Hardness testing - localized deformationBrinellVickersKnoopRockwell

Hardness/tensile strength correlation

Impact testing - energy absorbed upon fractureEffect of temperature

Hardness testing - localized deformationBrinellVickersKnoopRockwell

Hardness/tensile strength correlation

Impact testing - energy absorbed upon fractureEffect of temperature

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More mechanical testingFracture toughnessFracture surfacesCreepFatigue

Crystal structure

More mechanical testingFracture toughnessFracture surfacesCreepFatigue

Crystal structure

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Fracture toughness - KIc = Yc a

resistance to brittle fracture in presence of

a crack - resistance to crack propagationunder load

Fracture toughness - KIc = Yc a

resistance to brittle fracture in presence of

a crack - resistance to crack propagationunder load

Common specimen configurations

pre-cracked here before testing - usually 1000 cycles, 0.03 in/in strain

Common specimen configurations

pre-cracked here before testing - usually 1000 cycles, 0.03 in/in strain

Fracture toughness

Hypothetical example - surface crack in a semi-infinite sheet loaded in tension

Find critical crack size

Fracture toughness

Hypothetical example - surface crack in a semi-infinite sheet loaded in tension

Find critical crack size

Some fracture surfacesSome fracture surfaces

ductile fractureductile fracture

transgranularfracture

transgranularfracture

intergranularfracture

intergranularfracture

Crack originsCrack origins

Creep

deformation under small loads atelevated temps.

Creep

deformation under small loads atelevated temps.

Fatigue

deformation under small cyclic loads

Fatigue

deformation under small cyclic loads

Fatigue

S-N curves & endurance limit

Fatigue

S-N curves & endurance limit

Fatigue failure

fatigue crack w/ beachmarks

Fatigue failure

fatigue crack w/ beachmarks

Crystal structures of materials - where are the atoms?

Polymers - mostly not crystallinestructure extremely complicated

Ceramic materials - complicatedmany different types of atom arrangements

Crystal structures of materials - where are the atoms?

Polymers - mostly not crystallinestructure extremely complicated

Ceramic materials - complicatedmany different types of atom arrangements

Metals - really simple - most have one of three typesMetals - really simple - most have one of three types

Crystal structures of pure metalsCrystal structures of pure metals

Most pure metals exhibit one of three types

1. cubic close packing (ccp or A1)2. hexagonal close packing (hcp or A3)3. A2 (almost universally referred to by

the confusing notation 'bcc')

Most pure metals exhibit one of three types

1. cubic close packing (ccp or A1)2. hexagonal close packing (hcp or A3)3. A2 (almost universally referred to by

the confusing notation 'bcc')

Crystal structures of pure metals

cubic close-packed (ccp)

close-packed plane of atoms

Crystal structures of pure metals

cubic close-packed (ccp)

close-packed plane of atoms

Crystal structures of pure metals

cubic close-packed (ccp)

ABCABC layer sequence close-packed plane of atoms

Crystal structures of pure metals

cubic close-packed (ccp)

ABCABC layer sequence close-packed plane of atoms

AB

C

A

AB

C

Crystal structures of pure metals

hexagonal close-packed (hcp)

Crystal structures of pure metals

hexagonal close-packed (hcp)

Zn, Cd, Co, Ti, Zr……Zn, Cd, Co, Ti, Zr……

close-packed plane of atoms

hexagonhexagon

Crystal structures of pure metals

hexagonal close-packed (hcp)

ABAB layer sequence close-packed plane of atoms

Crystal structures of pure metals

hexagonal close-packed (hcp)

ABAB layer sequence close-packed plane of atoms

AB

AB

AB

Fe, V, Cr, Mo, W, Ta……Fe, V, Cr, Mo, W, Ta……

Crystal structures of pure metals

A2 structure - so-called "bcc" metal structure

almost close-packed atom planes

Crystal structures of pure metals

A2 structure - so-called "bcc" metal structure

almost close-packed atom planes

some empty space some empty space