TheeffectsofheattreatmentsonthemicrostructureandmechanicalpropertiesoftheTi–2.19Al–2.35ZralloyOriginalResearchArticle

Ti–2.19Al–2.35Zralloyisoneofthecandidatematerialsforthesteamgeneratortubingofanintegratedreactor,SystemModularIntegratedAdvancedReacTor(SMART)beingdevelopedinKorea.Inthisstudy,theeffectsofheattreatmentsonthemechanicalpropertiesofTi–2.19Al–2.35Zralloywereevaluated.Mechanicaltestswereimplementedtoexaminetheeffectsofanannealing,coolingrateandre-annealingtemperature/timeonthemechanicalpropertiesofthealloy.Theannealingtemperaturesrangedfrom600to1050°Candthecoolingrateswerecontrolledbyintroducingawater-quenching(WQ),air-cooling(AC),andfurnace-cooling(FC).Asforthere-annealingheattreatment,afteraβwaterquenching,there-annealingtemperaturewasselectedas800°Cfortheα-phaseheattreatmentand940°Cfortheα+β-phaseheattreatmentwithvarioustimeintervals(1,10and24h).Theresultsshowedthatanincreaseoftheannealingtemperaturetoabovetheβ-regiontemperatureinducedanincreaseofthetensilestrengthandadecreaseoftheelongationinthe25and300°Ctests.Adecreaseofthecoolingratesfromwater-quenchingtoafurnace-coolingrevealedadecreaseofthetensilestrengthandanincreaseoftheelongation.Alsoanincreaseofthere-annealingtimewithdifferentphaseregimesexhibitedadecreaseofthestrengthandanincreaseoftheelongation.Thesetendenciesweremoredominantinthe300°Ctestratherthantheroomtemperaturetestfromthecharacteristicsofthemicrostructureswhichwereaffectedbytheheattreatments.