Welding Fundamentals
| Terminology | Description |
|---|---|
| Arc Voltage | The voltage across the welding arc |
| Arc Blow | This is peculiar to D.C. The arc, instead of playing steadily on one spot, is deflected away from point of welding by influence of surrounding magnetic fields |
| Baking Strip | Material (metal,carbon,ceramic,etc.) backing up a joint during welding to help obtain a sound weld |
| Buffer Layer | Layer of weld metal on component to prevent crack formation or dilution effects in subsequent weld layers e.g. hardfacing, cast iron |
| Cold Crack | Crack occurring in weld metal or in the heat affected zone of the base metal after cooling |
| Concave Fillet | Fillet weld having concave face |
| Convex Fillet | Fillet weld having convex face |
| Crater | Depression at the termination of weld bead |
| Crater Crack | Crack in weld bead crater |
| Depth of Fusion | Distance that fusion extends into base metal |
| Dilution | Admixture of base metal and weld metal being deposited |
| Earth Lead | Cable between workpiece and power source |
| Electrode Lead | Conductor between source of current and electrode holder |
| Flux | Fusible material coated into electrodes for removal of oxides and other impurities |
| Fusion | The melting together of filler metal and base metal, resulting in coalescence |
| Haloes or "fish-eyes" | Small, shiny, circular areas displayed on the surface of weld metal after fracture by a tensile stress |
| Hard facing | The process of covering wearing areas with wear-resistant metal by welding |
| Heat Affected Zone | The region beneath the weld bead which has not melted, but whose mechanical properties or micro-structure has been altered by the heat of the weld |
| Hot Crack | Crack occurring in weld metal soon after solidification commences |
| Intermittent Welding | Welding wherein continuity is broken by recurring unwelded spaces |
| Interpass Temperature | In a multiple run weld, the lowest temperature of deposited metal before the next pass is started |
| Lack of Fusion | A weld fault wherein adequate fusion of weld and base metal is not obtained |
| Leg of Fillet Weld | Distance from root of joint to toe of fillet weld |
| Mitre Fillet | Fillet weld in which the face of the weld is approximately flat |
| Open-Circuit Voltage | Voltage between terminals of power source when current is flowing |
| Overlap | Protrusion of weld metal beyond bond at toe of weld |
| Parent Metal | The metal to be welded |
| Pass | A single welding run along a joint or weld deposit. The result of a pass is a weld bead |
| Peening | The mechanical working of metals by relatively light hammering |
| Penetration | The depth a weld extends into a joint from base metal surface |
| Porosity | Gas pockets or voids in metal |
| Post Heating | Application of heat to the weldment after welding is completed |
| Pre Heating | Application of heat to the base metal before welding commences |
| Reinforcement of Weld | Weld metal lying outside the plane joining the toes of a weld |
| Reverse Polarity | Arrangement of D.C. arc welding leads wherein the work is the negative pole and the electrode is the positive pole of the welding arc |
| Root of Weld | The zone on the side of the first run farthest from the welder |
| Root Face | Unbevelled or ungrooved portion of a fusion face at the root |
| Slag Inclusion | Non-metallic solid material trapped in weld metal or between weld and base metal |
| Spatter | Metal particles expelled during welding which do not form part of the weld |
| Straight Polarity | Arrangements of D.C. arc welding leads wherein the work is the positive pole and the electrode is the negative |
| Tack Weld | Small weld made to hold parts in proper alignment until final welds are made |
| Throat Thickness |
The minimum thickness of weld metal in: (a) Fillet weld, measured along a line passing through the root; (b) Close square butt joint, measured in the plane of abutting faces; (c) Open square butt weld, measured in centre of original gap parallel to fusion faces |
| Effective Throat Thickness | Dimension arbitrarily adopted as throat thickness for design purposes |
| Toe | Boundary between weld face and parent metal between weld faces |
| Underbead | Crack in the heat-affected zone which may or may not extend to surface of base metal |
| Undercut | A groove melted in the base metal adjacent to the toe of a weld, and left unfilled by weld metal |
| Weave Bead | Weld bead made with slow oscillating motion of the electrodes |
| Welding Sequence | The order of making welds in a weldment |