alloy element table
TRANSCRIPT
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7/28/2019 Alloy Element Table
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AlloyElementTable
NHML|22InterstateDrive | Somersworth,NH 03878|603.692.4110|www.nhml.com 1
Asubstitution
of
an
alloy
element
can
change
the
composition
of
the
alloyed
steel
causing
unforeseen
problems.
NHML
receives
numerous
calls
ayearrequestingtohavethealloyingelementsinsteelverifiedforthisreason.
Wehaveprovidedbelowatableofalloyingelements,theirprinciplefunctions,andcarbidetendencies.Ifyouworkwithanyofthesematerials
andexperiencedproblems,calltospeaktooneofourknowledgeablestaffmembers.Wemaybeabletohelpprovideananswer.
AlloyingElement CarbideFormingTendency PrincipleFunctions
Aluminum Lessthaniron,promotesgraphitization
Withnitrogenoroxygen,aluminumformsafinedispersionthatlimits
graingrowth
Adeoxidizerthatresultsinexcellenttoughnessbecauseofthe
resultingfinegrainsize
Formsasurfacehardenedlayerby(relatively)lowtemperature
diffusionofnitrogen(nitriding)
Boron Moderate Significantlyincreasedhardenabilityinthe0.0005to0.003%range,withoutsacrificingductilityormachinability
Calcium None Whenusedasadeoxidizer,itprovidesbettermachinabilitythanaluminumorsilicon ControlsinclusionshapeinHSLAsteels,improvingtoughness
Carbon None Themostimportantalloyingelementinsteelasitformspearlite,
bainite,spherodite,andironcarbonmartensite
Increasingcarbonincreaseshardness,strength,andductilebrittle
transitiontemperature
Increasingcarbondecreasestoughnessandductility
Chromium Greaterthanmanganeseandlessthantungsten
Providesamoderate
contribution
to
hardenability
up
to
about
1%
Mildlyresistssofteningduringtempering
Provideselevatedtemperaturestrengthandresistancetooxidation
Withhighcarbon,providesabrasionresistance
Cobalt Aboutthesameasiron Resistsofteningatelevatedtemperatures
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AlloyElementTable
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Copper None Improves
resistance
to
atmospheric
corrosion
in
the
0.20
0.50%
range
Decreasestheabilitytohotworksteelsduetomigrationtograin
boundaries
Lead None Doesnotdissolveinsteelandimprovesmachinability Cancauseliquidmetalembrittlementattemperaturesnearitsmeltingpoint
Manganese Greaterthaniron,lessthanchromium
Providesamoderatecontributiontohardenabilityuptoabout2%
Promotesretainedausteniteonquenching
Formssulfidesforimprovedmachinability
Producesahighcarbonausteniticsteel
ProducesaCrNiMnausteniticsteel(200seriesstainless)that
competeswiththe300seriesstainlesssteels
Increasesstrengthandreducesductilityinferriticsteels
Isadeoxidizerandpromoteshotworkability
Molybdenum Strongcarbideformer,greaterthanchromiumortungsten
Contributesgreatly
to
hardenability
up
to
about
1%
Contributesdeephardening
Increaseselevatedtemperaturestrengthandcreepresistance
Improvescorrosionresistanceinstainlesssteels,particularlyin
chlorideenvironments
Minimizesthetendencytowardtemperembrittlementinalloysteels
inthe0.15to0.30%range
Nickel Lessthaniron,promotesgraphitization
Providesamoderatecontributiontohardenability
Tendsto
promote
retained
austenite
with
medium
and
high
carbon
contents
Strengthensunhardenedsteelsbysolidsolution
Makeshighchromiumsteelsaustenitic
Providestoughnessinferriticpearliticsteels
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AlloyElementTable
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Niobium Strong Produces
fine
grain
size
Increaseselevatedtemperaturestrength
Asastrongcarbideformeritcandecreasethehardenabilityofsteel
byremovingcarbonfromsolution
Phosphorus None
Providesahighcontributiontohardenability
Promotesretainedaustenite
Strengthenscarbonsteelsbutseverelyreducestoughnessand
ductility
Improvescorrosion
resistance
Improvesmachinabilityishighsulfursteels
Decreasesductilitywithmediumandhighcarbonsteels
Contributestotemperembrittlement
Silicon
None,
promotes
graphitization
Providesamoderateincreaseinhardenability
Hardensferrite,morethanmanganesebutlessthanphosphorus,up
toabout1%
Increasesthe
strength
of
quenches
and
tempered
steels
Providessomeoxidationresistanceatelevatedtemperatures
Isageneralpurposesdeoxidizer,atabout0.05%inrimmedsteelsand
0.150.30%infullykilledsteels
Sulfur None Normallypresentasmanganesesulfidestringerssulfur
Decreasestransversstrengthandductilitybuthaslittleeffecton
longitudinalproperties
Decreasesweldability
Enhancesmachinability
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Titanium Strongerthanallotherelementsexceptniobium/columbium
Producescarbide
particles
that
restrict
grain
growth
Reducesmartensitehardnessbyremovingcarbonfromsolution
Removescarbonfromsolutioninausteniticstainlesssteels
preventinggrainboundarydeteriorationbychromiumcarbide
formation
Inhibitsausteniteformationinhighchromiumsteels
Actsasadeoxidizerbycombiningwithoxygenandnitrogen
Tungsten Strongerthanmolybdenum Decreasessofteningduringtempering
Formsabrasion
resistant
carbides
Promoteselevatedtemperaturehardness
Providessomecreepresistance
Vanadium Strong,butlessthantitaniumorniobium
Providesasignificantincreaseinhardenabilityuptoabout0.05%
Promotesfineaustenitegrainsize
Resistssofteningduringtempering
HardenabilityCalculation:Anumberofelementshavebeennotedashavingtheabilitytoincreasehardenability.Burns,Moore,andArcher(ASMTrans.1938)developeda
chemicalfactorcalculationtoquantifytheeffectofalloyingadditions.Thechemicalfactor,ascomputedbelowhasadirectrelationshipwith
Rockwellinch
hardenability.
Chemicalfactor=1000(%C)+500(%Mn)+400(%Cr)+100(%Ni)+25(%Cu)+1000(%Mo)
Notethatwhilenoalloyingadditionsresultinsuddenincreases,ordecreasesinmechanicalproperties,corrosionresistancemaybesignificantly
alteredbysmallchangesincomposition.