Welding Ferrous Metals 211

aged

A metal that has been heated to a certain temperature to cause a change in its grain structure. Metals are usually aged to increase their hardness.

alloy steels

A steel that contains intentionally added materials that change the property of the metal. Alloy steels commonly contain elements including chromium, manganese, molybdenum, and nickel.

alloying elements

A chemical or substance that is added to a metal to modify its properties. Common alloying elements include chromium, silicon, and nickel.

alloys

A metal consisting of a mixture of two or more materials. Stainless steel, for example, is an alloy of iron, carbon, and chromium.

annealing

The process of slowly heating and cooling a material to change its properties. Annealing is often used to increase a metal’s ductility.

arc welding

A welding process that uses electricity to generate the heat that melts the base and filler metals. Arc welding is the most commonly used welding process.

austenitic

Stainless steel with very high strength as well as excellent ductility and toughness. Austenitic stainless steel is the most corrosion resistant stainless steel.

base metal

One of the two or more metals to be welded together to form a joint. The type of base metals being joined determines how they should be welded.

brittle

A material’s resistance to being stretched, formed, or drawn. Brittle metals fracture easily, and brittleness often increases with hardness levels.

carbon

A common, non-metallic element found in all types of steel. Carbon is the main hardening element in steel.

cast iron

An alloy of iron, carbon, and silicon that contains at least 2.0% carbon. Cast irons generally need some form of heat treatment to be welded with satisfactory results.

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 steels are often made with low- or medium-carbon steel.

casting

A metal part that is formed by pouring molten metal into a mold. The metal cools and solidifies into its final shape.

cerium

A soft, ductile, silvery metal. As an alloying element, cerium can help deoxidize metal and make it more ductile.

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 welds and the HAZ.

chromium

A shiny, hard, steel-gray metal that increases corrosion resistance in metals. Chromium can create hazardous fumes, meaning fume extractors are essential when welding any metal containing chromium.

chromium oxide

A protective film that develops on the surface of stainless steel. Chromium oxide helps prevent corrosion.

clad steels

Steels that have been protected on one or more sides with a layer of a corrosion resistant metal. Common materials used to clad steel are nickel, stainless steel, and silver.

cold method

A welding procedure that limits the heat input to a weld. Cold methods often minimize the weld's exposure to the welding arc.

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.

corrosion resistance

The ability of a material to resist deterioration and chemical breakdown due to surface exposure in a particular environment. Stainless steel has high corrosion resistance.

crystal structure

The regular, repeating patter of atoms in a metal. Crystal structures develop as a metal solidifies.

deforming

The separation between neighboring crystals that are oriented in different directions. The elements that gather by grain boundaries can affect the properties of a metal.

deposition rate

The speed at which the filler metal is melted. Deposition rate is the amount of filler metal deposited in the weld measured in pounds per hour.

discontinuities

An irregularity in the specified and expected composition of a weld. Discontinuities include cracks, porosity, and excessive slag.

distortion

Warpage in the base metal due to stresses caused by heating and cooling. Stainless steels are prone to distortion if not welded using the proper procedures.

ductile cast iron

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

ductility

The measure of a material's ability to be stretched, drawn, or formed without fracturing. Ferrous metals with less carbon tend to be more ductile.

duplex

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.

durability

The ability of materials to withstand extended exposure to environmental wear and mechanical forces. Ferrous metals tend to have good durability.

electrode

A device that conducts electricity. Welding electrodes can also act as filler metal.

fatigue

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

ferritic

Stainless steel that contains mostly chromium and has low carbon content. Ferritic stainless steels are easy to weld and not hardenable by heat treatment.

ferrous metal

A metal in which iron is the main ingredient. Ferrous metals are the most commonly used commercial metals.

filler metal

A type of metal sometimes added to the joint of a weld. Filler metal adds strength and mass to a weld and can be deposited by the electrode or added to the joint manually or by machine.

fume extractor

Any device that uses suction to remove from the environment the smoke and gases generated by welding. A fume extractor is particularly important when welding metals that contain chromium or manganese.

fumes

A cloud of particles suspended in a gas. Applications that emit fumes require proper ventilation.

fusion zone

The area where welding joins the base metals and any filler metals. Fusion zones are subjected to the highest temperatures during welding.

gas metal arc welding

GMAW. An arc welding process in which the bare wire electrode and inert shielding gas are fed to the weld through a welding gun. GMAW is also referred to as MIG welding.

gas tungsten arc welding

GTAW. A very precise arc welding process that uses a nonconsumable tungsten electrode. GTAW is also referred to as TIG welding.

GMAW

Gas metal arc welding. An arc welding process in which the bare wire electrode and inert shielding gas are fed to the weld through a welding gun. GMAW is also referred to as MIG welding.

grain structure

The relationship between the small, individual crystals in a metal or alloy. Grain structure impacts the mechanical and physical properties of a metal.

granular flux

A non-metallic material that consists of numerous small particles used to protect the weld puddle and solid metal from atmospheric contamination. In SAW, this layer of granular flux covers the weld and prevents spark and spatter.

graphite

A form of carbon with metallic luster and a greasy texture. The structure of the graphite in cast iron affects its properties.

gray cast iron

An iron alloy with at least 2.0% carbon in which graphite flakes are dispersed throughout the metal. Gray cast iron has poor ductility.

hardenability

The ability of a metal to be hardened by normal heat treatment processes. Hardenability can influence the weldability of a metal.

hardness

A metal’s ability to resist penetration, indentation, and scratching. Hardness caused by welding can be controlled through heat treatment.

HAZ

Heat-affected zone. The portion of the base metal immediately surrounding the weld that does not melt but where the mechanical and physical properties have been altered. Heat treatment can limit the formation of HAZ.

heat treatment

The controlled heating and cooling processes used to change the structure of a material and alter its physical and mechanical properties. Heat treatments include preheating and post-heating processes.

heat-affected zone

HAZ. The portion of the base metal immediately surrounding the weld that does not melt but where the mechanical and physical properties have been altered. Heat treatment can limit the formation of heat-affected zones.

heating torch

A device for directing the heating flame produced by the controlled combustion of fuel gases. Heating torches are used to preheat base metals.

high-carbon steel

A plain carbon steel that contains more than 0.45% carbon. High-carbon steels are extremely strong, hard, and 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

The lightest and most abundant element in the universe. Excess hydrogen in weld metal can cause cracking.

infrared thermometers

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

iron

A malleable, silver-gray metal that is highly magnetic. Iron is alloyed with carbon to make steel.

iron carbides

A chemical compound of iron and carbon. Iron carbides come in a range of structures that influence a metal’s properties.

iron silicate

A non-metallic element that can form thin threads or fibers when dispersed in metal. Iron silicate gives metals a fibrous quality.

joint penetration

The depth to which a weld extends into the base metals. Joint penetration may be complete or partial.

low-carbon steel

A plain carbon steel that contains less than 0.30% carbon. Low-carbon steels are generally tough, ductile, and easily welded.

magnesium

A lightweight, brittle, gray-white metal. Magnesium is often used as an alloying element to improve corrosion resistance.

malleable cast iron

A metal created by annealing white cast iron for several days. Malleable cast iron has superior ductility.

manganese

A hard, brittle, gray-white metal that increases the hardenability of steel. Manganese can create hazardous fumes, meaning fume extractors are essential when welding any metal containing manganese.

martensitic

Stainless steel that is stronger than ferritic stainless steel but less corrosion resistant. Martensitic stainless steels are hardenable by heat treatment.

mechanical properties

A characteristic that describes how a material reacts when subjected to a force that attempts to stretch, compress, bend, dent, scratch, or break it. Mechanical properties include strength, toughness, ductility, and hardness.

medium-carbon steel

A plain carbon steel that contains between 0.30% and 0.45% carbon. Medium-carbon steels are strong, hard, and not as easily welded as low-carbon steels.

molybdenum

A hard, silvery-white metal. Molybdenum is used in alloys to increase a metal's toughness, creep strength, and wear resistance.

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 metal created by adding magnesium or cerium to gray cast iron to form small spheres of graphite. Nodular cast iron, sometimes referred to as ductile cast iron, has good tensile strength, impact resistance, and ductility.

nonferrous metals

A metal that does not contain a significant amount of iron. Nonferrous metals include aluminum, copper, and gold.

oxygen

A colorless, odorless, tasteless gas that exists naturally in the atmosphere. In welding, excess oxygen causes cracking and rusting in the 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 phosphorous can lead to cold shortness in metals.

physical properties

A characteristic of material that describes how it responds to nonmechanical forces. Physical properties include a metal’s magnetic, thermal, and electrical attributes.

plain carbon steel

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

porosity

The introduction of gas into a weld which creates bubbles that can lead to fracturing. Common causes of porosity are atmospheric contamination and excessive oxidation of the workpiece.

post-heating

The application of heat to the weld immediately after welding. Post-heating helps reduce stress in the weld metal.

post-weld heat treatments

A heat treatment applied after the welded workpiece has cooled completely. Post-weld heat treatments include annealing, stress relieving, and tempering.

precipitate

The separation of elements from a solution. Elements that precipitate out of a solution change the properties of a metal.

precipitation hardening

A stainless steel that has alloying additions such as aluminium or nickel which allows it to be hardened by solution heat treatment. Precipitation hardening steels have the corrosion resistance of austenitic steels and the hardenability of martensitic.

preheating

The controlled application of heat to a base metal before and during welding. Preheating helps reduce hardness in the metal.

quenched

Rapidly cooling a metal through the use of oil, water, or air. Quenched metals retain the grain structure they developed before quenching.

shielded metal arc welding

SMAW. An arc welding process that uses a flux-coated rod. Shielded metal arc welding is sometimes referred to as stick welding.

silicon

A dark, blue-gray metal. Silicon improves a metal's strength and oxidation resistance when used as an alloying element.

silver

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

slag

Another term for iron silicate. Slag is usually used to refer to the nonmetallic layer that forms on top of molten metal.

SMAW

Shielded metal arc welding. An arc welding process that uses a flux coated rod. SMAW is sometimes referred to as stick welding.

solution

A mixture in which a minor component, such as an alloying element, is evenly distributed in a major component, such as the base metal of an alloy. 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 step will not harden much on its own.

stainless steels

A type of steel that contains more than 11% chromium and exhibits excellent corrosion resistance. Stainless steels have good weldability if the right welding procedures are followed.

stamping die

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

steel

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

strength

A general measure of how well a metal withstands various mechanical forces. Types of strength include tensile, yield, and impact.

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. A type of arc welding process that uses granular flux as a shield and a continuously fed wire electrode as a filler metal. In SAW, the welding arc exists inside the weld pool.

sulfur

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

tack welds

A weld made to hold the parts of a weld in proper alignment before the final welds are made. 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 the thermal radiation. Temperature guns, also known as infrared thermometers, can be used to asses the preheat temperature of a workpiece before welding.

temperature-indicating sticks

A device that holds a compound designed to melt when exposed to a specific temperature. There are a wide array of temperature-indicating sticks rated to melt at a variety of different temperatures.

tensile strength

The ability of a material to resist forces attempting to pull it apart. Tensile strength is closely related to ductility.

thermal expansion

The increase in the dimensions of a metal due to an increase in its temperature. A metal’s rate of thermal expansion influences its weldability.

toughness

The ability of a material to deform and absorb energy without breaking or fracturing. Toughness indicates a material's ability to withstand a sudden stress or force.

weld bead

A layer of fused metal in a joint created from a single welding pass. A joint may require more than one weld bead.

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.

welders

A person who welds. Sources may refer to welders as weldors.

welding

The permanent joining of two metals through the use of heat or pressure. Welding can join most ferrous metals.

white cast iron

A metal formed by immediately cooling gray cast iron before the carbon can separate into graphite. White cast iron is hard, brittle, and unweldable.

workpiece

A part that is subjected to a manufacturing process such as welding or cutting. Any metal or metals being welded are referred to as workpieces.

wrought iron

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