Tsab xov xwm no tau pib tshaj tawm txog kev sib xyaw thiab kev sib txuas lus ntawm carbon steel cov ntaub ntawv uas feem ntau siv hauv kev lag luam. Lwm tus xws li txhuas aluminium, copper alloys, nickel alloys, titanium alloys, los yog super alloys kuj muaj cov yam ntxwv txawv thiab daim ntaub ntawv.
Ferroalloy chromium ntsiab lus ntawm ntau tshaj 12% yog hu ua stainless hlau, vim hais tias chromium yog ib tug tsis-corrosive keeb, yog li stainless hlau tau zoo corrosion tsis kam, lub siab dua lub chromium cov ntsiab lus, qhov zoo dua qhov corrosion ua hauj. Tag nrho cov tsis muaj stainless hlau muaj carbon ntxiv nrog rau hlau thiab chromium. Cov roj ua kom muaj zog, tab sis nws muaj kev phom sij ntawm qhov kev tawm tsam vim chromium thiab cov roj tau ua daim ntawv carbides. Lub chromium nyob nruab nrab ntawm cov carbide tsis muaj cov tshuaj antioxidant. Thaum cov ntsiab lus qis dua, cov ntsiab lus chromium yuav tsum tau nce, txwv tsis pub lub corrosion kuj yuav deteriorate, yog li feem ntau ntawm cov tsis muaj hlau tsis muaj cov ntsiab lus qis, thiab cov ntsiab lus cov roj yuav tsum nruj me ntsis tswj. Tsis tas li ntawd, tag nrho cov hlau tsis muaj cov ntxhuav muaj lwm cov ntsiab lus. Txhua lub caij muaj nws tus yam ntxwv. Piv txwv li, xee npe yog ib qho tseem ceeb tshaj plaws, uas tuaj yeem txhim kho kev txhuam kev ua haujlwm, tsis tshua muaj kev kub ntxhov, thiab kub siab zog. Txuas ntxiv, molybdenum, tooj liab, silicon, aluminium, selenium, sulfur, antimony, cobalt, titanium, etc. yog tag nrho cov tseem ceeb alloying ntsiab, thiab lawv lub peev xwm tswj tau thiab formulated kom tau txais yam mechanical khoom.
Qhov laj thawj yog vim li cas tsis muaj hlau tsis yoojyim rau xeb yog vim qhov hlau ntsa yuav tsim ib cov yeeb yaj duab tsis pom kev, uas yuav tiv thaiv tau ntxiv oxidation. Thaum lub sijhawm ua haujlwm ntawm kev sib tsoo xws li forging hau thiab tig, qhov chaw yuav kis tau nrog cov hlau me me uas yog tsim los ntawm cov cuab yeej ua pwm, thiab tom qab thaum tshav kub kub kuj yuav ua rau muaj kev sib kis. Yog hais tias tus ntsia thawv yog tsim tsis tau ntxuav tom qab nws yog manufactured, cov tsos ntawm xeb tsis yog ib yam khoom xeb. Nyob rau hauv qhov tseeb, nws yog tshwm sim los ntawm impurities los yog impurities fury nyob rau saum npoo. Yog li ntawd, qhov hlau tsis muaj steel hlau yuav tsum muaj kua qaub ua kua ua ntej xa khoom tuaj. Cov nplaim yuav ua sai sai ua ib zaj duab xis oxide thiab tshem tawm cov kab mob saum npoo av.
Stainless hlau faib ua plaub pawg: austenite, ferrite, martensite, thiab nag lossis daus steel, thiab txhua tus nws muaj nws qhov zoo thiab qhov tsis zoo. Austenitic stainless hlau yog cov feem ntau siv. Hais txog 80% ntawm stainless hlau screws yog ua los ntawm nws. Nws cov microstructure yog ib qho uas yog cov neeg ua haujlwm. Chromium thiab npib tsib xees yog cov tseem ntsiab lus tseem ceeb. Tsuav nws txias, nws cov khoom yuav ua kom zoo tuaj. . Feem ntau siv cov ntsiab lus yog 18% ntawm chromium, 8% ntawm nickel yog hu ua 18-8 lossis 300 tawm. Corrosion kuj yog zoo dua ferritic thiab martensitic stainless hlau, thiab nws tsis yog sib nqus. Nws muaj zog dua ntawm qhov tsawg kawg kub lossis kub. Thiab zoo toughness. Austenitic stainless hlau muaj xws li 301, 302, 303, 303 Se, 304, 305, 384, XM7, 316, 321, thiab 347.
303 thiab 303 Se (17/19% chromium, 8/10% nickel) yog ib qho yooj yim tig thiab tsis haum rau lub taub hau txias. 304 (18/20% chromium, 8 / 10.5% nickel, 0.08% los yog tsawg dua carbon) yog tsim rau txias thiab kub crucibles, thiab muaj kev txhuam tus corrosion. Nws yog nquag siv los tsim txoj kab-puab, loj-loj ua haujlwm screws. 305 (17/19% chromium, 10.5 / 13% nickel) txo tus nqi ntawm kev ua hauj lwm hardening thiab pub rau txias txias ua. 384 (15/17% chromium, 17/19% nickel, 0.08% los yog tsawg dua carbon) yog siv tshwj xeeb rau cov taub txias thiab cov ntoo ntawm cov ntoo cab. Vim yog cov ntsiab lus nickel loj, cov kev ua hauj lwm hardening ceev yuav txo. 384 Tom qab mob khaub thuas, tseem tsis muaj magnetism, tab sis lwm cov khoom siv hlau austenitic stainless hlau yuav muaj me ntsis ntawm sib nqus tom qab txias lub npe thiab yuav tsum tau muab khi dua los rau cov khoom tsis muaj hlau nplaum. XM7 (17/19% chromium, 8/10% nickel, 3/4% copper) yog ib qho khoos kas zoo dua 302 uas muaj kev txias txias thiab txo tus nqi tshaj 305, 384. 316 (16/18% chromium, 10/14% nickel, 2/3% molybdenum, thiab 0.08% los yog tsawg dua cov roj) muaj zoo txaus halogen corrosion vim muaj cov molybdenum thiab tseem ntau dua lwm lub austenitic stainless steels kom txias. Tensile siab zog thiab latent siv. 321 (17/19% chromium, 9/12% nickel) thiab 347 (17/19% tooj liab, 9/13% nickel) yog cov tsis muaj zog stainless steels. Lawv muaj kev txhuam tus kab mob zoo heev thaum sov li 820 ° C. Kev tsim cov lag luam aerospace los yog cov ciaj siv los ua kom paug thaj chaw muaj huab cua kub lossis tshuaj.
Lub microstructure ntawm ferritic stainless hlau yog yeej los ntawm ferrite, uas tso nyiaj rau txog 5% ntawm stainless hlau screws. Chromium yog lub ntsiab kev ua txhua yam. Nws muaj cov khoom sib nqus thiab muaj corrosion tsis muaj zog tshaj martensite. Cov ntsiab lus ntawm lwm cov ntsiab lus yog me me, thiab qhov no tsis muaj qab hau hlau yog tshwj xeeb yog tiv taus xeb thiab corrosion. 430 screws (14/18% chromium, 0.12% los sis tsawg dua cov roj) yog siv los ua ntsuas. Lawv feem ntau yog siv rau cov npe txias thiab kub npe. Qhov sib ntxiv ntawm leej faj nyob rau hauv 430F tuaj yeem txhim kho txoj kev ua yeeb yam. Yog tias koj xav txog kev lag luam, cov nqi khoom siv, thiab kev quab yuam kev, xaiv ferritic stainless hlau ua kom screws tsim nyog dua. Ob lub ferritic thiab austenitic stainless hlau tsis tuaj yeem ua tau quenched thiab tsuas yog twv thiab txias-reinforced los txhim kho lawv lub zog thiab hardness, tab sis lawv cov ductility deteriorates, ces lawv feem ntau yog annealed tshem residual stresses thiab restore ductility.
Martensitic hlau microstructure martensite, li ntawm 10% ntawm cov hlau tsis txhuam, nrog chromium raws li lub ntsiab alloying, sib nqus, yuav quenched kom tau lub siab tshaj plaws mechanical zog, thiab SAE 5, 8, ASTM A449 qib, A354 BD qib approximation. Txawm li cas los xij, qhov kev xeb hauv corrosion no tuaj tsis zoo dua li ntawm cov khoom siv hlau thiab cov ferritic stainless hlau. Feem ntau yog ua los ntawm 400 series khoom, xws li 410, 416, 416 Se thiab 431.
410 (12.5 / 13.5% chromium, carbon hauv qab 0.15%) zoo ib yam li SAE qib 5 lossis A449. Tom qab sov kho, nws tuaj yeem ua rau lub zog ntxiv thiab yooj yim kom txias thiab kub. Vim nws cov ntsiab lus tsawg chromium, nws yog qhov pheej yig tshaj plaws hauv cov hlau tsis muaj kab. Yog hais tias tus corrosion tsis kam ntawm SAE 5 galvanized los yog cadmium plated screws tsis txaus, 410 yuav siv tau.
416 thiab 416 Se (12/14% chromium, tsawg dua 0.15% carbon, sulphur los yog arsenic), txoj hlua tuaj yeem yog qhov zoo tshaj plaws ntawm tag nrho cov hlau tsis muaj hlau, mechanically sib npaug rau 410. 431 (15/17% chromium, 1.25 / 2.5% nickel, thiab 0.2% lossis tsawg dua cov pa roj carbon monoxide) feem ntau siv los ua kev tsim khoom ntawm aerospace screws. Vim lawv lub zog siab thiab kev xeb tuaj yeem tiv thaiv, lawv yooj yim rau txias thiab kub. Cov khoom vaj khoom tsev tsis muaj tsawg tshaj li SAE 8 thiab ASTM A354 chav kawm BD.
Nag lossis quenching steel screws tus account rau 5% ntawm stainless hlau screws, thiab lawv siv tau ua ntau thiab tseem ceeb. Lawv muaj corrosion kuj piv rau cov uas muaj zog thiab siab zog sib npaug ntawm cov martensite. Piv txwv li, 630 (15.5 / 17.5% chrome, 3/5% nickel, 0.07% los yog tsawg dua carbon, 0.15 / 0.45% yttrium thiab yttrium), los yog 17-4PH, yog feem ntau siv los nag lossis daus steel rau kev tsim khoom ntawm screws, tshwj tsis yog rau siab zog. Cov kab no kuj zoo, thiab nws tuaj yeem tiv taus siab thiab tsis kub.