Welding joins metals by melting them together at the joint — usually with filler metal — so the result is one continuous piece of steel. Everything a welder does on a job traces back to the same fundamentals: pick the right process, prep the joint, choose the consumables, and work safely. This guide covers the basics that apply to every shop and every project.

WHAT WELDING IS

An arc welder creates an electric arc between the electrode and the base metal. The arc generates enough heat — around 6,000°C at its core — to melt both the workpiece and the filler. When the arc is removed, the molten puddle cools into a solid weld that, done correctly, is as strong as the parent metal.

  • The arc needs a complete electrical circuit: work clamp, base metal, electrode, and power source.
  • The weld puddle must be protected from oxygen and nitrogen in the air, or the weld becomes porous and weak.
  • Heat input and travel speed decide penetration, bead shape, and distortion.

THE FOUR CORE PROCESSES

Most welding in fabrication shops falls into four processes. Each has a strength, and welders usually master more than one.

MIG (GMAW)

Wire is fed continuously through a gun while shielding gas protects the puddle. It is fast, easy to learn, and ideal for production work on steel, stainless, and aluminum. See the full MIG welding guide.

TIG (GTAW)

A tungsten electrode carries the arc while the welder feeds filler rod by hand. TIG gives the highest quality and best control over heat, which makes it the standard for thin materials, stainless pipe, and aerospace work. See the TIG welding guide.

Stick (SMAW)

A flux-coated electrode is consumed as it melts. No gas bottle is needed, so stick is the go-to for outdoor work, structural steel, and repairs. See the stick welding guide.

Flux-Cored (FCAW)

Like MIG, but the wire carries flux inside its core, which can replace external shielding gas. It deposits metal faster than solid wire and shines on thick plate and heavy fabrication. See the FCAW guide.

Pro Tip

Learn stick first. It forces you to master arc control and puddle reading, and those skills transfer to every other process.

JOINT DESIGN

The joint is the geometry of the connection. The five basic joints are butt, lap, tee, corner, and edge. Joints are further defined by their preparation — a groove (square, V, U, or J) when the weld sits inside the thickness, or a fillet when the weld is in the corner of two pieces.

  • Butt joints carry load efficiently and are used everywhere from pipe to plate.
  • Tee and lap joints are simple to fit and dominate structural work.
  • V-grooves with a root opening ensure penetration on thick plate — the root opening and included angle come straight from the welding procedure.
  • Fit-up mistakes — gaps, mismatch, tacking errors — are the number one cause of bad welds made by otherwise good welders.

CONSUMABLES

Consumables are the materials the process uses up. Picking the right ones is half of producing a code-quality weld.

  • Electrodes (stick): the E-number, such as E7018, tells you strength, position, and flux type.
  • Filler wire: solid or flux-cored, matched to the base metal grade.
  • Shielding gas: usually CO₂ or C25 for MIG steel, pure argon or argon mixes for TIG and aluminum.
  • Flux: used in stick and submerged arc welding to protect the puddle and add alloying elements.

Use the electrode guide and the filler metal selector to match consumables to your job.

SAFETY BASICS

The arc is hot enough to melt steel, and the light is intense enough to burn skin and eyes. Safety is not optional — it is part of the job.

  • Wear a proper auto-darkening helmet, welding gloves, and flame-resistant clothing. See the PPE guide.
  • Fumes are the hidden hazard. Work with local exhaust ventilation or a fume extractor whenever possible.
  • Keep flammables at least 10 m away, and watch for hot sparks falling into cracks and behind panels.
  • Inspect leads, clamps, and torch cables before every job — damaged insulation causes shocks and arc strikes.
Watch Out

"Flash" — arc eye — feels like sand in your eyes hours after exposure. It is preventable: never look at the arc with unprotected eyes, and keep your helmet down before the arc starts.

THE BOTTOM LINE

Every strong weld starts with the same four fundamentals: the right process, a properly prepared joint, matched consumables, and safety equipment that is used every single time. Master these and everything else — parameters, defect prevention, equipment — becomes detail work on top of a solid base.