Identifying Metals and Their Physical Properties

Identifying Metals andIdentifying Metals andTheir Physical PropertiesTheir Physical Properties

Lesson A5–1Lesson A5–1

Unit A Unit A Mechanical Systems and Mechanical Systems and

TechnologyTechnology

Problem Area 5Problem Area 5

Metal FabricationMetal Fabrication

Lesson 1Lesson 1

Identifying Metals and Identifying Metals and Their Physical PropertiesTheir Physical Properties

Interest ApproachInterest Approach

Here are some different types of Here are some different types of metals and alloys. metals and alloys.

Can you identify these metals?Can you identify these metals? Do you see these broken parts Do you see these broken parts

made of different metals? made of different metals? How would you repair the broken How would you repair the broken

parts?parts?

Student Learning ObjectivesStudent Learning Objectives

Identify and explain the terms Identify and explain the terms associated with metals.associated with metals.

Describe the properties and Describe the properties and structures of metals.structures of metals.

Explain how steel is manufactured.Explain how steel is manufactured. Describe how metal is classified.Describe how metal is classified. Describe the characteristics used to Describe the characteristics used to

identify metals.identify metals.

TermsTerms

AdhesionAdhesion AlloyAlloy AnnealingAnnealing CastingCasting Compressive Compressive

strengthstrength

Crystal structureCrystal structure Fatigue strengthFatigue strength Flexure strengthFlexure strength HardeningHardening HardnessHardness

Terms Terms

High temperature High temperature creepcreep

Impact strengthImpact strength MalleableMalleable Shear strengthShear strength

Space latticeSpace lattice SteelSteel TemperingTempering Tensile strengthTensile strength

What terms are commonly What terms are commonly used with metals?used with metals?

Because of the widespread use and Because of the widespread use and necessity for metals in agriculture, it necessity for metals in agriculture, it is important for the worker to have a is important for the worker to have a basic understanding of metals and basic understanding of metals and

metallurgy when fabricating and metallurgy when fabricating and making repairs on metals.making repairs on metals.

MetalMetal

Metal is an element. Metal is an element.

There are over 100 known There are over 100 known elements, and about 75 percent of elements, and about 75 percent of them are classified as metals.them are classified as metals.

AlloyAlloy

An alloy is a mixture of two or more An alloy is a mixture of two or more metals, or of metals and one or metals, or of metals and one or more non-metalsmore non-metals The elements added to a metal to The elements added to a metal to

form an alloy may be either metal or form an alloy may be either metal or non-metal.non-metal.

In most cases alloys have more In most cases alloys have more desirable properties and are less desirable properties and are less expensive than pure metals.expensive than pure metals.

High Temperature CreepHigh Temperature Creep

High temperature creep is the slow High temperature creep is the slow stretching of steel under stress at stretching of steel under stress at high temperatures.high temperatures.

AdhesionAdhesion

Adhesion is the sticking together of Adhesion is the sticking together of two unlike metals involving a two unlike metals involving a mechanical bond. mechanical bond.

The mechanical bond involves the The mechanical bond involves the flowing of a metal in a liquid form flowing of a metal in a liquid form into the pores of a metal in a solid into the pores of a metal in a solid form.form.

AnnealingAnnealing

Annealing is the softening of metal Annealing is the softening of metal and removing of the brittleness. and removing of the brittleness.

The annealing process is done by The annealing process is done by heating the metal to a cherry red heating the metal to a cherry red and then allowing it to cool slowly in and then allowing it to cool slowly in vermiculite, dry hot sand, or a vermiculite, dry hot sand, or a furnace.furnace.

TemperingTempering

Tempering is obtaining the desired Tempering is obtaining the desired hardness and toughness in metal.hardness and toughness in metal.

The process of making steel The process of making steel harder is known as hardening. harder is known as hardening.

This is done by heating the steel to a This is done by heating the steel to a cherry red color, then cooling it cherry red color, then cooling it quickly in water.quickly in water. Hardened steel is not only extremely Hardened steel is not only extremely

hard but also brittle.hard but also brittle. Hardening is the first step in tempering.Hardening is the first step in tempering. Hardness is the ability of a material to Hardness is the ability of a material to

resist being indented.resist being indented.

CastingCasting

Casting is pouring melted metal into Casting is pouring melted metal into a mold so that it will be a certain a mold so that it will be a certain shape after cooling.shape after cooling.

MalleableMalleable

The capability of being extended or The capability of being extended or shaped by being beaten with a shaped by being beaten with a hammer or by being pressed by hammer or by being pressed by rollers is known as malleable.rollers is known as malleable.

What are the properties What are the properties and structures of metals?and structures of metals?

The distinct characteristics The distinct characteristics used to help identify a given used to help identify a given metal are referred to as its metal are referred to as its properties.properties.

These characteristics include:These characteristics include:

brittlenessbrittleness color color corrosion resistancecorrosion resistance ductility ductility malleabilitymalleability strength.strength.

These properties can be These properties can be categorized into seven categorized into seven broad classifications.broad classifications.

1. Mechanical properties1. Mechanical properties

hardnesshardness brittlenessbrittleness ductility ductility percent elongation percent elongation toughness toughness wearwear strengthstrength

Tensile strength is the ability of a metal to resist being pulled apart.

Compressive strength is the ability Compressive strength is the ability of a metal to resist deformation by of a metal to resist deformation by

forces pushing it together.forces pushing it together.

Shear strength is the ability of a Shear strength is the ability of a metal to resist forces acting in metal to resist forces acting in

opposite directions.opposite directions.

Fatigue strength is the ability of a metal to take repeated loads

without deforming.

Impact strength is the ability of a Impact strength is the ability of a metal to resist shock.metal to resist shock.

Flexure strength is the ability of a Flexure strength is the ability of a metal to bend without deforming or metal to bend without deforming or breaking.breaking.

2. Chemical properties2. Chemical properties

refers to the chemical make-up of refers to the chemical make-up of the metal and its ability to resist the metal and its ability to resist reaction with the environment.reaction with the environment.

2. Chemical properties2. Chemical properties Chemical properties are oxide or Chemical properties are oxide or

compound composition, acidity or compound composition, acidity or alkalinity of the metal; corrosion alkalinity of the metal; corrosion resistance; resistance to acids and resistance; resistance to acids and salts; and resistance to other salts; and resistance to other chemicals.chemicals.

Corrosion resistant metal will resist Corrosion resistant metal will resist deterioration from heat, sunlight, deterioration from heat, sunlight, water, and humidity.water, and humidity.

3. Physical properties3. Physical properties

relates to the dimensions, shape, relates to the dimensions, shape, specific gravity, and weight of the specific gravity, and weight of the metal.metal.

4. Thermal properties4. Thermal properties

Characteristics such as: Characteristics such as: expansion expansion contraction contraction thermal conductivity thermal conductivity specific heatspecific heat

5. Optical properties5. Optical properties

luster luster color color light transmission light transmission light reflectionlight reflection

6. Electromagnetic properties6. Electromagnetic properties

electrical conductivity electrical conductivity magnetic permeabilitymagnetic permeability galvanic actiongalvanic action

7. Acoustical properties7. Acoustical properties

relate to the ability of a metal to relate to the ability of a metal to transmit and reflect soundtransmit and reflect sound

Crystal StructureCrystal Structure

The crystal structure of a metal is The crystal structure of a metal is the way molecules of a substance the way molecules of a substance are arranged or how they are are arranged or how they are packed or fitted together.packed or fitted together.

The pattern these atoms make is The pattern these atoms make is

called a space lattice. called a space lattice.

Crystal StructureCrystal Structure

There are 14 lattices involved in the There are 14 lattices involved in the study of metalsstudy of metals

Only three of the most common Only three of the most common structures are of real importance structures are of real importance here.here.

Crystal Structure Crystal Structure

The body-centered cubic The body-centered cubic arrangement has nine atoms.arrangement has nine atoms. The main characteristic is their The main characteristic is their

strength and the difficulty with which strength and the difficulty with which they are worked when cold.they are worked when cold.

Examples: iron, molybdenum, Examples: iron, molybdenum, chromium, tungsten, and vanadium at chromium, tungsten, and vanadium at room temperature.room temperature.

Crystal StructureCrystal Structure

The face-centered cube The face-centered cube arrangement has fourteen atoms.arrangement has fourteen atoms. The main characteristic is that they The main characteristic is that they

are plastic and malleable.are plastic and malleable. Examples: iron, aluminum, nickel, Examples: iron, aluminum, nickel,

copper, lead, platinum, and silver.copper, lead, platinum, and silver.

Crystal Structure Crystal Structure

The close-packed hexagon The close-packed hexagon arrangement has seventeen atoms.arrangement has seventeen atoms. The main characteristics are that they The main characteristics are that they

are non-plastic and must be heated are non-plastic and must be heated before they can be worked.before they can be worked.

Examples: cadmium, cobalt, bismuth, Examples: cadmium, cobalt, bismuth, magnesium, titanium, and zinc.magnesium, titanium, and zinc.

How is steel How is steel manufactured?manufactured?

Steel Steel is an alloy of iron and is an alloy of iron and carbon and usually other carbon and usually other

metals.metals.

There are hundreds of different There are hundreds of different steels, ranging in composition steels, ranging in composition from 99 percent iron and very from 99 percent iron and very small amounts of carbon, to small amounts of carbon, to

steels containing less than 55 steels containing less than 55 percent iron and a large percent iron and a large

percentage of other metals.percentage of other metals.

There are four major steel There are four major steel making processes:making processes:

the Bessemer furnace the Bessemer furnace

the open hearth furnacethe open hearth furnace

electric furnace electric furnace

the oxygen furnace the oxygen furnace

There are four major steel There are four major steel making processes:making processes:

All four processes are similar in All four processes are similar in principle in that pig iron is treated principle in that pig iron is treated with an oxygen-bearing material to with an oxygen-bearing material to burn out the carbon and impurities. burn out the carbon and impurities.

Alloying metals are then added.Alloying metals are then added.

There are two general types of There are two general types of steel: carbon and alloy.steel: carbon and alloy.

Approximately 80 to 90 percent of Approximately 80 to 90 percent of steel produced is carbon steel.steel produced is carbon steel.

Carbon steels contain 0.05 to 1 Carbon steels contain 0.05 to 1

percent carbon and less than 1.5 percent carbon and less than 1.5 percent of the other elements.percent of the other elements.

There are two general types of There are two general types of steelsteel

The strength of steel increases as The strength of steel increases as the carbon content increases, but the carbon content increases, but the hardness, brittleness, and the hardness, brittleness, and difficulty of fabrication also increase. difficulty of fabrication also increase.

There are hundreds of alloy steels. There are hundreds of alloy steels. The effects of additives varies. The effects of additives varies. Some of these effects are as Some of these effects are as

follows:follows:

Additive EffectsAdditive Effects

Chromium makes the alloy hard and Chromium makes the alloy hard and increases the wear and corrosion increases the wear and corrosion resistance of steel. resistance of steel. Steels containing more than 4 percent Steels containing more than 4 percent

chromium are called stainless steels.chromium are called stainless steels. Sulfur is added to aid in Sulfur is added to aid in

machinability of the steel.machinability of the steel.

Additive EffectsAdditive Effects

Silicon is added to improve the Silicon is added to improve the electrical, mechanical, and thermal electrical, mechanical, and thermal characteristics.characteristics.

Nickel is added to increase the Nickel is added to increase the toughness and strength.toughness and strength.

Vanadium is added to increase the Vanadium is added to increase the strength.strength.

Additive EffectsAdditive Effects

Tungsten is used to produce tool Tungsten is used to produce tool steels that will maintain a cutting steels that will maintain a cutting edge at high heat.edge at high heat.

Aluminum helps to provide a Aluminum helps to provide a hardened surface.hardened surface.

Molybdenum tends to increase the Molybdenum tends to increase the hardness and the endurance limits hardness and the endurance limits of steel.of steel.

Additive EffectsAdditive Effects

Oxygen forms iron oxide which is Oxygen forms iron oxide which is not desirable.not desirable.

Phosphorus is found in all steels. Phosphorus is found in all steels. When present in high percentages it is When present in high percentages it is

considered an impurity. considered an impurity. At low percentages it improves At low percentages it improves

machinability.machinability.

Additive EffectsAdditive Effects

Carbon added to iron changes the Carbon added to iron changes the physical properties. physical properties. The amount of change is directly The amount of change is directly

proportional to the amount of carbon proportional to the amount of carbon added to the iron.added to the iron.

How is metal classified?How is metal classified?

Of the known elements, about 80 to Of the known elements, about 80 to 90 are technically considered 90 are technically considered metals. metals.

Of these, 10 to 15 are considered Of these, 10 to 15 are considered important in agricultural mechanics.important in agricultural mechanics.

These metals can be broken down These metals can be broken down into four groups and classified as into four groups and classified as follows:follows:

How is metal classified?How is metal classified?

These metals can be broken down These metals can be broken down into four groups and classified as into four groups and classified as follows:follows: Ferrous MetalsFerrous Metals Non-ferrous metalsNon-ferrous metals Ferrous AlloysFerrous Alloys Non-ferrous AlloysNon-ferrous Alloys

A. Ferrous metalsA. Ferrous metals

Metals whose chief ingredient is Metals whose chief ingredient is iron. iron.

Pig iron, cast iron, wrought iron, and Pig iron, cast iron, wrought iron, and steel are examples.steel are examples.

Pig iron or cured ironPig iron or cured iron

is iron ore changed to pig iron by a is iron ore changed to pig iron by a blast furnace.blast furnace.

Cast ironCast iron

is a product of pig iron and contains is a product of pig iron and contains a considerable amount of carbon a considerable amount of carbon and some impurities.and some impurities.

It is brittle and granular in structure. It is brittle and granular in structure.

It is formed by pouring into special It is formed by pouring into special castings.castings.

Cast ironCast iron

Gray cast iron has been cooled Gray cast iron has been cooled slowly, allowing carbon to separate slowly, allowing carbon to separate from the iron into pockets of carbon from the iron into pockets of carbon in the form of graphite. in the form of graphite.

Gray cast iron is used in sprockets, Gray cast iron is used in sprockets, stoves, and manifolds.stoves, and manifolds.

Cast ironCast iron

White cast iron has been cooled White cast iron has been cooled quickly to prevent separation of quickly to prevent separation of carbon. carbon.

White cast iron is used for agitators White cast iron is used for agitators in grain drills.in grain drills.

Cast ironCast iron

Malleable cast iron has been made Malleable cast iron has been made soft, strong, and malleable through soft, strong, and malleable through a long re-heating and cooling a long re-heating and cooling process called annealing. process called annealing.

Malleable cast iron will bend slightly, Malleable cast iron will bend slightly, such as for a conventional mower such as for a conventional mower guard.guard.

Wrought ironWrought iron

a product of pig iron that has had a product of pig iron that has had most of the carbon removed, is a most of the carbon removed, is a two-component metal consisting of two-component metal consisting of high purity iron and iron silicate. high purity iron and iron silicate.

Wrought iron is the only ferrous Wrought iron is the only ferrous metal that contains siliceous slag. metal that contains siliceous slag.

Wrought ironWrought iron

The slag is responsible for the The slag is responsible for the desirable properties of wrought iron, desirable properties of wrought iron, particularly its resistance to particularly its resistance to corrosion and fatigue. corrosion and fatigue.

It is used for rivets, porch furniture, It is used for rivets, porch furniture, and decorative roof supports.and decorative roof supports.

SteelSteel

is iron characterized chiefly by its is iron characterized chiefly by its carbon content.carbon content.

B. Non-ferrous metalsB. Non-ferrous metals

are those which have no iron and are those which have no iron and are made up of a single element.are made up of a single element.

These are aluminum, copper, lead, These are aluminum, copper, lead,

magnesium, nickel, tin, tungsten, magnesium, nickel, tin, tungsten, zinc, silver, and gold.zinc, silver, and gold.

AluminumAluminum

is a silver-white, malleable, ductile is a silver-white, malleable, ductile metal. metal.

It is known for it’s electrical It is known for it’s electrical conductivity, heat conductivity, rust conductivity, heat conductivity, rust resistance, and light weight.resistance, and light weight.

CopperCopper

reddish-brown in color reddish-brown in color is used for tubes, wire, sheets, and is used for tubes, wire, sheets, and

plates. plates. It has excellent workability, either It has excellent workability, either

hot or cold, and the highest hot or cold, and the highest electrical and heat conductivity of all electrical and heat conductivity of all commercial metals.commercial metals.

LeadLead

has a bluish-white color and a bright has a bluish-white color and a bright luster. luster.

It is soft, highly malleable, and It is soft, highly malleable, and ductile; has slight tenacity; and is a ductile; has slight tenacity; and is a poor conductor of electricity. poor conductor of electricity.

It is used for making pipe and It is used for making pipe and containers for corrosive liquids.containers for corrosive liquids.

MagnesiumMagnesium is a very lightweight, silver-white is a very lightweight, silver-white

metal, which is malleable and ductile metal, which is malleable and ductile and burns in air. and burns in air.

It is usually found in the alloy known It is usually found in the alloy known as dowmetal. as dowmetal. It is useful for airplane bodies, truck It is useful for airplane bodies, truck

and auto wheels, ladders, lawn mower and auto wheels, ladders, lawn mower frames, and any place where weight frames, and any place where weight reduction is important.reduction is important.

NickelNickel

is a hard, malleable, ductile, is a hard, malleable, ductile, tenacious white metal that is tenacious white metal that is somewhat magnetic.somewhat magnetic.

It is valuable for the alloys it forms It is valuable for the alloys it forms with other metals.with other metals.

TinTin

does not corrode in humid does not corrode in humid conditions, adheres tenaciously to conditions, adheres tenaciously to iron, has a low melting pointiron, has a low melting point

used extensively in solder, brass, used extensively in solder, brass, bronze, and pewter.bronze, and pewter.

TungstenTungsten

one of the heaviest metalsone of the heaviest metals used for making filaments for used for making filaments for

incandescent lamps. incandescent lamps. Tungsten carbide is almost as hard Tungsten carbide is almost as hard

as diamond and is used extensively as diamond and is used extensively for cutting tools.for cutting tools.

ZincZinc

bluish-white metal at ordinary bluish-white metal at ordinary temperaturestemperatures

is brittle but malleable at high is brittle but malleable at high temperatures temperatures

used as a galvanizing metal coating used as a galvanizing metal coating to prevent corrosion.to prevent corrosion.

SilverSilver

shiny, white metal shiny, white metal used mostly for ornamental work, used mostly for ornamental work,

jewelry, and table-ware.jewelry, and table-ware. Silver is the best conductor of Silver is the best conductor of

electricity.electricity.

GoldGold

is most often used for ornamental is most often used for ornamental jewelry.jewelry.

C. Ferrous alloysC. Ferrous alloys

Metals made up largely of ferrous Metals made up largely of ferrous materials but having other elements materials but having other elements in sufficient quantities to change the in sufficient quantities to change the ferrous characteristics.ferrous characteristics.

Manganese steelManganese steel

can stand strain, hammering, shock, can stand strain, hammering, shock, and hard wear. and hard wear.

It is used for the jaws of ore It is used for the jaws of ore crushers, power shovels, chains, crushers, power shovels, chains, gears, and safes.gears, and safes.

Chromium steelChromium steel

resists rust, shock, scratches, and resists rust, shock, scratches, and stains. stains.

It is used for bearings, safes, ore It is used for bearings, safes, ore crushers, and is the basis for high-crushers, and is the basis for high-quality stainless steel.quality stainless steel.

Nickel steelNickel steel

is strong, hard, elastic, tough, and is strong, hard, elastic, tough, and durable.durable.

It does not rust easilyIt does not rust easily

used for springs, cables, axles, used for springs, cables, axles, shafts, and armor plate.shafts, and armor plate.

Stainless steelStainless steel

seldom rustsseldom rusts

used for cutlery, precision used for cutlery, precision measuring instruments, dentistry measuring instruments, dentistry supplies, auto parts, and engine supplies, auto parts, and engine valves.valves.

Tungsten steelTungsten steel

adds hardness to steel and allows it adds hardness to steel and allows it to withstand heat. to withstand heat.

Tungsten carbide is the hardest Tungsten carbide is the hardest metal known and is used for various metal known and is used for various cutting surfaces.cutting surfaces.

Molybdenum steelsMolybdenum steels

known for their strength and known for their strength and hardness hardness

used for hacksaw blades, high-used for hacksaw blades, high-grade machinery parts, bearings, grade machinery parts, bearings, and auto parts.and auto parts.

Vanadium steelVanadium steel

is tough and can withstand great is tough and can withstand great shocks as well as resist corrosion. shocks as well as resist corrosion.

used for springs, gears, and used for springs, gears, and vibrating parts of machinery.vibrating parts of machinery.

High-speed steelHigh-speed steel

contains one or more alloying contains one or more alloying elementselements

D. Non-ferrous alloys are D. Non-ferrous alloys are made up of two or more made up of two or more

nonferrous elements.nonferrous elements.

Brass Brass

an alloy of copper and zinc. an alloy of copper and zinc.

It is ductile, malleable, and acid It is ductile, malleable, and acid resistant.resistant.

Bronze Bronze

an alloy of copper and tin an alloy of copper and tin

behaves very much like brass when behaves very much like brass when welded.welded.

Solder typesSolder types

lead and tin solderlead and tin solder

copper and zinc alloy soldercopper and zinc alloy solder

silver and copper alloy solder.silver and copper alloy solder.

PewterPewter

an alloy of 92 percent tin, 5 percent an alloy of 92 percent tin, 5 percent antimony and 3 percent copper.antimony and 3 percent copper.

MonelMonel

is an alloy of 60 percent nickel and is an alloy of 60 percent nickel and 40 percent copper.40 percent copper.

Grading and classifying steel.Grading and classifying steel.

Because steel varies in carbon Because steel varies in carbon content and alloying elements, a content and alloying elements, a system to group it using standards system to group it using standards established by the Society of established by the Society of Automotive Engineers (SAE) was Automotive Engineers (SAE) was developed.developed.

Grading and classifying steelGrading and classifying steel

In the SAE numbering system, the In the SAE numbering system, the first digit indicates the general type first digit indicates the general type of steel. of steel.

The second digit indicates the The second digit indicates the percentage of the main alloy in the percentage of the main alloy in the steel. steel.

Grading and classifying steel.Grading and classifying steel.

The third and fourth digits show the The third and fourth digits show the percent of carbon in the steel in percent of carbon in the steel in hundredths of one percent.hundredths of one percent.

What characteristics are used to What characteristics are used to identify metals?identify metals?

Physical and chemical tests are Physical and chemical tests are used to determine the type of metal. used to determine the type of metal.

Because so many kinds of metals Because so many kinds of metals are used in agriculture it is very are used in agriculture it is very important that you learn to identify important that you learn to identify them.them.

The Appearance TestThe Appearance Test

involves identification of a metal by involves identification of a metal by its appearance and use. its appearance and use.

Color and appearance make certain Color and appearance make certain metals such as copper, brass, and metals such as copper, brass, and bronze easy to identify.bronze easy to identify.

The Magnetic TestThe Magnetic Test

involves identification of metal by involves identification of metal by the use of a magnet.the use of a magnet.

The Chisel TestThe Chisel Test

involves identification of metal by involves identification of metal by the use of a hammer and cold the use of a hammer and cold chisel.chisel.

The Fracture TestThe Fracture Test

involves identification of metal by involves identification of metal by fracturing the metal and observing fracturing the metal and observing the grain.the grain.

The Flame TestThe Flame Test

involves identification of metals by involves identification of metals by applying a flame to them and applying a flame to them and watching what occurs.watching what occurs.

The Spark TestThe Spark Test

involves identification of metals by involves identification of metals by applying them to a grinding wheel applying them to a grinding wheel and observing the spark that is and observing the spark that is generated.generated.

The color, shape, average length, The color, shape, average length, and activity of the sparks are and activity of the sparks are characteristics of the material being characteristics of the material being tested.tested.

Student ActivityStudent Activity

Identify the various Identify the various metalmetalss given given using the following materials:using the following materials:

Handouts of Metal Handouts of Metal IdentificationIdentification

Lab SheetLab Sheet

Various testing itemsVarious testing items

GrinderGrinder MagnetMagnet Hammer and ChiselHammer and Chisel Oxyacetylene flameOxyacetylene flame ViseVise

ReviewReview

Identify and explain the terms Identify and explain the terms associated with metals.associated with metals.

Describe the properties and Describe the properties and structures of metals.structures of metals.

Explain how steel is manufactured.Explain how steel is manufactured. Describe how metal is classified.Describe how metal is classified. Describe the characteristics used to Describe the characteristics used to

identify metals.identify metals.