Metal Terminology (M)金属术语M

MBGRADE
AtermappliedtoOpen-Hearthsteelwireinthe.45/75carbonrangeeitherharddrawnoroiltempered.OiltemperedwireofMBandWMBtypesarethemostwidelyusedofallspringwire.Oiltemperedwireismoresuitabletoprecisionformingandcastingoperationsthanharddrawnwirebecauseofclosecontroloftensilestrengthandsuperiorstraightness.

NOTE-MB,HBandextraHBdesignateBasicOpenHearthsteels,whileWMB,WHBandextraWHBdesignateAcidOpenHearthSteels.Thechemicalcompositionandthemechanicalpropertiesarethesameforbothbasicandacidsteel.

MACROETCHTEST
Consistsofimmersingacarefullypreparedsectionofthesteelinhotacidandofexaminingtheetchingsurfacetoevaluatethesoundnessandhomogeneityoftheproductbeingtested.

MACROGRAPH
Aphotographicreproductionofanyobjectthathasnotbeenmagnifiedmorethantentimes.

MACROSCOPIC
Visibleeitherwiththenakedeyeorunderlowmagnification(asgreatasabouttendiameters).

MACROSTRUCTURE
Thestructureofmetalasrevealedbymacroscopicexamination.

MAGNESIUM
(ChemicalsymbolMg.)-ElementNo.12oftheperiodicsystem;atomicweight24.305.Specificgravity1.77withameltingpointofapproximately1160癋.Asilver-whitelightmalleable,ductilemetallicelementthatoccursabundantlyinnature.Themetalisusedinmetallurgicalandchemicalprocesses;inphotography,insignaling,andinthemanufactureofpyrotechnicsbecauseoftheintensewhitelightitproducesonburning.MetalMartistheworld’slargeststockingdistributorofMagnesiumAlloysincluding;Sheet,Plate,Bar,Castings,Forgings,andExtrusions.CheckoutourMagnesiumpageforcompletedetails.

MALLEABILITY
Thepropertythatdeterminestheeaseofdeformingametalwhenthemetalissubjectedtorollingorhammering.Themoremalleablemetalscanbehammeredorrolledintothinsheetmoreeasilythanothers.

MALLEABILIZING
Aprocessofannealingwhitecastironinsuchawaythatthecombinedcarboniswhollyorpartlytransformedtographiticorfreecarbonorinsomeinstances,partofthecarbonisremovedcompletely.

MANGANESE
(ChemicalsymbolMn.)-ElementNo.25oftheperiodicsystem;atomicweight54.93.Lustrous,reddish-whitemetalofhardbrittleand,therefore,non-malleablecharacter.ThemetalisusedinlargequantitiesintheformofSpiegelandFerromanganeseforsteelmanufactureaswellasinmanganeseandmanycopper-basealloys.Itsprincipalfunctionisasanalloyinsteelmaking:(1)Itisaferrite-strengtheningandcarbideformingelement.Itincreaseshardenabilityinexpensively,withatendencytowardembrittlementwhentoohighcarbonandtoohighmanganeseaccompanyeachother.(2)Itcounteractsbrittlenessfromsulfur.

MARTENSITE
Adistinctiveneedlelikestructureexistinginsteelasatransitionstageinthetransformationofaustenite.Itisthehardestconstituentofsteelofeutectoidcomposition.Itisproducedbyrapidcoolingfromquenchingtemperatureandisthechiefconstituentofhardenedcarbontoolsteels.Martensiteismagnetic.

MARTENSITICSTAINLESSSTEEL
Hasabodycenteredtetragonal(BCT)structure.Thesealloysarechromiumstainlesssteelswithmediumtohighcarbonlevels.Theyworkhardenslowlyintheannealed(soft)conditionbutcanbeheat-treatedtoveryhightensilestrengths.

MATRIX
Theprincipalphaseinwhichanotherconstituentisembedded.

MATTORMATTEFINISH
(Steel)-Notassmoothasnormalmillfinish.Producedbyetchedormechanicallyroughenedfinishingrolls.

MECHANICALPROPERTIES
Thosepropertiesofamaterialthatrevealtheelasticandinelasticreactionwhenforceisapplied,orthatinvolvetherelationshipbetweenstressandstrain;forexample,themodulusofelasticity,tensilestrengthandfatiguelimit.Thesepropertieshaveoftenbeendesignatedas“physicalproperties,”buttheterm“mechanicalproperties”ismuchtobepreferred.Themechanicalpropertiesofsteelaredependentonitsmicrostructure.(SeePhysicalProperties)

MECHANICALSPRING
Anyspringproducedbycoldformingfromanymaterialwithorwithoutsubsequentheattreatment.

MECHANICALWORKING
Plasticdeformationorotherphysicalchangetowhichmetalissubjected,byrolling,hammering,drawing,etc.tochangeitsshape,propertiesorstructure.

MEDIUM-CARBONSTEEL
Containsfrom0.30%to0.60%carbonandlessthan1.00%manganese.Maybemadebyanyofthestandardprocesses.

MELTINGRANGE
Therangeoftemperatureinwhichanalloymelts,thatistherangebetweensolidusandliquidustemperatures.

METALLOGRAPHY
Thescienceconcerningtheconstituentsandstructureofmetalsandalloysasrevealedbythemicroscope.

METALLOID
(a)Elementintermediateinlusterandconductivitybetweenthetruemetalsandnon-metals.Arsenic,antimony,boron,tellurium,andselenium,etc.,aregenerallyconsideredmetalloids;frequentlyoneallotropicmodificationofanelementwillbenon-metallic,anothermetalloidincharacter.Obviously,nohardandfastlinecanbedrawn.(b)Insteelmetallurgy,metalloidinhasaspecialized,evenoferroneous,meaning;iscoverselementscommonlypresentinsimplesteel;carbon,manganese,phosphorus,siliconandsulfur.

METALSPRAYING
Aprocessforapplyingacoatingofmetaltoanobject.Themetal,usuallyintheformofwire,ismeltedbyanoxyhydrogenoroxyacetyleneblastorbyanelectricarcandisprojectedathighspeedbygaspressureagainsttheobjectbeingcoated.

MICROSTRUCTURE
Thestructureofpolishedandetchedmetalandalloyspecimensasrevealedbythemicroscope.

MILLEDGE
Theedgeofstrip,sheetorplateintheasrolledstate.Unsheared.

MILLFINISH
Asurfacefinishproducedonsheetandplate.Characteristicofthegroundfinishusedontherollsinfabrication.

MODULUSOFELASTICITY
(Tension)-Forcewhichwouldberequiredtostretchasubstancetodoubleitsnormallength,ontheassumptionthatitwouldremainperfectlyelastic,i.e.,obeyHooke’sLawthroughoutthetest.Theratioofstresstostrainwithintheperfectlyelasticrange.

MODULUSOFRIGIDITY
Ofamaterialsufferingshear,theratiooftheintensityoftheshearstressacrossthesectiontotheshearstrain,i.e.,totheangleofdistortioninradians;expressedonpoundsortonspersquareinch.

MOLD
Aformofcavityontowhichmoltenmetalispouredtoproduceadesiredshape.

MOLYBDENUM
(ChemicalSymbolMo)-ElementNo.42oftheperiodicsystem;atomicweight95.95.Hard,toughmetalofgrayish-whitecolor,becomingveryductileandmalleablewhenproperlytreatedathightemperatures;meltingpoint4748癋.;boilingpointabout6600癋;specificgravity10.2.Puremolybdenumcanbestbeobtainedasablackpowder,byreductionofmolybdenumtrioxideorammoniummolybdatewithhydrogen.Fromthispowder,ductilesheetandwirearemadebypowdermetallurgytechniques;theseareusedonradioandrelatedwork.Itsprincipalfunctionsasanalloyinsteelmaking:(1)Raisesgrain-coarseningtemperatureofaustenite.(2)Deepenshardening.(3)Counteractstendencytowardtemperbrittleness.(4)Raiseshotandcreepstrength,redhardness.(5)Enhancescorrosionresistanceinstainlesssteel.(6)Formsabrasion-resistingparticles.

MUNTZMETAL
(ARefractoryAlloy)-Alpha-betabrass,60%copperand40%zinc.Strongerthanalpha-brassandusedforcastingsandhot-worked(rolled,stamped,orextruded)products.Highstrengthbrassesaredevelopedfromthisbyaddingotherelements.

MUSICWIRE
Apolishedhightensilestrengthcolddrawnwirewithhighertensilestrengthandhighertorsionalstrengththananyothermaterialavailable.Thehightoughnesscharacteristicofthismaterialisobtainedbythepatenting.Suchwireispurchasedaccordingtotensilestrength,nothardness.