What Are the Different Types of Metal Welding?

Metal welding joins metal parts by applying heat, pressure, or both. The right process can create a clean seam on thin sheet or a strong joint on thick plate. But no method is best for every job. Material, joint design, working position, and available equipment all matter.

This guide introduces common types of metal welding, including MIG (GMAW), TIG (GTAW), stick (SMAW), flux-cored, submerged arc, and resistance welding. Each uses a different heat source, electrode, or shielding method. MIG is often valued for speed and steady production. TIG offers precise control and a neat finish, but usually demands more practice. Stick welding is useful in many outdoor settings, while flux-cored processes can suit heavier work. The details matter.

A process that works well on a bench may feel awkward overhead. Thin steel can warp; a rough, dirty surface can affect weld quality. That is where tidy comparisons meet real shop conditions. This overview explains how the methods differ, where they are commonly used, and what trade-offs to consider when choosing among them. It also points to the importance of proper training, protective equipment, and following equipment instructions and qualified welding procedures. The choice is rarely just about appearance or speed. Good results depend on matching the process to the metal, joint, and task—and checking the finished weld carefully.

Table of Contents [Hide]

1 How Metal Welding Processes Are Classified

2 Arc Welding Methods and Their Main Uses

3 Gas and Resistance Welding Techniques

4 Solid-State Welding Processes

5 How to Compare and Select a Welding Type

How Metal Welding Processes Are Classified

Metal welding is classified by how heat is produced, whether the base metal melts, and how the joint is formed. Fusion processes melt the edges, often adding filler metal. Arc welding uses an electric arc; gas welding uses a flame. Resistance welding heats the joint through electrical resistance and pressure, while laser and electron-beam methods concentrate energy into a narrow area. Small detail, big difference: a workshop may choose an arc process for a repair, but a factory may favor resistance welding for repeatable sheet-metal joints.

A second useful division separates fusion from solid-state welding. In friction welding, pressure and motion join parts without melting them; this can limit distortion in suitable components. ISO 4063 assigns reference numbers to welding and allied processes, helping engineers identify methods consistently in drawings and production records. These labels do not determine the best method by themselves. Joint shape, metal thickness, access, and inspection needs matter. The American Welding Society’s 2023 workforce report estimated that the United States would need 360,000 welding professionals by 2027, underscoring the value of clear process training. Still, classifications simplify real work; actual shop conditions can make a tidy chart less tidy.

What Are the Different Types of Metal Welding? - How Metal Welding Processes Are Classified

Process Family	Common Processes	Heat or Energy Source	How the Joint Is Formed	Typical Uses and Characteristics
Arc welding	Shielded Metal Arc Welding (SMAW); Gas Metal Arc Welding (GMAW); Gas Tungsten Arc Welding (GTAW); Flux-Cored Arc Welding (FCAW); Submerged Arc Welding (SAW)	Electric arc between an electrode and the workpieces	The arc melts the base metal; filler metal is used in many processes. Shielding gas, flux, or both protect the molten weld from contamination.	Widely used for steel, stainless steel, and aluminum fabrication, construction, maintenance, and manufacturing. Equipment and portability vary by process.
Oxyfuel gas welding	Oxyacetylene welding and other oxyfuel welding methods	Flame produced by burning a fuel gas with oxygen	The flame melts the edges of the workpieces, with filler metal added when needed.	Used for repair work, thin materials, and some nonindustrial applications. It is also commonly used for heating and cutting, which are distinct from welding.
Resistance welding	Spot welding; Seam welding; Projection welding; Resistance butt welding	Electrical resistance heating combined with pressure	Current flows through the contacting parts, generating heat at the joint. Pressure forms the weld; filler metal is generally not used.	Common in high-volume production, especially for sheet-metal assemblies. Spot welding is widely used to join overlapping sheets.
Laser beam welding	Laser Beam Welding (LBW)	Focused laser beam	A concentrated beam melts material at the joint, producing a narrow weld. Filler metal may be added in some setups.	Suitable for precise, fast welding and automated production. The focused heat source can limit the size of the heat-affected zone.
Electron beam welding	Electron Beam Welding (EBW)	Focused, high-energy electron beam	The beam converts kinetic energy into heat as it strikes the workpiece, melting the joint area. The process is commonly performed in a vacuum.	Used for deep, narrow welds and precision components. Specialized equipment and vacuum requirements can limit its use.
Solid-state welding	Friction welding; Friction Stir Welding (FSW); Ultrasonic welding; Diffusion welding	Mechanical friction, vibration, pressure, or heat and pressure below the melting point	The materials bond without melting the main joint area. Depending on the process, pressure and plastic deformation create the bond.	Can reduce melting-related defects and distortion. Used for selected metals and applications such as plate, tube, and dissimilar-material joints.
Thermite welding	Thermite welding	Heat from an exothermic chemical reaction	Molten metal produced by the reaction fills a prepared joint, where it solidifies to form the weld.	Used in specialized field applications, including joining rail sections and large metal components where conventional power equipment may be impractical.

Arc Welding Methods and Their Main Uses

Arc welding uses an electric arc to melt metal and join parts. The right method depends on material thickness, joint shape, work location, and finish requirements. Shielding protects the hot weld from air, but each process manages it differently.

Shielded metal arc welding, or stick welding, uses a flux-coated electrode. It suits repair work and outdoor jobs because it needs little extra equipment. Wind can still disrupt the weld, and removing slag between passes takes time. It is forgiving. Gas metal arc welding feeds wire continuously and uses shielding gas, making it efficient for clean, repeated welds in workshops. A draft can disturb that gas coverage. Gas tungsten arc welding offers precise control on thin stainless steel or aluminum, though it is slower and demands steady hands.

Flux-cored arc welding also feeds wire, but its flux can provide shielding and leaves slag to clean away. Some versions work well outdoors; check the wire and setup rather than assuming all do. Submerged arc welding covers the arc beneath granular flux, supporting long, consistent seams on thick steel. It is commonly suited to production work, not tight repair spaces. One easy detail to underestimate: clean edges and correct joint fit often matter as much as choosing a process. Follow qualified procedures, use suitable eye and skin protection, and check ventilation before welding.

What Are the Different Types of Metal Welding? — Arc Welding Methods and Their Main Uses

Indicative deposition-rate ranges are shown in kilograms per hour. Actual rates vary with equipment, material, settings, and welding position.

SMAW (stick): Repair, construction, and outdoor work.
GTAW (TIG): Precise welding of thin sections and high-quality joints.
GMAW (MIG/MAG): Production welding of sheet metal and fabrication.
FCAW (flux-cored): Structural and heavy fabrication, including outdoor work.
SAW (submerged arc): Long, straight welds on thick plate and pipe in production settings.

Gas and Resistance Welding Techniques

Gas welding uses a fuel-gas flame, commonly oxy-fuel, to melt metal edges and, when needed, a filler rod. The operator adjusts the flame and torch distance by watching the small molten pool. It suits repair work and some thin sections because the equipment is portable. Its broad heat input can also warp sheet metal or leave a larger heat-affected area. That matters.

Resistance welding joins metal through electrical current and pressure. In spot welding, two copper-alloy electrodes squeeze overlapping sheets; current heats their contact point and forms a weld nugget. No filler wire is usually required. The process is fast and repeatable on well-fitted parts, but worn electrodes, uneven pressure, or dirty surfaces can weaken a joint. A neat-looking spot is not proof of a sound weld.

The U.S. Bureau of Labor Statistics projects about 45,800 annual openings for welders, cutters, solderers, and brazers from 2023 to 2033. Its Occupational Outlook Handbook also projects 2% employment growth over that period. Those figures do not compare welding methods, but they underline the value of skilled setup and inspection. Gas welding rewards steady torch control; resistance welding demands consistent pressure and electrode condition. Small details, big consequences. A limitation remains: neither method is ideal for every alloy, thickness, or production rate.

Solid-State Welding Processes

Solid-state welding joins metals without forming a fully molten weld pool. That changes the defect picture. In friction stir welding (FSW), a rotating tool presses into the joint and travels along it, softening and stirring the metal. The tool leaves a narrow seam, often with visible shoulder marks. A technical review by Nandan, DebRoy, and Bhadeshia in Progress in Materials Science (2008) reports that FSW peak temperatures can reach roughly 0.8–0.9 of the material’s melting temperature. The metal softens, but normally does not melt.

Other methods suit different jobs. Diffusion bonding holds clean surfaces together under heat and pressure, often in a controlled atmosphere; it can join thin layers, but needs careful surface preparation. Ultrasonic welding uses high-frequency vibration and pressure, commonly for small parts and thin sheet. Explosive welding uses a rapid collision to bond dissimilar metals, usually in specialized industrial settings. Each process has limits.

For a shop engineer, access and joint shape matter as much as strength targets. FSW needs tool access along the seam and can leave an exit hole. Diffusion bonding may require long cycle times. I would not treat “no melting” as a guarantee of an easy weld: poor fit-up or process control can still produce weak bonds. That detail is easy to miss.

How to Compare and Select a Welding Type

Choosing a welding process starts with the joint, metal, and working conditions—not a popularity contest. MIG (GMAW) feeds wire continuously, making it practical for longer seams and production work. TIG (GTAW) offers precise control on thin sections, but usually takes more time and skill. Stick (SMAW) uses portable equipment and suits outdoor repairs, though slag cleanup adds work. Flux-cored welding can provide high deposition rates, but fumes, spatter, and shielding requirements vary by wire type. None is best for every job.

Compare material thickness, position, access, finish, operator skill, and total cost. For a thin stainless panel, TIG may limit burn-through; for a long steel frame, MIG or flux-cored welding may improve throughput. Check the procedure against the material and joint, then test a sample. Small changes in fit-up can alter results. The U.S. Bureau of Labor Statistics projects 2% employment growth for welders, cutters, solderers, and brazers from 2023 to 2033, with about 45,800 openings annually. That workforce outlook makes training and process consistency practical selection factors, not afterthoughts.

Tips: Make a short test weld on matching scrap. Inspect the bead, penetration, distortion, and cleanup time. Record settings and results; a quick visual check alone can miss internal defects. Revisit the choice when the production volume or work environment changes.