MetalTerminology(G)金属术语G
GAGES
(Metal)-Mfrs.standardnumberingsystemsindicatingdecimalthicknessordiameters.
GALLING
Thedamagingofoneorbothmetallicsurfacesbyremovalofparticlesfromlocalizedareasduetoseizurecuringslidingfriction.
GALVANIZING
Coatingsteelwithzincandtin(principallyzinc)forrustproofingpurposes.Formerlyforthepurposeofgalvanizing,cutlengthsteelsheetswerepassedsinglythroughabathofthemoltenmetal.Today’sgalvanizingprocessingmethodconsistsofuncoilingandpassingthecontinuouslengthofsuccessivecoilseitherthroughamoltenbathofthemetaltermedHotDippedGalvanizingorbycontinuouslyzinccoatingtheuncoiledsheetelectrolytically-termedElectro-Galvanizing.
GAMMAIRON
Theformofironstablebetween1670癋.,andcharacterizedbyaface-centeredcubiccrystalstructure.
GILDINGMETAL
Acopper-zincalloycontaining95%copperand5%zinc.Whilesimilartodeoxidizedcopperinphysicalproperties,itissomewhatstrongerandveryductile.Ithasthermalandelectricalconductivityslightlybetterthanhalfthatofelectrolyticcopperandcorrosionresistancecomparabletocopper.
GRAIN
Asolidpolyhedral(ormanysidedcrystal)consistingofgroupsofatomsboundtogetherinaregulargeometricpattern.Inmillpracticegrainsareusuallystudiedonlyastheyappearinoneplane.(1)Directionof:Referstograinfiberfollowingthedirectionofrollingandparalleltoedgesofstriporsheets.(2)Tobendacrossthegrainistobendatrightanglestothedirectionofrolling.(3)Tobendwiththegrainistobendparalleltothedirectionofrolling.Insteel,theductilityinthedirectionofrollingisalmosttwicethatatrightanglestothedirectionofrolling.
GRAINBOUNDARY
Boundingsurfacebetweencrystals.Whenalloysyieldnewphases(asincooling),grainboundariesarethepreferredlocationfortheappearanceofthenewphase.Certaindeteriorations,suchasseasoncrackingandcausticembrittlement,occuralmostexclusivelyatgrainboundaries.
GRAINGROWTH
Anincreaseinmetalliccrystalsizeasannealingtemperatureisraised;growthoccursbyinvasionofcrystalareasbyothercrystals.
GRAINS
Individualcrystalsinmetals.
GRAINSIZE
Averagediameterofgrainsinthemetalunderconsideration,oralternatively,thenumberofgrainsperunitarea.Sinceincreaseingrainsizeisparalleledbylowerductilityandimpactresistance,thequestionofgeneralgrainsizeisofgreatsignificance.Theadditionofcertainmetalsaffectsgrainsize,forexamplevanadiumandaluminumtendtogivesteelafinegrain.TheASTMhassetupagrainsizestandardforsteels,andtheMcQuaid-EhnTesthasbeendevelopedasamethodofmeasurement.
GRANULATED
Acoarsegrainorpebblysurfaceconditionwhichbecomesevidentduringdrawing.(SeeOrangePeel)
GRANULATION
Theformationofgrainsimmediatelyuponsolidification.
GRAPHITIZING
Aheatingandcoolingprocessbywhichthecombinedcarbonincastironorsteelistransformed,whollyorpartly,tographiticorfreecarbon.
GROUNDFLATSTOCK
Annealedandpreground(toclosetolerances)toolsteelflatsinstandardsizesreadyfortoolroomuse.Thesearethreecommongrades;waterhardening,oilhardeningandairhardeningquality.
GUIDE
Deviceforholdingthemetalintheproperposition,duringrolling,orslitting.
GUIDESCRATCH
(Defect)-Scratchesormarksappearingparalleltoedgesofcoldrolledstripcausedbyscaleorotherarticleswhichhavebecomeimbeddedinorhaveadheredtotherollingmillguide.Alsoappliestosimilarscratchesappearingasaresultofslitting.
MetalTerminology(H)金属术语H
HALFHARDTEMPER
(A)No.2Temper.Inlowcarboncold-rolledstripsteel,producedbycoldrollingtoahardnessnexttobutsomewhatsofterthanfullhardtemper.(B)InbrassStainlessSteelStrip,tempersarebasedonminimumtensileoryieldstrength.ForChromium-NickelgradesHalf-HardTemper150,000TS.,110,000YS.Min.
HARDDRAWING
Drawingmetalwirethroughadietoreducecrosssectionandincreasetensilestrength.
HARDDRAWN
Wireortubingdrawntohightensilestrengthbyahighdegreeofcoldwork.
HARDDRAWNSPRINGSTEELWIRE
Amediumhighcarboncolddrawnspringsteelwire.Usedprincipallyforcoldsprings.
HARDENABILITY
Theabilityofametal,usuallysteel,tohardenindepthasdistinguishedfromtheterms“hardness.”
HARDENEDANDTEMPEREDSPRINGSTEELSTRIP
Amediumorhighcarbonqualitysteelstripwhichhasbeensubjectedtothesequenceofheating,quenchingandtempering.
HARDENING
Anyprocesswhichincreasesthehardnessofametal.Usuallyheatingandquenchingcertainironbasealloysfromatemperatureeitherwithinorabovethecriticaltemperaturerange.
HARDNESS
Degreetowhichametalwillresistcutting,abrasion,penetration,bendingandstretching.Theindicatedhardnessofmetalswilldiffersomewhatwiththespecificapparatusmeasuringhardness.(SeeBrinellHardness,RockwellHardness,VickersHardness,ScleroscopeHardness)TensileStrengthalsoisanindicationofhardness.
HARDTEMPER
(A)ForSteelseeFullHardTemper.(B)Inbrassmillterminology.HardTemperisfourB&Snumbershardor37.1%reduction.
HEATOFSTEEL
Theproductofasinglemeltingoperationinafurnace,startingwiththechargingofrawmaterialsandendingwiththetappingofmoltenmetalandconsequentlyidenticalinitscharacteristics.
HEATTREATMENT
Alteringthepropertiesofametalbysubjectingittoasequenceoftemperaturechanges,timeofretentionatspecifictemperatureandrateofcoolingthereforebeingasimportantasthetemperatureitself.Heattreatmentusuallymarkedlyaffectsstrength,hardness,ductility,malleability,andsimilarpropertiesofbothmetalsandtheiralloys.
HIGHBRASS
65%-Acopper-zincalloycontaining35%zinc.Possesseshightensilestrengthandisusedforsprings,screws,rivets,etc.
HOOKE’SLAW
Stressisproportionaltostrainintheelasticrange.ThevalueofthestressatwhichamaterialceasestoobeyHooke’slawisknownastheelasticlimit.
HOTDIP
Insteelmillpractice,aprocesswherebyferrousalloybasemetalsaredippedintomoltenmetal,usuallyzinc,tinorterne,forthepurposeoffixingarustresistantcoating.
HOTSHORT
Brittlenessinhotmetal.
HOTTOP
(SeeSinkhead)
HOTWORKING
Plasticdeformationofmetalatatemperaturesufficientlyhighnottocreatestrainhardening.Thelowerlimitoftemperatureforthisprocessistherecrystallizationtemperature.
HYDROGENEMBRITTLEMENT
(1)Brittlenessofmetal,resultingfromtheocclusionofhydrogen(usuallyasaby-productofpicklingorbyco-depositioninelectroplating).(2)Aconditionoflowductilityresultingfromhydrogenabsorptionandinternalpressuredevelopedsubsequently.Electrolyticcopperexhibitssimilarresultswhenexposedtoreducingatmosphereatelevatedtemperature.
HYPEREUTECTOIDSTEEL
Asteelhavingmorethantheeutectoidpercentageofcarbon.(SeeEutectoidSteel)
HYPOEUTECTOIDSTEEL
Steelwithlessthaneutectoidpercentageofcarbon.(SeeEutectoidSteel)