Ipayipi lensimbi engagqwali i-Duplex iwuhlobo lwensimbi oluhlanganisa izakhiwo eziningi ezinhle njengokumelana nokugqwala okuhle kakhulu, amandla aphezulu, kanye nokwenza lula ukukhiqiza nokucubungula. Izakhiwo zabo ezibonakalayo ziphakathi kwe-austenitic stainless steel kanye ne-ferritic stainless steel, kodwa iseduze ne-ferritic stainless steel ne-carbon steel. Ukumelana ne-chloride pitting kanye nokugqwala kwe-crevice yamapayipi ensimbi engagqwali ayi-duplex kuhlobene nokuqukethwe kwayo kwe-chromium, i-molybdenum, i-tungsten, ne-nitrogen. Ingase ifane nensimbi engagqwali engu-316 noma ibe phezulu kunamanzi olwandle insimbi engagqwali njenge-6% Mo austenitic stainless steel. Amandla awo wonke amapayipi ensimbi engagqwali ayi-duplex ukumelana ne-chloride stress corrosion fracture anamandla kakhulu kunalelo le-300 series austenitic stainless steel, futhi amandla ayo nawo aphakeme kakhulu kune-austenitic stainless steel kuyilapho ebonisa ubupulasitiki obuhle nokuqina.

Ipayipi lensimbi engagqwali i-Duplex libizwa nge-"duplex" ngoba i-microstructure yayo ye-metallographic yakhiwe ngezinhlamvu ezimbili zensimbi engagqwali, i-ferrite ne-austenite. Esithombeni esingezansi, isigaba se-austenite esiphuzi sizungezwe isigaba se-ferrite eluhlaza okwesibhakabhaka. Uma ipayipi lensimbi engagqwali eliyi-duplex lincibilika, liqala liqine libe isakhiwo esiphelele se-ferrite lapho liqina lisuka kusimo soketshezi. Njengoba izinto ziphola ezingeni lokushisa elilingana negumbi, cishe ingxenye yezinhlamvu ze-ferrite ishintsha ibe izinhlamvu ze-austenite. Umphumela uba ukuthi cishe u-50% we-microstructure yisigaba se-austenite futhi u-50% yisigaba se-ferrite.

Ipayipi lensimbi engagqwali eDuplex linezigaba ezimbili ze-austenite ne-ferrite
Izici zepayipi lensimbi engagqwali ye-duplex
01-Amandla aphezulu: Amandla epayipi lensimbi engagqwali eliphindwe kabili cishe aphindwe izikhathi ezingu-2 kunawensimbi evamile ye-austenitic engagqwali noma insimbi engagqwali ye-ferritic. Lokhu kuvumela abaklami ukuthi banciphise ukujiya kodonga ezinhlelweni ezithile.

02-Ukuqina okuhle nokudumba: Naphezu kwamandla aphezulu amapayipi ensimbi engagqwali ayi-duplex, abonisa ubupulasitiki obuhle nokuqina. Ukuqina nokuqina kwamapayipi ensimbi engagqwali ayiduplex angcono kakhulu kunalawo ensimbi engagqwali ye-ferritic ne-carbon steel, futhi asalondoloza ukuqina okuhle ngisho emazingeni okushisa aphansi kakhulu afana -40°C/F. Kodwa namanje ayikwazi ukufinyelela izinga lobuhle bensimbi engagqwali ye-austenitic. Ubuncane bemikhawulo yezakhiwo zamapayipi ensimbi engagqwali ayi-duplex ecaciswe amazinga e-ASTM kanye ne-EN

I-03-Corrosion resistance: Ukumelana nokugqwala kwensimbi engagqwali ikakhulukazi kuncike ekwakhekeni kwamakhemikhali. Amapayipi ensimbi engagqwali e-Duplex abonisa ukumelana nokugqwala okuphezulu ezinhlelweni eziningi ngenxa yokuqukethwe kwawo okuphezulu kwe-chromium, evumelana ne-oxidizing acid, namanani anele e-molybdenum ne-nickel ukumelana nokuncipha okumaphakathi Ukugqwala emithonjeni ye-asidi. Ikhono lamapayipi ensimbi engagqwali ayi-duplex ukumelana ne-chloride ion pitting kanye nokugqwala kwe-crevice lincike ku-chromium, i-molybdenum, i-tungsten, kanye nokuqukethwe kwe-nitrogen. Okuqukethwe okuphezulu kwe-chromium, i-molybdenum kanye ne-nitrogen yamapayipi ensimbi engagqwali ayi-duplex kuwanikeza ukumelana ne-chloride pitting kanye nokugqwala kwemifantu. Ziza ezinhlobonhlobo zokumelana nokugqwala okuhlukene, kusukela kumabanga alingana no-316 ensimbi engagqwali, njengepayipi lensimbi engagqwali le-duplex elinomnotho elingu-2101, ukuya kumamaki alingana no-6% wensimbi engagqwali ye-molybdenum, njenge-SAF 2507. Amapayipi ensimbi engagqwali ayi-Duplex anomuhle kakhulu. ukumelana ne-stress corrosion cracking (SCC), "okuzuzwe njengefa" kusukela ohlangothini lwe-ferrite. Amandla awo wonke amapayipi ensimbi engagqwali ayi-duplex ukumelana nokuqhekeka kokugqwala kwe-chloride angcono kakhulu kunalelo le-300 series austenitic stainless steel. Amabanga ajwayelekile ensimbi engagqwali ye-austenitic afana no-304 no-316 angase ahlupheke ngenxa yokuqhekeka kokugqwala kwengcindezi lapho kukhona ama-ion e-chloride, umoya oswakeme, namazinga okushisa aphakeme. Ngakho-ke, ezinhlelweni eziningi embonini yamakhemikhali lapho kunengozi enkulu yokugqwala kwengcindezi, amapayipi ensimbi engenasici ayi-duplex avame ukusetshenziswa esikhundleni se-austenitic stainless steel.

04-Izakhiwo ezibonakalayo: Phakathi kwe-austenitic stainless steel ne-ferritic stainless steel, kodwa eduze ne-ferritic stainless steel ne-carbon steel. Ngokuvamile kunenkolelo yokuthi ukusebenza okuhle kungatholakala lapho isilinganiso sesigaba se-ferrite nesigaba se-austenite epayipini lensimbi engagqwali i-30% kuya ku-70%. Kodwa-ke, amapayipi ensimbi engagqwali ayi-duplex avame ukubhekwa njengengxenye ye-ferrite nengxenye ye-austenite. Emkhiqizweni wamanje wezohwebo, ukuthola ukuqina okuhle kakhulu nezici zokucubungula, ingxenye ye-austenite inkulu kancane. Ukusebenzisana phakathi kwezakhi eziyinhloko ze-alloying, ikakhulukazi i-chromium, i-molybdenum, i-nitrogen, ne-nickel, kuyinkimbinkimbi kakhulu. Ukuthola isakhiwo esinezigaba ezimbili esizinzile esinenzuzo ekucutshungulweni nasekukhiqizeni, kufanele kuqashelwe ukuze kuqinisekiswe ukuthi isici ngasinye sinokuqukethwe okufanele.

Ngaphezu kwebhalansi yesigaba, ukukhathazeka okukhulu kwesibili mayelana nepayipi lensimbi engagqwali eliyi-duplex kanye nokwakheka kwamakhemikhali awo ukwakheka kwezigaba eziyingozi ze-intermetallic emazingeni okushisa aphakeme. Isigaba sika-σ kanye nesigaba sika-χ kwakheka nge-chromium ephezulu kanye nensimbi engagqwali ye-molybdenum ephezulu futhi anciphe ngokukhethekile esigabeni se-ferrite. Ukwengezwa kwe-nitrogen kubambezela kakhulu ukwakheka kwalezi zigaba. Ngakho-ke kubalulekile ukugcina inani elanele le-nitrogen esixazululweni esiqinile. Njengoba ulwazi ngokukhiqizwa kwamapayipi ensimbi engagqwali e-duplex kukhula, ukubaluleka kokulawula ububanzi obuncane bokuqamba kuya ngokuya kuqashelwa. Ibanga lokuqamba elimisiwe ekuqaleni lepayipi lensimbi engagqwali le-2205 libanzi kakhulu. Okuhlangenwe nakho kubonisa ukuthi ukuze uthole ukumelana nokugqwala okungcono kakhulu futhi ugweme ukwakheka kwezigaba ze-intermetallic, okuqukethwe kwe-chromium, i-molybdenum, ne-nitrogen ye-S31803 kufanele kugcinwe emikhawulweni emaphakathi nangaphezulu yohlu lokuqukethwe. Lokhu kuholele ekuthuthukisweni kwensimbi ye-UNS S32205 enezigaba ezimbili ezithuthukisiwe ezinobubanzi obuncane bokuqamba.