Q: Posachedwapa tayamba kugwira ntchito yomwe imafuna kuti zinthu zina zipangidwe makamaka ndi chitsulo chosapanga dzimbiri cha kalasi 304, chomwe chimalumikizidwa chokha komanso ku chitsulo chofewa. Takumana ndi mavuto ena osweka pa zitsulo zosapanga dzimbiri mpaka zitsulo zosapanga dzimbiri zokwana 1.25″. Zanenedwa kuti tili ndi kuchuluka kochepa kwa ferrite. Kodi mungalongosole chomwe ichi ndi chiyani komanso momwe mungachikonzere?
A: Funso ili ndi labwino. Inde, tingakuthandizeni kumvetsetsa tanthauzo la kuchuluka kwa ferrite komanso momwe mungapewere.
Choyamba, tiyeni tiwone tanthauzo la chitsulo chosapanga dzimbiri (SS) ndi momwe ferrite imagwirizanirana ndi zolumikizira zoswedwa. Chitsulo chakuda ndi ma alloy ali ndi chitsulo choposa 50%. Izi zikuphatikizapo kaboni yonse ndi zitsulo zosapanga dzimbiri ndi magulu ena odziwika. Aluminiyamu, mkuwa ndi titaniyamu zilibe chitsulo, kotero ndi zitsanzo zabwino kwambiri za ma alloy osapanga dzimbiri.
Zigawo zazikulu za alloy iyi ndi chitsulo cha kaboni chokhala ndi chitsulo chosachepera 90% ndi SS yokhala ndi chitsulo chosachepera 70 mpaka 80%. Kuti itchulidwe ngati SS, iyenera kukhala ndi chromium yosachepera 11.5% yowonjezera. Kuchuluka kwa chromium pamwamba pa malire ochepera awa kumalimbikitsa kupangika kwa mafilimu a chromium oxide pamwamba pa zitsulo ndikuletsa kupangika kwa okosijeni monga dzimbiri (iron oxide) kapena dzimbiri loyambitsidwa ndi kuukira kwa mankhwala.
SS imagawidwa m'magulu atatu: austenite, ferrite ndi martensite. Dzina lawo limachokera ku kapangidwe ka kristalo kotentha kwa chipinda komwe kamawapanga. Gulu lina lodziwika bwino ndi duplex SS, yomwe ndi mgwirizano pakati pa ferrite ndi austenite mu kapangidwe ka kristalo.
Magiredi a Austenitic, mndandanda wa 300, ali ndi 16% mpaka 30% ya chromium ndi 8% mpaka 40% ya nickel, zomwe zimapangitsa kuti kristalo ya austenitic ikhale yolimba kwambiri. Pofuna kulimbikitsa kupangika kwa chiŵerengero cha austenite-ferrite, zinthu zokhazikika monga nickel, carbon, manganese ndi nayitrogeni zimawonjezedwa panthawi yopanga zitsulo. Magiredi ena odziwika bwino ndi 304, 316 ndi 347. Amapereka kukana dzimbiri kwabwino; amagwiritsidwa ntchito makamaka pazakudya, ntchito zamakemikolo, zamankhwala ndi ntchito zowunikira. Kuwongolera kupangika kwa ferrite kumapereka kulimba kwabwino kwambiri kutentha kochepa.
Ferritic SS ndi mtundu wa 400 series grade womwe uli ndi maginito okwanira, uli ndi 11.5% mpaka 30% ya chromium, ndipo uli ndi kapangidwe ka kristalo ka ferritic. Pofuna kulimbikitsa mapangidwe a ferrite, zokhazikika zimaphatikizapo chromium, silicon, molybdenum, ndi niobium popanga chitsulo. Mitundu iyi ya SS imagwiritsidwa ntchito kwambiri mumakina otulutsa utsi wamagalimoto ndi mafakitale amphamvu ndipo imakhala ndi ntchito zochepa zotentha kwambiri. Mitundu ingapo yomwe imagwiritsidwa ntchito kwambiri ndi 405, 409, 430 ndi 446.
Ma grade a Martensitic, omwe amadziwikanso ndi mndandanda wa 400 monga 403, 410 ndi 440, ndi a maginito, ali ndi 11.5% mpaka 18% ya chromium, ndipo ali ndi martensite ngati kapangidwe ka kristalo. Kuphatikiza kumeneku kuli ndi golide wochepa kwambiri, zomwe zimapangitsa kuti zikhale zotsika mtengo kupanga. Amapereka kukana dzimbiri; mphamvu yabwino kwambiri; ndipo amagwiritsidwa ntchito kwambiri patebulo, zida zamano ndi opaleshoni, zida zophikira, ndi mitundu ina ya zida.
Mukalumikiza SS, mtundu wa substrate ndi momwe imagwiritsidwira ntchito zidzasankha chitsulo choyenera kugwiritsa ntchito. Ngati mugwiritsa ntchito njira yotetezera mpweya, mungafunike kuyang'anitsitsa kwambiri zosakaniza za mpweya kuti mupewe mavuto ena okhudzana ndi kuwotcherera.
Kuti musokeretse 304 yokha, mufunika electrode ya E308/308L. "L" imayimira carbon yochepa, yomwe imathandiza kupewa dzimbiri la intergranular. Ma electrode awa ali ndi carbon content yochepera 0.03%; chilichonse chomwe chili pamwamba pa izi chimawonjezera chiopsezo cha carbon ku malire a tirigu ndikuphatikizana ndi chromium kupanga chromium carbides, zomwe zimachepetsa bwino kukana kwa dzimbiri kwa chitsulo. Izi zimaonekera bwino ngati dzimbiri litachitika m'dera lomwe lakhudzidwa ndi kutentha (HAZ) la ma SS welded joints. Chinthu china chomwe muyenera kuganizira pa L grade SS ndichakuti ali ndi mphamvu zochepa zomangika pa kutentha kwakukulu kuposa ma SS grade olunjika.
Popeza 304 ndi mtundu wa austenitic wa SS, chitsulo chofananacho chidzakhala ndi austenite yambiri. Komabe, electrode yokha idzakhala ndi ferrite stabilizer, monga molybdenum, kuti ilimbikitse mapangidwe a ferrite mu chitsulo chosungunula. Opanga nthawi zambiri amalemba mitundu yosiyanasiyana ya ferrite ya chitsulo chosungunula. Monga tanenera kale, kaboni ndi chokhazikika champhamvu cha austenitic, ndipo pazifukwa izi ndikofunikira kuti isawonjezedwe ku chitsulo chosungunula.
Manambala a Ferrite amachokera ku chithunzi cha Schaeffler ndi chithunzi cha WRC-1992, zomwe zimagwiritsa ntchito ma formula ofanana ndi nickel ndi chromium kuti ziwerengere mtengo, womwe ukajambulidwa pa chithunzicho umapanga nambala yokhazikika. Nambala ya ferrite pakati pa 0 ndi 7 imagwirizana ndi kuchuluka kwa voliyumu ya kapangidwe ka kristalo ka ferrite komwe kali mu chitsulo chosungunula; komabe, pamaperesenti apamwamba, nambala ya ferrite imawonjezeka mwachangu. Kumbukirani kuti ferrite mu SS si yofanana ndi ferrite ya carbon steel, koma gawo lotchedwa delta ferrite. Austenitic SS ilibe kusintha kwa gawo komwe kumakhudzana ndi njira zotentha kwambiri monga kutentha.
Kupangidwa kwa ferrite n'kofunika chifukwa ndi kofewa kwambiri kuposa austenite, koma kuyenera kulamulidwa. Kuchuluka kwa ferrite kochepa kungapangitse ma welds omwe ali ndi kukana dzimbiri bwino m'magwiritsidwe ena, koma nthawi zambiri amasweka kwambiri panthawi yowotcherera. Pazinthu zomwe zimagwiritsidwa ntchito nthawi zonse, kuchuluka kwa ferrite kuyenera kukhala pakati pa 5 ndi 10, koma pa ntchito zina kungafunike kutsika kapena kukwera. Ma Ferrite amatha kutsimikiziridwa mosavuta pantchitoyo pogwiritsa ntchito chizindikiro cha ferrite.
Popeza mwanena kuti muli ndi mavuto osweka komanso kuchuluka kwa ferrite kochepa, muyenera kuyang'anitsitsa chitsulo chanu chodzaza ndikuwonetsetsa kuti chimapanga kuchuluka kokwanira kwa ferrite - pafupifupi 8 ziyenera kuthandiza. Komanso, ngati mukugwiritsa ntchito flux cored arc welding (FCAW), zitsulo zodzaza izi nthawi zambiri zimagwiritsa ntchito mpweya woteteza carbon dioxide 100% kapena 75% argon/25% CO2, zomwe zingayambitse kutenga carbon mu chitsulo chosungunula. Mungafune kusintha njira yosungunula chitsulo chosungunula (GMAW) ndikugwiritsa ntchito 98% argon/2% oxygen mixture kuti muchepetse kuthekera kwa carbon pickup.
Kuti mulumikize SS ku chitsulo cha kaboni muyenera kugwiritsa ntchito zinthu zodzaza za E309L. Chitsulo chodzazachi chimagwiritsidwa ntchito makamaka polumikira zitsulo zosiyana ndipo chimapanga kuchuluka kwa ferrite pambuyo poti chitsulo cha kaboni chasungunuka mu weld. Popeza chitsulo cha kaboni chimayamwa kaboni pang'ono, zokhazikika za ferrite zimawonjezedwa ku chitsulo chodzaza kuti zithetse vuto la kaboni popanga austenite. Izi zithandiza kupewa kusweka kwa kutentha pakugwiritsa ntchito zolumikira.
Mwachidule, ngati mukufuna kuchotsa ming'alu yotentha pa malo olumikizirana a austenitic SS, onetsetsani kuti chitsulo chokwanira cha ferrite filler ndikutsatira njira zabwino zolumikizirana. Sungani kutentha kolowera pansi pa 50 kJ/inchi, sungani kutentha kocheperako mpaka kotsika, ndikuwonetsetsa kuti malo olumikizirana a solder alibe kuipitsidwa kulikonse musanagwiritse ntchito solder. Gwiritsani ntchito gauge yoyenera kuti muwonetsetse kuchuluka kwa ferrite pa malo olumikizirana, cholinga chake ndi 5 mpaka 10.
WELDER, yomwe kale inali Practical Welding Today, ikuwonetsa anthu enieni omwe amapanga zinthu zomwe timagwiritsa ntchito komanso zomwe timagwira ntchito nazo tsiku lililonse. Magazini iyi yakhala ikutumikira anthu ogwiritsira ntchito welding ku North America kwa zaka zoposa 20.
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