What Is Welding?- Definition | Types of Welding

What is Welding?

Welding is a fabrication process that uses heat, pressure, or both to fuse two or more parts together, forming a joint as the parts cool. Welding is typically used on metals and thermoplastics, but can also be used on wood. The completed welded joint can be referred to as a weldment.

Some materials require the use of specific processes and techniques. Some are considered “unweldable,” a term not typically found in dictionaries but useful and descriptive in engineering.

The parts that are joined are known as base material. The material that is added to form the joint is called a filler or consumable. Because of the shape of these materials, they can be referred to as a base plate or tube, flux-cored wire, consumable electrode (for arc welding), etc.

Consumables are usually chosen to be similar in composition to the base material, thus forming a homogenous weld, but there are occasions, such as when welding brittle cast irons, when a filler with a very different composition and, therefore, properties are used. These welds are called heterogeneous.

The completed welded joint may be referred to as a weldment.

Welding is a fabrication process whereby two or more parts are fused together by means of heat, pressure, or both forming a join as the parts cool. Welding is usually used on metals and thermoplastics but can also be used on wood. The completed welded joint may be referred to as a weldment.

Definition of welding

Welding is a fabrication process whereby two or more parts are fused together by means of heat, pressure, or both forming a join as the parts cool. Welding is usually used on metals and thermoplastics but can also be used on wood. The completed welded joint may be referred to as a weldment.

How Does Welding Work?

Welding works by joining two materials together without a separate binder material. Unlike brazing and soldering, which use a binder that has a lower melting point, welding joins the two workpieces directly together.

Most welding done today falls into one of two categories: arc welding­ and torch welding.

Arc welding use­s an electrical arc to melt the work materials as well as a filler material (sometimes called the welding rod) for welding joints. Arc welding involves attaching a grounding wire to the welding material or other metal surface.

Another wire known as an electrode lead is placed on the material to be welded. Once that lead is pulled away from the material, an electric arc is generated. It’s a little like the sparks you see when pulling jumper cables off a car battery. The arc then melts the workpieces along with the filler material that helps to join the pieces.

Feeding the filler into the welding joint takes steady hands and an eye for detail. As the rod melts, the welder must continuously feed the filler into the joint using small, steady, back-and-forth motions. These motions are what give welds their distinctive appearance. Going too fast or slow, or holding the arc too close or far away from the material can create poor welds.

Shielded metal arc welding (SMAW or stick welding), gas metal arc welding (more commonly known as a metal inert gas, or MIG welding), and gas tungsten arc welding (frequently called tungsten inert gas, or TIG, welding) all exemplify arc welding.

These three common methods each offer unique advantages and drawbacks. Stick welding, for instance, is inexpensive and easy to learn. It’s also slower and less versatile than some other methods. Oppositely, TIG welding is difficult to learn and requires an elaborate welding rig. TIG welding produces high-quality welds, however, and can weld materials that other methods can’t.

Torch welding represents another popular welding method. This process typically uses an oxyacetylene torch to melt the working material and welding rod. The welder controls the torch and rod simultaneously, giving him or her a lot of control over the weld. While torch welding has become less common industrially, it’s still frequently used for maintenance and repair work, as well as in sculptures.

Types of Welding

There are four main types of welding. MIG – Gas Metal Arc Welding (GMAW), TIG – Gas Tungsten Arc Welding (GTAW), Stick – Shielded Metal Arc Welding (SMAW), and Flux-cored – Flux-cored Arc Welding (FCAW). We dive deeper into each type of welding here.


MIG welding is one of the most common types of welding that beginners need to learn. MIG welding is used in the auto industry to repair vehicle exhaust and also in the construction of houses and buildings. This is a type of arc welding that uses a continuous wire called an electrode. You also use a shielding gas that flows through the welding gun and protects against contamination.

MIG welding is actually two different types of welding. The first use bare wire and the second uses flux core. Bare wire MIG welding can be used to join thin pieces of metal together. Flux core MIG welding can be used outdoors as it does not require a flow meter or gas supply. MIG welding is usually the welding of choice for DIY and amateur welders who don’t have the cash to spend on expensive equipment.


Like MIG, TIG welding also uses the arc, but it is also one of the more difficult welding techniques to learn. TIG welding uses a tungsten electrode. Tungsten is one of the hardest metal materials. It does not dissolve or burn off.

Tig welding can be done by a process known as fusion, which may or may not use a filler metal. TIG also uses an external gas supply such as argon or helium.

Two hands are required for TIG welding. One hand guides the rod while the other holds a TIG torch. This torch produces the heat and arc used to weld most common metals including aluminum, steel, nickel alloys, copper alloys, cobalt, and titanium.

TIG welders can be used to weld steel, stainless steel, chromoly, aluminum, nickel alloys, magnesium, copper, brass, bronze, and even gold. TIG is a useful welding process for bike frames, lawnmowers, door handles, fenders, and more.

The aerospace and automotive industries use TIG welding as do other industrial markets. This is also a great type of welding for Iowa as it can be very useful for farmers to weld wagon frames, fenders, and other vital equipment.


Want to take your welding to go? A major benefit of stick welding is that it is portable. Stick welding is used in construction, maintenance and repair, underwater pipelines, and industrial manufacturing. For this type of welding, use shielded metal arc welding, better known as stick welding.

Stick welding, also known as arc welding, does it the old-fashioned way. Stick welding is a bit more difficult to master than MIG welding, but you can buy stick welding equipment for very little money if you want to try it at home. Stick welding uses a stick electrode welding rod.

They use a consumable and protected electrode or stick. The stick softens and bonds metals by heating with an electric arc between a covered metal electrode and the base metal workpiece. As the stick melts, its protective cover also melts, shielding the welding area from oxygen and other gases that may be in the air.


This type of welding is similar to MIG welding. In fact, MIG welders can often double duty as FCAW welders as well. Just like MIG welding, a wire that serves as the electrode and filler metal is passed through your rod. This is where things start to differ. For FCAW, the wire has a flux core that forms a gas shield around the weld. This eliminates the need for an external gas supply.

FCAW is better suited for thicker, heavier metals as it is a high-temperature type of weld. Because of this, it is often used for repairs on heavy equipment. It’s an efficient process that doesn’t generate a lot of waste. Since no external gas is required, it is also cost-effective. There will be some slag left over, however, and it needs a bit of cleaning up to make a nicely finished weld.


Plasma arc welding is a precision technique and is commonly used in aerospace applications where the metal thickness is 0.015 inches. An example of such an application would be an engine blade or air seal. Plasma arc welding is technically very similar to TIG welding, but the electrode is recessed and the ionizing gases in the arc are used to generate heat.

The usual gas combination is argon as the plasma gas, with argon plus 2 to 5% hydrogen as the shielding gas. Helium can be used for a plasma gas, but as it is hotter this reduces the amperage of the nozzle.

Want to know more about Plasma Welding? Check out this article.


This type of welding can be used on metals or thermoplastics. As the name suggests, a laser is used as a heat source to create the welds. It can be used on carbon steels, stainless steels, HSLA steels, titanium, and aluminum. It can be easily automated with robotics and is therefore widely used in manufacturing, for example in the automotive industry.


This is a type of welding in which a high-speed electron beam uses kinetic energy to generate heat and weld two materials together. This is a very demanding form of welding that is carried out mechanically, mostly in a vacuum.


Gas welding is only rarely used and has been largely superseded by TIG welding. Gas welders require oxygen and acetylene and are very portable. They are still sometimes used to weld parts of car exhaust back together.


Atomic hydrogen welding is a form of extremely high heat welding formerly known as Atomic Arc Welding. In this type of welding, two tungsten electrodes are shielded with hydrogen gas. It can reach temperatures in excess of that of an acetylene torch and can be conducted with or without filler metal. This is an older form of welding that has been replaced by MIG welding in recent years.


This is an advanced welding process used to join the thin edge of two metal plates together vertically. Instead of the weld being made on the outside of a joint, it takes place between the edges of the two panels.

A copper electrode wire is passed through a consumable metal guide tube that serves as the filler metal. When current is applied, the arc is created and a weld begins at the bottom of the seam and is slowly moved up, creating the weld instead of the seam as it progresses. This is an automated process and is done by machine.

Types Of Welds

1. Fillet Welds

Fillet welding refers to the process of joining two pieces of metal together when they are perpendicular or at an angle. These welds are commonly referred to as tee joints, which are two pieces of metal perpendicular to each other, or lap joints, which are two pieces of metal that overlap and are welded at the edges.

The weld is triangular in shape and may have a concave, flat, or convex surface depending on the welder’s technique. Welders use fillet welds when connecting flanges to pipes and welding cross-sections of infrastructure, and when bolts are not strong enough and will wear off easily.

A fillet weld joins two surfaces perpendicularly, forming an approximate right angle between them. This style of weld can be further categorized into the following subtypes:

  • Full fillet weld. With full fillet welds, the weld size is equal to the thickness of the thinner part being joined.
  • Staggered intermittent fillet weld. Staggered intermittent fillet welds are characterized by the formation of two lines of offset intermittent welding on both sides of the joint.
  • Chain intermittent fillet weld. Chain intermittent fillet welds involve the formation of two lines of intermittent fillet welds that are approximately opposite to one another on either side of a T joint.

The versatility and low cost of fillet welds have made them one of the most widely-used joints in the welding industry. Typical applications include:

  • Connecting flanges to pipes
  • Bracing connections
  • Shear tabs
  • Cover plates
  • Column bases
  • Seam and stitch welds

2. Groove Welds

A groove weld is defined as an opening between the two joint members which provides the space to contain the metal. Groove welds are the most used welds after the fillet weld. The second most popular type of weld is the groove weld.

The groove weld refers to beads that are deposited in a groove between two members to be joined. The type of weld used will determine the manner in which the seam, joint, or surface is prepared.

Groove welds allow parts to be joined in the same plane by depositing welding beads in a groove between them. The basic types of groove welds include:

  • Flare-bevel weld
  • Flare-V weld
  • Single-bevel groove weld
  • Single-J groove weld
  • Single-U groove weld
  • Single-V groove weld
  • Square groove weld

Compared with other forms of welding, the groove welding process is generally more time-consuming, harder to perform, and typically requires special beveling on one or both surfaces being joined.

However, it creates an easy-to-inspect, high-strength weld and offers good distortion control. Common applications of groove welds include:

  • Moment connections
  • Column splices
  • Hollow structural steel (HSS) connections

3. Surfacing Weld

These are welds composed of one or more strings or weave beads deposited on an unbroken surface to obtain desired properties or dimensions.

Surfacing is a welding process used to apply a hard, wear-resistant layer of metal to surfaces or edges of worn-out parts. It is one of the most economical methods of conserving and extending the life of machines, tools, and construction equipment.

A surfacing weld is composed of one or more stringer or weave beads. Surfacing, sometimes known as hard facing or wear facing, is often used to build up worn shafts, gears, or cutting edges.

The most common types of surfacing welds include:

Surfacing welds are commonly used to add a wear-resistant layer of metal to an object to strengthen its surface or rebuild worn areas. In these cases, a metal with a greater wear resistance than the base metal is used to perform the welding.

This technique is one of the most cost-effective methods for protecting and prolonging the life of equipment and tools used in aggressive, high-wear applications. Surface welding can also be used in conjunction with square butt joints to enhance the quality of the final weld.

4. Plug Weld

A Plug Weld, also known as the Rosette Weld, is when two metals are fused through welds placed in small circular holes. This process is typically done on two overlapping metals, with the top metal having the holes for the weld to be deposited.

Plug welding is an alternative to spot welding used by vehicle manufacturers where there is insufficient access for a spot welder. For DIY car restoration, it’s generally used instead of spot welding on panels flanges that would have originally been spot welded.

Plug welds when done properly tend to be stronger than the original spot welds. Rally car builders often use the technique, and it is acceptable in a UK MOT test as an alternative to spot welds were repairing older cars

Other applications include:

  • Welding rods inside a pipe
  • Joining metals that differ in thickness
  • Auto body manufacturing and repair

5. Slot Weld

A slot weld joins the surface of a piece of material to another piece through an elongated hole. The hole can be open at one end and can be partially or completely filled with weld material.

This is a weld made in an elongated hole in one member of a lap or tee joint joining that member to the surface of the other member that is exposed through the hole. This hole may be open at one end and may be partially or completely filled with weld metal.

With slot welds, one surface is joined to another through an elongated hole. The difference between plug and slot welds is that the plug weld’s shape is characterized by its diameter, whereas the slot weld’s shape is characterized by both diameter and length.

Depending on the part’s specifications, one end of the hole may be open, or the hole can be partially or completely filled with weld material.

Slot welds are beneficial when the part’s design requires an overlapping between two surfaces. Specific uses of slot welds include:

  • Transmitting shear force in lap joints
  • Preventing buckling in overlapped parts

6. Flash Weld

Flash welding is a method of resistance welding that eliminates the need for filler metals. During the flash welding process, a current is applied to create a resistance between the two surfaces to be joined. When the two surfaces come together at small contact points, the current flows and melt the material.

The melted material then exits the joint in a spray of molten particles, which creates a distinctive flashing action. Oxides and other contaminants are eliminated from the interface while a heat-softened zone is formed at the ends of the two surfaces.

When enough material has melted, a force is then applied to join the surfaces. This facilitates the creation of a butt weld with no residual melted material in the joint.

The flash welding process is fast, economical, and capable of fusing dissimilar metals with different melting points. Flash welds are often used for:

  • Joining sections of mainline rail in railway construction
  • Connecting thick workpieces such as chains or pipes
  • Merging metal sheets, rods, and bars

7. Seam Weld

Seam welding is the process of joining two similar or dissimilar materials at the seam by the use of electric current and pressure. Seam welding is possible thanks to the contact resistance created between the two metals. As current passes between the metals, heat gets generated at the small gap.

The process is mostly used on metals since they conduct electricity easily and can sustain relatively high pressures. As current passes between the metals, heat gets generated at the small gap. Electrodes maintain and control the flow of electricity.

This type of weld can be created using two methods:

  • Resistance seam welding. Resistance seam welding is an adaptation of spot welding that uses motor-driven wheels instead of stationary rods for the welding electrodes. Common uses include sheet metal fabrication and the manufacturing of automotive components such as fuel tanks, radiators, and steel drums.
  • Friction seam welding. With friction seam welding, heat is generated using friction instead of electrodes. This allows the surfaces to be merged while in the solid phase, thereby eliminating the occurrence of interdiffusion. Friction seam welding is often preferred for materials that are inherently difficult to weld using traditional arc welding methods.

Benefits of seam welding include:

  • Provides sturdy, durable welds
  • Relatively easy to perform
  • Ideal for manufacturing liquid- and gas-tight vessels

8. Spot Weld

Spot welding (also known as resistance spot welding) is a resistance welding process. This welding process is used primarily for welding two or more metal sheets together by applying pressure and heat from an electric current to the weld area.

It works by contacting copper alloy electrodes to the sheet surfaces, whereby pressure and electric current are applied and heat is generated by the passage of current through resistive materials such as low carbon steel.

Spot welds are relatively easy and inexpensive to create, making them a popular weld choice in several key industries, including:

  • Automotive
  • Aerospace
  • Construction
  • Electronics
  • Metal furniture building
  • Railway

9. Upset Weld

Upset welding (UW)/resistance butt welding is a welding technique that produces coalescence simultaneously over the entire area of abutting surfaces or progressively along a joint, by the heat obtained from resistance to electric current through the area where those surfaces are in contact.

Pressure is applied before heating is started and is maintained throughout the heating period. The equipment used for upset welding is very similar to that used for flash welding. It can be used only if the parts to be welded are equal in cross-sectional area.

The abutting surfaces must be very carefully prepared to provide for proper heating. The difference from flash welding is that the parts are clamped in the welding machine and force is applied bringing them tightly together.

High-amperage current is then passed through the joint, which heats the abutting surfaces. When they have been heated to a suitable forging temperature an upsetting force is applied and the current is stopped. The high temperature of the work at the abutting surfaces plus the high pressure causes coalescence to take place. After cooling, the force is released and the weld is completed.

The upset welding process delivers several distinct benefits, including:

  • High-quality welds with fewer fusion defects
  • Compatibility with a wide variety of standard and difficult-to-weld materials
  • Welding equipment that is easy to control, operate, and maintain

Advantages Of Welding

  • Welded joint has high strength, sometimes more than the parent metal.
  • Different material can be welded.
  • Welding can be performed anyplace, no need enough clearance.
  • They give smooth appearance and simplicity in design.
  • They can be done in any shape and any direction.
  • It can be automated.
  • Provide a complete rigid joint.
  • Addition and modification of existing structures are easy.

Disadvantage of welding

  • Members may become distorted due to uneven heating and cooling during welding.
  • They are permanent joint, to dismantle we have to break the weld.
  • High initial investment.

Application Of Welding

The welding is widely used for the fabrication of pressure vessels, bridges, building structures, aircraft and space crafts, railway coaches, and general applications in shipbuilding, automobile, electrical, electronic, and defense industries, laying of pipelines and railway tracks, and nuclear installations.

  • Fabrication of sheet metal.
  • Automobile and aircraft industries.
  • Joining ferrous and non-ferrous metals.
  • Joining thin metals.


What is Welding?

Welding is a fabrication process whereby two or more parts are fused together by means of heat, pressure or both forming a join as the parts cool. Welding is usually used on metals and thermoplastics but can also be used on wood. The completed welded joint may be referred to as a weldment.

How Does Welding Work?

Welding works by joining two materials together without a separate binder material. Unlike brazing and soldering, which use a binder that has a lower melting point, welding joins the two workpieces directly together.

What are the 4 Types of Welding?

There are four main types of welding. MIG – Gas Metal Arc Welding (GMAW), TIG – Gas Tungsten Arc Welding (GTAW), Stick – Shielded Metal Arc Welding (SMAW) and Flux-cored – Flux-cored Arc Welding (FCAW).

What are the 3 types of welding?

Three of the most common are Arc, MIG (Metal, Inert Gas) or GMAW (Gas, Metal Arc Welding), and TIG (Tungsten Inert Gas) welding. In order to know which process is best for the particular job you’re working on, here’s what you should know about each of them. Arc welding is the oldest of these three welding processes.

How much do welders make a year?

How much does a welder make? Well, in welding, you can make anywhere from $29,000 to $117,000 per year, with the median annual salary being $58,000. Experience and education level factor into how much a welder earns. Excellent skill and experience can lead to higher pay.

Is welding difficult?

For most people, welding is moderately to very difficult to learn how to do, as it’s a hands-on skill that requires more than just reading. Furthermore, welding is very difficult to actually do for most people, because it takes years and years of practice, on top of learning how to do it.

Is welding a good career?

Welding is an excellent career, and welders commonly praise their profession and extol the many benefits they get from welding as a career. Overall, if you can handle extreme conditions, long hours, and smoke and fire regularly, a career in welding can be rewarding.

Is welding a easy job?

It’s easy to get into. Becoming a welder requires no formal education, and sometimes, not even experience. The more you know, the better, but it’s a great trade because you can start from the bottom in a workshop and learn it all on the job.

Which welding is strongest?

TIG welding produces cleaner and more precise welds than MIG welding or other Arc welding methods, making it the strongest. That said, different welding jobs may require different methods, while TIG is generally stronger and higher in quality, you should use MIG or another method if the job calls for it.

What welding should I learn first?

Mig Welding. MIG welders are among the best type for beginners, as they’re designed with a wire welding electrode on a spool that is fed at a pre-selected speed through a welding gun. As a semi-automatic or automatic process, gas metal arc welding (GMAW or MIG), is the easiest to learn.

Can a welder make 100k?

Because these types of jobs require specialized skills and can be potentially risky, contract welders can earn well over $100,000 in a year.

Can you teach yourself to weld?

Most people can learn the fundamentals of welding on their own to make basic fabrications and do common repair work by researching content from reliable sources and a lot of practice. However, if you have professional intentions, you cannot reach a high skill level fast enough without the guidance of experts.

What is the hardest welding to learn?

TIG welding is the hardest form of welding to learn for a variety of reasons. The process of TIG welding is slow and takes time to get used to as a beginner. A TIG welder requires a foot pedal to feed the electrode and control the variable amperage while maintaining a steady hand at the welding torch.

What are the 5 types of Welds?

Different types of welding and what they are used for

  • MIG Welding. MIG welding is one of the easier types of welding for beginners to learn.
  • Stick Welding. Stick welding, also known as Arc welding, is doing it the old-fashioned way.
  • TIG Welding.
  • Plasma Arc Welding.
  • Electron Beam and Laser Welding.
  • Gas Welding.

What are the 7 basic types of welding?

Basic types of welding:

  • MIG Welding – Gas Metal Arc Welding (GMAW)
  • TIG Welding – Gas Tungsten Arc Welding (GTAW)
  • Stick Welding – Shielded Metal Arc Welding (SMAW)
  • Flux Welding – Cored Arc Welding (FCAW)
  • Energy Beam Welding (EBW)
  • Atomic Hydrogen Welding (AHW)
  • Gas Tungsten-Arc Welding.
  • Plasma Arc Welding.

Which type of welding is best?

Shielded Metal Arc Welding (Stick) is the most popular welding process. It is the most versatile and uses the simplest equipment. The small light electrode and holder can be used in very tight places or reach several hundred feet away from the welding power supply.

What are the basics of welding?

Welding is essentially the joining of two objects together using heat and a filler material. The filler is heated to the point where it melts and is able to pool between the two objects. This results in a strong joint (also known as a weld).

Which welding is better TIG or MIG?

TIG welds are better for thinner metals and smaller projects because they produce precise and clean welds. MIG welds work well with larger projects with thick metals that need longer, continuous runs. MIG is typically easier to control and is better for beginners. Costs: TIG is a more expensive method than MIG welding.

What are the 4 things you need before welding?

You should always have the proper safety equipment before you even begin — the most important things that you should have include safety glasses, welding gloves, an auto-darkening helmet (to protect your eyes from the flash), and a fire-resistant jacket.

What is G in welding?

F stands for fillet weld, while G is a groove weld. A fillet weld joins together two pieces of metal that are perpendicular or at an angle. A groove weld is made in a groove between workpieces or between workpiece edges. Using this system, a 2G weld is a groove weld in the horizontal position.

How do I choose a welding type?

To evaluate the welding process most appropriate for the job at hand, the following factors would typically be considered:

  • Type of material being welded (see table below)
  • Thickness of the material.
  • The welding position.
  • Type of welding power source and the amount of current available.
  • Time requirements.
  • Working conditions.