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1、鈮在汽車(chē)用熱鍍鋅高強(qiáng)度鋼中的應(yīng)用HardyMohrbacherNiobelConbvba(2970Schilde,Belgium)+32-3-4845260,hm@niobelcon.net摘要:先進(jìn)高強(qiáng)度鋼板在現(xiàn)代汽車(chē)車(chē)體生產(chǎn)中所占比例不斷增加。這些鋼級(jí)主要用于熱鍍鋅或鍍鋅表面處理。因此,在CGL(連續(xù)熱鍍鋅線(xiàn))生產(chǎn)線(xiàn)特有的熱循環(huán)條件下,合理制定這類(lèi)鋼的冶金過(guò)程以獲得預(yù)期性能是必要的。根據(jù)現(xiàn)代車(chē)輛生產(chǎn)中獲得的經(jīng)驗(yàn),鋼板的性能尤其是成形性和焊接性能是需要改善的目標(biāo)。在這方面,鈮微合金化值得人們注意。鈮在熱機(jī)械軋制過(guò)程中的主要作用是的
2、晶粒細(xì)化,從而使鋼強(qiáng)度提高的同時(shí)也能改善韌性。熱軋帶中的晶粒細(xì)化會(huì)保持到冷軋之后。鈮的第二個(gè)作用是獲得更為均勻的微觀組織,特別是對(duì)多相鋼來(lái)說(shuō)。在特殊情況(例如彎曲和翻邊)下,這一作用能夠提高鋼板的成型性能。并且由于晶粒細(xì)化和/或沉淀硬化獲得的強(qiáng)度增加可以使鋼中的合金元素含量降低,從而提高鋼板的焊接性能。鈮的另外一個(gè)作用是在CGL生產(chǎn)線(xiàn)熱循環(huán)過(guò)程中對(duì)相變行為的影響從而擴(kuò)大工藝操作窗口進(jìn)一步優(yōu)化鋼的使用性能。關(guān)鍵詞:鈮微合金化,微觀組織細(xì)化,沉淀硬化,相變控制EFFECTSOFNIOBIUMINGALVANIZEDADVANCEDHIG
3、HSTRENGTHSTEELSFORAUTOMOTIVEAPPLICATIONSHardyMohrbacherNiobelConbvba(2970Schilde,Belgium)+32-3-4845260,hm@niobelcon.netAbstract:Advancedhighstrengthsteelgradesarebeingsignificantlyusedinrecentautomotivebodiesandtheirshareiscontinuouslyincreasing.Typicallythesesteelgrad
4、esareappliedwithahotdipgalvanizedorgalvannealedsurfacetreatment.ThereforethemetallurgyofsuchsteelshasbeendesignedtoachievethedesiredpropertiesunderthetypicalthermalcycleofaCGLline.Havinggainedexperiencewiththesesteelgradesduringrecentvehiclegenerations,theimprovementof
5、specificpropertiesparticularlyconcerningformabilityandweldabilityisbeingtargeted.Inthisrespect,microalloyingbyniobiumhasdrawnconsiderableattention.Thetypical,well-knowneffectofniobiumisthatofgrainrefinementoccurringduringhotrollingunderthermomechanicalprocessingconditi
6、onsleadingtoincreasedstrengthaswellasbettertoughness.Grainrefinementinthehotbandiscarriedoveraftercoldrolling.Aresultingsecondaryeffectespeciallyinmultiphasesteelsisamorehomogeneousmicrostructure.Thisimprovestheformingbehaviorunderspecificconditionssuchasbendingandflan
7、ging.Furthermore,thestrengthgainbygrainrefinementand/orprecipitationhardeningprincipallyallowsreducingthealloyingcontentimprovingweldability.AnotherinterestingeffectofniobiumisitsinfluenceonthetransformationbehaviorduringthethermalcycleintheCGLline.Thisinfluencecanbeut
8、ilizedtoenhancetheprocessingwindowandfurtheroptimizethesteel’sapplicationproperties.Keywords:Niobiummicroalloying,mic