Duplex bakin karfe bututu wani nau'i ne na karfe wanda ya haɗu da kyawawan kaddarorin kamar kyakkyawan juriya na lalata, ƙarfin ƙarfi, da sauƙi na masana'anta da sarrafawa. Kaddarorinsu na zahiri suna tsakanin bakin karfe austenitic da bakin karfe na ferritic, amma kusa da bakin karfe na ferritic da carbon karfe. Juriya ga rami na chloride da lalatar bututun bakin karfe na duplex yana da alaƙa da chromium, molybdenum, tungsten, da abun ciki na nitrogen. Yana iya zama kama da bakin karfe 316 ko sama da bakin karfe na ruwan teku kamar 6% Mo austenitic bakin karfe. Ikon duk duplex bakin karfe bututu don tsayayya chloride danniya lalata karaya ne muhimmanci karfi fiye da na 300 jerin austenitic bakin karfe, da kuma ƙarfi ne ma fiye da austenitic bakin karfe yayin da nuna kyau plasticity da taurin.

Duplex bakin karfe bututu ana kiransa "duplex" saboda ta metallographic microstructure kunshi biyu bakin karfe hatsi, ferrite da austenite. A cikin hoton da ke ƙasa, lokacin rawaya austenite yana kewaye da lokacin shuɗi na ferrite. Lokacin da duplex bakin karfe bututu ya narke, da farko yana ƙarfafa cikin cikakken tsarin ferrite lokacin da ya ƙarfafa daga yanayin ruwa. Yayin da kayan ke sanyaya zuwa zafin jiki, kusan rabin hatsin ferrite sun canza zuwa hatsi austenite. Sakamakon shine kusan 50% na microstructure shine lokacin austenite kuma 50% shine lokacin ferrite.

Duplex bakin karfe bututu yana da biyu-lokaci microstructure na austenite da ferrite
Halayen duplex bakin karfe bututu
01-High ƙarfi: Ƙarfin duplex bakin karfe bututu ne kamar 2 sau na al'ada austenitic bakin karfe ko ferritic bakin karfe. Wannan yana ba masu zanen kaya damar rage girman bango a wasu aikace-aikace.

02-Kyakkyawan tauri da ductility: Duk da babban ƙarfin duplex bakin karfe bututu, suna nuna kyakkyawan filastik da tauri. Tauri da ductility na duplex bakin karfe bututu ne muhimmanci fiye da na ferritic bakin karfe da carbon karfe, kuma har yanzu suna kula da kyau tauri ko da a sosai low yanayin zafi kamar -40°C/F. Amma har yanzu ba zai iya kaiwa matakin kyawun austenitic bakin karfe ba. Ƙananan ƙayyadaddun ƙayyadaddun kayan inji don bututun bakin karfe na duplex da aka ƙayyade ta ASTM da EN

03-lalata juriya: Rashin juriya na bakin karfe ya dogara ne akan abubuwan sinadaransa. Duplex bakin karfe bututu nuna high lalata juriya a mafi yawan aikace-aikace saboda high chromium abun ciki, wanda yake shi ne m a oxidizing acid, da isasshen adadin molybdenum da nickel don jure matsakaici rage Lalata a acid kafofin watsa labarai. Ƙarfin bututun bakin ƙarfe na duplex don tsayayya da pitting ion chloride da lalata ɓarna ya dogara da chromium, molybdenum, tungsten, da abun ciki na nitrogen. In mun gwada da babban chromium, molybdenum da nitrogen abun ciki na duplex bakin karfe bututu ba su da kyau juriya ga chloride pitting da crevice lalata. Sun zo a cikin kewayon daban-daban lalata juriya, jere daga maki daidai da 316 bakin karfe, kamar tattalin arziki duplex bakin karfe bututu 2101, zuwa maki daidai da 6% molybdenum bakin karfe, kamar SAF 2507. Duplex bakin karfe bututu suna da kyau sosai. juriya corrosion cracking (SCC), wanda aka "gado" daga gefen ferrite. Ikon duk duplex bakin karfe bututu don tsayayya chloride danniya lalata fatattaka ne muhimmanci fiye da na 300 jerin austenitic bakin karfe. Daidaitaccen makin bakin karfe na austenitic kamar 304 da 316 na iya wahala daga lalatawar damuwa a gaban ions chloride, iska mai danshi, da kuma yanayin zafi mai tsayi. Saboda haka, a yawancin aikace-aikace a cikin masana'antar sinadarai inda akwai haɗarin lalata damuwa, ana amfani da bututun bakin karfe na duplex maimakon austenitic bakin karfe.

04- Kaddarorin jiki: Tsakanin bakin karfe austenitic da bakin karfe, amma kusa da bakin karfe na ferritic da carbon karfe. An yi imani da cewa ana iya samun kyakkyawan aiki lokacin da rabon lokaci na ferrite zuwa lokaci austenite a cikin bututun bakin karfe na duplex shine 30% zuwa 70%. Duk da haka, Duplex bakin karfe bututu ana daukar su kusan rabin ferrite da rabin austenite. A cikin samar da kasuwanci na yanzu, don samun mafi kyawun ƙarfi da halayen sarrafawa, rabon austenite ya fi girma kaɗan. Haɗin kai tsakanin manyan abubuwan haɗakarwa, musamman chromium, molybdenum, nitrogen, da nickel, yana da rikitarwa sosai. Don samun tsayayyen tsari mai sassa biyu wanda ke da fa'ida ga sarrafawa da ƙira, dole ne a kula don tabbatar da cewa kowane abu yana da abun ciki mai dacewa.

Baya ga ma'aunin lokaci, babban abin damuwa na biyu game da bututun bakin karfe na duplex da sinadarinsa shine samuwar matakan tsaka-tsaki mai cutarwa a yanayin zafi mai tsayi. σ lokaci da χ lokaci an kafa su a cikin babban chromium da babban molybdenum bakin karfe kuma an fi son hazo a cikin lokacin ferrite. Ƙarin nitrogen yana jinkirta samuwar waɗannan matakan. Don haka yana da mahimmanci don kula da isasshen adadin nitrogen a cikin ingantaccen bayani. Kamar yadda gwaninta tare da duplex bakin karfe masana'anta bututu ke ƙaruwa, muhimmancin sarrafa kunkuntar abun da ke ciki jeri ana ƙara gane. Matsakaicin abin da aka saita na farko na 2205 duplex bakin karfe bututu ya yi fadi da yawa. Kwarewa ta nuna cewa don samun mafi kyawun juriya na lalata da kuma guje wa samuwar matakan tsaka-tsaki, chromium, molybdenum, da abubuwan da ke cikin nitrogen na S31803 yakamata a kiyaye su a matsakaici da babba na kewayon abun ciki. Wannan ya haifar da ingantaccen 2205 dual-phase karfe UNS S32205 tare da kunkuntar kewayon abun da ke ciki.