Introduction
Welding is the most important process of joining metals used industrially. It has very wide range of applications.
Range of applications
From construction of simple items, often used in applications of 'little responsibility', to sophisticated structures and components that, if they fail, can endanger human life, cause damage to the environment and generate huge losses.
Bridges, ships and pressure vessels are examples of equipment manufactured by Welding. Welding also has a significant influence on the cost and performance of these products.
In many of these applications, Welding can complement or compete with other joining processes (mechanical joining, gluing and others) and fabrication (such as casting, mechanical forming and machining). The success of each application depends on the correct choice of Welding process(es) and procedures.
A quick illustration of 'what is Welding'
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Definition of Welding
After a lot of research and reflection, please find below my definition and answer to the question “What is Welding?”:
Welding is the operation of joining, coating or repairing parts, which aims to obtain the continuity of physical and chemical properties in the welded joint.
The term “continuity” used here is necessary to differentiate Welding from other manufacturing methods such as brazing and bonding.
Simplified representation of Welding:
What is a weld?
Welding is nothing more than the result of Welding, that is, the material or connections resulting from this operation.
A theoretically perfect weld is indistinguishable from the original base materials. The weld below, while well executed and “beautiful”, is still noticeable to the naked eye.
Advantages and disadvantages
The following are some advantages of Welding compared to other processes such as riveting, screwing:
BENEFITS | DISADVANTAGES |
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Note: Some authors (and other internet sites) tend to present the advantage of reducing the weight of the equipment. This particular feature cannot be generalized as it is easier to reduce weight using other manufacturing methods. The other characteristics were addressed more generally for the purposes of this comparison.
Grouping of Welding processes
There are many ways to carry out Welding. We call each way of Welding as "Welding Process".
In this topic I will address the major groups of Welding processes and in the next topic I will only talk about the main Welding processes.
Pressure Welding
In this process, a tension ("force") is applied to the parts in order to deform them and produce a solubilization of the materials. Solubilization is an exchange of atoms between materials and goes somewhat along the lines of the theoretical representation of Welding (presented earlier).
Fusion Welding
Fusion Welding is the most common and most intuitive. In this case the ends become liquid and "blend".
Gas Welding is usually done by "flame" or torch. This Welding is sometimes known as oxy-acetylene, although acetylene is not the only type of gas that can be used.
Electric arc Welding
Electric arc Welding is a particular case of fusion Welding where an electric arc is the heat source that will melt the end of the base material. The electric arc is formed thanks to a potential difference generated by a Welding machine (or source).
Welding with consumable electrode
The most common Welding type has a consumable that is melted together with the part in order to facilitate Welding.
Welding without consumable electrode
This is the case with TIG Welding. The electrode (where the current passes) is not consumed during the process.
In this process the consumable can be added (or not) by means of an additional dipstick.
Welding with gas shield
In processes of this type, an inert shielding gas or a mixture of gases is added.
Welding with coating (or flux) protection
In this case the process is said to be self-protected. The coating burns and generates a gaseous shield against the atmosphere.
Welding without gas shield
Processes of this type have not been used anymore because they generate poor quality welds due to contamination by atmospheric air.
What is TIG Welding (GTAW)?
TIG is the process of electric arc Welding with a non-consumable tungsten or tungsten alloy electrode under a gas shield of inert gas or inert gas mixtures. Addition material may or may not be used.
It is also known as Gas Tungsten Arc Welding (or GTAW).
What is Shielded Metal Arc Welding (SMAW)?
Coated electrode arc Welding is a process that produces coalescence between metals by heating and melting them with an electric arc established between the tip of a coated electrode and the surface of the base metal at the joint being welded.
It is also known in english as 'Stick Welding'.
What is MIG, MAG or GMAW Welding?
MIG (or MAG) is the process of electric arc Welding with a consumable electrode under gas shielding, which uses a solid wire as electrode and an inert gas (MIG) or an active gas (MAG) as a gas shield. It is also known as Gas Metal Arc Welding (or GMAW).
What is FCAW (Cored Wire) Welding?
The process of Welding flux cored wire (or FCAW) is an arc Welding that produces coalescence of metals by heating them with an electric arc established between a continuous, consumable, tubular metallic electrode and the base metal.
Arc and bead protection is provided by a Welding flux contained within the electrode, which can be supplemented by additional shielding gas provided by an external source.
Note: FCAW is the acronym in English: Flux Cored Arc Welding.
What is submerged arc Welding (SAW)?
Submerged arc is the process of electric arc Welding with consumable electrodes, in which the electric arc and the weld pool are protected from the environment by the products resulting from the burning of a flux that is added independently of the electrode.
It can be used as an electrode: solid wire, tubular wire or tape.
What is plasma Welding (PAW)?
The plasma arc Welding process, also known as PAW (Plasma Arc Welding), is one in which the fusion of metals is caused by an electric constrictor arc, established between a tungsten electrode and the workpiece. The Plasma that names this process refers to the gas that is ionized.
Welding is a special process
The ISO 9000 series of standards for the quality system considers Welding as a special process that, depending on the complexity of the welded construction, requires control methods that can cover design activities, selection of manufacturing materials and inspection. This is necessary to ensure that the specified quality is achieved.
With regard to Welding inspection, it is important that this activity is carried out by a duly qualified and certified professional, that is, the Welding inspector.
Citation
When you need to include a fact or piece of information in an assignment or essay you should also include where and how you found that piece of information (What Is Welding).
That gives credibility to your paper and it is sometimes required in higher education.
To make your life (and citation) easier just copy and paste the information below into your assignment or essay:
Luz, Gelson. What Is Welding?. Materials Blog. Gelsonluz.com. dd mmmm. yyyy. URL.
Now replace dd, mmmm and yyyy with the day, month, and year you browsed this page. Also replace URL for the actual url of this page. This citation format is based on MLA.
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