汽车用钢技术途径

MaterialsSection,R&DCenter,FAW,ChinaShanqiangYingMay,22,2013ResearchontheApplicationofAutomotiveSteels2Qualified/StabilitySiliconsteelSpringSteelBoltingSteelGearsteelRolledproductsNon-quenchedandtemperedsteel33M3Comparedwithtraditionalmaterial16MnL,thenewmaterialshouldbehighstrengthtomeetweightreductionsteelplatesusedasframesofthecommercialvehicle

Forexample,withtheyieldstrengthof500MPagradecanincreaseyieldstrengthby43%,makingweightofthewholebodyframedecreasedbyabout300kg.Materialswiththeyieldstrengthof700MPacanmaketheweightreductiontoachieve23%.4Mostofthehot-rolledsteelsheetsusedasframesmustbepickledtogetridoftheoxideonthesurface,butpicklingprocessmaymakethesurfaceroughandraisethecostoftheprocessaswell.Itwillbeappreciatedtohavesteelsheetstogetridofpickling.Byimprovingtherollingprocess,alayerofFe3O4appearsonthesurfaceofthesteelsheets.Thiskindofsteelcanperformwellwhenbeingstamped,andthecostwillbedecreasedaswell.Thiskindofsocalled“blacksurfacesteel”isbeingdevelopedbymanysteelsuppliers,includingcompaniesinEurope,JapanandChina.AlthoughChinesesuppliershavebeenmakingalotofefforts,domesticsteelproductsforcarmanufacturerarenotasgoodasthosebyEuropeanandJapanesesuppliers.5VolvoS60FordFocusSkodaRapidBesternB50MildSteel3843.642.952.3HSS29.529.74741.3AHSS14.5UHSS&PHS14.411.88.5Others3.6BycomparisonamongBesturnB50andsomeotherforeignautomotives,itcanbeseenthatinFAWmodels,theuseoftheAHSSespeciallyUHSSisstillneededtobebroadened.WearemakingoureffortsontheapplicationofAHSSandUHSS.Inthemodelnewlydeveloped,PHSandthe3rdgenerationsteelareutilized,andthescaleoftheapplicationofAHSSandUHSSisincreasingonourcars.6Hopeforsupportfromsteelsuppliers7Thespringsteelsaremainlyusedassuspensionspring,valvespring,supportingspringforstabilizerbarandgearbox,etc.Springsteels8Leafspringsaremainlyusedasasignificantpartinsuspensionofheavy-dutyvehicles.Duetotheneedoflightweight,comfortandreliability,theworkingstressoftheleafspringsincreasesalot.Asthetaperedleafspringsareusedmorewidely,therequirementsforthespringsteelsarehigheringoodhardenability,highstressandlongfatiguelife,whichisonenewchallengeformanufacturingofspringsteels.ForFAW,materialsmainlyusedcontain60Si2MnA,55CrMnAand50CrVA.LeafspringofoneChinesetruckFurthermore,wealsodevelopsomeothermaterialsindependently,suchas50CrMnSiVNband50CrMnMoVNb.Springsteels——LeafspringLeafspringofoneMercedestruck9Withthedevelopmentofheavy-dutyvehicles,theloadthattheleafspringbornisincreasing.Thethicknessofoneleafspringincreasesfrom13mmto24mmevento50mm,sogoodhardenabilityisrequired.Accordingly,theFAWdevelopssomenewmaterialsincluding50CrMnVAandFAS3550,whichmakesagreatcontributiontothelightweightdesign.Springsteels——theapplicationofleafspringwithgoodhardenablilityHighhardenabilityLowhardenabilityMediumhardenability1953200260Si2MnA50CrVA50CrMnVAFAS35502005YearHardenability10MaterialsChemicalCompositation（%）CSiMnCrMoVNbNiCuPS60Si2MnA0.56/0.641.60/2.000.70/1.00≤0.35≤0.35≤0.25≤0.025≤0.02555CrMnA0.52/0.600.17/0.370.65/0.950.65/0.95≤0.35≤0.25≤0.025≤0.02550CrVA0.48/0.540.17/0.370.65/0.800.95/1.100.10/0.15≤0.35≤0.25≤0.025≤0.02550CrMnVA0.47/0.550.15/0.400.80/1.100.90/1.200.10/0.15≤0.35≤0.25≤0.020≤0.01550CrMnSiVNb0.47/0.530.80/1.100.80/1.200.90/1.200.02/0.060.02/0.05≤0.35≤0.25≤0.020≤0.01550CrMnMoVNb0.47/0.530.15/0.400.70/1.100.90/1.200.15/0.250.05/0.100.02/0.05≤0.35≤0.25≤0.020≤0.015Springsteels——materialsofleafspringinFAW11Coilspringsareusedwidelyincarsandoff-roadvehicles,requiredwithgoodfatigueperformanceandelasticextenuationresistance.SothematerialsaremainlySi-Crseriessteel,usuallyheatformed.

ThereareseveralkindsofmaterialsmainlyusedascoilspringsinFAW,suchas60Si2MnA,50CrVA,50CrMnVA,50CrMnSiVNb,50CrMnMoVNb,etc.Assupportingspringforstabilizerbarandgearbox,materialsareoilquenchingandtemperingspringwires:carbonsteelwiresand55CrSi,etc.(a)Coilspringusedforoff-roadvehiclessuspension;(b)Coilspringusedforcarssuspension;(c)Valvespringsinengine.Springsteels——CoilSpring12

MaterialsChemicalcomposition（%）CSiMnCrMoVNbNiCuPS700.62/0.750.17/0.370.50/0.80≤0.25≤0.25≤0.25≤0.035≤0.035850.82/0.900.17/0.370.50/0.80≤0.25≤0.25≤0.25≤0.035≤0.03565Mn0.62/0.700.17/0.370.90/1.20≤0.25≤0.25≤0.25≤0.035≤0.03555CrSi0.51/0.591.20/1.600.50/0.800.50/0.80≤0.35≤0.25≤0.025≤0.02555SiCrV0.51/0.591.20/1.600.50/0.800.50/0.800.15/0.25≤0.25≤0.20≤0.025≤0.02560Si2MnA0.56/0.641.60/2.000.70/1.00≤0.35≤0.35≤0.25≤0.025≤0.02550CrVA0.48/0.540.17/0.370.65/0.800.95/1.100.10/0.15≤0.35≤0.25≤0.025≤0.02550CrMnVA0.47/0.550.15/0.400.80/1.100.90/1.200.10/0.15≤0.35≤0.25≤0.020≤0.01550CrMnSiVNb0.47/0.530.80/1.100.80/1.200.90/1.200.02/0.060.02/0.05≤0.35≤0.25≤0.020≤0.01550CrMnMoVNb0.47/0.530.15/0.400.70/1.100.90/1.200.15/0.250.05/0.100.02/0.05≤0.35≤0.25≤0.020≤0.015

Thevalvespringsbarehighalternatingloadandhighrotatingspeed,soitisrequiredforthematerialstopossessgoodfatigueperformance,goodwearresistanceandgoodheatresistance.ThematerialsusedinFAWareusually55CrSi(oilquenchingandtemperingspringwires),mostofwhichareproducedbycompaniesofJapanandKorea,whileChinesematerialscan’tmeetthedemandoflongfatiguelife.Methodssuchasnitridingandshotblastingarebeingresearchedintheworldtoimprovethedesignstresstoahigherlevel.Springsteels——materialsofcoilspringinFAW13Springsteels——torsionbarsprings&stabilizerbar

Thetorsionbarspringsforsuspensionareusedinsomelight-dutyvehicles，whichmainlyrequiresgoodfatigueperformance.Thetorsionbarspringsforover-turndeviceareusedforturningoverthecaborthetrunk,whichmainlyrequiresgoodlooseresistanceperformanceandstronglypre-twist.Therearetwodifferentkindsofmaterialswithdifferentheattreatmentusedasthetorsionbarsprings.Onekindofmaterialiscarbonsteelwithinductionhardening,suchas45,40Cr.Theotherisspringsteelwithquenchingandtempering,suchas60Si2MnA,50CrMnVA,50CrMnMoVNb,45CrNiMoVA,etc.

Thestabilizerbarisanelasticpartforkeepingstablewhencarsaremakingaturn,usuallywithacomplicatedshape.Therearetwokindsofstabilizerbar,hollowandsolid.Thehollowstabilizerbarcandecreasetheweightforabout30%~40%,whichhasbeenusedinheavy-dutyvehicles.Typicalmaterialsforhollowstabilizerbarincludetubesmadeby30CrMoA,35CrMoA,35Mn2,whilecommonmaterialsforsolidstabilizerbarinclude60Si2MnA,40CrMnVA,55CrMnA,55CrSiA,etc.14Thespringsteelwithhighlevelofstress,fatigueresistanceandelasticextenuationresistancearenecessaryfortheautomotiveindustry.Comparedwithothercountries,thedesignstressofleafspringandstabilizerbarislowerfor100~200MPa.Forexample,thetypicaldesignstressofleafspringweproduceisusually500~600MPa,whileinEuropeandAmerica,thisvalueis700~800MPa.Similarly，thetypicaldesignstressforstabilizerbarisabout500MPa,whilethisvalueis700MPainEuropeandAmerica.Nowthevalvespringswithhighlevelofstressareusuallyproducedbymaterialssuppliedbyforeigncountries.Inmanyothercountries,thedataofperformanceoffatigueandelasticextenuationofthematerialsandtheCCTcurveareallprovidedbythesteelcompanies.Forus,itisappreciatedifwecangetallthesedataweneededfromdomesticsteelcompanies.Springsteels——issuestobesolvedbysteelsuppliers15KindsofmotorsautomotivedrivingmotorsSiliconsteelSiliconSteel16

ItisputforwardbytheNationalOutlineforMediumandLongTermScience&TechnologyDevelopment(2006～2020)thatprioritieswillbeassignedtoresearchonanddevelopmentofkeytechnologiesforhigh-efficiencyandlow-emissioninternalcombustionengines,fuelcellengines,accumulatorbatteries,drivingmotors,andothercriticalcomponents,andtechnologiesfordevelopingexperimentandtesttechniquesandinfrastructureforautomobilesusingnewenergy.Asamagneticpermeabilitymaterial,thesiliconsteelplaysasignificantroleinthedrivingmotors.Itweighsmorethanhalfofthetotalweightofdrivingmotor,andthecostofmaterialis40%ofthetotalcost.Thewholepowerofdrivingmotorsisdeterminedbytheelectromagneticpropertiesofthesiliconsteel,andthereliabilityofdrivingmotorsisdeeplyaffectedbythemechanicalpropertiesofthesiliconsteel.17First,thefrequencyiswayhigher.Inotherindustry,thefrequencyofthedrivingmotorisusually60~120Hz,whileinautomotiveindustry,thefrequencyofthedrivingmotorapproachesto1KHz.Second,thedrivingmotorworksunderahightemperatureforabout200℃causedbythehighfrequency,whichaffectsthepropertiesofthematerials.Last,goodmechanicalandfatiguepropertiesarerequiredduetohighworkingfrequencyandhighrotatingspeed(about12000rpm).2/3ofthewholesiliconsteelsintheworldareproducedinChina,whilethebestandadvancedproductisproducedbytheNipponSteelinJapan.Forrecentyears,Chinabecomesthebiggestsupplierofthesiliconsteel.Thekeymaterialofthedrivingmotorsusedinautomotiveindustryisdifferentfromthoseusedinotherindustries.Unfortunately,thereisnostandardofmaterialandtestingtechniquesforthematerialyet,whichbecomesanobstacleoftheresearchanddevelopmentofthedrivingmotorsforFAWandthewholeindustry.Siliconsteel——thecharacteristicoftheautomotivedrivingmotors18Siliconsteel——MainimpactfactorsofthemagneticpropertiesMainfactorsaffectingthemagneticpropertiesofsiliconsteelThicknessFrequencyTemperatureProcessstatusHeattreatment19Thefrequencyofautomotivedrivingmotorskeepsincreasing,whickmakesthecorelossincreasessharply.Sothereductionofthethicknessisthemostefficientmethodtoreducethecoreloss.Withthedecreaseofthicknessofsteelsheets,thecorelossgoesdownsharply.Comparedwithsteelforthethicknessof0.35mm,theP10/P400ofthesteelforthethicknessof0.30mmdecreasesforabout11%,whiletheP10/P400ofthesteelforthethicknessof0.27mmdecreasesforabout15%.Soitwillincreasetheefficiencyofdrivingmotorsifthethicknessgoesdown,whichisalsothetrendofdevelopmentofsiliconsteel.Siliconsteel——thetrendofthinnersheet20Siliconsteel——thedevelopmentprocessManufacturingofdrivingmotorsApplicationofsiliconsteel21

FAWhasestablishedsomestandardsofthesiliconsteelandtestingtechniques,andkeepresearchingonthedevelopment,applicationandtestingtechniquesofthesiliconsteel.PropertiesoftypicalsiliconsteelsbeingusedinFAWSiliconsteel——materialsusedinFAWMaterialNominalthickness(mm)Maximumspecifictotallossat50Hzandat1.5T(W/kg)MinimummagneticpolarizationTInanalternatingmagneticfieldstrength(A/m)Maximumanisotropyoflossat50Hzand1.5T(%)MinimumstackingfactorDensity(kg/dm3)FAS35N2500.352.501.6217.10.957.60FAS35N3000.353.001.6218.30.957.65FAS35N3600.353.601.6219.80.957.65221.Thesteelcompaniesshoulddevelopthesiliconsteelusedinelectricmotorsofhighperformancevehiclewithhigheconomicalefficiency,reliabilityandfriendlytotheenvironment.2.Weshoulddevelopthetestingmethodsandthestandardsofthesiliconsteelwiththecharacteristicofhightemperatureandfrequency.3.Weshoulddevelopthetestingmethodsandthestandardsofthemechanicalpropertiesforthedesignofthedrivingmotors.4.Itisexpectedthatthesteelcompaniescanprovidethekeydatafordesigningtheelectricmotorofvehicles.Siliconsteels——issuestobesolved23Aftertheyearof2000,FAWmadecooperationwiththeNortheastSpecialSteelGroupanddevelopedsteelFAS2271andFAS2237forfracture-spiltconnectingrod,steelFAS2225forfrontaxle,FAS2239forcrankshaft,andnon-quenchedandtemperedsteelFAS2241withlowcost.FAWalsodevelopedsteelFAS2340forfrontaxle

withShiJiazhuangsteelcompany.Thenon-quenchedandtemperedsteel——currentsituationinFAW1980199035V45V35MnVS40MnV40MnVS45MnV200048MnVSC70S616Mn2VBFAS2271FAS2237FAS2225FAS2340FAS2239FAS2241Year24Thenon-quenchedandtemperedsteelHardness(HB)Impactvalue(J/cm2)TensileStrength(MPa)HighductilityHighstrengthHighstrength&ductility(Martensitetype)Highstrength&ductility(Bainitetype)25thenon-quenchedandtemperedsteelusedinconnectingrodTensilestrength(MPa)MaterialApplicationManufacturerbelow90035MnVS40MnVfracture-spiltconnectingrodofcommercialvehicleabove900FAS2271fracture-spiltconnectingrodofcarandcommercialvehicleNortheastSpecialSteelGroupabove950FAS2237fracture-spiltconnectingrodofcarNortheastSpecialSteelGroupMaterialCMnVBrinellhardness(HBW)Tensilestrength(MPa)FAS22710.68~0.730.45~0.650.03~0.04270~300900~1050FAS22370.34~0.410.95~1.050.20~0.35280~320950~1100ConnectingrodofMAZDA626Duetothedemandofthereliabilityandlow-noiseoftheengine,theaccuracyofmanufacturingofcrankshaftmustbeimproved.Theshapeanddistributionofsulfidecanaffectthecuttingperformanceofcrankshaft,andthesegregationofsulfidemaycausesurfacedefect.InFAW’sproducts,steelFAS2239isutilizedinthecrankshaftsofthe6DLseriesandDEUTZseriesengine.thenon-quenchedandtemperedsteelusedincrankshaft2716Mn2VB32SiMnVTiSFAS2225Year1986,45Mn2V……Year1992,12Mn2VB,16Mn2VB

……

Now,32SiMnVTiS,FAS2225thenon-quenchedandtemperedsteelusedinfrontaxleThroughtheresultsoftheexperiments,itisimpliedthatthefatigueperformanceofthesteelweusesatisfiestherequirementscompletely.Frontaxle28YieldtorqueT0.3/NmShearstrengthτ0.3/MPaMaximumtorqueTb/NmTorsionalstrengthΤb/MPaDuctility

N•m/°FracturePositionDesignfoudationoffracturetorqueKNm1380659007141016801614Nearspline﹥495002377568907126416801583Nearspline3370128707024116601578NearsplineAveragetorqueMm/NmRangeoftorqueMa/NmFatiguelife×103TestingresultDemandoffatiguelifeRemark4165001375099.6B50=103.13B10=33.05B50≥30B10≥20Notfractured541.29Fractured47.76NotfracturedYear1984 40MnV

Nowadays FAS2230thenon-quenchedandtemperedsteelusedinhalfshaftofautomobiles29FAWhasmadesomeexperimentswiththecooperationofNipponSteelofJapanandNortheastSpecialSteelGrouponthesteelforgrade8.8bolts,ofwhichthemainelementsincludemanganese,chromiumandniobium.Throughtheanalysisofthemicrostructure,itisimpliedthatthereishardlythetendencytodecarburization.Comparingthefatigueperformanceinhighfrequencywitheachother,wecanseethedifference.Thefatiguelimitoftheonequenchedandtemperedis496N/mm2,whilethefatiguelimitoftheonenon-quenchedandtemperedis512N/mm2,whichisbetterthantheother.Wekeepdevelopingandresearchingonthehighstrengthnon-quenchedandtemperedsteelusedforgrade10.9bolts,ofwhichtheseriesofelementsarelowcarbon-manganese-boron.thenon-quenchedandtemperedsteelusedinfasteningbolts30ItemsQuenchedandtemperedSteelNon-quenchedandtemperedsteel0.2%proofload(KN)42.3740.740.2%proofstrength(N/mm2)730700Tensileload(KN)52.9650.93Tensilestrength(N/mm2)915880Rockwellhardness(HRC)29.028.5Vickershardness(HV)312297thenon-quenchedandtemperedsteelusedinfasteningbolts311.Sinceitisbenefittoutilizethenon-quenchedandtemperedsteel,itisnecessaryfortheautomotiveindustriesandthesteelcompaniestokeepdevelopingandspreadingtheproduct.2.Thenon-quenchedandtemperedsteelwithhighstrengthandhighductilityshouldbedeveloped.3.Theimprovementisnecessaryforthestandardsofthenon-quenchedandtemperedsteel.4.Theresearchshouldbekeptdoingforthenon-quenchedandtemperedsteelwithlowcost.Suggestionsforthesteelsuppliers32Nowadays,boltsaremainlyusedinautomotiveindustry,electronicindustryandarchitectureindustry,amongwhichautomotiveindustryisthebiggestclient,whosedemandis23.2%ofallthesalesvolume.In2011,thevolumeofboltproductioninChinareached6.8milliontons,withthesalesrevenueof66billionRMB.Thankstotherapiddevelopmentofautomotiveindustry,architectureindustryandmanufacturingindustry,thesalesrevenueofourboltingmarketmaygoto200billionRMBuntil2015.In2011,theaggregatedemandoftheboltsintheglobalmarketis64.4billiondollars,andthisquantityisincreasingby5.2%everyyear,whichwillreach82.9billiondollarsin2016.Theboltingsteel——currentsituation33ThevolumeofboltproductioninChinaisaboutaquarteroftheglobalproduction,40%ofwhichisforexporting.Chinahasbecomethebiggestproducerandexportingmerchant.In2011,thevalueofourexportis4.6billiondollars,whilethevalueofourimportis3billiondollars.Theaveragepriceforexportis1260dollarsperton,whiletheaveragepriceforimportismorethan9000dollarsperton.In2008,thecoldheadingsteelsofhighqualityareusedmorethan1.8milliontons,whichis7%~12%ofallthesteelsofhighqualityinautomotives.Thereare14tonsofthiskindofsteelsuesdinFAWforoneyear.Accordingtosomestatistics,thereareabout4000boltsweighing50kginacaroralight-dutyvehicle,whilethereareabout7500boltsweighing90kginamedium-dutyorheavy-dutyvehicle,4/5ofwhicharehighstrengthbolts.Toonevehicle,thecostofboltsmakesup2.5%~3%ofthetotal,andthenumberofboltsmakeup40%ofthenumberofalltheparts.Theboltingsteel——currentsituation34AlargequantityofboltsusedinFAWisprovidedbyJilinstandardfastenercompany,andtheydohavesomeprinciplesaboutthematerialstheyusetoproducehighstrengthbolts.Forexample,ML42CrMo(SCM440)isusedforgrade12.9bolt,ML35CrMoZ(SCM435)isusedforgrade10.9bolt,andML40Crisusedforgrade8.8bolt.MaterialsChemicalComposition%CSiMnPSCrMoML40Cr0.38-0.430.15-0.350.60-0.85≤0.030≤0.0300.90-1.20ML35CrMoZ0.33-0.380.10-0.350.60-0.85≤0.030≤0.0300.90-1.200.15-0.30ML42CrMo0.38-0.45≤0.30050-0.80≤0.030≤0.0300.90-1.200.15-0.30Theboltingsteel——CurrentsituationStandardCBoundSiBoundMnBoundCrBoundMoBoundISO683-10.30~0.370.070.10~0.400.300.60~0.900.300.90~1.200.300.15~0.300.15GB/T64780.32~0.400.08≤0.300.300.60~0.900.300.90~1.200.300.15~0.250.10FAWstandard0.33~0.380.050.15~0.350.200.65~0.850.200.90~1.200.300.15~0.350.20JISG35090.33~0.380.050.15~0.350.200.60~0.900.300.90~1.200.300.15~0.300.15KAMAX0.34~0.370.03≤0~0.900.201.05~0~0.300.10Aoyoma0.33~0.350.020.16~2~0.800.180.92~1.060.140.15~0.180.0335Hereisoneofhighstrengthmaterialsusedforbolts,whichiscalledML35CrMoinChinesestandard(GB/T6478-2001).Equivalently,thismaterialiscalled34CrMointheinternationalstandard(ISO863.1),34CrMo4inDINstandardandSCM435inJISstandard.Inaddition,KAMAXHoldingGmbHofGermanandAoyomaSeisakushoCo.,Ltd.ofJapanbothdeveloptheequivalentmaterials.

Boltingsteel——IssuestobesolvedThecomparisonamongdifferentmaterials36AlloftheboltingsteelsusedinAoyomaSeisakushoCo.,Ltd.AreimportedfromJapan,andthemechanicalpropertiesofthematerialsaretested.

Boltingsteel——Issuestobesolved37DateMaterialsdemensionSirialnumbersupplierweight(t)Qualityissues2.28ML40CrΦ24183646Baosteel201795tested,1disqualified3.3ML35Φ14366419Baosteel316555tested,1disqualified3.16ML20MnVBΦ13.66(Φ15)183473Baosteel825434.3ML42CrMoD12683343Baosteel63303tested,1disqualified

ML35CrMoZD11183914Baosteel20403tested,1disqualified4.4S22AD24366548Baosteel89824tested,1disqualified4.7ML35CrMoZD23183973Baosteel734335tested,2disqualified4.1ML35CrMoZD131839*50Baosteel300265tested,1disqualified8.6ML35D15367031Baosteel

5tested,1disqualified9.1ML35CrMoZD9184233Baosteel

abunchtested,1disqualified11.1S38KD11367318Baosteel

5tested,1disqualifiedStatisticofqualitydefectofboltsmadebyJilinstandardfastenercompanyatyear2007

Boltingsteel——Issuestobesolved38Asforhighstrengthboltsusedaspartsoftheengine,thematerialsareusuallyimported.

Thematerialsaremainlyboronsteel,andforgrade10.9bolts.InGermany,27MnB4,23MnB4,32CrB4and32CrMo4(DINEN10263-4)areusuallyused.InJapan,SCM435andSCM440(JISG4053)areusuallyused.

Boltingsteel——importedboltingsteelwithhighstrength39DelayedfractureSolvingdelayedfractureAftertheyearof2000,thestrengthofboltsisrequiredtobeimprovedduetothedemandofhighstressandlightweightfromautomobileandmachineryindustry.Theapplicationperformanceofgrade12.9boltisresearchedandbeingsolvedbymanycountriesallovertheworld.Now,90%ofthegrade12.9boltsneedtobeimported.Boltingsteel——developmentofthestrength40

Boltingsteel——suggestionsforthesteelsupplier41

Atthefirstbeginning,thegearsteelweuseistheCr-Mn-TiseriessteeldevelopedbySovietUnion.Inthe1990s,withtheintroductionoftechniques,wedevelopedsomenewsteelincludingCr-Moseriessteel,Mn-CrseriessteelandCr-Ni-Moseriessteelsuccessively.Asthecontinuousimprovementofthequalityofthegearsteelandtheequipmentforprocessinggears,thestrengthgradeofourgearsteelhasreachedthegradeMEofISOstandard,thustheseriesstandardsforourgearsteelaremadeup.Now,inourstandards,thereare22kindsofgearsteel,7ofwhichareusuallyusedintrucks.20CrMnTiH20CrMoH22CrMoH20CrNiMoHSAE8620HFAS3220HFAS3420H1953199020CrMnTiHGearsteel——currentsituation42Therearemainly7kindsofgearsteelsusedintheheavy-dutyvehiclesofFAW.MaterialsParts120CrMnTiHGearsof457axleGearsandaxlesof8TAand10TA220CrMoHGearboxgears,gearsofaxles322CrMoHGearsof498axleGearboxoutputshaftsof10TA420CrNiMoHGearsof498axle5FAS3220HGearsofMV36FAS3420HGearsandshaftsof10TA7SAE8620Gearboxgearsandshaftsof8TA,10TAand12TA43StatisticsoftestingMaterialsAmountQualifiedrateofhardenabilityJ9J1518CrMnTiH5398.11%100%20CrMnTiH4092.5%85%20CrMo