🔥 Welding I: Fundamentals

What you’ll learn

1. What Welding Actually IsDefine fusion welding and distinguish it from bolting, brazing, and soldering.Welding melts base metal so two parts solidify as one continuous piece, unlike fasteners or brazed joints where parts stay separate. Sound welds can match the strength of the surrounding metal, which is why the built world runs on them.
2. A Short History of Joining MetalTrace welding from the forge to the arc and through its WWII mass expansion.Blacksmiths forge-welded for millennia; the arc arrived with Benardos (1885) and coated electrodes with Kjellberg (1904). WWII Liberty ship production made welding a mass profession and taught hard lessons when early welded hulls cracked.
3. Safety First: Arc, Heat, and FumesApply the core protections against arc radiation, burns, and welding fume.The arc emits UV that burns eyes (arc eye) and skin, so welders use shade 10–13 filters and full flame-resistant cover. Fume is the invisible hazard — zinc and hexavalent chromium especially — controlled by ventilation and keeping your head out of the plume.
4. The Electric ArcExplain what an arc is, how amperage controls heat, and what the weld pool tells you.The arc is sustained current across an ionized gap, concentrating heat far beyond steel's ~1,400–1,500 °C melting range. Amperage is the heat dial, and the molten puddle — not the arc — is what a welder actually reads and steers.
5. What Heat Does to SteelDescribe how welding heat changes steel structure, including the HAZ and cooling effects.Steel's properties come from its grain structure, which heating and cooling rewrite. Every weld creates a heat-affected zone that can embrittle, and fast cooling plus hydrogen causes delayed cracking — the reason for preheat and low-hydrogen rod ovens.
6. The Big Four ProcessesCompare SMAW, GMAW, FCAW, and GTAW and match each to its typical use.All four arc processes make a shielded molten puddle; they differ in filler feed and shielding method. Stick rules outdoor repair, MIG wins shop speed, flux-core handles thick and windy work, and TIG delivers precision on thin and critical joints.
7. Stick Welding Up CloseExplain how a coated electrode works and decode classifications like E7018.A stick electrode's flux coating makes shielding gas, arc stabilizers, and protective slag as it burns. The AWS code is a spec sheet: E7018 promises 70,000 psi weld metal, all-position use, and a low-hydrogen coating.
8. Joints and PositionsIdentify the five joint types and the 1–4 F/G welding position system.Butt, lap, tee, corner, and edge joints cover assemblies, welded with groove or fillet welds. Positions run 1 (flat) to 4 (overhead) with F for fillet and G for groove; fixed pipe (5G/6G) combines them all in one joint.
9. Why Welds FailRecognize porosity, lack of fusion, undercut, and cracking, and their root causes.Porosity comes from contamination and moisture; lack of fusion from cold, rushed technique; cracks — the disqualifying defect — often from hydrogen and fast cooling. Clean metal, dry rods, correct settings, and patience prevent nearly all of them.
10. Your First BeadSet up a station safely, strike an arc, and run and evaluate a first stick bead.Setup is a safety ritual: clear flammables, sound cables, correct amps, ventilation. Strike like a match, hold a rod-diameter arc length, drag at 10–15°, and read every cooled bead — ripple shape diagnoses your heat and speed.

Questions this course answers

Grounded in trusted sources

• American Welding Society (AWS) — Welding Fundamentals resources
• ANSI Z49.1: Safety in Welding, Cutting, and Allied Processes
• OSHA — Welding, Cutting, and Brazing standards (29 CFR 1910 Subpart Q)
• Larry Jeffus, Welding: Principles and Applications (Cengage)
• Lincoln Electric — The Procedure Handbook of Arc Welding

Every Wunder lesson is built from real, reputable sources — never invented.

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