简介:Theadvancedultra-supercriticalpowerplantsofthefuturewillutilizesteampressuresandtemperaturesthataretoohighfortraditionalferriticsteels,thusrequiringausteniticmaterials.Oldernickel-basesuperalloyssuchas263and617wereinitiallyevaluatedundertheEuropeanTHERMIEprojectbeginninginthe1990s.Anentirelynewage-hardenedalloy740whichpossessesexceptionalfiresidecorrosionresistanceandcreepstrengthwasalsodevelopedforboilertubingcapableofservingat700C.Subsequently,interestintheUSAconsideredotherproductformssuchassteamheaderpipingandsteamturbineforgingsforserviceashighas760C.Amorestableandweldablealloyversionnowcalled740Hwasdevelopedtomeetthesemoredemandingconditions.Thispapersummarizesthecurrentstatusofworkonalloys740and740H.