Guide to Welding Processes

There are over 30 different welding processes recognized today. Some are fairly complex, requiring costly technical equipment not typically available in everyday applications. Others are used in common day-to-day welding operations and are readily available at most major welding supply distributors. This article discusses the factors you should consider to select the correct welding process for your specific application.

Jump to a section: Common Welding Processes | Factors Influencing the Choice of Welding Process | Deciding on the Right Welding Process | Advancement in Welding Technology | FAQ 

Common Welding Processes

Shielded Metal Arc Welding (SMAW) or Stick Welding

Shielded metal arc welding is a mainstay in the welding industry due to several factors:

Simplicity of the equipment required 

Welders only need a power source, lead cable, and ground to perform a weld with the SMAW process.

Portability

Welders only need to drag the “stinger” (electrode holder) around the work area, meaning they can easily move over a vast area.

Simple process

Welders can learn the SMAW process fairly quickly.

High degree of operator control

Welders can compensate for inconsistencies within the weld joint by making subtle adjustments to travel speed, arc length, and rod angle.

Possible in outdoor environments

Welding can happen in harsh and remote conditions where other welding processes might be impractical.

Versatility

Electrodes are available to weld on a wide array of metals, including stainless steel and aluminum. Suitable for welding numerous joint configurations.

Use for any welding position

The SMAW process can be used for nearly any welding position, provided the electrode you select is rated for out-of-position welding.

However, there are some limitations to the stick welding process, such as:

  • Lower efficiency of use of consumable electrodes.
  • Slag in the completed weld that welders must remove by either chipping or grinding.

Picture of a welder using the SMAW “stick” welding process on a pipe welding project. Photo courtesy of Glenn Weidman // PrimeWeld

Stick welding is a highly versatile process that can produce high-quality welds even in tough outdoor conditions, as displayed in the picture.

Gas Tungsten Arc Welding (GTAW) or Tungsten Inert Gas (TIG) Welding

TIG welding continues to be a top choice wherever high-quality welds are required. TIG welding is widely used for welding aluminum, stainless steel, and nickel alloys. GTAW welding offers:

  • A high degree of operator control enables the welder to compensate for inconsistencies in the weld joint.
  • Clean welds that require little to no post-weld cleaning. 
  • High versatility in the variety of metals that are suitable for the process. 
  • Suitability for a wide variety of joint configurations.
  • Welding in any position.

The limitations of TIG welding include:

  • Its slow process with limited deposition rates.
  • Its susceptibility to impurities in the base metal, meaning pre-weld cleaning is critical.
Picture of a welder using the TIG welding process to make a weld on a stainless steel pipe spool. Photo courtesy of Glenn Weidman // PrimeWeld

The TIG welding process is a great way to produce X-ray-quality welds on stainless steel pipe projects.

Gas Metal Arc Welding (GMAW) or Metal Inert Gas (MIG) Welding

MIG welding is a mainstay in the welding industry due to its versatility and ease of use. It is probably the most common welding process in the industry today for many reasons:

  • High deposition rates. 
  • Suitable for a variety of materials.
  • The semi-automatic welding process greatly enhances weld consistency. 
  • Efficient use of electrode and filler metals.
  • Capability to weld effectively out of position.

As with any welding process, MIG welding has limitations. Those can include:

  • The necessity to protect welds with a shielding gas means it is not well suited to welding outdoors.
  • Limited operator control makes it difficult to adjust for inconsistencies in the weld joint.
  • Welds made with the MIG welding process are susceptible to surface contaminants like paint, dirt, and grease, meaning preparation and cleaning is critical.

Flux-Cored Arc Welding (FCAW)

Flux-core welding has many similarities to MIG welding. However, it offers larger wire diameters for higher deposition rates than it is typically possible to achieve with the MIG welding process. The use of flux-core welding provides the following advantages:

  • Higher deposition rates.
  • Deep penetrating weld characteristics that result in high-strength welds.
  • The capability to run at high amps and volts is a great choice for welding thicker materials.
  • The semi-automatic process greatly enhances the consistency of welds.

However, there are some limitations to welding with flux core that you should consider:

  • Flux-core welding, particularly dual-shield flux-core wire (FCAW-G), is prone to porosity that, given the deep penetrating welds the flux-core process is capable of producing, may be time-consuming and costly to repair. 
  • It is unsuitable to use in workplace conditions where there may be drafts. 
  • The susceptibility of porosity in flux-core welding means it’s necessary to clean the material to ensure it is free from surface contaminants before beginning welding operations.
  • It’s necessary to clean and remove the resulting slag in the complete weld. 

Submerged Arc Welding (SAW)

Submerged arc welding is an automated process favored by many production facilities for its high productivity. It involves a wire-feed system to deliver the welding wire into the weld puddle, which is shielded by a granular flux. Submerged arc welding has some distinct advantages, including:

  • High deposition rates make it highly efficient for welding thicker sections of metal.
  • An automatic welding process capable of producing consistent, high-quality welds.

The disadvantages of SAW welding are:

  • Limited to the flat and horizontal positions.
  • Requires expensive equipment, which is costly to set up and operate.
  • Requires post-weld cleaning of slag from the completed weld.
  • Limited operator control makes it difficult to adjust for inconsistencies in the weld joint.

The image above shows a typical submerged arc welding setup. Note the use of rollers to rotate the pipe to weld in the flat position. 

Electron-Beam Welding (EBW)

Electron beam welding (EBW) is a fusion welding process that creates a bond between materials with a highly-concentrated beam composed of high-velocity electrons. These produce enough heat in the base metals to fuse the workpieces and the filler metal.

The electron beam welding process offers several advantages:

  • Highly-versatile welding process. It’s possible to weld nearly all metals with the electron beam welding process, including combinations of alloys.
  • Deep penetrating welds with lower heat inputs result in a smaller heat-affected zone, which may be advantageous in many applications.

The main disadvantage of electron beam welding is the high cost. Given the equipment involved, electron beam welding may be cost-prohibitive for many shops and welding facilities. For this reason, it is used only in specific applications. EBW was developed in the 1950s for use in the atomic industry due to the need to weld on refractory and reactive metals.

Factors Influencing the Choice of Welding Process

Let's look at the factors that determine the right welding process for the job.

Material Type

The type of material plays a major role in determining the right choice of welding process. It’s possible to weld carbon steel with most welding processes. The equipment, filler metals, and electrodes are suitable for a wide array of carbon steel grades and specifications. 

Stainless steel has unique characteristics and may require specific electrodes and specialized equipment to make the required welds. SMAW, MIG, and FCAW wires and electrodes for welding stainless steel work with the same equipment to weld carbon steel. They are a great choice for welding thicker pieces of stainless steel.

Since welding stainless steel out of position is challenging, a process that offers a greater degree of operator control, such as TIG or stick welding, may make it easier to achieve the desired welds.

The MIG or stick welding process is also suitable for welding aluminum quickly and efficiently. The MIG welding process involves using a spool gun, especially on thicker sections of aluminum. Welding out of position on aluminum with the stick welding process is extremely difficult — it may take time and practice before a welder is able to perform it properly.

The tremendously high thermal conductivity of aluminum and the tendency of aluminum to absorb contaminants like oils and grease means a welding process that offers a higher degree of operator control (like the TIG welding process) may prove more effective. The TIG welding process enables the welder to adjust travel speed, heat, and the rate of filler metal added to the molten weld puddle according to the increasing heat or potential weld defects caused by subsurface contaminants encountered during welding operations.

Material Thickness

It’s also necessary to evaluate the material thickness involved in welding projects when choosing the best welding process. For jobs that weld on thicker sections of heavy plate, it’s best to use a technique that offers high deposition rates, like the flux-core welding process. Given the TIG welding process speed and deposition rate limitations, this, conversely, would be a poor choice for heavy plate sections.

It’s best to weld thinner sections of materials more susceptible to distortion, warping, or burn-through with a welding process that operates efficiently at lower amperages to minimize heat input. MIG is common for welding on thinner sessions of auto-body applications, such as to patch fenders, hoods, and various other components. 

TIG may be a good choice if alloys like stainless steel or aluminum are involved.

Welding Position

Welding positions have a major impact on the choice of welding processes. For example, when welding heavy plate sections in the flat position, the higher deposition rates inherent to submerged arc and flux-core welding processes may be the best choice. Welding with flux-core out of position is possible, but might require adjusting the wire size, heat, and travel speed to achieve the necessary quality. 

Welding pipe requires welding in essentially all positions within the same joint. For this reason, a welding process that gives the welder a greater degree of operator control tends to be the best choice. Refineries and gas plants all over the world still use stick welding on pipelines and process pipes for its versatility in all positions welding applications.

Joint Design and Project Specifications

Joint designs affect the selection of the best welding process. For example, for welding CJP (complete joint penetration) weld joints from one side (like those encountered in pipe welds), a welding process that produces these welds consistently is essential. SMAW and TIG are both well suited to these applications, given the high degree of operator control these processes offer. 

When fillet welds are required, particularly with thicker plate material, the flux-core welding process can offer advantages. Flux-core operates at higher heat and offers penetrating welds, even where little to no gap in the fit-up weld joint is present.

Welding Speed and Productivity

Jobs that require high productivity and, therefore, higher welding speeds may require a process like flux-cored arc welding, which offers high deposition rates. Submerged arc welding is also suitable where high deposition rates are a determining factor. 

Using the SMAW process has the limiting factor that it forces the welder to stop working to switch out the nearly-consumed electrode and place a new one in the stinger prior to resuming welding operations. One of the leading advantages of MIG, flux-core, and submerged arc welding is that, since the electrode is now in the form of a wire wrapped around a spool, it is possible to weld at much longer distances without needing to stop to change electrodes, which increases efficiency and productivity.

It’s also worth considering the efficiency of the welding electrodes themselves. In SMAW, the operator can only consume a finite amount of the welding electrode. In no application is it possible to consume 100% of the electrode, given that a small amount must remain in the holder and it is necessary to stop welding before burning the electrode holder or the welder's hands. With MIG or flux-core and submerged arc welding, it is possible to continuously feed the wire through the wire feeder, which uses a greater amount of the electrode. There is minimal waste of electrodes (welders may only need to cut a small portion of the welding wire before restarting) with SAW, MIG, or flux-core welding, which results in more efficient utilization of the welding consumables.

Environmental Conditions

If the welding takes place outdoors where wind may be an issue, processes more susceptible to porosity (like FCAW-G, MIG, or even TIG) may not be the best choices. SMAW remains an industry standby for this reason. With the right welding process, it’s possible to make consistent, high-quality welds even in relatively harsh weather conditions. 

There are some applications where cleanliness is of primary importance. When welding in a medical facility, food processing plant, or other ultra-clean environment, processes that produce high amounts of sparks, fumes, or slag might be impractical. Given that the TIG welding process throws no sparks and emits only low levels of fumes, TIG welding is well suited to jobs indoors where sparks caused by other welding processes would be problematic.

It is important to study and understand the environment of the worksite before you start welding operations. Check for things like the presence of flammables and cleanliness requirements.

Deciding on the Right Welding Process

Understand the Project Requirements

Consider the big picture before starting work on a welding project. What is the project? What sort of load or stresses will the welded parts be subject to? What would the consequences of failure be if the weld doesn’t hold? For example, if the project involves repairing a fender on a trailer, the MIG welding process may prove to be well-suited, given its capability to weld thinner materials.

If the project involves welding on a heavy section of beam in a remote, outdoor environment, the SMAW process may be more suitable. It will be possible to transport a simple engine-drive machine to the worksite and produce all the electrical power necessary to weld even heavy, thick beam webs and flanges.

Assessing Skills

Take into account the welder’s skills and experience to select the right welding process. If a welder has only ever done MIG welding, a job that requires ultra-high-quality sanitary welds on stainless steel with the TIG welding process may lead to frustration. TIG welding on stainless steel takes time to learn and practice. Welders who need this skill for a project should seek the assistance of someone who can properly perform these welds.

Welders could also consider enrolling in night classes at a trade school to learn essential skills. Many welding distributors also offer welding classes. Reach out to your local welding supplier to ask about class schedules.

Consider Equipment Availability

Equipment is another major factor in selecting the right welding process. This is one of the reasons why stick welding remains one of the most popular welding processes. Stick welding requires only a power source capable of producing enough current to burn the electrodes at the proper rate to weld the material. A ground and lead cable, a box of electrodes, and a selection of hand and power tools are all that are necessary to do the job. 

Many other forms of welding require far more extensive tolls and equipment than stick welding. For example, MIG welding in many applications requires a power source of sufficient amperage, a wire feeder, possibly a bottle of shielding gas, a regulator, and hoses. The consumable list may also include a spool of wire, shielding gas, and tips and liners for the MIG gun. If you’re welding in an environment generally protected from the elements and if your job will involve a lot of repetitive welding, the expense may be worthwhile.

Note that there are many affordable options on the market for MIG welding. For smaller, simple projects, there are small wire feed welders capable of running on standard 110v outlets using small diameter, self-shielding welding wire. Shop around to explore your options.

Review Cost and Efficiency

Cost is often a factor in the welding process selection. You should consider not only the cost of the machine itself but all the related consumables you’ll need. Stick welding is often quite advantageous for this reason. The stick electrodes are typically all you need in terms of consumables.

MIG welding requires a greater amount of consumables, such as tips, liners, usually a shielding gas, a regulator, hoses, and all the necessary hardware and fitting to connect these, in addition to the spool of welding wire itself. 

Perform Tests and Trials

Before starting your project, consider welding some test pieces to see if the process you have selected will produce the desired results. Set up some test or scrap pieces of metal of comparable type and thicknesses. Make a few welds in each position the job may require. 

Assess the completed welds and consider the following:

  • Is the welding process capable of producing strong welds on the type of metal you are using for all the thicknesses you need?
  • Is the welder’s skill adequate to produce welds of sufficient quality, consistently and in all positions? (Consider making test welds, overhead, vertical, and around possible obstructions to ensure the welder can make these welds in even the toughest conditions that he or she may encounter on the job.)
  • Is the welding equipment of sufficient size and capable of generating enough amps or volts to produce welds of sufficient quality for the duration of the project?
  • Is the welding equipment in proper working order — cleaned and maintained as per manufacturer’s recommendations? (Proper welding equipment maintenance helps ensure the welding machine can produce consistent welds and reduces the chance of a breakdown, which would result in potentially costly delays.)

Advancements in Welding Technology

Let's take a closer look at how technological advancements in the welding industry might help influence your choice of welding processes.

Laser welding

There have been numerous developments in the laser welding process in recent years. For example, the hybrid laser welding process combines laser welding with other processes, like electron-beam welding. The combination increases welding speed and better control over weld quality.

Laser welding has also benefited from improved computer technology. Laser systems are being integrated into Industry 4.0 systems for data collection and process monitoring, which helps improve weld quality and process control.

Automation in Welding Processes

Automation has benefited from the major advancements in technology in recent years. In various welding processes, it has led to an increase in efficiency by reducing human error and ensuring consistency in weld quality. 

Automation greatly reduces hazard exposure to welders by enabling the welder to remain safely removed from sparks, fumes, and other hazards inherent to the welding process.

Future Trends in Welding

The welding industry is constantly evolving with new and innovative ways to increase quality, efficiency, and safety. There is likely to be an increase in the use of robotics in welding. Collaborative robots, also called cobots, are working alongside their human counterparts to increase welding productivity.

Augmented and virtual reality technology now has a role in welder training. Welders can use glasses and headsets to visualize welding parameters and techniques in a safe environment that improves their skills while reducing consumable expenditure in materials, filler metals, electrodes, and related tools. 

FAQ

Which welding process is best for beginners? 

Shielded Metal Arc Welding (SMAW), or Stick Welding, is often recommended for beginners due to its simplicity and ease of learning. The equipment required is minimal, and it allows for a high degree of operator control, making it easier to compensate for inconsistencies in the weld joint. It is also versatile, capable of welding a variety of metals and joint configurations.

What factors should I consider when choosing a welding process? 

When selecting a welding process, consider the material type, material thickness, welding position, joint design, project specifications, welding speed and productivity, environmental conditions, the welder's skill level, and equipment availability. Each of these factors can significantly impact the suitability and efficiency of a welding process for a given project.

Can I use MIG welding for outdoor projects? 

MIG welding is generally not well-suited for outdoor projects due to the need for shielding gas, which can be disrupted by wind, leading to weld contamination. For outdoor projects, processes like Shielded Metal Arc Welding (SMAW) or Flux-Cored Arc Welding (FCAW) are more appropriate as they are less affected by environmental conditions.

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