Duplex stainless hlau yeeb nkab yog ib hom hlau uas ua ke nrog ntau yam khoom zoo xws li kev tiv thaiv corrosion zoo heev, siab zog, thiab yooj yim ntawm kev tsim thiab kev ua haujlwm. Lawv lub cev muaj zog yog nruab nrab ntawm austenitic stainless hlau thiab ferritic stainless hlau, tab sis ze rau ferritic stainless hlau thiab carbon hlau. Kev tiv thaiv rau chloride pitting thiab crevice corrosion ntawm duplex stainless hlau kav yog hais txog nws cov chromium, molybdenum, tungsten, thiab nitrogen cov ntsiab lus. Nws tuaj yeem ua tau zoo ib yam li 316 stainless hlau lossis siab dua seawater stainless hlau xws li 6% Mo austenitic stainless hlau. Lub peev xwm ntawm tag nrho cov duplex stainless hlau kav los tiv thaiv chloride kev nyuaj siab corrosion puas yog qhov muaj zog dua li ntawm 300 series austenitic stainless hlau, thiab nws lub zog kuj tseem ntau dua li austenitic stainless hlau thaum uas qhia cov yas zoo thiab toughness.

Duplex stainless hlau yeeb nkab yog hu ua "duplex" vim nws metallographic microstructure yog tsim los ntawm ob stainless hlau nplej, ferrite thiab austenite. Nyob rau hauv daim duab hauv qab no, lub daj austenite theem yog surrounded los ntawm xiav ferrite theem. Thaum duplex stainless hlau yeeb nkab melts, nws thawj zaug solidifies rau hauv ib tug ua tiav ferrite qauv thaum nws solidifies los ntawm cov kua xeev. Raws li cov khoom txias rau chav tsev kub, li ntawm ib nrab ntawm cov nplej ferrite hloov mus rau austenite nplej. Qhov tshwm sim yog tias kwv yees li 50% ntawm microstructure yog theem austenite thiab 50% yog theem ferrite.

Duplex stainless hlau yeeb nkab muaj ob-theem microstructure ntawm austenite thiab ferrite
Cov yam ntxwv ntawm duplex stainless hlau yeeb nkab
01-Lub zog siab: Lub zog ntawm duplex stainless hlau yeeb nkab yog kwv yees li 2 npaug ntawm cov pa austenitic stainless hlau lossis ferritic stainless hlau. Qhov no tso cai rau cov neeg tsim qauv kom txo cov phab ntsa tuab hauv qee yam kev siv.

02-Zoo toughness thiab ductility: Txawm tias lub zog siab ntawm duplex stainless hlau kav, lawv pom zoo plasticity thiab toughness. Lub toughness thiab ductility ntawm duplex stainless hlau kav yog qhov zoo dua li cov ferritic stainless hlau thiab carbon hlau, thiab lawv tseem tuav tau zoo toughness txawm nyob rau hauv kub tsawg heev xws li -40 ° C / F. Tab sis nws tseem tsis tuaj yeem ncav cuag qib zoo ntawm austenitic stainless hlau. Yam tsawg kawg nkaus cov cuab yeej txwv rau duplex stainless hlau kav tau teev tseg los ntawm ASTM thiab EN cov qauv

03-Corrosion tsis kam: Lub corrosion kuj ntawm stainless hlau tsuas yog nyob ntawm nws cov tshuaj muaj pes tsawg leeg. Duplex stainless hlau kav pom muaj kev tiv thaiv corrosion nyob rau hauv feem ntau daim ntawv thov vim lawv cov ntsiab lus chromium, uas yog qhov zoo rau oxidizing acids, thiab txaus cov nyiaj molybdenum thiab npib tsib xee los tiv thaiv kev txo qis Corrosion hauv acid media. Lub peev xwm ntawm duplex stainless hlau kav los tiv thaiv chloride ion pitting thiab crevice corrosion nyob ntawm lawv cov chromium, molybdenum, tungsten, thiab nitrogen cov ntsiab lus. Lub siab chromium, molybdenum thiab nitrogen cov ntsiab lus ntawm duplex stainless hlau kav muab lawv zoo tiv thaiv chloride pitting thiab crevice corrosion. Lawv tuaj nyob rau hauv ntau qhov sib txawv corrosion resistances, xws li qib sib npaug rau 316 stainless hlau, xws li kev lag luam duplex stainless hlau yeeb nkab 2101, rau qib sib npaug rau 6% molybdenum stainless hlau, xws li SAF 2507. Duplex stainless hlau kav muaj qhov zoo heev. Kev ntxhov siab corrosion cracking (SCC) tsis kam, uas yog "kho" los ntawm sab ferrite. Lub peev xwm ntawm tag nrho cov duplex stainless hlau kav los tiv thaiv chloride kev nyuaj siab corrosion cracking yog ho zoo dua li ntawm 300 series austenitic stainless hlau. Standard austenitic stainless hlau qib xws li 304 thiab 316 tej zaum yuav raug kev nyuaj siab corrosion tawg nyob rau hauv lub xub ntiag ntawm chloride ions, huab cua ntub, thiab siab kub. Yog li ntawd, nyob rau hauv ntau daim ntawv thov nyob rau hauv tshuaj lom neeg kev lag luam uas muaj ib tug ntau dua kev pheej hmoo ntawm kev nyuaj siab corrosion, duplex stainless hlau kav feem ntau siv es tsis txhob ntawm austenitic stainless hlau.

04-Lub cev muaj zog: nruab nrab ntawm austenitic stainless hlau thiab ferritic stainless hlau, tab sis ze rau ferritic stainless hlau thiab carbon hlau. Nws yog feem ntau ntseeg tias kev ua tau zoo tuaj yeem tau txais thaum qhov piv ntawm ferrite theem rau austenite theem hauv duplex stainless hlau yeeb nkab yog 30% mus rau 70%. Txawm li cas los xij, duplex stainless hlau kav feem ntau suav tias yog ib nrab ferrite thiab ib nrab austenite. Hauv kev lag luam tam sim no, kom tau txais qhov zoo tshaj plaws toughness thiab ua cov yam ntxwv, qhov feem ntawm austenite yog me ntsis loj dua. Kev sib cuam tshuam ntawm cov ntsiab lus alloying tseem ceeb, tshwj xeeb tshaj yog chromium, molybdenum, nitrogen, thiab npib tsib xee, yog qhov nyuaj heev. Yuav kom tau txais cov qauv ruaj khov ob theem uas muaj txiaj ntsig zoo rau kev ua thiab kev tsim khoom, yuav tsum tau saib xyuas kom ntseeg tau tias txhua lub ntsiab lus muaj cov ntsiab lus tsim nyog.

Ntxiv nrog rau theem sib npaug, qhov kev txhawj xeeb loj thib ob hais txog duplex stainless hlau yeeb nkab thiab nws cov tshuaj lom neeg muaj pes tsawg leeg yog tsim los ntawm cov theem teeb meem intermetallic ntawm qhov kub siab. σ theem thiab χ theem yog tsim nyob rau hauv siab chromium thiab siab molybdenum stainless hlau thiab precipitate precipitate nyob rau hauv lub ferrite theem. Qhov sib ntxiv ntawm nitrogen heev qeeb qhov tsim ntawm cov theem no. Yog li ntawd, nws yog ib qho tseem ceeb uas yuav tsum tswj kom muaj cov nitrogen txaus hauv cov kua dej. Raws li kev paub nrog duplex stainless hlau yeeb nkab raug nce, qhov tseem ceeb ntawm kev tswj qhov nqaim ntawm qhov sib txawv yog nce ntxiv. Qhov pib txheej txheem ntau yam ntawm 2205 duplex stainless hlau yeeb nkab yog dav dhau. Kev paub qhia tau hais tias kom tau txais qhov zoo tshaj plaws corrosion kuj thiab zam qhov tsim ntawm intermetallic theem, cov chromium, molybdenum, thiab nitrogen cov ntsiab lus ntawm S31803 yuav tsum tau khaws cia nyob rau hauv nruab nrab thiab sab sauv txwv ntawm cov ntsiab lus ntau yam. Qhov no coj mus rau kev txhim kho 2205 dual-theem steel UNS S32205 nrog rau qhov nqaim ntau yam.