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ID:33349582
大小:2.41 MB
页数:60页
时间:2019-02-25
《az31镁合金板材高温气胀成形性能研究》由会员上传分享,免费在线阅读,更多相关内容在学术论文-天天文库。
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
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