ʻO Duplex stainless steel pipe he ʻano kila e hui pū ai i nā waiwai maikaʻi loa e like me ke kūpaʻa ʻana o ka corrosion maikaʻi, ka ikaika kiʻekiʻe, a me ka maʻalahi o ka hana ʻana a me ka hana ʻana. ʻO kā lākou mau waiwai kino ma waena o ke kila kila austenitic a me ke kila kila ferritic, akā kokoke i ke kila kila ferritic a me ke kila kalapona. ʻO ke kūʻē ʻana i ka lua chloride a me ka corrosion crevice o nā paipu kila stainless duplex e pili ana i kāna chromium, molybdenum, tungsten, a me ka ʻike nitrogen. Hiki iā ia ke like me 316 kila kila a i ʻole kiʻekiʻe ma mua o ke kila kila kila e like me 6% Mo austenitic stainless steel. ʻOi aku ka ikaika o nā paipu kila kila duplex a pau e kūʻē i ka haʻihaʻi koʻikoʻi o ka chloride ma mua o ka 300 series austenitic stainless steel, a ʻoi aku ka kiʻekiʻe o kona ikaika ma mua o ka austenitic stainless steel oiai e hōʻike ana i ka plasticity maikaʻi a me ka paʻakikī.

Ua kapa ʻia ʻo Duplex stainless steel pipe he "duplex" no ka mea, ua haku ʻia kona microstructure metallographic me ʻelua mau mea kila kila, ferrite a me austenite. Ma ke kiʻi ma lalo nei, ua hoʻopuni ʻia ka māhele austenite melemele e ka pae ferrite polū. Ke hoʻoheheʻe ʻia ka paipu kila kila duplex, paʻa mua ia i loko o kahi ʻano ferrite piha i ka wā e paʻa ai ia mai ke kūlana wai. I ka wā e maʻalili ai ka mea i ka lumi wela, ma kahi o ka hapalua o nā hua ferrite e hoʻololi ʻia i mau ʻano austenite. ʻO ka hopena, aia ma kahi o 50% o ka microstructure ka pae austenite a ʻo 50% ka pae ferrite.

ʻO ka paipu kila kila Duplex he microstructure ʻelua-phase o austenite a me ferrite
Nā hiʻohiʻona o ka paipu kila kuhiliʻole duplex
01-Ka ikaika kiʻekiʻe: ʻO ka ikaika o ka paipu kila kila duplex ma kahi o 2 mau manawa ma mua o ke kila austenitic maʻamau a i ʻole ke kila kila ferritic. ʻAe kēia i nā mea hoʻolālā e hōʻemi i ka mānoanoa o ka pā i kekahi mau noi.

02-Maikaʻi paʻakikī a me ka ductility: ʻOiai ka ikaika kiʻekiʻe o nā paipu stainless steel duplex, hōʻike lākou i ka plasticity maikaʻi a me ka paʻakikī. ʻOi aku ka maikaʻi o ka paʻakikī a me ka ductility o ka duplex stainless steel paipu ma mua o ka ferritic stainless steel a me ke kila kalapona, a mālama mau lākou i ka paʻakikī a hiki i nā haʻahaʻa haʻahaʻa loa e like me -40°C/F. Akā ʻaʻole hiki ke piʻi i ke kiʻekiʻe o ka maikaʻi o ke kila stainless austenitic. ʻO nā palena waiwai mīkini liʻiliʻi no nā paipu kila kila ʻole i kuhikuhi ʻia e nā kūlana ASTM a me EN

03-Corrosion resistance: ʻO ke kūpaʻa corrosion o ke kila kila ma muli o kona haku mele. ʻO nā paipu kila kila Duplex e hōʻike ana i ke kūpaʻa corrosion kiʻekiʻe i ka hapa nui o nā noi ma muli o ko lākou kiʻekiʻe chromium maʻiʻo, i mea maikaʻi i ka oxidizing acids, a me ka nui o ka molybdenum a me ka nickel e pale aku i ka hoʻohaʻahaʻa haʻahaʻa ʻo Corrosion i loko o ka media acid. ʻO ka hiki ʻana o nā paipu kila kila duplex e kūʻē i ka chloride ion pitting a me ka crevice corrosion e pili ana i kā lākou chromium, molybdenum, tungsten, a me ka ʻike nitrogen. ʻO ke kiʻekiʻe o ka chromium, molybdenum a me ka nitrogen i loko o nā paipu kila kila duplex e hāʻawi maikaʻi iā lākou i ke kūpaʻa maikaʻi i ka lua chloride a me ka ʻinoʻino. Hele mai lākou i loko o nā ʻano like ʻole o ka corrosion resistances, mai nā māka e like me 316 stainless steel, e like me ka duplex stainless steel pipe 2101, a i nā māka e like me 6% molybdenum stainless steel, e like me SAF 2507. He maikaʻi loa nā paipu stainless steel duplex. stress corrosion cracking (SCC) kū'ē, i "hoʻoilina" mai ka ʻaoʻao ferrite. ʻOi aku ka maikaʻi o ka hiki ʻana o nā paipu kila kila duplex a pau e kūʻē i ka chloride stress corrosion ma mua o ka 300 series austenitic stainless steel. Loaʻa paha i nā māka kila kuhili ʻole austenitic maʻamau e like me 304 a me 316 i ka pohā ʻana o ke koʻikoʻi ma mua o nā ion chloride, ea haʻahaʻa, a me nā mahana kiʻekiʻe. No laila, i nā noi he nui i ka ʻoihana kemika kahi i ʻoi aku ka nui o ka pilikia o ke koʻikoʻi koʻikoʻi, hoʻohana pinepine ʻia nā paipu stainless steel duplex ma kahi o ka austenitic stainless steel.

04-Nā waiwai kino: Ma waena o austenitic stainless steel a me ferritic stainless steel, akā kokoke i ka ferritic stainless steel a me carbon steel. Manaʻo nui ʻia e hiki ke loaʻa ka hana maikaʻi ke loaʻa ka lakio o ka pae ferrite i ka pae austenite i ka paipu kila kila duplex he 30% a 70%. Eia naʻe, manaʻo pinepine ʻia nā paipu kila kila duplex ma kahi o ka hapalua ferrite a me ka hapalua austenite. I ka hana pāʻoihana o kēia manawa, no ka loaʻa ʻana o ka paʻakikī maikaʻi loa a me nā ʻano hana, ʻoi aku ka nui o ka austenite. ʻO ka pilina ma waena o nā mea hoʻohui nui, ʻoi aku ka chromium, molybdenum, nitrogen, a me ka nickel, paʻakikī loa. No ka loaʻa ʻana o kahi hoʻolālā paʻa ʻelua-phase e pono ai i ka hana ʻana a me ka hana ʻana, pono e mālama pono i ka loaʻa ʻana o kēlā me kēia mea i kahi ʻike kūpono.

Ma kahi o ka pae kaulike, ʻo ka lua o ka hopohopo nui e pili ana i ka paipu stainless steel duplex a me kāna ʻano kemika ʻo ka hoʻokumu ʻana i nā pae intermetallic ʻino i nā mahana kiʻekiʻe. Hoʻokumu ʻia ka ʻāpana σ a me ka χ i loko o ka chromium kiʻekiʻe a me ka molybdenum kiʻekiʻe i ke kila kila a ʻoi aku ka maikaʻi o ka precipitate i ka pae ferrite. Hoʻopaneʻe loa ka hoʻohui ʻana o ka nitrogen i ka hoʻokumu ʻana o kēia mau pae. No laila he mea nui e mālama i ka nui o ka nitrogen i loko o ka hopena paʻa. Ke piʻi nei ka ʻike me ka duplex stainless steel pipe production, ʻike nui ʻia ke koʻikoʻi o ka mālama ʻana i nā pae haku mele haiki. ʻO ka laulā hoʻonohonoho mua o 2205 duplex stainless steel paipu ākea loa. Hōʻike ka ʻike no ka loaʻa ʻana o ke kūpaʻa corrosion maikaʻi loa a pale aku i ka hoʻokumu ʻana o nā ʻāpana intermetallic, pono e mālama ʻia ka chromium, molybdenum, a me ka nitrogen o S31803 ma nā palena waena a me luna o ka pae maʻiʻo. Ua alakaʻi ʻia kēia i ka 2205 i hoʻomaikaʻi ʻia i ke kila ʻelua-phase UNS S32205 me kahi papa hana haiki.