Umbhobho wentsimbi engatyiwa yi-Duplex luhlobo lwentsimbi edibanisa iipropathi ezininzi ezigqwesileyo ezifana nokumelana nokugqwesa okugqwesileyo, ukomelela okuphezulu, kunye nokulula kokwenziwa kunye nokusebenza. Iimpawu zabo zomzimba ziphakathi kwe-austenitic stainless steel kunye ne-ferritic stainless steel, kodwa kufutshane ne-ferritic stainless steel kunye ne-carbon steel. Ukuxhathisa kwi-chloride pitting kunye ne-crevice corrosion yemibhobho ye-duplex yensimbi engenasici inxulumene ne-chromium, i-molybdenum, i-tungsten, kunye nomxholo we-nitrogen. Inokuthi ifane ne-316 yensimbi engenasici okanye iphezulu kunamanzi olwandle ensimbi engenasici efana ne-6% Mo austenitic steel stainless. Isakhono sayo yonke imibhobho yensimbi engenasici ephindwe kabini ukuxhathisa i-chloride yoxinzelelo lwe-corrosion fracture yomelele kakhulu kune-300 series austenitic steel stainless steel, kwaye amandla ayo aphezulu kakhulu kune-austenitic stainless steel ngelixa ibonisa iplastiki efanelekileyo kunye nokuqina.

I-Duplex yensimbi engenasici ibizwa ngokuba yi-"duplex" kuba i-metallographic microstructure yayo yenziwe ngeenkozo ezimbini zentsimbi, i-ferrite kunye ne-austenite. Kulo mfanekiso ungezantsi, isigaba se-austenite esiphuzi sijikelezwe yisigaba se-blue ferrite. Xa umbhobho wentsimbi engatyiwa kabini unyibilika, uqala uqina ube sisakhiwo esipheleleyo seferrite xa uqina ukusuka kulwelo. Njengoko izinto zipholile kwiqondo lokushisa, malunga nesiqingatha se-ferrite iinkozo ziguqula zibe yi-austenite grains. Isiphumo kukuba malunga ne-50% ye-microstructure yisigaba se-austenite kunye ne-50% yisigaba se-ferrite.

I-Duplex ipayipi yensimbi engenasici ine-microstructure yesigaba sesibini se-austenite kunye ne-ferrite
Iimpawu ze-duplex ipayipi yensimbi engenasici
I-01-Amandla aphezulu: Amandla ombhobho we-duplex wensimbi engenasici malunga namaxesha angama-2 e-austenitic eqhelekileyo yentsimbi okanye i-ferritic stainless steel. Oku kuvumela abaqulunqi ukuba banciphise ubukhulu bodonga kwizicelo ezithile.

I-02-Ukuqina okulungileyo kunye ne-ductility: Ngaphandle kwamandla aphezulu eepayipi zensimbi ezingenasici, zibonisa iplastiki efanelekileyo kunye nokuqina. Ukuqina kunye ne-ductility ye-duplex imibhobho yensimbi engenasici ingcono kakhulu kuneyentsimbi ye-ferritic stainless steel kunye ne-carbon steel, kwaye igcina ukuqina okulungileyo nakwiqondo lokushisa eliphantsi kakhulu njenge -40 ° C / F. Kodwa okwangoku ayikwazi ukufikelela kwinqanaba lokugqwesa kwe-austenitic stainless steel. Ubuncinci bemida yepropathi yomatshini kwimibhobho yentsimbi ye-duplex echazwe yi-ASTM kunye nemigangatho ye-EN

I-03-Ukumelana nokubola: Ukuxhatshazwa kwe-corrosion yensimbi engenasici ikakhulu kuxhomekeke kukwakheka kweekhemikhali. Imibhobho yentsimbi engatyiwayo ye-Duplex ibonisa ukuxhathisa okuphezulu kwe-corrosion kwizicelo ezininzi ngenxa yomxholo we-chromium ephezulu, ethandeka kwi-acids oxidizing, kunye nezixa ezaneleyo ze-molybdenum kunye ne-nickel ukumelana nokunciphisa okuphakathi Ukonakala kwimidiya ye-asidi. Isakhono semibhobho yentsimbi ephindwe kabini ukuxhathisa i-ion ye-chloride kunye ne-crevice corrosion ixhomekeke kwi-chromium, i-molybdenum, i-tungsten kunye nomxholo we-nitrogen. Iziqulatho zechromium eziphezulu, imolybdenum kunye nenitrogen kwimibhobho yentsimbi ephindwe kabini ibanika ukuxhathisa ngokufanelekileyo kwimingxuma yekloridi kunye nokuhlwa kwemingxuma. Ziza kuluhlu oluhlukeneyo lokuchasana kwe-corrosion, ukusuka kumabakala alingana ne-316 yensimbi engenasici, efana ne-economic duplex steel stainless pipe 2101, ukuya kumabakala alingana ne-6% yensimbi engenasici ye-molybdenum, efana ne-SAF 2507. Imibhobho ye-duplex yensimbi engenasici intle kakhulu. i-stress corrosion cracking (SCC) ukuxhathisa, "ifa" ukusuka kwicala le-ferrite. Ukukwazi kwayo yonke imibhobho yentsimbi ephindwe kabini ukuxhathisa i-chloride yoxinzelelo lwe-corrosion cracking ingcono kakhulu kune-300 series austenitic stainless steel. Amanqanaba asemgangathweni e-austenitic steel stainless steel anje nge-304 kunye ne-316 inokubandezeleka ngenxa yoxinzelelo lwe-corrosion cracking phambi kwee-ion ze-chloride, umoya omanzi, kunye namaqondo obushushu aphakamileyo. Ngoko ke, kwizicelo ezininzi kwishishini lemichiza apho kukho umngcipheko omkhulu woxinzelelo lwe-corrosion, iipayipi zensimbi ezingenasici ze-duplex zihlala zisetyenziselwa endaweni ye-austenitic stainless steel.

Iimpawu ze-04-Physical: Phakathi kwe-austenitic stainless steel kunye ne-ferritic stainless steel, kodwa kufuphi ne-ferritic steel stainless kunye ne-carbon steel. Ngokuqhelekileyo kukholelwa ukuba ukusebenza kakuhle kunokufumaneka xa umlinganiselo wesigaba se-ferrite ukuya kwisigaba se-austenite kwipayipi yensimbi engenasici ye-duplex i-30% ukuya kwi-70%. Nangona kunjalo, imibhobho yensimbi engenasici ephindwe kabini ihlala ithathwa njengesiqingatha se-ferrite kunye nesiqingatha se-austenite. Kwimveliso yentengiso yangoku, ukufumana eyona nto inzima kunye neempawu zokuqhuba, ubungakanani be-austenite bukhulu kancinci. Ukusebenzisana phakathi kwezinto eziphambili ze-alloying, ngakumbi i-chromium, i-molybdenum, i-nitrogen, kunye ne-nickel, inzima kakhulu. Ukufumana ulwakhiwo oluzinzile lwezigaba ezibini olunenzuzo ekusebenzeni nasekuveliseni, kufuneka kuthathelwe ingqalelo ukuqinisekisa ukuba into nganye inomxholo ofanelekileyo.

Ukongeza kwibhalansi yesigaba, inkxalabo enkulu yesibini malunga ne-duplex yombhobho wensimbi engenasici kunye nokubunjwa kwayo kweekhemikhali kukubunjwa kwezigaba ezinobungozi ze-intermetallic kumaqondo okushisa aphezulu. Isigaba se-σ kunye nesigaba se-χ zenziwe kwi-chromium ephezulu kunye ne-molybdenum ephezulu yensimbi engenasici kwaye ngokufanelekileyo i-precipitate kwisigaba se-ferrite. Ukongezwa kwenitrogen kulibazisa kakhulu ukusekwa kwezi zigaba. Ngoko ke kubalulekile ukugcina isixa esaneleyo senitrogen kwisisombululo esiqinileyo. Njengoko amava kunye duplex stainless steel ukwenziwa umbhobho ukwanda, ukubaluleka kokulawula imida emxinwa yokwakheka kuyanda ukuqaphela. Uluhlu lokuqala olusetiweyo lwe-2205 duplex umbhobho wensimbi engenasici lubanzi kakhulu. Amava abonisa ukuba ukufumana ukuchasana kwe-corrosion engcono kwaye ugweme ukubunjwa kwezigaba ze-intermetallic, i-chromium, i-molybdenum, kunye ne-nitrogen contents ye-S31803 kufuneka igcinwe kwimida ephakathi kunye nephezulu yoluhlu lomxholo. Oku kwakhokelela ekuphuculweni kwe-2205 ye-double-phase yentsimbi ye-UNS S32205 kunye noluhlu oluncinci lokubunjwa.