-metallic material that collects on the upper surface of the weld pool. Slag is created as a result of welding flux, which is a chemical component used to protect welds against contamination by surrounding gases.
Common Welding Materials
Welding process commonly used to join two metals therefore it is very important to know which materials are used to join them. Some common welding materials are described below.
Filler Metal
Filler metals are used in welding, soldering, and brazing to fill the gap between two closely fitting materials. These alloys or unalloyed metals melt on heating and flow into the gaps between two very close components to form a welded joint. However, the grade of filler metal is slightly different from the grade of the workpiece. Depending on the type of product, filler metal can be utilized as welding wire or rod.
Welding Electrode
Metal wires coated with chemicals are known as welding electrodes. The welding electrode provides a welding arc as well as streams the filler metal for a welding joint. After welding, the coating creates slag to enhance the weld’s chemical makeup and functionality. The welding electrode comes in a variety of diameters and is a lengthy strip.
Flux-cored Welding Wire
The specific welding wire is generally used to weld two or more pieces of metal, and it is fed by a gun. Welding wire with flux core is the opposite of welding electrodes. A filler metal is applied on its outer surface. The flux core is located in the middle of the metal, and when melted, it likewise becomes slag. Unlike welding electrodes, flux-cored wire is commonly coiled on a spool.
Common Welding Methods
SMAW
Shielded metal arc welding is a very common welding method, mostly used in industries. In the stick welding process, a consumable electrode covered with flux melts to create a weld pool. Shielding gas is not necessary for SMAW. When the coating melts, it emits some gas and forms a slag pool to protect the molten pool.
GTAW
GTAW stands for Gas Tungsten Arc Welding, which is sometimes referred to as TIG (tungsten inert gas) welding. (GTAW) is an arc welding technology that employs a tungsten electrode that is not consumable to form the weld. When GTAW welding, argon is utilized as a shielding gas, allowing the metal to be welded directly or with the aid of welding rods. Welders must possess a particular level of expertise since welding with welding rods requires manual wire feeding.
GMAW
GMAW stands for gas metal arc welding, and it is also known as MIG (metal inert gas). GMAW and GTAW utilize very similar welding equipment, and argon is likewise used as a shielding gas. The main difference is tungsten electrodes are used in GTAW, whereas the welding material is directly used as an electrode in the GMAW welding technique. As a result, GMAW is automatic wire feeding, which also indicates that continuous welding wire is required.
PAW
PAW stands for plasma arc welding. Plasma arc welding (PAW) uses a non-consumable electrode and an electric plasma arc. It is comparable to the GTAW welding process. Tungsten is used as the electrode in both of them. Because of its high energy density, PAW is an excellent choice for welding thicker metals.
FCAW
The full-form FCAW is flux-coated arc welding. The welding process is nearly identical to GMAW. The sole distinction is that flux-cored wire is used instead of the original welding substance. The FCAW process produces materials with excellent purity and beauty because the shielding gas and flux core protect the molten pool. Additionally, FCAW’s welding efficiency is very high.
SAW
Submerged Arc Welding (SAW) creates uniform, high-quality welds with less spatter by shielding the weld from contamination with a blanket of flux. Welding wire is also required as a welding material because submerged arc welding is so automated.
ESW
ESW is stand for electro slag welding. This method of welding is best for a vertical or nearly vertical position. The weld must remain vertical before welding, and a slag pool is created at the weld by heating the flux. This extremely effective welding method uses a filler metal, as well as the heat produced by an arc and electrical resistance between two materials.
Brazing
Brazing is a special method for joining metals through capillary action. A filler metal with a lower melting point is used to braze metals together without melting the base materials. Brazing is a versatile procedure that can be used to combine different metals while maintaining the mechanical qualities of the base materials.
Flat Welding, Butt Welding and Socket Welding
There are different types of welding methods are employed in industries according to the nature of work. The most frequently used techniques include flat welding, butt welding, and socket welding. Flat welding is a simpler method of welding. The term “flat welding” implies welding directly on a metal surface. To join the pipe with a flange through the welding process is the best example of flat welding.
Butt welding is the process of aligning two pipes end to end in the same plane and welding them together. Butt welds are generally utilized in the construction of pipe systems and constructions. Butt welding involves beveling at the pipe end, which improves sealing.
Flat welding and socket welding are comparable. The distinction is that the socket welding flange has a groove inside that fixes the pipe’s insertion depth and supports the pipe’s port.
FAQs
Are the metal at the weld and the metal weldment the same in terms of performance?
The strength and microstructure of welding are not much stronger than welded metals because the welding only joins the metal with heat, pressure, and filler metal. Due to this fact, the performance of seamless pipes is better than welded pipes.
Why are the components of some welding materials different from those of the weldment itself?
The welding wires specially designed with specific composition. Additional alloying elements are frequently added to electrodes and filler materials to enhance particular qualities that’s why the properties of welding material is differ from weldment.
Can different grades of metal be welded together?
Yes, it is possible to weld different grades of metal together, but in order to guarantee compatibility and a strong, long-lasting weld, proper welding procedures and filler material selection are necessary.
Conclusion
Welding has been a great importance in many industries since a long time.
This article introduces 8 common welding methods. Different welding methods should be used according to different welding requirements. We can achieve good-quality welding joints by choosing the proper welding material and welding technique.
However, better results can be achieved by following the given terms and information.
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