Investigations of microstructures and properties in electron beam welded joints of TiAl to TC4

(整期优先)网络出版时间:2007-03-13
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Thenormallycenteredelectronbeamandnon-centeredelectronbeamweldingofTiAltoTC4wasinvestigatedinordertoanalyzetheelectronbeamweldabilitybetweenTiAl/TC4dissimilarmaterials.MacroscopiccoldcrackeasilyoccurrednearTiAlsubstrateinthejoints.Theoptimaltensilestrengthwasrelatedtotheweldingheatinput.Theweldstructureswerecomposedofbulkycolumnargrainsandequiaxedgrains.Theisolatedphasesconsistedoflargequantitiesofα2-Ti3Alphase,smallquantityofB2phase,γ-TiAlphaseandYAl2phase.InsufficientmeltingofthebasemetaloccurredintheweldwhenthebeampositionleanedtotheTC4side.Thetensilestrengthcouldbeimprovedwhenthedeflectionwaslimitedintheoptimumrange.Otherwise,non-fusionzonewaseasilygeneratedintheweld,whichledtothelowtensilestrength.