glossary of welding and metallurgical terms

8/13/2019 Glossary of Welding and Metallurgical Terms

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PROCEDURES AND DATA

GLOSSARY

WELDING/ METALLURGICAL TERMS

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PROCEDURES AND DATA

Abrasive Wear – Abrasive wear is caused by foreign materials rubbingagainst a metal part and is the most frequent reason for hard surfacing.

Abrasive wear is usually broken down into three main categories:

1. Low-stress scratching abrasion – Normally the least severe type of abra-sion, metal parts are worn away through the scouring action of hard, sharpparticles such as sand sliding down a chute.

2. High-stress grinding abrasion – This results when small hard abrasiveparticles are forced against a metal part. The surface becomes scored andsurface cracking can occur. The drilling action of an auger is the bestexample.

3. Gouging abrasion – This occurs when massive objects are forced with

pressure against a metal component. A good example of this is a draglinebucket digging into the earth.

AC (Alternating Current) – Electricity which reverses its direction periodi-cally, e.g., for 60 cycle current, the current goes in one direction and then inthe other direction 60 times in the same second, so that the current changesits direction 120 times in one second.

Adhesive Frictional Wear (Metal-to-Metal Wear) – Metal surfaces,regardless of their finish, are composed of microscopic high and low areas.

As metal surfaces slide against each other, the high areas are broken and tinyfragments of metal are torn away. The continual removal of metal roughensand wears the working surface.

In some applications, adhesive wear can be minimized by proper lubrication.Adhesion also lessens when the sliding metals are different, or when themetal is extremely hard.

Alloy – A substance that has metallic properties and is composed of two ormore chemical elements of which at least one is a metal.

Alloy Steel – Carbon steel with the addition of other alloying elements likechromium, nickel, molybdenum, vanadium, tungsten and manganese.Generally the chemical makeup of alloy steels contains greater than 5% of some combination of these elements. The additional elements are added forthe definite purpose of changing the hardenability or response to heat treat-ment. When properly heat treated, alloy steels provide varying degrees of hardness, strength, ductility, machinability and impact resistance that cannotbe secured in plain carbon steels. Since they are heat treatable, special pre-cautions are usually required for welding, e.g., preheat and postheat.

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C O N F I D E N T I A L M A T E R I A L , R

E P R O D U C T I O N , I N W H O L E O R I N

P A R T , P R O H I B I T E D

Printed in U.S.A. (Rev. 6/97)

GLOSSARY — WELDING/METALLURGICAL TERMS– Continued –





PROCEDURES AND DATA

Aluminum – One of the most commonly used light/white metals. Symbol Al, obtained chiefly from bauxite. This metal is light weight (about 1/3 the

weight of steel) and has a relatively low melting point at 1220°F. Aluminumis non-magnetic, highly reflective, soft and ductile in the annealed condition.It can be cold worked to moderate tensile strength (about 16,000 PSI). It alsohas a high coefficient of electrical and thermal conductivity. It resists corro-sion in many environments due to the presence of a thin Al oxide film. It isreadily weldable and can be alloyed with various elements to improvemechanical properties, primarily strength, with a slight sacrifice in density,thus increasing its strength to weight ratio.

Amperage – A measure of the electrical units which indicate the amount of

current traveling through a circuit.

Annealing – Softening of metals by heat treatment. This most commonlyconsists of heating the metal up to a critical temperature and then coolingslowly. For steels, annealing consists of heating the steels to slightly abovethe recrystallization temperature, holding for austenite to form, then slowlycooling to produce small grain size, softness, ductility and other properties.On cooling slowly, the austenite transforms to ferrite and pearlite.

Anodize – A reverse plating process. This process is used on aluminum to

remove a thin film of material to allow the aluminum to oxidize evenly giv-ing a dull satin finish. If a colored finish is desired, the oxidized surface maybe treated with a dye solution.

Arc Welding – Fusing two metals together using an electric arc as thesource of heat. Filler metal may or may not be added.

A.S.T.M. – American Society for Testing and Materials

Atomic Hydrogen – Atomic hydrogen welding is an arc welding processwherein coalescence is produced by heating with an electric arc maintainedbetween two metal electrodes in an atmosphere of hydrogen. Shielding isobtained from the hydrogen. Pressure may or may not be used, and fillermetal may or may not be added.

Austenite – A non-magnetic cubic structure that occurs in carbon steelsabove the critical temperature range (~1350°F to 1750°F depending on car-bon content). The 300 series stainless steels are austenitic at room tempera-ture, as such they are non-magnetic & relatively soft with good corrosionresistance.

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PROCEDURES AND DATA

Back Step Welding – A method of controlling welding heat, by making a longweld in a series of short increments. It is, for example, welding from left to

right, by going right to left in short increments. Each weld causes a minimumof warpage, since the heat travels ahead of the weld, into a segment which isalready welded.

Base Metal – The metal to welded, soldered or brazed.

Bevel – Angling the metal edge where welding is to take place. This is gener-ally required to achieve full penetration when welding heavy sections. Typicalbevel shapes are V, U, J grooves either on one side of the joint or both.

Bond Line – The transition zone between the weld deposit and base metal.Sometimes called “interface.”

Brass – Brass is a copper zinc ( Zn) alloy whose zinc content ranges from5% up to 40%. As the Zn content increases in these alloys the melting point,density, electrical and thermal conductivity and modules of elasticitydecrease, while the coefficient of expansion, strength and hardness increases.Work hardening also increases with higher zinc content. The color of these

brasses range from reddish brown (like copper) for the low zinc alloys,through bronze and gold colors, to the yellow of high zinc brasses. This willaffect the selection of a filler metal when joint appearance is important.

Brazing – A joining process where the filler metal is non-ferrous metal oralloy whose melting point is greater than 800°F but lower than the metals tobe joined.

Brinell Hardness – The hardness value (BHN) of a metal expressed in threedigits. For steels, the first two numbers are a close approximations of the

Rockwell “C” hardness number, e.g. BHN 500 is approx. equal to Rc 50.

Brinell Hardness Tester – The Brinell Hardness Tester consists of a rigidframework with an adjustable anvil on which the specimen is placed. Byhydraulic pressure a small steel ball is forced into the surface of the speci-men with a definitely controlled load. The size of the impression varies withthe hardness of the metal. The diameter of the impression is read with asmall microscope which is calibrated by fine parallel measuring lines so thatthe diameter of the impression can be determined in millimeters. This figureis converted to a Brinell hardness number by reference to a standard table.

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Direction of Welding

1 2 3 4 5

Deposit Sequence



PROCEDURES AND DATA

Generally speaking, hardness bears a direct relationship to tensile strength.The Brinell hardness number of steel when multiplied by 500 will approxi-

mate the tensile strength in pounds per square inch.

Bronze – The term bronze is generally applied to any copper alloy that hasas the principle alloying element a metal other than zinc or nickel. Originallythe term was used to identify copper-tin alloys that had tin as the only, orprinciple, alloying element. Most commercial copper-tin bronzes are nowmodified with zinc, lead or other elements to alter physical and mechanicalproperties. Bronzes containing more than 90% copper are reddish and below90% the color changes to orange-yellow, which is the typical bronze color.

Butt Weld – A weldment formed by placing the edge of two plates togetherand depositing a weld down the joint.

Buzz Box – Slang term for a small alternating current (AC) arc weldingmachine.

Capillary Action – The combination force, adhesion and cohesion, whichcauses liquids, including molten metals, to flow between very closely spacedsolid metal surfaces even against gravity.

Carbide Precipitation – A chemical reaction sometimes occurring inchrome-nickel steels, e.g., austenitic stainless steel, in which the chromium,near the boundaries of the grains, flows to the boundaries and unites withcarbon, thus forming the chrome carbides and depleting the chromiumsupply in the metal near the grain boundaries. This makes the steel suscepti-ble to intergranular corrosion when brought into contact with various acidsor alkalis.

Carbon Arc Cutting – Carbon arc cutting is a method for cutting or remov-ing metal by melting it with an electric arc and then blowing away themolten metal with a high velocity jet of compressed air. The air jet is exter-nal to the consumable carbon-graphite electrode. It removes the moltenmetal immediately behind the arc.

Carbon Arc Welding – Carbon arc welding is a process in which an arc isestablished between a nonconsumable carbon (graphite) electrode and thework, or between two carbon electrodes. The latter is a variation known astwin carbon arc welding. Two other variations known as shielded and gascarbon arc welding no longer have commercial significance.

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PROCEDURES AND DATA

Carbon Steel – Steel containing carbon up to about 2.00% and only residualquantities of other elements except those added for deoxidation, with silicon

usually limited to 0.60% and manganese to about 1.65%. Also termed “plaincarbon steel” and “straight carbon steel”.

Carburizing Flame – A flame in an oxygen-fuel gas system with an excessof the fuel gas.

Casting – (1) An object at or near finished shape obtained by solidificationof a substance in a mold. (2) Pouring molten metal into a mold to produceobject of desired shape.

Cast Iron – A wide range of iron-carbon-silicon alloys (ferrous alloys) con-taining from 2.0 to 4.0% carbon and 0.25 to 3.00% silicon. In addition, otheralloying elements, i.e. nickel, chromium, molybdenum, etc., are added forspecial applications. Common types of cast iron include gray, ductile (nodu-lar), white and malleable. Gray and ductile are most frequently used in themanufacture of machinery. White cast iron is used primarily in wear resistantapplications and is generally considered unweldable.

Cast Steel – Steel castings can be made from any of the many types of carbonand alloy steel produced in wrought form. Such castings are produced bypouring molten steel of the desired composition into a mold of the desired con-figuration and allowing the steel to solidify. Steel castings produced in any of the various types of molds and wrought steel of equivalent chemical composi-tion respond similarly to heat treatment, have the same weldability, and similarphysical and mechanical properties. Cast steels do not exhibit the effects of directionality on mechanical properties that are typical of wrought steels.

Chamfering – Removing an edge from material so it becomes an angled flatsurface like one side of a Vee (see Beveling).

Chipping – A method for removing seams and other surface defects withchisel or gouge so that such defects will not be worked into the finish product.

Coefficient of Expansion – Is the amount a given material will expandwhen subjected to a certain amount of heat.

Contact Welding – The use of a welding electrode with complete contact of electrode end to base metal, rather than using an arc-gap.

Continuous Weld – A weld which extends without interruption for its entire length.

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PROCEDURES AND DATA

Convex – A surface that is rounded outwardly, i.e. curved like the outsidesurface of a sphere.

Copper – Copper and copper alloys constitute one of the major groups of commercial metals. They are widely used because of their excellent electri-cal and thermal conductivities, outstanding resistance to corrosion, ease of fabrication, and good strength and fatigue resistance. They are generallynonmagnetic. They can be readily soldered and brazed, and many coppersand copper alloys can be welded by various gas, arc, and resistance methods.

Corrosion – Gradual chemical or electrochemical attack on a metal byatmosphere, moisture, or other agents.

Corrosion Resistance – Ability to resist oxidation such as rust or deteriora-tion and loss of weight by chemical action.

Cover Glass (Plastic) – A clear glass or high impact plastic used to protectthe shaded lens in goggles and welding helmets.

Cracking (Metals) – Fracturing or fissuring of a material.

Cracking (Gas Cyl. Valve) – Term applied to the action of opening a valveslightly and then closing the valve immediately.

Cross Checks (Relief Checks) – Small transverse cracks that occur natu-rally in some carbide bearing hard facing products.

Cushioning Layer – A relatively soft deposit on a metal to be succeeded bya harder layer.

DC (Direct Current) – Electricity which flows in one direction only asopposed to AC which periodically reverses direction. There are two kinds of direct current depending on the direction of the electrical flow (see Straightand Reverse Polarity).

Dense Deposit – A weld deposit which is free from holes, slag, inclusions,cracks, or other imperfections.

Dendrite – A crystal formed by solidification of metal which has a pine treeor fir tree like pattern with many branches.

Deoxidized – Special processing to remove harmful oxides from metals.

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PROCEDURES AND DATA

Deposited Metal – Metal that has been added by a welding process.

Depth of Fusion – The distance that fusion extends into the base metal fromthe surface melted during welding.

Die Castings – These metals are injected under pressure into heat-resistantsteel molds. The method is used for making inexpensive small parts wheresmall dimensional tolerances are required.

Die Castings (Aluminum) – Aluminum die castings differ from zinc diecastings by their light weight. Aluminum die castings also have clean, sharpedges compared to zinc castings. They can be welded, using the same meth-

ods as for aluminum sand castings.

Direction of Travel – Is the direction in which the deposits are going. Theangle at which the electrode is held, in relation to the direction of travel, isthe angle between the electrode and the surface of the part to be welded.

Discoloration – Darkening, staining, or discoloring by oxidation caused byhot metal exposed to air.

Distortion – Loss of dimensional tolerances from twisting and bending dueto welding expansion and contraction stresses.

Drag Technique – Using an electrode by maintaining complete contact withbase metal, i.e., dragging electrode in contact with base metal. This is per-formed with electrodes having coating which cups over the end of electrodeto insulate electrode from base metal.

Ductility – The ability of a material to deform plastically without fracturing,being measured by elongation or reduction of area in a tensile test, or byother means.

Electrical Conductivity – Ability to conduct electrical current.

Electrode Coating – The flux coating on the outside of a stick electrodewhich is used primarily for cleaning and protecting the hot weld metal fromexposure to air. In some cases alloying elements are added to the depositthrough the flux.

Electrode Holder – A device used for mechanically holding the electrodeand conducting current to an electrode during welding or cutting.

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PROCEDURES AND DATA

Elongation – The mathematical measurement of ductility usually expressed asa percentage of the original gage length after fracturing in a tensile (pull) test.

The higher the percentage elongation the greater the ductility (ability to stretch).The lower the percentage elongation the lower the ductility (more brittle).

Embrittlement – Reduction in the normal ductility of a metal due to aphysical or chemical change.

Exothermic – Marked by the liberation of heat – opposite of endothermic.

Extrusion – Shaping metal into a chosen continuous form by forcing itthrough a die with the approximate shape of the final product.

Face of Weld – The exposed surface of a weld, made by an arc or gas weld-ing process, on the side from which welding was done.

Fatigue – The tendency for a metal to break under conditions of cyclicstressing considerably below the ultimate tensile strength.

Faying Surfaces – That surface of a member which is in contact or in closeproximity with another member to which it is to be joined.

Ferrite – Is practically pure iron (in plain carbon steels) existing below the

lower critical temperature. It is magnetic and has very slight solid solubilityfor carbon.

Ferrous Metal – A metal which is primarily iron bearing (such as steel orcast iron).

Filler Metal – The wire or electrode used to make the weld deposit.

Fillet Weld – A fillet weld is a weld applied to the joint where one plate isplaced perpendicular to another.

Finger Nailing – The action when the end of the electrode arcs to one sidecausing an uneven deposit and poor operability. This is usually caused by anexcentric coating.

Flame Hardening – This process consists of heating the surface of a hard-enable steel to its recrystallization temperature with an oxy-fuel or inductionsystem, followed immediately by a rapid quench (usually a water spray).This case hardens the steel to a certain depth which is usually predeterminedby making some mock-up tests.

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PROCEDURES AND DATA

Flame Straightening – Correcting distortion in metal structures by localizedheating with a gas flame.

Forging – Plastically deforming metal, usually hot, into desired shapes withcompressive force, with or without dies.

Frictional Wear – (see Adhesive Wear)

Fusion Welding – A group of welding processes in which metals broughtto the molten state at the surfaces to be joined are welded with or withoutthe addition of filler metal and without the application of mechanical pres-sure or blows.

Galvanized – The coating of steel with zinc to prevent rust.

Gamma Iron – A non-magnetic complex cubic structure found in carbonsteels at elevated temperature and in 300 series stainless steels at roomtemperature (see Austenite).

Gas Cutting – The process of severing ferrous metals by means of thechemical reaction of oxygen and iron in the base metal.

Gas Pocket – A cavity in a weld deposit caused by entrapped gas (air).

Gas Tungsten-Arc Welding (GTAW) – An arc-welding process whereincoalescence is produced by heating with an arc between a single tungsten(nonconsumable) electrode and the work. Shielding is obtained from a gas orgas mixture. Pressure may or may not be used and filler metal may or maynot be used. (This process is frequently called TIG welding.)

Gas Welding – Welding of metals in which the fusion is accomplished byand oxygen/fuel flame.

Globular – A mode of metal transfer in gas metal-arc welding in which theconsumable electrode (wire) is transferred across the arc in large droplets.Usually the droplets are larger in diameter than the electrode wire itself.

Gouging – The forming of a bevel or groove by mechanical or thermalremoval of metal surfaces.

Gradient – Rate of change in a variable quantity (slope).

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PROCEDURES AND DATA

Grains – Individual crystals in metals.

Gray Cast Iron – A weldable grade of cast iron with linear shaped graphiteuniformly distributed in an iron matrix.

Groove Weld – A weld made in the groove between two members to be joined. The standard types of groove welds are as follows:

Square Groove WeldSingle-Vee Groove WeldSingle-Bevel Groove WeldSingle-U Groove WeldSingle-J Groove Weld

Double-Vee Groove WeldDouble-Bevel Groove WeldDouble-U Groove WeldDouble-J Groove Weld

Ground Connection – See preferred term, “welding ground.”

Hard Surfacing – Application of wear resisting welding deposits to thesurface of a metal to improve its wear resistance and service life.

Heat-Affected Zone – The portion of the base metal next to the welddeposit whose structure and properties has been altered by the heat of welding, brazing, soldering or thermal cutting.

Heat Treatable – A material which can be hardened by a heat treatmentprocess.

Heat-Treatment of Metals – Metals are usually heat-treated to impart cer-tain desirable mechanical properties such as hardness, toughness, softness,or intermediate stages of these properties.

This is accomplished by heating a metal to a high temperature, followed by acontrolled rate of cooling, and then tempering by reheating.

Heliarc Welding (TIG Welding) – (see Gas Tungsten Arc Welding)

Helmet (Shield) – A protective headgear with shaded filter lens used in arcwelding processes for shielding the face and neck from harmful infra-redand ultra-violet radiation.

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PROCEDURES AND DATA

High Alloy Steel – Steels with a high percentage of alloying elements likechromium, nickel, molybdenum etc. These steels are heat treatable and

require special procedures for welding.

High Carbon Steel – Plain carbon steel (no alloying elements) with0.60–2% carbon content. These steels are normally heat treated to a highhardness. To avoid cracking during welding special precautions are requirede.g. preheat, postheat, etc.

High Speed Steel – A tool steel formulated to maintain a high hardnessvalue at elevated temperatures (>1000°F).

High Thermal Energy – Energy produced by heat.

Hot Shortness – Brittleness in metal in the hot forging range.

Hydro-Flo – A trade name for special gas welding alloys developed by theresearch teams of Cronatron especially for maintenance welding applica-tions. They produce higher strength and greater application ease than ordi-nary welding rods.

Impact Wear – The forceful impact from a foreign object onto a metal partthat deforms the metal permanently. Some alloys can withstand high impactloads, while others are too brittle and cannot withstand severe blows. A goodexample of impact wear is rotary hammers becoming deformed by crushingrock.

Inconel – A group of nickel base alloys formulated for excellent corrosionresistance and high temperature properties.

Induction Heating – Induction heating is a process in which heat is gener-ated in a metal part by placing it in an alternating magnetic field. The rever-sal of this magnetic field rapidly generates a high degree of heat which canbe used very effectively for metal joining. This process is readily adaptableto mass production.

Infra-red & Ultra-violet Rays – The two forms of harmful radiation givenoff by an electric arc.

Intermittent Welding – Welding wherein the continuity is broken by leavingrecurring unwelded spaces.

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PROCEDURES AND DATA

Internal Stresses – (see Residual Stresses)

Ion – An atom or group of atoms bearing an electric charge.

Lap Welds – A lap weld is used where two plates are allowed to overlap andthe edge of the one plate is welded to the side of the other by fillet welding.

Low Carbon Steel – Iron with added carbon in the range of 0.05 to 0.29%.This steel cannot be heat treated so it is soft and has excellent weldability.Commonly called “Mild Steel”.

Low Hydrogen Electrode – The removal of moisture from an electrode by

long time baking. The maximum moisture content for a given electrode isgiven in the AWS specifications. In general, the higher the tensile strengththe lower the moisture limit.

Machinability – The ability to remove metal using machine tools like alathe, milling machine, shaper, etc. Machinability varies with the metal’shardness value. If metals are too hard, either from heat treatment or coldworking, they may not be machinable. In these cases they would have to beground.

Magnesium – A light/white metal which has little industrial value in its purestate. It can, however, be readily alloyed with other metals like aluminum,zinc, etc. This produces alloys comparable in strength to aluminum, yethaving only 65% of the weight of aluminum (0.06 lb./cu.in. vs. 0.09 lb./cu.in.for Al). CAUTION: In its fine form (like powder or machining chips), magne-sium will burn in an uncontrollable manner and is very difficult to extinguish,so proper precautions must be taken when welding or processing magnesium.

Manganese Steel – (Austenitic Manganese) also called “Hadfield’s man-ganese steel” after its inventor, is an extremely tough nonmagnetic alloywhich will work harden to a high degree (approx. Rc 50). This steel is char-acterized by high strength, high ductility and excellent resistance to impactwear. Because of its novel composition (typically 1.2% C and 12-14% Mn),it is particularly useful for severe service that combines abrasion and heavyimpact. Manganese is readily weldable, but should not be overheated (500°Fmaximum interpass temperature).

Manual Weld – A weld made by an operator unaided by mechanically orelectrically controlled equipment.

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PROCEDURES AND DATA

Martensite – A metallurgical phase in ferrous metals which forms duringcooling from elevated temperatures (above the critical temperature). As

quenched martensite is extremely hard and brittle, it usually requires reheat-ing or tempering to impart toughness for usability.

Meehanite – Refers to a group of gray cast irons whose chemical analysisconforms to a given specification to obtain certain properties. These castirons are readily weldable.

Melting Rate – The weight of electrode consumed in a unit of time.

Metal Arc Welding – See preferred term “Shielded Metal Arc.”

Microstructure – The structure of a polished and etched metal as revealedunder a microscope. Examples: ferrite, austenite, martensite, etc.

Mild Steel – (see Low Carbon Steel)

Monel – Alloys composed of approx. 60% nickel & 30% copper with tracesof other elements to affect mechanical properties. Monels are primarily usedfor industrial applications that demand high strength and good resistance todestructive chemical action and galling. They are readily weldable with thestandard welding processes. They also can be soldered and brazed.

Nickel – Nickel ( Ni) in its pure form is a relatively soft, ductile metal. It ismagnetic and displays good mechanical properties and corrosion resistance.Commercially pure Ni is sometimes used in welding electrodes designed forcast iron. It is very valuable when alloyed with other elements. When addedto steel it dramatically increases strength and toughness at low temperatures.Nickel base alloys (greater than 50% Ni) are very useful for applicationsrequiring good high temperature properties and high corrosion resistance,e.g. inconels, hastelloys.

Nonferrous Metal – A metal that does not have iron as its primary element(such as copper & aluminum alloys).

Outgassing – The loss of certain elements during brazing and welding byvolatilization from a solid phase to a gas.

Overhead Position – The position of welding wherein welding is performedfrom the underside of the joint.

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PROCEDURES AND DATA

Overlay – The deposition of filler metal on a metallic surface to obtaindesired properties or dimensions.

Oxides – A chemical reaction where oxygen in the atmosphere combineswith a metal to form a metallic oxide. E.g., in steels, iron combines withoxygen to form iron oxide (Fe2O3) more commonly known as rust.

Peening – The mechanical working of metal by hammering the surface witha peening tool or hand held hammer to develop compressive surface stressesto eliminate cracking.

Penetration – Depth of fusion of a weld into the base metal.

Pinholing – Small holes in a weld (see Porosity).

Pearlite – A microstructural phase with alternating layers of ferrite and ironcarbide. In some cases, with special heat treatment, the iron carbide phasecan be spheroidized to soften for machinability. Generally speaking pearliteis a soft structure and is readily weldable.

Porosity – Small holes in a weld deposit caused by entrapped gas.

Plastic Deformation – Deformation that remains permanent after removalof the load which caused it.

Position Welding – The four positions for welding: flat, horizontal, verticaland overhead.

Pot Metal – Slang term for white metal, or zinc die castings.

Preheat Broadly – Moving the preheat torch over the entire structure beingheated, rather than heating just one spot.

Preheating – Heat applied to base metal prior to welding or cutting. Heatingof a metal before welding to cause controlled uniform expansion & slowercooling rates after welding.

P.S.I. – Pounds per square inch. A standard used in testing materials.

Puddle – In welding language the molten metal consisting of melted fillerrod and/or melted base metal.

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PROCEDURES AND DATA

Pyrolysis – Chemical decomposition of substances by the action of heat.

Reducing Flame – Same as carburizing, or excess fuel flame.

Refractory Metal – A metal having an extremely high melting point. In thebroad sense, it refers to metals having melting points above the range of iron,cobalt and nickel.

Residual Stress – Internal stress resulting from thermal or mechanical treat-ment which remains in a structure or member after all fabrication has beencompleted and the part has cooled to a uniform temperature.

Reverse Polarity– The arrangement of direct current arc welding leads withthe work as the negative pole and the electrode as the positive pole of the

welding arc. A synonym for direct current electrode positive.

Rockwell Hardness Tester – The Rockwell Hardness Tester has anadjustable table on which the specimen is placed and a sharp penetratorpoint through which the load is applied to the specimen by a system of weights and levers. A light or minor load is used to seat the penetrator in thespecimen, the major load is then applied. The additional depth to which thepenetrator is driven by the heavy load is indicated on a dial in terms of Rockwell Hardness. For testing softer materials, a rounded ball penetrator isused and hardness number is read on the “B” scale. For material havinggreater hardness, a diamond point penetrator is used with a heavier load andthe hardness is read on the “C” scale.

Root of Joint – The location of closestapproach between parts of a joint to bewelded (see Fig. 1).

Root Opening – The separation between themembers to be joined at the root of joint.

Searing – A surface treatment by flame of ametal. Usually an oxidizing torch flame isused to decompose and remove surfaceimpurities.

Shear Strength – The stress required to produce fracture in the plane of cross section, the conditions of loading being such that the directions of force and of resistance are parallel and opposite.

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Root of joint

Root and groove face

Root of joint

Rootand

grooveface

Grooveface

Root of joint

Root of joint

Grooveface

Rootface

Fig. 1 Root of Joint



PROCEDURES AND DATA

Shielded Metal Arc Welding (SMAW) – An arc welding process whichproduces coalescence of metals by heating them with an arc between a cov-

ered metal electrode and the work. Shielding is obtained from decompositionof the electrode covering. Pressure is not used and filler metal is obtainedfrom the electrode.

Shim – A thin sheet of metal.

Short Arc – A term applied to gas metal arc welding when the current andvoltage are held to a low level making it suitable for joining thin metals.

Size of Weld – Groove weld : the joint penetration (depth of bevel plus the

root penetration when specified). The size of a groove weld and its effectivethroat are one and the same. Fillet weld*: for equal leg fillet welds, the leglengths of the largest isosceles right triangle which can be inscribed withinthe fillet weld cross section. For unequal leg fillet welds, the leg lengths of the largest right triangle which can be inscribed within the fillet weld crosssection. When one member makes an angle with the other member greaterthan 105°, the leg length (size) is of less significance than the effective throatwhich is the controlling factor for the strength of a weld.

*Fillet Weld – A weld of approximately triangular cross section joiningtwo surfaces approximately at right angles to each other in a lap joint,

or corner joint.

Skip Welding – Skip welding is, as the name implies, welding inter-mittently. Each pass is applied as far from the last pass as possible. Theunconnected beads are finally joined with other series of passes.

Slag – A hard glassy type covering on a weld deposit resulting from theaction of the electrode flux and the molten base metal.

Slag Inclusion – Non-metallic material entrapped in a weld.

Slag Removal – This is a term given to loosening and removing the slagadhering to weld deposits. The deposit is struck with a needle descaler orpointed hammer and then brushed with a wire brush. This removes the slagand exposes the weld deposit.

Slot Weld – A weld made in an elongated hole in one member of a lap joint joining to the surface of another member which is exposed through the hole.

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PROCEDURES AND DATA

Soldering – A joining process wherein coalescence is produced by heatingto suitable temperatures generally below 800°F and by using non-ferrous

filler metals (solders) having melting temperatures below those of the basemetals. The solder is usually distributed between the properly fitted surfacesof the joint by capillary attraction.

Stabilizing – Heating austenitic stainless steels that contain titanium,columbium or tantalum to a suitable temperature below that of a full annealin order to inactivate the maximum amount of carbon by precipitation as acarbide of titanium, columbium or tantalum.

Stainless Steel – Steels with 12% or higher chromium content. Used primar-

ily for corrosion resistance.

Stinger – Slang term for electrode holder.

Stringer Beads – A type of weld bead made without appreciable weavingmotion (see also Weave Bead).

Straight Polarity – The arrangement of direct current arc welding leads inwhich the work is the positive pole and the electrode is the negative pole of the welding arc. An alternate term is direct current electrode negative.

Stress Relieving – A heat treatment process used to eliminate internalstresses set up by welding. Generally, the weldment is placed in a furnace setat 1100°F to 1200°F and held for 1 hour per inch of thickness.

Striker Plate – A piece of metal which is placed near the weld area for thepurpose of striking the electrode on it, to avoid scarring or damaging thework piece by striking the arc on it.

Strip Form – A welding alloy made in a strip rather than a wire form. Alsoknown as ribbon or shim.

Submerged Arc Welding – An arc-welding process wherein coalescence isproduced by heating with an electric arc or arcs between a bare metal electrodeor electrodes and the work. The welding is shielded by a blanket of granular,fusible material on the work. Pressure is not used and filler metal is obtainedfrom the electrode wire(s).

Surface Checking – Transverse cracks on the surface of some hardfacingproducts that usually contain some type of elemental carbide phase.

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PROCEDURES AND DATA

Surface Tension – Interfacial tension between two phases one of which is a gas.

Tack Weld – Small scattered welds made to hold parts of a weldment inproper alignment while the final welds are being made.

Tee Joint – A welded joint at the junction of two parts located at approxi-mate right angles to each other to form a tee.

Tempering – Reheating hardened steel or hardened cast iron to some tem-perature below the critical for the purpose of decreasing the hardness andincreasing the toughness.

Tensile Strength– Tensile strength or “ultimate strength” is the maximumstress per unit of area, which can be sustained without fracture. Any load in

excess of the tensile strength will cause the specimen to break.

Tensile Testing – A tensile test consists of applying a steadily increasingpull or load to a standard sample and recording the results as the sample ispulled and ultimately broken. The tensile testing machines may be either of ahydraulic or mechanical type.

Thermal Stress – Stresses in metal, resulting from nonuniform temperaturedistribution.

Thin-Flowing – A fluid alloy which flows by capillary action when heated.

Transformer – A device used to transfer electric energy from one circuitto another.

Undercut – Groove made in base metal along bead edges by heat of the arcand left unfilled by deposited weld metal.

Underbead Crack – A crack in the heat-affected zone not extending to thesurface of the base metal.

Volt – Measure of potential causing flow of electric current.

Warpage – Synonym for distortion—loss of dimensional tolerances as aresult of welding contraction and expansion stresses.

Weave Bead – A type of weld bead made with transverse oscillation.

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PROCEDURES AND DATA

Weaving – When wider beads are required, the electrode is moved from sideto side in a weaving motion. The greatest efficiency results from a weave of

not more than 2-1/2 times the diameter of the electrode.

Weld – A localized coalescence of metal produced by heating to suitabletemperatures, with or without the application of pressure or the use of fillermetal.

Welding Ground – An electrical connection from the welding machineframe to the earth for safety.

Welding Leads – Conductors furnishing an electrical path between source

of welding power and electrodes.

Wetting Action – The ability of a filler material to flow freely into tightgaps. Usually associated with brazing and soldering (see Capillary Action).

White Cast Iron – A form of cast iron that is used exclusively for abrasionresistance. It is very hard, brittle, magnetic and considered unweldable.

White Metal – A general term covering low melting alloys that are based ontin, zinc, lead, or antimony.

Work Hardening – Hardness developed in metal as a result of cold working.

Yield Point – The point at which a metal begins to deform permanentlyunder a given load.





glossary of welding and metallurgical terms

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