7055铝合金熔体超声处理与凝固研究

《7055铝合金熔体超声处理与凝固研究》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、摘要在材料制各和加工过程中引入外场增强对过程和材料组织结构的调控是材料研究的前沿领域。本文研究了A卜zn—Mg—cu系超高强铝合金超声熔体处理和凝固的工艺方法，结合铸锭宏观与显微组织及其力学性能的考察，研究了作用效果和机理。对7055铝合金熔体凝固过程作超声处理，发现超声作用可细化晶粒，结晶方式由树枝晶向等轴晶转变，凝固组织显示了半固态加工凝固的特征，但铸锭含少量夹杂和气孔。对7055铝合金熔体作超声处理后进行重力模铸，铸锭组织观察表明，在630℃～710℃的温度下对熔体作超声处理均可细化铸锭晶粒。熔体经超声处理铸态均匀化合金与未经超声处理的合金相比，布氏

2、硬度提高10％，伸长率由3．8％提高到7．7％，电导率和抗拉强度也有所提高。7055铝合金熔体超声处理后半连铸，与熔体未经超声处理相比，铸锭凝固组织均匀，缺陷少，宏观开裂现象被抑制，且合金电导率、抗拉强度和伸长率有所提高。采用水冷变幅杆对7055铝合金熔体作超声处理，可消除熔体对变幅杆的浸蚀，而且半连铸铸锭凝固组织更加均匀，均匀化后合金的布氏硬度、电导率及抗拉强度和伸长率均较无水冷变幅杆超声熔体处理的铸锭有所改善。关键词超声熔体处理，超声凝固，水冷变幅杆，半连铸，均匀凝固ABSTRACTIt’s眦advancedtechnologyfortheintrod

3、uctionofoutfieldinthefabricationandprocessingofmaterialstocontroltheprocessingandthestmctureofthematerials．ndspaperinvestigatedtheeffectsofultrasonictreatmentofmeltandultrasonicsolidificationonAl-Zn—Mg—Cuseriesultrahighstrengthaluminumalloys，Boththemacro—andmicro-structureofthecas

4、tingotswereanalyzed，theirmechanicalpropertieswerestudiedtodiscusstheeffectsandmechanismsoftlleultrasonictreatment．Ultrasonictreatmentduringsolidificationof7055aluminumalloyresultsindendrite-freegrainstructureandleadstothefiningofgrainstructure．Thestructureofthecastingotspresentsth

5、echaracterofsemisolidsolidification．Ultrasonictreatmentofthe7055aluminumalloymeltbeforegravitycastingfinedthegrainstructureinthecastatthetemperaturerangefrom630。Cto710"C．Comparedtothecastingotswithoutultrasonicmelttreatment，hardnessofhomogenizedas—castalloyincreasesby10％anditselon

6、gationincreasesfrom3．8％t07．7％．meanwhileitselectricconductivityandtensilestrengthimprovesrespectively．Thestudyonultrasonicmelttreatmentofthe7055aluminumalloyfollowedbysemi-continuouscastingconfirmsthatultrasonicmelttreatmentcoulduniformthecaststructure，andreducethedefectsinthecast，

7、especiallysuppressesthecracking，meanwhileimprovestheelectricconduct。ivity、tensilestrengthandelongation．Bydesigningawater-cooledvibratorandapplyingitintheultrasonicmelttreatmentofthe7055aluminumalloys，thecorrosionofthevibratorWaseliminated．mestructureofthe7055aluminumalloycastbecom

8、esmoreuniform．Thehardness，electri