Welding Ferrous Metals 211

aged

Heated to a certain temperature to cause a change in grain structure. Metals are usually aged to increase their hardness.

alloy steels

A steel that contains small percentages of purposely added materials that change its properties. Alloy steels commonly include chromium, manganese, molybdenum, and nickel.

alloying elements

A material that is intentionally added to a metal in order to change its properties. Alloying elements can improve the strength, ductility, hardness, and toughness of a finished weld.

alloys

A material consisting of a mixture of two or more elements, at least one of which must be a metal. Alloys combine the beneficial properties of the mixed elements.

aluminum

A lightweight, highly conductive, silvery metal. Aluminum may be found in ferritic stainless steels.

amperage

A measurement that indicates the amount of current flowing in a circuit. Amperage is measured in amperes.

annealing

The process of steadily heating a metal above the recrystallization phase and then gradually cooling it. Annealing can reduce hardness, improve machinability, and facilitate cold working.

arc welding

A group of welding processes that use electricity to generate the heat needed to melt the base metals. Arc welding is portable and economical, making it the most common form of welding.

austenitic stainless steels

A stainless steel that contains the greatest amounts of chromium, nickel, and other alloying elements. Austenitic stainless steels are the most corrosion-resistant stainless steels.

base metal

One of the metals that are welded together to form a joint. The base metal and its properties influence the type of welding and the type of electrode that should be used.

brittle

Unwilling to be drawn, stretched, or formed. Brittle materials tend to fracture when subjected to these forces.

butter layer

A layer of weld metal deposited on one or more surfaces of a base metal before welding. Butter layers can help join metals that are typically difficult to join, including the layers in clad steels.

carbon

A common nonmetallic element found in ferrous metals like steel and cast iron. Increasing the carbon content of a metal typically increases hardness.

carbon steel

The most basic form of steel, containing less than 3.0% alloying elements. Carbon steels are divided into low-, mild, medium-, and high-carbon steels.

cast iron

A ferrous alloy of iron, carbon, and silicon that contains at least 2.0% carbon. Cast iron offers heat resistance and compressive strength.

cast parts

A workpiece formed by pouring molten metal into a mold and cooling it into a solid shape. Cast parts are near their finished shape directly after they are formed.

cast steels

Steel that is transferred to a mold and left to cool into its final shape directly after leaving the steel-making furnace. Cast steel parts are often made with low- or medium-carbon steel.

cerium

A soft, ductile metal that oxidizes easily. Cerium is added to gray cast iron to make ductile cast iron.

chill bars

A piece of metal, usually copper or aluminum, clamped to the back of a weld to dissipate heat from the weld area faster than atmospheric cooling alone. Chill bars help reduce distortion in the weld and HAZ.

chromium

A shiny, gray nonferrous metal that provides high corrosion resistance. Chromium is a common alloying element used in metals such as stainless steel.

chromium carbide

A solid, gray metal compound formed by chromium and carbon. Chromium carbide formation can weaken corrosion resistance in stainless steel.

chromium oxide

A protective film that forms on the surface of stainless steel when chromium reacts with oxygen. Chromium oxide helps prevent corrosion.

clad steels

Steel that has a layer of corrosion-resistant metal on one or both sides. Clad steels commonly use nickel, stainless steel, and silver cladding materials.

coefficient of thermal expansion

A value that indicates the degree to which a material increases in size as temperature increases. Higher coefficients of thermal expansion can lead to distortion in metals at high levels.

cold shortness

A characteristic that makes metals brittle at room temperature or lower. Cold shortness is often caused by an excess of phosphorus in a metal.

cold welding methods

A welding procedure in which pressure is used at room temperature to control heat input and deformation at the weld. Cold welding methods often minimize the weld's exposure to the heat from the welding arc.

corrosion resistance

The ability of a material to resist deterioration and chemical breakdown due to surface exposure to certain conditions. Corrosion resistance is an important physical property of finished welds.

crystal structure

The regular, repeating pattern of atoms in a material. The crystal structure of a metal develops as the metal drops below the recrystallization temperature and solidifies.

defects

An irregularity in the specified and expected composition of a weld that exceeds the part design‘s tolerances. A defect is an unacceptable discontinuity.

deforming

Changing or altering in shape. Deforming causes objects to permanently lose their original shape.

deposition rates

The rate at which filler metal melts into the molten weld puddle to form a weld. The deposition rate can be measured in pounds per hour or in grams per minute.

discontinuities

An irregularity in the expected composition of a weld that does not exceed specifications. A discontinuity is not always a defect.

distortion

The non-uniform expansion of weld metal during the heating and cooling process of welding. Distortion can be caused by using incorrect welding variables.

ductile cast iron

A type of cast iron created by adding magnesium or cerium to gray cast iron to form small spheres, or nodules, of graphite. Ductile cast iron, also known as nodular cast iron, has good tensile strength, impact resistance, and ductility.

ductility

A material's ability to be drawn, stretched, or formed without breaking. Ductility is more common in softer metals.

duplex stainless steels

A stainless steel that typically consists of a microstructure of 50% ferrite and 50% austenite. Duplex stainless steels have higher strength than austenitic steels and better corrosion resistance than ferritic steels.

electrical strip heaters

A device with a heating element that generates heat when electricity passes through. Electric strip heaters can be used for preheating welding base metals.

electrodes

Components in an electrical circuit that conduct electricity. A welding electrode can also act as filler metal.

excessive joint penetration

A weld discontinuity that occurs when too much heat is applied to the weld zone, causing the weld metal to fall through the joint. Excessive joint penetration includes burnthrough.

fatigue

The weakening of metal caused by repeatedly applied force. Fatigue can weaken even very strong and hard metals over time.

ferritic stainless steels

A stainless steel that contains high amounts of chromium and can include small amounts of molybdenum, aluminum, and titanium. Ferritic stainless steels have high hardness but low ductility.

ferrous metal

A metal that contains iron. Ferrous metals are the most common type of welded materials.

field welding

Welding that occurs on a jobsite and not in a welding facility. Field welding typically occurs outdoors.

flux

A nonmetallic material that is intended to protect the weld puddle and solid metal from atmospheric contamination. Flux is often a part of an electrode.

fume extractor

Any device that uses suction to remove gases and particulate matter from the environment. A fume extractor should always be used during welding but is especially important when welding alloy steels containing chromium or manganese.

fumes

A potentially hazardous combination of gas and particulate matter generated at the electric arc during welding processes. Fumes include particulates from the electrode, shielding gas, base metal, and any coatings.

fusion zone

The area where welding joins the base metals and any filler metal. The fusion zone, also called the weld metal zone, is subjected to the highest temperatures during welding.

gas metal arc welding

GMAW. An arc welding process in which a bare wire electrode and shielding gas are fed to the weld through a welding gun. Gas metal arc welding releases more gases but less fumes than other arc welding processes.

gas tungsten arc welding

GTAW. A precise arc welding process that uses a non-consumable tungsten electrode and inert shielding gas. Gas tungsten arc welding is also known as tungsten inert gas welding (TIG welding).

GMAW

Gas metal arc welding. An arc welding process in which a bare wire electrode and shielding gas are fed to the weld through a welding gun. GMAW is also referred to as MIG or MAG welding, although these terms are nonstandard in the United States.

grain structure

The size, arrangement, and orientation of small, hard particles in a metal or alloy. Grain structure helps determine the properties of a metal.

graphite

A soft, black form of carbon that is found alone and in other materials. Graphite is brittle and found as flakes or nodules in cast irons.

gray cast iron

A type of cast iron with high levels of carbon in the form of graphite flakes. Gray cast iron has excellent compressive strength and is the most common cast iron.

hardenability

The ability of a metal to be hardened by heat treatment or other processes. Steels have varying degrees of hardenability depending on their alloying elements.

hardness

A material's ability to resist penetration, indentation, or scratching. Hardness in a metal may change due to the heat generated during welding.

HAZ

Heat-affected zone. The portion of the base metal immediately surrounding the weld metal zone. The HAZ does not melt during welding, but its mechanical and physical properties are altered.

heat dissipation

The loss or transfer of heat. Heat dissipation can help control thermal expansion.

heat treatment

A controlled heating or cooling process used to change the structure of a material. Heat treatment alters a material's physical and mechanical properties.

heat-affected zone

HAZ. The portion of the base metal immediately surrounding the weld metal zone. The heat-affected zone does not melt during welding, but its mechanical and physical properties are altered.

heating torch

A device that uses the controlled combustion of fuel gases to produce a flame. Heating torches are used to preheat base metals for welding.

high-carbon steel

A plain carbon steel that contains more than 0.50% carbon. High-carbon steels are extremely strong and hard, and they always require heat treatment for effective welding.

hot shortness

A characteristic that makes metals brittle at elevated temperatures. Hot shortness is often caused by an excess of sulfur in a metal.

hydrogen

A colorless, odorless gas that is the most abundant element on the planet. Hydrogen can cause weld metal to crack.

hydrogen entrapment

The absorption of hydrogen into metal during welding. Hydrogen entrapment can cause metals to lose ductility and crack.

incomplete joint penetration

A discontinuity characterized by an unpenetrated and unmelted area in a joint that occurs when weld metal does not extend through the full thickness of the joint. Incomplete joint penetration can result from insufficient welding heat, improper joint design, and improper lateral control of the welding arc.

induction heaters

A device that uses electromagnetic induction to heat electrically conductive materials. Induction heaters can be used for preheating welding base metals.

infrared thermometers

A device that can measure the temperature of an object at a distance by sensing its thermal radiation. Infrared thermometers, also known as temperature guns, can be used to assess the preheat temperature of a workpiece before welding.

interpass temperature

The temperature of the weld metal between passes of a multi-pass weld. The interpass temperature is often maintained until the weld is complete.

iron

A common silvery-white metal found in nature as ore. Iron is alloyed with carbon to make steel.

iron carbide

A hard, brittle compound made from iron and carbon. Iron carbide solutions are found in white cast iron.

iron silicate

A non-metallic compound of iron and silicon that can form thin threads or fibers when dispersed in metal. Iron silicate gives metals a fibrous quality.

low-carbon steels

A plain carbon steel that contains less than 0.15% carbon. Low-carbon steels are generally tough, ductile, and easy to weld.

low-hydrogen electrodes

An SMAW electrode that limits the amount of hydrogen in the weld metal to produce high-quality welds. Low-hydrogen electrodes are ideal for metals that are susceptible to cracking and for welding in awkward positions.

magnesium

A grayish white, extremely light metal that is brittle and has poor wear resistance. Magnesium can be combined with other metals to create an alloy with excellent weldability.

malleable cast iron

A type of cast iron created by annealing white cast iron to form small spheres, or nodules, of graphite. Malleable cast iron is more ductile and less brittle than gray or white cast iron.

manganese

A hard, brittle, gray-white nonferrous metal often added to electrodes. Manganese acts as a deoxidizer and increases strength and hardness in alloy steels.

martensitic stainless steels

A stainless steel that contains chromium and small amounts of molybdenum, nickel, and carbon. Martensitic stainless steels are the strongest stainless steels.

mechanical properties

A characteristic that describes how a material responds to forces that attempt to compress, stretch, bend, scratch, dent, or break it. Mechanical properties include tensile strength and ductility.

medium-carbon steel

A plain carbon steel that contains between 0.30% and 0.50% carbon. Medium-carbon steels are strong, hard, and not as easy to weld as low-carbon steels.

mild steels

A plain carbon steel that contains less than 0.30% carbon. Mild steels are generally tough, ductile, and easy to weld.

molybdenum

A hard, silvery-white metal that is strong and corrosion resistant. Molybdenum can add toughness, creep strength, and wear resistance to alloys.

nickel

A hard, malleable, silvery-white metal. Nickel is used in various alloys to add strength, toughness, and impact resistance to metals.

nodular cast iron

A type of cast iron created by adding magnesium or cerium to gray cast iron to form small spheres, or nodules, of graphite. Nodular cast iron, also known as ductile cast iron, has good tensile strength, impact resistance, and ductility.

nodules

The presence of graphite as small spheres. Nodules of graphite are part of the structure of some cast irons.

nonferrous metals

A metal that does not contain a significant amount of iron. Common nonferrous metals include aluminum, titanium, copper, and nickel.

oxidation

A material's chemical reaction with oxygen. Oxidation takes place in the welding arc when the heated metal reacts with oxygen in the atmosphere.

oxyfuel welding

OFW. A fusion welding process that uses a flame produced by a mixture of oxygen and acetylene gas. Oxyfuel welding is also known as oxyacetylene welding.

oxygen

A colorless, odorless, tasteless gas that naturally exists in the atmosphere. Oxygen can cause cracking, porosity, and rusting in welded metals.

peening

The process of working a metal's surface to improve its properties, usually using light blows. Peening is often done with a hammer.

phosphorus

A waxy, non-metallic element that can be either white or red. Excess phosphorus can lead to cold shortness in metals.

physical properties

A characteristic of a material that describes how it responds to environmental, electrical, magnetic, and thermal forces. Physical properties include corrosion resistance and conductivity.

plain carbon steel

The most basic form of steel, which contains less than 3.0% alloying elements. Plain carbon steels, also called carbon steels, are divided into low-, mild, medium-, and high-carbon steels.

porosity

A weld discontinuity characterized by the appearance of tiny voids resulting from trapped gases. Excessive porosity can weaken a weld.

post-heating

The application of heat to a weld immediately after welding, before the weld has cooled. Post-heating helps reduce stress in the weld metal.

post-weld heat treatment

PWHT. The process of heating a weld after welding is complete. Post-weld heat treatment reduces stress in the welded metal.

precipitate

To separate elements from a solution. Elements that precipitate out of a solution change the properties of a metal.

precipitation hardening stainless steels

A stainless steel that goes through a hardening process. Precipitation hardening stainless steel is made by heating an element to a temperature at which it precipitates and then cooling it at a specific rate to prevent it from returning to the original structure.

preheating

The application of heat to a base metal immediately before welding. Preheating provides several benefits, such as reducing hardness, improving ductility, and decreasing the likelihood of hydrogen cracking.

PWHT

Post-weld heat treatment. The process of heating a weld after welding is complete. PWHT reduces stress in the welded metal.

quenching

The controlled cooling of a metal after it has been heated to very high temperatures during heat treatment processes. Quenching rates are determined by the metal type.

radiant heaters

A device that uses infrared radiation to transfer heat to surfaces and spaces. Radiant heaters can be used for preheating welding base metals.

sensitization

A reduction in corrosion resistance in the heat-affected zone due to carbide formation and precipitation. Sensitization is caused by overheating stainless steel.

shielded metal arc welding

SMAW. An arc welding process that uses a flux-coated, stick-like consumable electrode. Shielded metal arc welding is also referred to as stick welding or manual welding.

shielding

A gas that protects the weld puddle and arc from reacting negatively with the atmosphere. Shielding can be provided by an external supply of gas or by a type of flux material.

shrinkage

The reduction in size that a part experiences as it contracts while cooling after exposure to intense heat. Shrinkage can change the microstructure of metal and plastic parts.

silicon

A nonmetallic material that is often present in arc welding electrodes and flux. Silicon acts as a deoxidizer and is used as an alloying element in some alloy steels.

silver

A soft, lustrous nonferrous metal. Silver has the greatest thermal conductivity, electrical conductivity, and reflectivity of any metal.

SMAW

Shielded metal arc welding. An arc welding process that uses a flux-coated, stick-like consumable electrode. SMAW is also referred to as stick welding or manual welding.

solution

A mixture of components or elements. Solutions can be created in alloys through controlled heating and cooling processes.

solution heat treatment

The first step of precipitation hardening in which an alloy is heated to a temperature high enough to allow the alloying element to form a solution with the base metal. Solution heat treatment steps will not harden much on their own.

stainless steels

A type of steel that contains 11-30% chromium and exhibits excellent hardness and corrosion resistance. Stainless steel can be welded with many different welding processes.

stamping die

An assembled device with an upper and lower plate that open and close to cut or shape metal. Stamping die components are often made using medium-carbon steel.

steel

A ferrous alloy of iron and carbon containing less than 2.0% carbon. Steels often contain other elements to enhance various aspects of the metal.

strength

The ability of a material to resist forces that attempt to break or deform it. A material exhibits tensile, compression, or shear strength, depending on the deforming force.

stress relieving

The process of raising the temperature of a manufactured workpiece to a set point for an extended period of time to reduce stresses created during welding or other work processes. Stress relieving after welding is particularly important when working with ferrous metals that contain greater amounts of carbon.

submerged arc welding

SAW. An arc welding process that uses a consumable wire electrode and a layer of flux over the weld to shield the arc. Submerged arc welding, also known as subarc welding, has no visible arc and produces a clean, spatter-free weld.

sulfur

A pale yellow, brittle, non-metallic element. Excess sulfur can cause hot shortness in base metals and cracking in welds.

tack welds

A temporary weld that holds workpieces in proper alignment for a final welding process. Tack welds are also used to aid in preheating.

temperature guns

A device that can measure the temperature of an object at a distance by sensing its thermal radiation. Temperature guns, also known as infrared thermometers, can be used to assess the preheat temperature of a workpiece before welding.

temperature-indicating crayons

A device that holds a compound designed to melt when exposed to a specific temperature. Temperature-indicating crayons are rated to melt at a variety of different temperatures.

tensile strength

A material's ability to resist forces that attempt to pull it apart or stretch it. Materials with high tensile strength tend to deform, bend, or stretch before breaking.

thermal expansion

An increase in a metal's dimensions in response to heat. Thermal expansion varies for different metals.

thermochromic paint

A type of paint that absorbs heat and changes colors or appearance at certain temperatures. Thermochromic paint can be used during heat treatment and welding to monitor metal temperatures.

titanium

A silver-white metal that has a high strength-to-weight ratio and high corrosion resistance. Titanium is more difficult to weld than iron or steel.

toughness

The ability of a metal to absorb energy without breaking or fracturing. Toughness is a key property because it determines the ability of a material to withstand a sudden stress.

weld bead

The end product of a joint that has been welded. Weld beads are formed using a variety of different techniques.

weld metal

The portion of a weld that has been melted during welding. Weld metal may consist of base metal only or a combination of base metal and filler metal.

weld metal zone

The area where welding joins the base metals and any filler metal. The weld metal zone, also called the fusion zone, is subjected to the highest temperatures during welding.

weld pools

The small area of molten metal that forms during welding which, when cooled, forms the permanent joint. Weld pools are sometimes called weld puddles.

weldability

The ability of a material to be welded under imposed conditions into a specific, suitable structure and to perform satisfactorily for its intended use. Weldability varies based on the type of metal being welded, its thickness, and environmental conditions.

welding codes

A collection of standards that outline practices for particular welding applications. Welding codes ensure safe welding practices and high-quality welded products.

white cast iron

A type of cast iron created by molding and rapidly cooling gray cast iron to form an iron carbide solution. White cast iron has high hardness and wear resistance.

wrought iron

A ductile and fibrous metal made of iron and iron silicate. Wrought iron has good corrosion and fatigue resistance properties.