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1、北京有色金屬研究總院碩士學(xué)位論文鎂合金及其半固態(tài)觸變成形工藝研究姓名:王懷國(guó)申請(qǐng)學(xué)位級(jí)別:碩士專業(yè):材料學(xué)指導(dǎo)教師:張奎;徐駿20030301箍螫結(jié)合半固態(tài)加工的特點(diǎn),確定了鎂臺(tái)金觸變成形二次加熱的方法,即直立式電磁瓣應(yīng)熱熱的方式。試驗(yàn)洽磁了二次加熱竣禱參數(shù)以及AZ91D合會(huì)擠壓坯零}優(yōu)化熬二次加熱工藝參數(shù),麓決了鎂食金半戳態(tài)坯料二次熱熱的技術(shù)難題。搽討了鎂臺(tái)塞半露態(tài)坯秘在二次掇熱邈毽中液穗產(chǎn)生蛉秘毽,建立了滾穗體被分?jǐn)?shù)與再終鼴晶靛尺寸稆襲層熔純厚發(fā)瓣關(guān)系模型,接導(dǎo)爨了滾楣體積分?jǐn)?shù)與縛縮晶組織的關(guān)系式。對(duì)于AZ91D和ASE6
2、40鎂合金半固態(tài)坯料,在二次搬熱避稷中發(fā)生圈復(fù)、搿絡(luò)晶與Mgl7A{{2漿溶麟,基俸續(xù)織交減零捐Ⅸ.Ug基溶{奉縫織,燕爨區(qū)域?yàn)殄繟l醫(yī),斑點(diǎn)懲,楚純楚扶磊綏鑫羆粒靜鑫器牙始懿。在液疆產(chǎn)生藏晶羧滾純羧緩愎,在螽霧產(chǎn)壘液裙盾球純鴦羹漆。試滁證明:增大坯料的塑性變形程度和提黼二次加熱的升溢速度可以細(xì)化搭結(jié)菇黼粒,增灝一定條件下鷯液相體積分?jǐn)?shù),從而改善合金坯料納觸變性能,寄剝予合金的半陵態(tài)觸變艘形。試驗(yàn)也黢諼了艨提出靜渡鼴體積勢(shì)數(shù)與驏結(jié)鑫器藏尺≮‘窩表瑟潘倪蓐發(fā)瓣熒系模型。鎂含念液態(tài)雁鑄易產(chǎn)生顯微夾雜和氣≯L等缺隧。贏!}耋固態(tài)囂鑄
3、剝不懲,出于坯料蠛充模具更加平穩(wěn),使得夾雜和氣孔都很少,避免了產(chǎn)生皮下氣孔和疏松等凝攢缺隆。在生產(chǎn)瑗場(chǎng)袋瘸拳藿態(tài)魅變成澎工藝壓鐐了AZ91D鎂臺(tái)壘簿汽車室壓壤連抒,零俘縫緩為纓,l、瓣等贛爨緩織,零饞懿臺(tái)穆率穢綴合力學(xué)翟麓垮俄子液態(tài)壓鎊。鎂合念拳強(qiáng)態(tài)壓鑄套荔產(chǎn)生充獾簌麓,但是通道會(huì)理設(shè)詩(shī)澆道系統(tǒng)、提高壓射比壓和模熙溫度,可以避免充型缺陷的產(chǎn)生。關(guān)鍵灝:鎂含裊,=次麓燕,壤緩溪佬,中闋臺(tái)壘,半罄愨融變戲形一囂。壘呈!!堡壘里!一.—一ABSTRACTSemi.solidprocessingwasappliedintomagnes
4、iumalloyforming0nthebasisofpilotstudyinthispaper,Semi—solidfeedstocksofAZ91DandASE640magnesiumalloywerepreparedandoptimizedreheatingparameterswereestablished·Themeltmechanismandmicrostructuralevolutionofsemi-solidfeedstockduringreheatingwereinvestigatedandthefeature
5、sofsemi—soliddie-castingformagnesiumalloyswerealsoanalyzed,Inaddition,theconnectingrodofaircompressorformotorcarwascastbythixoformingandthequalityofthecastingwasevaluated.FeedstocksofAZ91DandASE640alloyweredirectchillcastandthenhotextrudedtOpreparesemi-solidbillets.
6、Theextrusionprocesswasdetermined.Itisshowedthatthegrainsinextrudedmaterialsarestretchedalongextrusiondirectionformingfiberstructure,andnoapparentrecrystallizationOccursduringhotwextrusion.TheASE640alloyisaspeciallydevelopedheat-resistantalloywithhighsiliconcontent,w
7、hichissmeltunderthecoveringfluxprotection.DifferentadditionformsofsiliconelementtomagnesiummeltarecomparedandtheA1-Simasteralloymethodisselected,whichresolvesthehard—to—dissolveproblemofpuresilicon。Thedissolutionprocessofsiliconinmagnesiummeltisdiscussed.Itindicates
8、thatthesmallertheprimarysiliconstripsinthemaster-alloy,thehigherthedissolutionrateandthelessthedissolutiontime.Therearefourphasesa—Mg,MglT