TERMS: WELDING ROP ENGINEERING
Acetylene: A highly combustible gas composed of carbon and hydrogen. Used as a fuel gas in the oxy acetylene welding process.
Air-Arc Cutting (Plasma): Thermal cutting using an arc for melting the metal and a stream of air to remove the molten metal to enable a cut to be made.
ANSI: American National Standards Institute. - www.ansi.com
ANGLE: The angle in which you hold your torch, electrode, or gun
Anti-Spatter Fluid (Also known as: antisplatter, anti-splatter, antispatter)
Prevents spatter build up. Products are available in fluid, tip dips, gels, spray bottles and aerosol cans.
Arc length: The distance between the tip of the electrode and the weld puddle.
Arc Strikes: Striking an arc on base metal that is not being fused into the weld metal should be avoided. A small volume of base metal may be momentarily melted when the arc is initiated. The molten metal may crack from quenching, or a small surface pore may form in the solidified metal. These discontinuities may lead to extensive cracking in service. Any cracks or blemishes caused by arc strikes should be ground to a smooth contour and reinspected for soundness.
Arc Voltage: The voltage between electrodes or between an electrode and the work, measured at a point as near as practical to the work.
Arc Welding: A group of welding processes in which fusion is obtained by heating with an electric arc or arcs, with or without the use of filler metal.
Argon: An extremely unreactive colorless odorless element of the rare gas series that forms almost 1 per cent (by volume) of the atmosphere.
As Welded: The condition of weld metal prior to any mechanical treatment.
ASME American Society of Mechanical Engineers.
AWS: American Welding Society, Introduction Page of the American Welding Society, the worlds largest organization devoted to promoting welding and related processes, and to supporting all those who contribute to the industry- with links to related sites and services. Host of the largest annual Welding Show, Welding Exposition in the world - www.aws.org
Base Metal: The metal to be welded.
Bead Weld: A type of weld composed of one or more string or weave beads deposited on an unbroken surface.
Blowhole: A cavity generally over 1.6 mm in diameter, formed by entrapped gas during solidification of molten metal.
Brazing: A metal joining technique that uses a molten filler metal alloy having a melting temperature greater than about 425 degrees C (800 F).
Burn Back: Fusing of the electrode wire to the current contact tube by sudden lengthening of the arc in any form of automatic or semi-automatic metal-arc welding using a bare electrode.
Burn Off Rate: The linear rate of consumption of a consumable electrode.
Butt Joint: A joint between two work pieces in such a manner that the weld joining the parts is between the surface planes of both of the pieces joined.
Butt Weld: A weld joining two members lying in the same plane.
Carbon Steel: Steel, which owes its properties chiefly to various percentages of carbon without substantial amounts of other alloying elements; also known as ordinary, straight carbon, or plain carbon steel.
CO2 Flux Welding: Metal-arc welding in which a flux-coated or flux containing electrode is deposited under a shield of carbon dioxide.
Continuous Weld: A weld extending along the entire length of a joint.
Cracks: Cracks will occur in weld metal and base metal when localized stresses exceed the ultimate strength of the metal. Cracking is generally associated with stress amplification near discontinues in welds and base metal, or near mechanical notches associated with the weldment design. Hydrogen embrittlement often contributes to crack formation in steel. Plastic deformation at crack edges is very limited.
Cracks can be classified as either hot or cold cracks. Hot cracks develop at elevated temperatures. They commonly form during solidification of the metal at temperatures near the melting point. Cold cracks develop after solidification of a fusion weld as a result of stresses. Such cracks in steel are sometimes called delayed cracks when they are associated with hydrogen embrittlement. Hot cracks propagate between the grains while cold cracks propagate both between grains and through grains.
1. Cracks may be longitudinal or transverse depending on their orientation with respect to the weld axis.
2. Longitudinal cracks are parallel to the axis of the weld regardless of location in the weld metal or the heat-affected zone.
3. Throat cracks run longitudinally in the face of the weld extending toward the root of the weld. They are generally, but not always hot cracks. Root cracks also run longitudinally but in the root of the weld. They are generally hot cracks.
4. Crater cracks are formed by improper termination of a welding arc. They are usually shallow hot cracks and sometimes are referred to as star cracks when they form a star-like cluster.
5. Toe cracks are generally cold cracks that initiate approximately normal to the base material surface and then propagate from the toe of the weld where residual stresses are higher. These cracks are generally the result of thermal shrinkage strains acting on a weld heat-affected zone that has been embrittle. Tow cracks sometimes occur when the base metal cannot accommodate the shrinkage strains that are imposed by welding.
Cutting Oxygen: Oxygen used at a pressure suitable for cutting.
Cutting Torch: A device used in gas cutting for controlling the gases used for preheating and the oxygen used for cutting the metal.
Dip Transfer: A method of metal-arc welding in which fused particles of the electrode wire in contact with the molten pool are detached from the electrode in rapid succession by the short circuit current, which develops every time the wire touches the molten pool.
FCAW: Flux Cored Arc Welding.
Fillet Weld: A weld of approximately triangular cross section joining two surfaces at right angles to each other.
Fusion Penetration: In fusion welding. The depth to which the parent metal has been fused.
Gas Pocket: A weld cavity caused by the trapping of gases released by the metal when cooling.
Gas Regulator: A device for attachment to a gas cylinder or pipeline for reducing and regulating the gas pressure to the working pressure required.
Gas Welding: A process in which the welding heat is obtained from a gas flame.
GMAC: Gas Metal Arc Cutting (Air Arc).
GMAW: Gas Metal Arc Welding (MIG).
Goggles: A device with colored lenses which protect the eyes from harmful radiation during welding and cutting operations.
Groove Weld: A weld made in the groove between two plates to be joined.
GTAW: Gas Tungsten Arc Welding (TIG).
Hand Shield: A device used in arc welding to protect the face and neck. It is equipped with a filter glass lens and is designed to be held by hand.
Hard Facing: A particular form of surfacing in which a coating or cladding is applied to a surface for the main purpose of reducing wear or loss of material by abrasion, impact, erosion, galling, and cavitations.
HEAT: The temperature (amps) used during the welding process.
Heat Treatment: An operation or combination of operations involving the heating and cooling of a metal or an alloy in the solid state for the purpose of obtaining certain desirable conditions or properties. Heating and cooling for the sole purpose of mechanical working are excluded from the meaning of the definition.
Helmet: A device used in arc welding to protect the face and neck. It is equipped with a filter glass and is designed to be worn on the head to protect the head, face and eyes.
Hose Protector: A small non-return valve fitted to the blowpipe end of a hose to resist the retrogressive force of a flashback.
Inert Gas: A gas, which does not normally combine chemically with the base metal or filler metal, or support combustion.
Intermittent Weld: A series of welds at intervals along a joint.
Metal Arc Welding: An arc welding process in which a metal electrode is held so that the heat of the arc fuses both the electrode and the work to form a weld.
MIG – Welding Inert-gas welding using a consumable electrode (inert-gas metal-arc welding).
MSDS: Material Safety Data Sheet. - http://www.spattershield.com/msds.html
Multi-Stage Regulator: A gas regulator in which the gas pressure is reduced to the working pressure in more than one stage.
Porosity: Porosity is the result of gas being entrapped in solidifying weld metal. The discontinuity is generally spherical, but may be elongated. Porosity will be present in a weld if the welding technique, materials used, or condition of the weld joint preparation promotes gas formation and entrapment. If the molten weld metals cool slowly and allow all gas to rise to the surface before solidification, the weld will be virtually free of porosity.
1. Uniformly scattered porosity may be distributed throughout single pass welds or throughout several passes of multiple pass welds. Whenever uniformly scattered porosity is encountered, the cause is generally faulty welding technique or defective materials, or both.
2. Cluster porosity is a localised grouping of pores that may result from improper initiation or termination of the welding arc.
3. Linear porosity may be aligned along (1) a weld interface, (2) the root of a weld, or (3) a boundary between weld beads. Linear porosity is caused by gas evolution from contaminants along a particular boundary.
4. Piping porosity is a term for elongated gas pores. Piping porosity in fillet welds normally extends from the root of the weld toward the face. When one or two pores are seen in the surface of the weld, it is likely that many subsurfacing piping pores are interspersed among the exposed pores. Much of the piping porosity found in welds does not extend to the surface. Piping porosity in electroslag welds may be relatively long.
Regulator: A device used to reduce cylinder pressure to a suitable torch working pressure.
Resistance Welding: A group of welding processes in which fusion is produced by heat obtained from resistance to the flow of electric current in a circuit of which the work piece is a part and by the application of pressure.
SMAW: Shielded Metal Arc Welding.
Spatter: The metal particles expelled during arc and gas welding which do not form a part of the weld.
Speed: The speed in which you move your torch, electrode or gun to create the welding bead.
Tack Weld: A weld made to hold parts of a weldment in proper alignment until final welds are made.
TIG – Welding: Inert-gas welding using a non-consumable electrode (inert-gas tungsten-arc welding).
Undercut: Visible undercut is generally associated with either improper welding techniques or excessive welding currents, or both. It is generally located parallel to the junction of weld metal and base metal at the toe or root of the weld. Undercut discontinuities create a mechanical notch at the weld interface. If examined carefully , all welds have some undercut. When undercut is controlled within limits of the specifications and does not constitute a sharp or deep notch, it is usually not considered a weld defect.
The term undercut is sometimes used in the shop to describe melting away of the groove face of a joint at the edge of a layer or bead of weld metal. It forms a recess in the joint face where the next layer or bead of weld metal must fuse to the base metal. If the depth of fusion at this location is too shallow when the next layer of weld metal is supplied, voids may be left in the fusion zone. These voids would be identified as incomplete fusion. This type of undercut is usually associated with incorrect manipulation of the welding electrode while depositing a weld bead or layer next to the joint face.
Underfill: Underfill results simply from the failure of the welder operator to fill the joint with weld metal as called out in the welding procedure specification or on the design drawing. Normally, the condition is corrected by adding one or more additional layers of weld metal in the joint prior to subsequent processing.
Welding Procedure: A specified course of action followed in welding including the list of materials and, where necessary, tools to be used.
Welding Sequence: The order and direction in which joints, welds or runs are made.