Metallurgy For Practical Applications

Front 1

what is an atom?

Back 1

the smallest particle of an element that can take part in a chemical reaction

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Front 2

define crystal ?

Back 2

the symmetrical arrangement of atoms in a solid (metals crystalline arrangement is the grain structure)

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Front 3

what is cubic structure?

Back 3

a particular atomic arrangement in which a set number of atoms form a crystal pattern (also known as a unit cell) of the metal

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Front 4

what is a dendrite?

Back 4

a treelike branching structure.(resembles coniferous trees) formed of crystals

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Front 5

what is an element?

Back 5

a pure substance that cannot break down into other substances

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Front 6

what is a grain boundaries?

Back 6

area of a crystal structure where one grain abuts against another

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Front 7

what do grain boundaries look like on a micrograph?

Back 7

clearly visible dark lines

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Front 8

what is the first crystals to form as a metal freezes or solidifies?

Back 8

the seed crystal(first crystal of a dendrite)

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Front 9

a group of atoms with the same orientation are what?

Back 9

a grain

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Front 10

each grain is formed from what?

Back 10

seed crystals

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Front 11

dendrite formation relates directly to what?

Back 11

the solidification of the metal (quick cool=finer grain / slow cool=coarse grain)

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Front 12

what is space lattice?

Back 12

the crystalline arrangement of atoms within each crystal

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Front 13

below the lower critical temperature iron has what type of space lattice structure?

Back 13

Body Centred Cubic structure (BCC)

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Front 14

above the upper critical temperature iron has what space lattice structure?

Back 14

Face Centred Cubic structure (FCC)

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Front 15

Body Centred Cubic structure contains how many atoms?

Back 15

Nine

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Front 16

what space lattice formation happens in martensitic formations?

Back 16

body centred tetragonal structure

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Front 17

hexagonal close-packed structure contains how many atoms?

Back 17

17 atoms

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Front 18

what is allotropy?

Back 18

the ability of a material to exist in two or more atomic structure forms without any change in atomic composition

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Front 19

what is space lattice?

Back 19

the arrangement of atoms within each molecule

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Front 20

define lower critical temperature.

Back 20

the temperature at which steel begins changing it's space-lattice or crystal structures. 723°c(1333°F)

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Front 21

define upper critical temperature.

Back 21

temperature in which steel completely changes it's space-lattice structures. 723°C-1130°C(1333°F to 2000°F)

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Front 22

define ferrite.

Back 22

a solid solution of one or more elements in a body centred cubic iron.(pure iron is called ferrite)

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Front 23

what is cementite?

Back 23

a hard brittle compound of iron and carbon (iron carbide)

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Front 24

define pearlite

Back 24

a limner mixture composed of layers of ferrite and cementite

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Front 25

in pearlite what determines the amount formed?

Back 25

carbon content of the steel

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Front 26

define austenite

Back 26

a solid solution of carbon in face centred cubic iron.

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Front 27

when is steel austenite?

Back 27

above the upper critical temperature

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Front 28

what determines a metals upper critical temperature?

Back 28

amount of cordon in the metal

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Front 29

what is martensite?

Back 29

a type of grain structure that rapid cooling causes

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Front 30

martensite is a hard grain structure that looks like what?

Back 30

densely packed needles

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Front 31

the composition of steel (weldable grades) is primarily iron with what range of carbon?

Back 31

0.1%-0.35%

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Front 32

steels with a carbon level below 0.83% will have a grain structure of what?

Back 32

ferrite and pearlite

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Front 33

steels with a carbon level of 0.83% will have a grain structure of what?

Back 33

pearlite(100%)

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Front 34

steels with a carbon level greater than 0.83% will have a grain structure of what?

Back 34

pearlite with cementite surrounding it

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Front 35

the transition between two atomic structures is called what?

Back 35

allotropic change

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Front 36

when does allotropic change takes place?

Back 36

when the carbon steel is in its solid state

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Front 37

When carbon heats above the upper critical temperature it has what type of structure?

Back 37

Face centred cubic structure

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Front 38

carbon steel below the lower critical temperature has what type of structure?

Back 38

body centred cubic

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Front 39

an iron atom in a BCC formation can hold what percentage of carbon in it's atomic structure?

Back 39

0.00025%

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Front 40

an iron atom in FCC formation can hold watt percent of carbon in it's atomic structure?

Back 40

2%

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Front 41

what is the currie point?

Back 41

the temperature at which steel becomes non-magnetic

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Front 42

what is the temperature of the currie point?

Back 42

770°C(1415°F)

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Front 43

what is blue brittleness?

Back 43

a strain aging mechanism that occurs in a heat temperature range of 150°C to 370°C(300°F to 700°F)

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Front 44

what should you not do in the blue brittleness range?

Back 44

peen or work steels

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Front 45

when does blue brittleness occur?

Back 45

when nitrogen atoms are pushed out of the grain boudaries

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Front 46

what is annealing?

Back 46

the process of softening a material or bringing it to it's softest, toughest weakest state

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Front 47

how do you anneal a material?

Back 47

heat it past the upper critical temperature then slow cool in an oven

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Front 48

what is normalizing?

Back 48

heating an entire structure to about 10°C to 40°C (50°F to 100°F) above the upper critical temperature and slow cool it in air

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Front 49

what is quenching?

Back 49

is the rapid cooling of a material from a temperature above the upper critical temperature to a temperature below the lower critical temperature

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Front 50

what is martensite?

Back 50

forms in carbon steel when steel heated above the upper critical temperature and then cooled rapidly in water, oil, or some other quenching medium

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Front 51

An extremely had and brittle form of steel is what?

Back 51

Martensite

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Front 52

what is tempering?

Back 52

a heat-treating process that reduces hardness and promotes toughness

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Front 53

what are the steps for tempering?

Back 53

-quench the steel
-reheat the steel
-liquid quench the steel to halt the withdrawal of hardness

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Front 54

where it the heat affected zone?

Back 54

the area in the base material adjacent to the weld

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Front 55

single pass fillet welds have what type grain structure?

Back 55

Large columnar grains

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Front 56

multi-pass welds produce what grain structure with each successive passes?

Back 56

each successive pass refines (or shrinks) the grains

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Front 57

a weld with finer grain structure has better mechanical properties than a coarse.
true or false?

Back 57

True

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Front 58

what two things affect your quenching rate?

Back 58

-the mass of the material on which you are working
-environment in which you are working

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Front 59

What is a common and effective method of impeding the quenching rate?

Back 59

preheating

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