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Welding
Processes, metallurgy, symbols and the qualification system — what each test proves, and which ticket your branch of the trade actually needs.
Learning paths
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Content
Processes 8 lessons
Arc
- Welding Fundamentals: Heat, Arc and the Weld Pool
An arc weld is one electric circuit with a deliberate gap in it, and understanding that circuit, the pool it melts, and how each process shields that pool turns four separate-looking processes into variations on a single theme.
- SMAW (Stick)
Stick welding carries its shielding, its filler and its slag in one coated rod, which is why it works outdoors on dirty steel and why reading the electrode classification is the first real skill in the trade.
- GMAW (MIG)
MIG feeds a bare solid wire under shielding gas at a set speed, and the way that metal crosses the arc, short-circuit or spray, decides what thickness and what position the process can actually handle.
- FCAW (Flux-Core)
Flux-cored welding is a stick electrode turned inside out and made continuous, and the split between self-shielded wire that works in wind and gas-shielded wire that does not is the whole decision.
- GTAW (TIG)
TIG separates the arc from the filler so you control heat and metal independently, and polarity, DCEN for steel and AC for aluminium, is where the process is actually won or lost.
- Choosing the Right Process
Process selection is six questions asked in order, location, metal, thickness, position, quantity and required quality, and answering them honestly usually picks the process for you.
Cutting
- Oxy-Fuel Cutting
Oxy-fuel does not melt steel, it sets the iron on fire and steers the burn, which is exactly why it cuts carbon steel beautifully and stainless, aluminium and copper not at all.
- Plasma Cutting
Plasma cuts by melting rather than burning, so it will cut anything that conducts electricity, and its limits are electrical and pneumatic rather than chemical.
Science 7 lessons
Metallurgy
- Welding Metallurgy Basics
Every arc weld is a casting poured into forged metal, and the heat-affected zone beside it gets a heat treatment nobody designed, which is where most cracking actually lives.
- Heat Input and Distortion Control
Heat input is one number computed from volts, amps and travel speed, and travel speed is the lever that changes it most while touching no dial on the machine.
- Preheat and Interpass Temperature
Preheat is a head start on cooling that attacks hydrogen and hardness at the same time, and interpass temperature is that protection kept alive pass after pass, inside a window with a ceiling as well as a floor.
- Filler Metal Selection
Choosing a rod or wire is choosing what half of the finished weld will be made of, so the classification number has to satisfy strength, chemistry, service and position before anything else.
Quality
- Weld Defects and Discontinuities
A discontinuity is any interruption in a weld and a defect is a discontinuity the governing code rejects, so whether your weld has defects depends on which code is holding the ruler.
- Visual Inspection
Visual inspection catches more weld problems than every other method combined because it is applied to every weld at every stage, and doing it properly means lighting, gauges and a written acceptance table rather than a glance.
- NDT Methods Overview
Five nondestructive methods do nearly all the work in welding, and the useful way to hold them is by the slice of the weld each one can actually see: surface, just below it, or all the way through.
Documents 4 lessons
- Reading Welding Symbols
A welding symbol is a sentence written on a horizontal line, and the whole language hangs on one rule: below the line means weld the side the arrow touches, above it means weld the far side.
- WPS and PQR: How Procedures Work
A WPS is the recipe, a PQR is the lab report proving the recipe works, and a WPQ proves the person can follow it, and keeping those three straight is the central paperwork skill of code welding.
- Navigating AWS D1.1
AWS D1.1 is a book nobody reads cover to cover, so the working skill is classifying a question and knowing which part answers that kind of question.
- ASME Section IX Basics
ASME Section IX answers only two questions, is this welding procedure proven and is this person proven to run it, and every pressure construction code points at it for both.
Qualification 5 lessons
- Welder Qualification: How It Actually Works
Welding has no journeyman licence, it has qualification: witnessed proof that you can make a sound weld with one process, on one material, in one position, to one code.
- The AWS Certified Welder Program
The AWS Certified Welder programme records a performance test you take at an Accredited Test Facility to a specific procedure in a national registry, and keeps it alive only while you file a maintenance form every six months.
- Position Qualifications (1G-6G)
Welding positions are numbered because gravity changes the job, and the position on your test coupon is one of several variables that together define what you are actually qualified to weld.
- Becoming a CWI
The Certified Welding Inspector credential moves you from making welds to judging them, through a three-part exam sat in one event and held on a nine-year cycle with renewals at years three and six.
- Welding Career Paths: Shop, Structural, Pipe, Inspection
Shop, structural, pipe and inspection are four different economic lives built on the same base skill, and the credential ladder you climb depends entirely on which branch you pick.