Glossary
A
Abrasion-resistance the ability of the galvanized coating to resist damage caused by contact with hard, rough, or coarse media or objects
Abrasive blasting the process of using a forceful stream of particles, available in varying hardness, to remove residue and contaminants from steel surfaces to prepare for galvanizing and/or to profile steel surfaces for paint application
Adherence the act, action, or quality of zinc bonding to steel, measured in pounds per square inch (psi) or mega pascals (MPa)
Aggressive environment an environment that is particularly corrosive
Alloy layers the interior layers of the galvanized coating comprised of iron/zinc intermetallics formed when molten zinc reacts with iron in the steel
Aluminum element found in the galvanizing bath (added to molten zinc through a product commonly called brightener bar) that gives the hot-dip galvanized coating a shiny appearance
Aluminum-killed steel steel treated with aluminum as an oxidizing agent in order to reduce the oxygen content to such a level that no reaction occurs between carbon and oxygen during solidification
Amphoteric having the characteristics of an acid and a base and capable of reacting chemically either as an acid or a base
Anion a negatively charged ion, especially the ion that migrates to an anode in electrolysis
Anode the electrode of an electrolytic cell at which corrosion (oxidation) occurs, positive current flows from the anode through the electrolyte to the cathode; with respect to hot-dip galvanizing, anode refers to zinc, which corrodes sacrificially to protect steel
Anodic exhibiting the properties of an anode; zinc is anodic to steel
Application the act of putting to use; specifically, the use to which galvanized steel will be put
Aqueous relating to, similar to, containing, or dissolved in water; watery
Ash solid byproduct formed in the galvanizing process, consisting primarily of zinc oxides, that remains on the surface of the kettle; commonly referred to as skimmings
Ash inclusions ash or skimmings carried out of the kettle on parts; ash inclusions remain solidified in the coating
Assemblies the fitting together of manufactured parts into a complete structure, machine, or unit of a machine; assemblies sometimes require specific design features in order to be optimally galvanized
ASTM American Society of Testing and Materials
Atmosphere a surrounding influence or environment that affects the rate of corrosion; frequency and amount of moisture, humidity, chlorides, sulfides, and wind are some of the atmospheric components affecting corrosion rates
B
Barrier protection the protection provided by inhibiting oxidation (rust) by an insoluble top-coating such as zinc, which isolates steel from any electrolytes that would assist the corrosion process
Bond strength the strength with which two or more items are joined; the resistance that must be overcome in order to separate the joined materials, e.g. steel and zinc-iron alloy layers of the galvanized coating, or galvanized reinforcing steel and concrete
Brown staining reaction between exposed intermetallic layers (specifically the iron portion of the layers) and oxygen, resulting in surface color changes from gray to brown
Bracing metal that is attached to a fabrication prior to galvanizing in order to provide support so that the steel does not change shape during heating and cooling; can be temporary or permanent
C
Camber the condition of having an arched surface
Carbon naturally occurring element commonly found in steel
Cast iron a generic term for a large family of cast ferrous alloys
Cast steel steel in the form of an object at or near finished shape, produced by pouring molten steel into a mold
Casting an object at or near finished shape obtained by solidification of a metal or alloy in a mold
Cathode the electrode of an electrolytic cell at which reduction occurs; positive current flows from the anode (zinc) through the electrolyte to the cathode (steel)
Cathodic exhibiting properties of a cathode; steel is cathodic in relation to zinc
Cathodic protection reduction or prevention of corrosion of a metal surface by making it a cathode in an electrolytic cell, using either a galvanic or impressed current; zinc cathodically protects steel, i.e. sacrificially giving up electrons to protect the steel from corrosive attack
Caustic cleaning the cleaning of steel in a solution with high alkalinity; in the hot-dip galvanizing process, organic residues are removed by immersing steel in a tank of caustic solution
Centrifuging the process of removing excess zinc from small hot-dip galvanized parts by placing them in a perforated, rapidly spinning cylindrical container
Chemical cleaning the process of immersing steel in chemical solvents to remove (dissolve) residues that would otherwise prevent the galvanized coating from forming
Chemical composition the makeup of steel, broken down into naturally occurring elements; usually carbon, manganese, phosphorous, silicon as primary elements
Chromate quenching treating metal in a tank of containing a solution of chronium compounds to produce a conversion coating consisting of trivalent and hexavalent chromium compounds; chromate passivations sometimes are used on galvanized reinforcing bar to control reactions between zinc and concrete while the concrete cures, particularly the hydrogen evolution that adversely affects bonding; chromate quenching other galvanized articles prevents the formation of wet storage stain
Chromating chromate quenching a galvanized article
Cleaning the process of chemically or mechanically removing unwanted residue or contaminants (mill scale, rust, dirt, oil) from the surface of a steel article prior to galvanizing
Cleaning solutions liquids used to remove unwanted residue or contaminants (mill scale, rust, dirt, oil) from the surface of steel prior to galvanizing, typically alkalai caustic solution, hydrochloric or sulfuric acid, and zinc ammonium chloride flux solution
Coating thickness the thickness of the zinc coating, measured in mils (0.001 inches) or micrometers (10-6 meters)
Cold-galvanizing See zinc-rich paint
Cold-rolled steel steel that has been produced from a hot-rolled pickled coil and given substantial cold reduction at room temperature; cold-rolled steel is characterized by improved surface smoothness, greater uniformity in thickness and improved mechanical properties when compared to hot-rolled steel
Cold-working bending or forming ambient-temperature steel; this action induces stresses that may be released during the galvanizing process
Containment the act, process, or means to keep within prescribed limits
Contraction the shrinkage of steel due to cooling of the part after removal from the galvanizing kettle
Corrosion the chemical or electrochemical reaction between a material and its environment that produces a deterioration of the material and its properties; zinc chemically reacts with elements in the atmosphere, thereby sacrificially corroding to prevent underlying steel corrosion
Cracking (concrete) the breaking of concrete due to the expansive forces caused by the formation of iron-oxide corrosion products on unprotected reinforcement bars
CSA Canadian Standards Association
D
Delta layer the second layer of zinc-iron alloy growth from the base steel formed during the galvanizing process; the Delta layers chemical composition is approximately 90% zinc and 10% iron; the Delta layer is 60% harder than the base steel it protects from abrasion and corrosion
Design to create, fashion, execute, or construct steel according to plan so that it will yield a quality hot-dip galvanized coating
Diamond Pyramid Number (DPN) system of assigning values to metals quantifying their hardness
Dissimilar metals two or more different metals in contact; due to varying surface conductivity, one or more metals may experience accelerated corrosion; because zinc is high in the galvanic series (see Galvanic Series of Metals), it preferentially corrodes to protect most dissimilar metals
Dissolution the act of dissolving, sundering, or separating into component parts; separation
Distortion any deviation from an original size, shape or contour that occurs when the application of heat during the galvanizing process releases stress from the steel induced in the fabrication process or during the steel-making process; distortion is of concern when galvanizing asymmetric structural shapes and/or fabrications
Double-dipping (see progressive-dipping) the act of dipping steel, too large in one dimension to completely fit into the galvanizing kettle, more than once in cleaning solutions and molten zinc metal in order to produce a coating that covers the entire surface of the steel
Drainage the act, process, or mode of becoming emptied or freed of cleaning solutions and/or zinc
Dross byproduct of the galvanizing process that forms by reactions between zinc and loose particles of iron; dross may exist at all depths of the kettle, but usually sinks to the bottom
Dross inclusions dross that is carried out on the work upon removal from the galvanizing kettle
Drossing removing dross buildup from the bottom of the kettle
Dry galvanizing dipping steel in an aqueous zinc ammonium chloride solution and then thoroughly drying before immersing in the molten zinc bath
Ductile iron molten iron treated with an element such as magnesium or cerium to induce a measurable degree of ductility to the metal; these additives do not affect galvanizeability
Ductility the ability of a material to be formed without fracturing; galvanized steel is ductile within certain recommended bending radii
Duplex systems galvanized steel that has been coated with an additional corrosion-inhibiting product, typically liquid or powder paint; the two separate coating systems work synergistically to provide enhanced corrosion protection
E
Electrical isolation separating two conductive materials from electrical contact; galvanized steel is sometimes electrically isolated in order to prevent rapid consumption of the zinc coating
Electrode see anode or cathode, whichever is appropriate
Electrolyte an ionized chemical substance or mixture, usually liquid, that will conduct electric currents; water, soil, or many chemical solutions
Embrittlement reduction in the normal ductility of a metal due to a physical or chemical change that may occur when cold-worked steel is immersed in molten zinc in the galvanizing kettle
Environment the complex of physical, chemical, and biotic factors (climate, soil, living things) that act upon metal and ultimately affect the corrosion rate
Eta layer the fourth, outer layer of the galvanized coating solely comprised of zinc
Excess zinc extra amounts of zinc that may accumulate on the steel because of chemical composition of the steel or the profile/design of the steel and/or fabrication
External venting holes that prevent high-pressure gas buildup in enclosed fabrications dipped in the molten zinc of the galvanizing bath
F
Fabrication steel configurations constructed from diverse and usually standardized steel members
Fasteners manufactured steel products (bolts, nails, etc.) used to connect two or more steel members
Fatigue strength the maximum stress that can be sustained for a specified number of cycles without failure, the stress being completely reversed within each cycle unless otherwise stated
Faying surfaces the surface of a piece of metal (or a member) in contact with another to which it is or is to be joined
Ferrous metals metals containing iron
Finishing final stages of inspection and preparing galvanized steel so that it complies with specification(s)
Flux chemicals used to protect steel from oxidation prior to entering the molten zinc-containing kettle
Flux inclusions Flux carried out onto the work from the top flux blanket incorporated in the wet process; occurs only in the wet galvanizing process
Fluxing the process by which steel is dipped in aqueous zinc ammonium chloride to remove undesirable substances and to protect it from further oxide formation prior to entering the galvanizing bath
Forged steels steels formed by plastically deforming metal, usually hot, into desired shapes with compressive force, with or without dies
Fresh water sodium-chloride-free water, especially when considered as a natural resource
G
Galling a condition whereby excessive friction between high spots on two different steel parts results in localized welding
Galvanic corrosion corrosion associated with the current of a galvanic cell consisting of two dissimilar conductors in an electrolyte solution, or two similar conductors in dissimilar electrolytes
Galvanic Series of Metals a listing of metals and alloys arranged according to their relative electrode potentials in a specified environment; indicates what metal(s) will corrode first when two or more metals are in contact
Galvanizing the act of coating steel with zinc in order to provide barrier and cathodic protection from corrosion
Galvanizing temperature the temperature at which the molten zinc bath is kept in order to react with the steel; typically, this temperature is between 830 F (443 C) and 850 F (454 C)
Gamma layer the first layer of zinc-iron alloy growth from the base steel formed during the galvanizing process; the chemical composition of this layer is approximately 75% zinc and 25% iron; the Gamma layer has a DPN of 250, compared to the base steels DPN of 159
Grinding mechanically removing material from a work-piece with a grinding wheel or abrasive belt
Grit-blasting abrasive blasting with small irregular pieces of steel, malleable cast iron or hard nonmetallic materials
H
Handling the process by which steel articles are carried throughout the galvanizing facility, by chain, wire, hook, or racked in a fixture
Hardness resistance of metal to plastic deformation, usually by indentation; the term may also refer to stiffness or temper, or to resistance to scratching, abrasion or cutting
Heat-treating heating and cooling a solid metal or alloy in such a way as to obtain desired conditions or properties
High-strength low-alloy (HSLA) steel steels with a high yield point and low percentages (<1.25%) of other alloying components
High-strength steel steels that have a tensile strength over 150 ksi (1100 MPa)
Hinges a jointed or flexible device upon which a door, lid, or other swinging part turns
Holding devices fixtures used to connect fabrications/parts to be galvanized to handling equipment in the galvanizing facility
Hot-rolled steel steel deformed plastically at such a temperature and strain-rate that re-crystallization takes place simultaneously with the deformation, thus avoiding strain-hardening; this is the most common type of steel galvanized
Hydrochloric acid solution used in the cleaning stages of the galvanizing process and consisting of one hydrogen ion and one chloride ion (chemical formula: HCl) in mixture with water
Hydrogen embrittlement a condition of low ductility in metals resulting from the absorption of hydrogen
I
Identification marking/labeling steel so that different customer products can be distinguished from one another after galvanizing
Impact resistance the ability to avoid damage due to contact with a forceful motion or object; galvanized coatings uppermost, pure zinc Eta layer is relatively soft and absorbs impact shock, protecting the underlying alloy layers
Impurities elements or compounds in which their presence is undesired
Insoluble not soluble; in capable or difficult of being dissolved, as by liquid; as, chalk is insoluble in water
Inspection coating thickness and surface condition verifications
Intermetallic interior layers of the galvanized coating that have distinct proportions of the alloying metals iron and zinc; e.g. Delta, Gamma & Zeta layers
Internal stress also known as residual stress, stress present in a steel member or fabrication that is free of external forces or thermal gradients
Internal venting holes on the inside of enclosed fabrications that allow cleaning solutions, zinc, and any gases to freely flow throughout the structure
ISO: International Organization for Standardization A network of national standards institutes from 140 countries working in partnership with international organizations, governments, industry, business and consumer representatives. The source of ISO 9000 and more than 13,000 international standards for business, government and society. Click here to view the Foreign Specification & ASTM Cross-Reference Chart.
K
Kettle molten zinc-filled tank where the metallurgical bonding of zinc and steel takes place
L
Lifting points connectors (sometimes temporary) directly on the steel article that aid the galvanizer in handling the article throughout the galvanizing process
M
Machined surfaces surfaces cleaned or otherwise altered by a power-driven machine
Malleable iron iron that permits plastic deformation in compression without rupture
Manganese a grayish white, usually hard and brittle metallic element found in steel that resembles iron but is not magnetic
Masking using a material to produce intentionally ungalvanized areas, typically used in areas that are to be welded, on faying surfaces, or areas where the galvanized coating is not necessary for uniform corrosion protection
Matte dull, lacking or deprived of shine; matte-gray galvanized appearance may result from steel chemistry or may be intentionally induced when the galvanized steels use defines reflectivity limits
Mechanical cleaning removing residues or impurities from steel using mechanical force such as grinding or sand blasting
Mechanical properties the properties of a material that reveal its elastic and inelastic behavior when force is applied, thereby indicating its suitability for mechanical applications; for example, elasticity, tensile strength, elongation, hardness, and fatigue limit
Metalizing forming a metallic coating by atomized spraying with molten zinc or by vacuum deposition; also called spray metalizing; applying an electrically conductive metallic layer to the surface of another material
Metallurgical relating to the study of metals and their properties in bulk an at the atomic level
Metallurgical bond the bonding of iron/zinc intermetallic layers to the base steel
Mill lacquer organic protective coating applied to steel parts, usually pipes or tubes, to protect the parts during shipping; this material cannot be removed by the usual galvanized cleaning methods
Mill scale a heavy, imbedded iron oxide layer formed during hot fabrication or heat-treatment of steels
N
Nickel common element found in the galvanizing kettle to suppress the reactivity of silicon and phosphorus in the steel
Notching cutting out various shapes from the edge of a strip, blank or part
O
Organic contaminants surface impurities (dirt, grease, oil, paint markings) that will hinder the formation of the galvanized coating, usually removed in the caustic cleaning stages of the galvanizing process
Overlapping surfaces created when one area of a metal structure is covered by the surface of another metal structure
Overtapping cutting female fastener threads of nuts or threaded holes larger than standard to account for the increased diameter of the galvanized (male) mating part
Oxidized to combine with oxygen; make into an oxide
P
Passivation changing chemically active metal surfaces to a much less reactive state (see phosphating and chromating)
Patina relatively insoluble zinc carbonate layer that forms as the galvanized coating weathers, providing added corrosion protection and abrasion resistance
Phosphating forming an adherent phosphate coating on a metal by immersion in a suitable aqueous phosphate solution, commonly used to promote better adhesion of paint to galvanized steel
Phosphorus naturally occurring element commonly found in steel, particularly reactive in molten zinc metal
Pickling removing surface oxides from metals by immersion in ambient temperature, dilute hydrochloric acid or hot (180 F/82 C) sulfuric acid
Pinhole small hole left in a weld area that allows low viscosity liquids to enter and become pressurized under the high temperature conditions of the molten zinc bath
Pitch diameter the diameter of a fastener cylinder prior to threading
Pitted surfaces areas of metal where small, sharp cavities exist, usually formed by corrosion
Polarization the partial or complete polar separation of positive and negative electric charges in a nuclear, atomic, molecule or chemical system
Post-treatment subjecting the steel to specific processes after it has been galvanized (see quenching, phosphating, and chromating)
Pre-flux the process of fluxing steel before it enters the galvanizing kettle as opposed to using a top-flux layer, which would be located on top of the molten zinc in the kettle
Pre-treatment subjecting steel to specific processes before galvanizing
Progressive dipping the act of dipping steel more than once in cleaning solutions and molten zinc metal in order to produce a coating that covers the entire surface of the steel; commonly done when the steel article/fabrication is too large to fit entirely into the kettle in one dip
Q
Quenching rapid cooling by dipping galvanized steel in a tank filled with a liquid solution; usually water or a dilute chromate or phosphate solution
R
Racking the process of arranging articles on a rack in order to transport them more efficiently through the galvanizing process
Reduce to remove oxygen from (a compound)
Reinforcing steel steel embedded in concrete to increase the concretes load strength
Repair performing finishing work after galvanizing in order to meet standards or specifications, or coating areas of steel that have been exposed due to post-galvanizing fabrication, installation, or extremely rough handling
Residue contaminants (oil, grease, dirt, rust, mill scale) that unless removed, will prevent complete galvanizing of the steel surface
Return current path the path through which the current in an electric cell returns to the source
Rinsing removing any active solution from the surface of steel by immersion in water Rust -* corrosion product consisting of hydrated iron oxides; this term is applicable only to ferrous (iron-containing) alloys
Rust corrosion product consisting of hydrated iron oxides; this term is applicable only to ferrous (iron-containing) alloys
Rust staining reaction between exposed intermetallic layers (specifically the iron portion of the layers) with oxygen, that cause mild red or brown staining.
S
Salt water water with high concentrations of sodium chloride or other salts
Scale a thick layer of imbedded oxidation (rust) products on metals
Seal-welding a weld used primarily to obtain tightness and prevent the flow of cleaning solutions and zinc into otherwise enclosed areas, to prevent flash steaming that causes localized ungalvanized areas
Service-life anticipated length of time zinc will protect steel; the amount of time until enough of the galvanized coating is consumed and 5% of the substrate steel surface area shows signs of rust
Shearing the type of force that causes or tends to cause two parts of the same body that are touching along a boundary to slide relative to each other in a direction parallel to their plane of contact
Shot-blasting abrasive blasting steel with metal shot, usually to remove deposits or mill scale more rapidly or more effectively than can be done by sand-blasting or chemical cleaning
Silicon naturally occurring element commonly found in steel; silicon is particularly reactive in molten zinc metal
Silicon-killed steel steel treated with silicon as an oxidizing agent in order to reduce the oxygen content to such a level that no reaction occurs between carbon and oxygen during solidification
Skimmings (ash) galvanizing byproduct comprised mainly of zinc oxides; skimmings are recyclable
Skip-welding alternating the weld so that it is not continuous or complete
Spalling (concrete) the complete failure of concrete due to the expansive forces caused by the formation of corrosion products on unprotected reinforcement bars
Soluble susceptible of being dissolved in a fluid; capable of solution; as, some substances are soluble in alcohol which are not soluble in water
Spangle the characteristic crystalline form exhibited by the solidified, hot-dipped zinc coating
Stainless steel type of steel alloy that contains significant amounts of chromium and/or nickel and is typically very corrosion resistant due to its ability to passivate upon atmospheric exposure
Stamping a general term covering almost all press operations, including blanking, shearing, hot-forming, cold-forming, drawing, bending, coining
Stenciling the process by which lettering or a design through which a substance (ink, paint, or metallic powder) is forced onto a surface to be printed; commonly used to mark steel fabrications but generally does not remain after the galvanizing process
Storage the area where galvanized articles are staged for pick-up or delivery
Strain-age embrittlement the loss in ductility accompanied by an increase in hardness and strength that occurs when low-carbon steel (especially rimmed or capped steel) is aged following plastic deformation; the degree of embrittlement is a function of aging time and temperature, occurring in a matter of minutes at the galvanizing temperature but requiring a few hours to years at room temperature
Stress-relieving heating to a suitable temperature, holding long enough to reduce residual stresses and then cooling slowly enough to minimize the development of new residual stresses
Structural steel member of specific cross-sectional dimensions used in fabrication and/or construction, (e.g. H-beam, angle, I-beam, W-flange)
Structural steel shape piece of steel of any specific design accepted as standard by the structural branch of the steel industry
Sulfuric acid solution used in the cleaning stages of the galvanizing process that consists of two hydrogen ions and one sulfate ion (chemical formula: h2SO4) in a water mixture
Surface condition state of the surface of the steel
Surface preparation stages of cleaning that prepare the steel for finishing (galvanizing)
Sweep direction or departure of a curve, a road, an arch, or the like, away from a rectlinear line
T
Tank container for chemicals used in the galvanizing process; steel is dipped sequentially in solution-containing tanks
Temporary bracing metal that is attached to a fabrication prior to galvanizing in order to provide added support so that the steel does not change shape during heating and cooling; temporary bracing is removed after galvanizing.
Thermal expansion the process by which steel becomes larger upon heating
Thermodynamic characteristics of or resulting from the conversion of heat into other forms of energy
Threaded parts parts such as bolts and rods that allow nuts to be screwed on to one or both ends
Touch-up performing finishing work after galvanizing in order to meet standards or specifications, or coating areas of steel that have been exposed due to post-galvanizing fabrication, installation, or extremely rough handling
V
Venting providing holes in fabrications to be galvanized to allow entrapped, heated liquids and gases to escape as pressure increases
Vibrating the process of removing excess zinc by rapidly shaking galvanized articles
Viscosity the property of resistance to flow in a fluid or semi-fluid state
Voluminous having great volume, fullness, or size
W
Warping twisting or curving of steel originally flat or straight
Weathering steel corrosion-resistant steel that initially corrodes; the presence of corrosion products then limits the further oxidation of the metal
Weepage the leaching out of trapped liquid solutions in galvanized structures, primarily through pinholes or gaps in welds that were not sealed over by zinc
Weld beads deposits of filler metal from a welding pass
Weld flux material used to prevent the formation of, or to dissolve and facilitate removal of, oxides and other undesirable substances
Weld residue impurities left from the welding process; weld residue will inhibit localized formation of the galvanized coating.
Weld slag material resulting from the combination of weld material and weld flux; weld slag will inhibit localized formation of the galvanized coating
Welding joining two or more pieces of material by applying heat or pressure, or both, with or without filler material, to produce a localized union through fusion or recrystallization across the interface
Wet galvanizing using a liquid flux layer floated on top of the molten zinc; in the galvanizing process, final cleaning occurs as the material passes through the flux blanket before entering the molten zinc bath
Wet storage stain white surface oxide and hydroxide that forms on newly galvanized steel when excessive moisture is present in poorly ventilated storage
Wheel-abrading mechanical cleaning method used to remove small amounts of residues found on steels by means of a rough, rotating wheel
White rust white, sticky substance comprised of basic zinc carbonate; forms when galvanized surfaces are constantly covered by water or water containing sulfides or chlorides
Z
Zinc major element found in the galvanizing kettle that provides both barrier and cathodic protection for steel
Zinc ammonium chloride typical component of the flux solution used in the cleaning phase of the galvanizing process
Zinc carbonate patina relatively insoluble zinc carbonate layer that forms as the galvanized coating weathers, providing added corrosion protection and abrasion resistance
Zinc hydroxide corrosion product formed in response to the presence of moisture on galvanized articles
Zinc oxide basic corrosion product formed almost instantaneously on freshly galvanized articles after withdrawal from the molten zinc metal
Zinc patina relatively insoluble zinc carbonate layer that forms as the galvanized coating weathers, providing added corrosion protection and abrasion resistance
Zinc solder material used to touch-up and/or repair hot-dip galvanized surfaces
Zinc-iron alloy layers inner layers of the galvanized coating formed from interdiffusion reactions between iron in the base steel and molten zinc metal, (e.g. Delta, Gamma, Zeta)
Zinc-rich paint (also called cold galvanizing) material used to touch-up and or repair hot-dipped galvanized surfaces, providing barrier protection and some cathodic protection (if the concentration of zinc is above 94% in dry film thickness)
© American Galvanizers Association. The information provided herein has been developed to provide accurate and authoritative information about after-fabrication hot-dip galvanized steel. This material provides general information only and is not intended as a substitute for competent professional examination and verification as to suitability and applicability. The information provided herein is not intended as a representation or warranty on the part of the AGA. Anyone making use of this information assumes all liability arising from such use.