半固态坯料制备的完备化技术

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1、Y10ll；¨五分类号：—j鱼睡一uDc汁1：缱二篁江：薛太lI

2、i擎JlANGSUUNlVERSlTY密级：压丑一硕士学位论文MASTER’SDISSERTATl0N论文题目：—j堑丝垄堕缝邋坐鱼叠墼型羔—二学科专业：必魁盘圣圣．整．一作者姓名：逃蛆一指导教师：一隧：到答辩日期：迎丝2笪：』!江苏大学硕士学位论文摘要半固态金属加工(半厨态成形)技术是近年来金属加工技术研究的热点，通过该技零形成的零件具有尺寸糖度离、表醚质量高翻蛙麓好等特点。铝合金半固态成形技术为汽车工业、航空工业所急需，而制备菲树枝晶的半固态坯料

3、是锅台金半固态成形的关键技术之一。本文在概述半固态坯料制备方法研究现状舱基蓉爨～t-，提出半固态坯料制备方法的优化措施，分别采用低温铸造法和电磁搅拌方法制备亚共黥镐硅合金半固态坯料。对低温铸造和电磁搅拌时菲棱潞缝织秘形成枧理进行了分析探讨。磷究表明，优化低滥铸造翻电磁搅拌的工艺参数，戆够利备性能优越憋拳固态坯料。针对低温铸造方法制取的坯料中存在的缩松缺陷，本文提出采用吹入氮气处瑾的方法，秘＆是逶过气泡群懿运动来诱发液体的环漉运动，从而促进液体的流动，增加金属的补缩能力，从而减少缩松甚至使其游失。通过数值推导和模拟试

4、验，对凝霹过程中欧入氮气澄除翁松的机理进行了初步攘讨。关键嗣：弧共爵锱硅合金；半圆态成形坯料；低溢铸造法；露磁搅拌法；氮气搅拌江苏大学硕士学位论文OptimumFabricationTechniquesofSemi—SolidFonningBilletsA8STRACTSemi—solidforming(SSF)hasbecomethefocusofstudiesonmetalformingtechniquesinrecentyears．Thecomponentsobtainedbyusingthistechniq

5、uehavenotonlyhi曲dimensionprecisionandgoodsurfacequatity；butalsogoodproperties．SSFofaluminumalloysisnecessaryinbothautomobileindustry"andspaceindustr)：Theproductionof1301"I—dendriticsenti—solidbilletisoneofthekeytechniquesintheSSFofaluminumalloys，Followingarevi

6、exvofpreviousresearchworksoilfabricationtechniquesofsemi—solidformingbillets，theoptimizationoftbefabricationtechniquesofsemi—solidframingbilletsusinglowtemperaturecastingandelectromagneticstirring(EMS)，respectively,hasbeencarriedout。TheformationmechanismsofnOD

7、—dendriticmicmstructmeinbilletsobtainedbyusingthesetwoteclmiqueshavebeenstudied．Itishldicatedthatthesemi—-solidformingbilletshavegoodmechanicalpropertiesastheprocessparametel＼,；havebeenoptimized．Astherearemieroporositiesinthebilletsobtainedbylowtemperaturecast

8、ing，nitrogenstirringhasbeenemployedinthecurrentresearchtoinducetheconvectionofliquidaluminumalloy．TheinstantaneousimpactpowerisformedwhenthenitrogenbubblestransgressthesurfaceofliquldaluminumandbreakThispowercarldrivetheflowageofliquidaluminumandimprove狂sfilli

9、ngability．Thus，themieropomsitiescanhereducedoreveneliminated．Accordingtomathdeductionandexperimentalsimulation，themechanismoftheinfluenceofthenitrogenstirringduringthesolidificatio