254 SMO (UNS S31254): 6% Molybdenum Super-Austenitic rau Kev Pabcuam hnyav Chloride

 

Dab tsi yog cov tshuaj muaj pes tsawg leeg thiab kev ntsuas qhov tseem ceeb ntawm 254 SMO?
254 SMO is defined by its high alloy content: ~20% chromium, ~18% nickel, 6.1% molybdenum, ~0.8% copper, and 0.18-0.22% nitrogen. This composition gives it a very high Pitting Resistance Equivalent Number (PREN >43). Cov npib tsib xee siab muab kev ruaj ntseg hauv kev txo qis ib puag ncig, lub siab molybdenum thiab chromium tiv thaiv chlorides, thiab tooj liab txhim kho kev tiv thaiv sulfuric acid. Nws qhov kev ntsuas tseem ceeb yog nws lub peev xwm los tswj cov cheeb tsam hnyav uas 316L thiab txawm tias duplex 2205 tuaj yeem ua tsis tiav.

Hauv qhov chaw pabcuam hnyav twg yog 254 SMO suav tias yog cov khoom siv pom zoo yam tsawg kawg nkaus?
Nws yog qhov tsawg kawg nkaus pom zoo cov khoom siv rau cov dej hiav txwv txias uas tsis tau kho, tshwj xeeb tshaj yog nyob rau qhov kub siab tshaj 40 ° C. Nws yog ib qho tseem ceeb rau cov txheej txheem tshuaj siv cov khoom siv kub, muaj zog chlorides, oxidizing acids (xws li cov khoom sib xyaw uas muaj chlorides thiab nitric acid), thiab kev tawm tsam hnyav hauv cov pa roj desulfurization scrubbers. Cov ntawv thov suav nrog cov dej hiav txwv thim rov qab osmosis daim nyias nyias, cov kav dej tawm sab nrauv, thiab cov evaporators tuav cov kua qaub heev. Nws raug xaiv thaum corrosivity tshaj qhov txwv ntawm duplex steels.

Yuav ua li cas nws corrosion kuj piv rau duplex 2205 thiab npib tsib xee alloys zoo li Alloy 625?
254 SMO muab kev tiv thaiv zoo dua rau kev xeb thiab pitting hauv chlorides dua li duplex 2205, tshwj xeeb tshaj yog nyob rau hauv qhov kub thiab txias. Nws kuj ua tau zoo tshaj 2205 hauv qhov muaj zog oxidizing thiab sib xyaw acid ib puag ncig. Piv rau npib tsib xee alloys xws li Alloy 625, 254 SMO muab piv los yog superior pitting tsis kam nyob rau hauv ntau chloride daim ntaub ntawv ntawm tus nqi qis heev. Txawm li cas los xij, rau cov uas tsis yog -oxidizing acids xws li hydrochloric los yog txo qis, cov nickel alloys tseem yuav zoo dua. Nws yog tus nqi-tshwj xeeb zoo rau cov alloys hauv nruab nrab-corrosivity ntau yam.

Dab tsi yog qhov tseem ceeb ntawm fabrication thiab vuam kev txiav txim siab?
Vim nws cov ntsiab lus alloy siab, 254 SMO muaj kev ua haujlwm siab - hardening npaum li cas, yuav tsum tau muaj zog machining cov cuab yeej thiab ua rau cov cuab yeej siv ceev dua. Vuam yuav tsum tau ua siv tshaj -alloyed muab tub lim hlau, feem ntau npib tsib xee-raws li alloys xws li ERNiCrMo-3 los yog ERNiCrMo-4, los tiv thaiv corrosion nyob rau hauv cov hlau weld. Kev tswj xyuas nruj ntawm cov khoom siv hluav taws xob thiab kev sib cuam tshuam kub yog tsim nyog. Kev tiv thaiv roj thiab rov qab purging yog qhov tseem ceeb los tiv thaiv oxidation. Tom qab vuam tu kom tshem tawm cov cua sov yog qhov tseem ceeb.

Yam dab tsi ua pov thawj rau kev nqis peev hauv 254 SMO tshaj qis dua -qib stainless hlau?
Qhov kev ncaj ncees yog nyob ntawm tus nqi ntawm lub neej thiab kev pheej hmoo txo ​​qis. Yog tias cov khoom siv tsis ua haujlwm uas siv cov qib qis dua -qib alloy yuav ua rau muaj kev puas tsuaj loj, kev nyab xeeb, lossis kev puas tsuaj ib puag ncig, kev nqis peev hauv 254 SMO yog lav. Nws cov nqi pib siab dua yog offset los ntawm kev tshem tawm qhov xav tau ntawm corrosion inhibitors, cathodic tiv thaiv, lossis hloov ntxov ntxov. Rau cov haujlwm tshiab hauv qhov zoo- tau txhais cov cheeb tsam hnyav, qhia txog 254 SMO txij thaum pib yog feem ntau pheej yig dua li kev rov ua dua tom qab ua tsis tiav. Kev ntsuam xyuas corrosion ntxaws yog qhov tseem ceeb rau qhov kev txiav txim zaum kawg.