az31镁合金板材高温气胀成形性能研究

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1、颈士学撞论变摘要近年裳，镁台垒虫子其霄密度低、毙强艘糊耽嚣g瘦裹、胃隧牧性等钱焘，其疲震臻究爨戮了掇交靛重税。瘀予筑镁帮大部分镁舍金露整捧六方绩梅(hep)，导致其成形性能较差，其痘用受到了极大限制。镁合金板材可广泛厢于制造备种覆藏停、鬻髂、藿钵、嚣援等。本文逡瑕AZ31镁会金蔽瓣必研究辩象，分耩了该念金在高温下的成形性能和微观结构，进而研究了AZ31镁合念趟耀性气胀成形工艺。本瓷文器舅宠了囊搂羹簧澎、涎酚段骚黟饕多除段涨黪工艺。遥过灏薰了藏形律麓尺寸变化，得出了三种胀形方式的豢要成形参数：等效流变成力口、等效应变8窝应变遮攀敏感掇数m。实验结暴发现，誊媸鞭形过程

2、孛，在艨形湛度673K、胀形压强0．7MPa时镁合金檄树的胀形高度可遮23．34mm，高径比为H／d=0．67。谯673K下m值最大可以达到0。38，从而可以毅褥一是静超塑性。在蕊阶段胀形与多除段骚黪过程巾，夔饕胀形过程戆续避行，金属不凝菱生软纯，各个除段熬簿效流交敝力。持续下降。谶过对徽躐结构酌势糯，本文还探讨了乳制AZ31镁合金板豺姻胀形枫制。分析衮嬲：鑫爨’涛移是气胀戚形过程中主簧熟变形枫镪，嚣动态再绪黼、空洞形核和晶内滑移则为重要的辅助机制。最后本文采用内行研制的朗模，程673K、0．9MPa下胀形90rain，成功嫩制各逡了簋黟镁合金张澎律，并对黻彩嵇懿

3、金属流变褥舞蠢鼯瘦变纯避嚣了蕊察。磷巍绪暴表骥，篱黪鞭_形俸酌浮秘应变较均匀，胀形件硬都交形鏊鞍小，{掰懋空变形区较大，阅模转角处变形躐最大。美键词；镁金金；越鳖洼；气胀或形；残黟缝r三些查垒垄!堡盒垒堡塑塑望壁篁竖堕垄堡!!婴茎，!．．AbstractMagnesiumalloyshasbeenpaidagreatdealofattentionsinrecentyearsbecauseofitslowdensity,excellentspecificstrength。specificrigidityandrecovery．Howeverthekeyrestric

4、tionofmagnesiumalloysapplicationispoorworkabilitybecauseofhexagonalclosepacked(hcp)structure．Magnesiumalloysheetcanhighlyfabricatecomplicatepartswhichwilldeveloptheapplicationofmagnesiumalloys，suchas：overlay,cylinder，caseandfrontpanel．Aimedattheapplicationofmetalsheetforming，atypicalc

5、ommercialAZ31magnesiumalloyhasbeenselectedandthesuperplasticpropertiesatelevatedtemperaturestogetherwiththemicrostructuralevolutioningas-bulgingforminghavebeenstudiedinthisdissertation．Inthisdissertation，one-stage，two·stageandmulti—stagegasbulgingformingwasresearched．Themechanicalprop

6、ertiesofsampleswerecarefullyinvestigatedbygas-bulgingforming．Theregularityofchiefparameterssuchaseffectiveflowstress0．effectivestrain6andstrainratesensitivitymwassummarizedbymeasuringheightandthickness．Asaresult，in673K，thehighestmvaluecanget0．38andintheconditionof673K，0．7MPa，thehighes

7、theightcanget23．4mm，I-Ud=O．78．Intheprocessofmulti—stagegasbulgingforming，theeffectiveflowstressisdecreasedwiththeeffectivestrain．Theoptimalsuperplasticdeformationrageoftemperaturesandstrainrateswasdeterminedtoo．Themicrostructurewasanalyzedtoclarifythesuperplasticdeformationmechanismof

8、rolle