机械英文论文2.pdf

Availableonlineat1^nⅣ、^f．sciencedirect．com Transactionsof ’： ScienceDirect NonferrousM etals SocietyofChina 一 ELs】三VIER Press Trans．NonferrousMet．Soc．China20(2010)1792—1798 www ．tnmsc．c11 SemisolidjoiningofaluminumA356alloyby partialremeltingandmechanicalstirring s．M ．J．ALVANI，H．AASHURI，A．KOKABI，R．BEYGI MaterialsScienceandEngineeringDepartment，SharifUniversityofTechnology,AzadiAve．，Tehran，Iran Received13May2010；accepted25June2010 Abstract：A methodtoreachtheglobularweldstructureofA356aluminum alloyusingstirringthelocalizedsemisolidzoneduring butt-joiningisdeveloped．Sincetheheatconductivityofthisalloyisveryhigh，theaccuratecontrollingoftemperatureduringjoining mustbeconsidered．A gasheatingsystem wasusedtoheatupthenirtogengasuptotherequiredtemperautre．A driedandfree oxygengaswaspreparedwhenastream ofnitrogengascouldpasscloselyaroundahotelement．Hotandpureni~ogengasflow throughapreciseceramicnozzlewasusedtocreatealocalizedsemisolidpoo1．Atthisstageafinestirrerwasin仃oducedintohte weldseam inordertomixthetwosidesintoasingleuniform ionit．Substratesweremovedindirectionofiointlinebyasmallrtolley toavoidhtedeviationofnozzlefromtheiointlinenaditsdistaneenadanglerfom thesubstrate．A fixturesystemwasusedtohold wt o subsrtatestogetheronthertolley．A narrow hotplatewaslocatedonthetrolleytoheatuptheiointlineduetohighheat conductivityofalmu inum ．E雎 ctofgastemperaturewasinvestigatedonthemicrostructurena dm