简介：Ultrapureferriticstainlesssteelisakindofnewstainlesssteelgradewithhighqualitydevelopedinthemid-twentiethcentury,itischaracterizedbyultralowCarbonandNitrogencontentandmicro-alloyingwithTi,Nb,V,Cuetc.,soitovercomesalotofuseshortcomingsoftheordinaryferriticstainlesssteel,suchasintergranularcorrosionsensitivity,lowductilityandtoughnessunderatmospheretemperature,crackincliningattheweldzoneetc.,namely,ithasbetterperformancethantheordinaryferriticstainlesssteelintheaspectofcorrosionresistance,toughnessandweldabilityetc.Furthermore,aseriesofsecondaryrefiningequipmentsandtechnologieshavebeeninventedfromthe1960s,loworultralowCarbonandNitrogencontentinthemoltenstainlesssteelcanbeobtainedduringmanufacturingproduction.Therefore,suchsteelhasbeenappliedinmanyfields,leadingtotheveryrapiddevelopmentoverthepasthalfcentury.Thispaperfocusesonthesecondaryrefiningprocesswhichisthemostimportantstepofthewholesteel-makingprocessfortheultrapureferriticstainless.Firstly,somedifficultiesofthesecondaryrefiningprocessaredescribed,includingthehighpurificationintermsofbothCarbonandNitrogencontents,highefficientandstablecontrol.Secondly,thedevelopmentandprogressofthesecondaryrefiningtechnologyforultrapureferriticstainlessisintroducedintermsoftherefiningequipments,metallurgicalprocessandassistanttechnologies.SomemostfamoussecondaryrefiningequipmentsandmetallurgicaltechnologiesforultrapureferriticstainlesssteelhadbeeninventedmainlybyJapanandEuropeancompaniesfrom1960sto1990s,suchasVOD,SS-VOD,AOD-VCR,VOD-PBetc..Duringthesametimeofwideapplicationofthesesecondaryrefiningequipmentsandtechnologies,inordertostrengthenthefunctionandcapacityoftheserefiningequipments,someadvancedassistanttechnologieswerealsointroducedandapplied,whichconsistsoftoplance,specialrawmaterials,ladlerefracto