Bakin ƙarferukuni ne na ƙarfe-carbon gami tare da abun ciki na carbon fiye da 2%.Amfaninsa yana samuwa daga ƙananan zafin jiki na narkewa.Abubuwan da ke cikin gami suna shafar launin sa idan sun karye: farin simintin ƙarfe yana da ƙazanta na carbide wanda ke ba da damar tsagewa su wuce kai tsaye, baƙin ƙarfe mai launin toka yana da flakes na graphite wanda ke karkatar da tsagewar wucewa kuma yana fara fashe marasa adadi yayin da kayan ke karye, kuma baƙin ƙarfe na ductile yana da sassauƙa. graphite "nodules" wanda ke hana fasa daga ci gaba.

Carbon (C) wanda ke jere daga 1.8 zuwa 4 wt%, da silicon (Si) 1–3 wt%, sune manyan abubuwan haɗakar da baƙin ƙarfe.Ƙarfe gami da ƙananan abun ciki na carbon da aka sani da karfe.

Ƙarfe na simintin gyare-gyare yana kasancewa mai karyewa, sai dai ƙarfen simintin gyaran kafa.Tare da ƙananan ƙarancin narkewa, ƙarancin ruwa mai kyau, ƙaddamarwa mai kyau, kyakkyawan machinability, juriya ga nakasawa da juriya, simintin ƙarfe ya zama kayan aikin injiniya tare da aikace-aikace masu yawa kuma ana amfani dashi a cikin bututu, inji da sassan masana'antar kera, irin su Silinda. shugabannin, tubalan silinda da akwati gearbox.Yana da juriya ga lalacewa ta hanyar oxidation.

Farkon kayan tarihi na simintin gyare-gyaren ƙarfe na farko sun kasance a ƙarni na 5 BC, kuma masu binciken kayan tarihi sun gano su a yankin Jiangsu na China a yanzu.An yi amfani da simintin ƙarfe a tsohuwar kasar Sin don yaƙi, aikin gona, da gine-gine.A cikin karni na 15, simintin ƙarfe ya zama abin amfani da igwa a Burgundy, Faransa, da kuma a Ingila a lokacin gyarawa.Yawan simintin ƙarfe da aka yi amfani da shi don igwa yana buƙatar samar da babban sikeli. An gina gadar simintin ƙarfe na farko a cikin shekarun 1770 ta Abraham Darby III, kuma ana kiranta da Gadar Iron a Shropshire, Ingila.An kuma yi amfani da simintin ƙarfe wajen gina gine-gine.

Abubuwan haɗin gwiwa

Ana canza kaddarorin simintin ƙarfe ta hanyar ƙara abubuwa masu haɗawa daban-daban, ko alloli.Kusa da carbon, silicon shine mafi mahimmancin abubuwan haɗin gwiwa saboda yana tilasta carbon daga mafita.Ƙananan kaso na silicon yana ba da damar carbon ya kasance a cikin maganin samar da carbide baƙin ƙarfe da samar da farin simintin ƙarfe.Wani babban kaso na silicon yana tilasta carbon daga mafita mai yin graphite da kuma samar da baƙin ƙarfe mai launin toka.Sauran abubuwan da aka haɗa, manganese, chromium, molybdenum, titanium da vanadium suna hana silicon, suna haɓaka riƙewar carbon, da samuwar waɗannan carbides.Nickel da jan ƙarfe suna ƙara ƙarfi, da machinability, amma kada su canza adadin graphite da aka kafa.Carbon a cikin nau'i na graphite yana haifar da ƙarfe mai laushi, yana rage raguwa, rage ƙarfi, kuma yana rage yawa.Sulfur, mafi yawan gurɓataccen abu idan akwai, yana samar da sulfide na ƙarfe, wanda ke hana samuwar graphite kuma yana ƙara taurin.Matsalar sulfur ita ce ta sanya baƙin ƙarfe da aka narkar da shi ya zama ɗan ɗanɗano, wanda ke haifar da lahani.Don magance tasirin sulfur, ana ƙara manganese saboda su biyun sun zama manganese sulfide maimakon ƙarfe sulfide.Sulfide na manganese ya fi narke wuta, don haka yana ƙoƙarin yin iyo daga narke kuma a cikin slag.Adadin manganese da ake buƙata don kawar da sulfur shine 1.7 × sulfur abun ciki + 0.3%.Idan an ƙara fiye da wannan adadin manganese, to, manganese carbide ya samar da shi, wanda ke ƙara ƙarfi da sanyi, sai dai a cikin baƙin ƙarfe mai launin toka, wanda har zuwa 1% na manganese yana ƙara ƙarfi da yawa.

Nickel yana daya daga cikin abubuwan da aka fi sani da alloying saboda yana tsaftace tsarin lu'u-lu'u da zane-zane, yana inganta ƙarfi, kuma yana fitar da bambance-bambance tsakanin kauri na sashe.Ana ƙara Chromium a cikin ƙananan kuɗi don rage graphite kyauta, samar da sanyi, kuma saboda yana da ƙarfi carbide stabilizer;Ana ƙara nickel sau da yawa tare.Za a iya ƙara ɗan ƙaramin tin a madadin 0.5% chromium.Ana ƙara jan ƙarfe a cikin ladle ko a cikin tanderun, akan tsari na 0.5-2.5%, don rage sanyi, tsaftace graphite, da ƙara yawan ruwa.Ana ƙara molybdenum akan tsari na 0.3-1% don ƙara sanyi da kuma tsaftace tsarin graphite da pearlite;sau da yawa ana ƙara shi tare da nickel, jan ƙarfe, da chromium don samar da ƙarfe mai ƙarfi.Ana ƙara titanium a matsayin degasser da deoxidizer, amma kuma yana ƙara yawan ruwa.0.15-0.5% vanadium an ƙara don jefa baƙin ƙarfe don daidaita siminti, ƙara taurin, da ƙara juriya ga lalacewa da zafi.0.1-0.3% zirconium yana taimakawa wajen samar da graphite, deoxidize, da ƙara yawan ruwa.

A cikin malleable baƙin ƙarfe narke, an ƙara bismuth, a kan sikelin na 0.002-0.01%, don ƙara nawa silicon za a iya ƙara.A cikin farin ƙarfe, ana ƙara boron don taimakawa wajen samar da baƙin ƙarfe;Hakanan yana rage tasirin bismuth.

Karfe mai launin toka

Iron simintin simintin gyare-gyaren launin toka yana da siffa ta ƙirar ƙirar ƙirar sa, wanda ke haifar da karyewar kayan ya yi launin toka.Ita ce simintin ƙarfe da aka fi amfani da shi da kuma kayan simintin da aka fi amfani da shi bisa nauyi.Yawancin ƙarfe na simintin gyare-gyare suna da sinadarai na 2.5-4.0% carbon, 1-3% silicon, da sauran baƙin ƙarfe.Iron simintin gyare-gyaren launin toka yana da ƙarancin juriya da juriya fiye da ƙarfe, amma ƙarfinsa na matsawa yana kama da ƙaramin ƙarfe da matsakaicin ƙarfe.Waɗannan kaddarorin injinan ana sarrafa su ta hanyar girma da sifar flakes ɗin graphite da ke cikin ƙaramin tsari kuma ana iya siffanta su bisa ga jagororin da ASTM ta bayar.

Farin simintin ƙarfe

Farin simintin ƙarfe yana nuna farar fashe-fashe saboda kasancewar hazo na ƙarfe na carbide da ake kira cementite.Tare da ƙananan abun ciki na silicon (wakilin graphitizing) da saurin sanyaya, carbon da ke cikin farin simintin ƙarfe yana hazo daga narke kamar siminti mai daidaitawa, Fe.₃C, maimakon graphite.Siminti wanda ke tsirowa daga narkakkun ya zama kamar manyan barbashi.Yayin da carbide na baƙin ƙarfe ke tsirowa, yana janye carbon daga narke na asali, yana motsa cakuda zuwa wanda ke kusa da eutectic, kuma ragowar lokaci shine ƙananan ƙarfe-carbon austenite (wanda akan sanyaya zai iya canzawa zuwa martensite).Wadannan eutectic carbides suna da girma da yawa don samar da fa'idar abin da ake kira hardening hazo (kamar yadda a cikin wasu karafa, inda mafi ƙarancin siminti hazo zai iya hana [nakasar filastik] ta hanyar hana motsi na ɓarna ta hanyar matrix ƙarfe mai tsabta).Maimakon haka, suna ƙara yawan taurin ƙarfen simintin kawai ta hanyar ƙarfin nasu mai girman gaske da ɗigon juzu'insu, wanda za'a iya kimanta girman taurin ta hanyar ƙa'idar gaurayawan.A kowane hali, suna ba da tauri a kashe tauri.Tun da carbide ya ƙunshi babban juzu'i na kayan, farin simintin ƙarfe na iya zama mai ƙima a matsayin cermet.Farin ƙarfe yana da ƙarfi sosai don amfani da shi a yawancin sassan tsarin, amma tare da tauri mai kyau da juriya da ƙarancin farashi, yana samun amfani a cikin irin waɗannan aikace-aikacen kamar faɗuwar lalacewa (impeller da volute) na famfunan slurry, harsashi liners da sanduna masu ɗagawa a cikin ball. niƙa da injunan niƙa ta atomatik, ƙwallaye da zobe a cikin injin kwal, da haƙoran bokitin tono na baya (ko da yake simintin ƙarfe-carbon martensitic karfe ya fi yawa ga wannan aikace-aikacen).

Yana da wahala a sanyaya simintin gyare-gyare mai kauri da sauri don ƙarfafa narkewar kamar farin simintin ƙarfe har zuwa gaba.Koyaya, ana iya amfani da saurin sanyaya don ƙarfafa harsashi na farin ƙarfe na simintin ƙarfe, bayan haka sauran yakan yi sanyi a hankali don samar da ainihin baƙin ƙarfe mai launin toka.Sakamakon simintin gyare-gyare, wanda ake kira asanyin simintin gyaran kafa, yana da fa'idodin fage mai ƙarfi tare da ɗan ƙaran ciki.

Haɗaɗɗen farin ƙarfe na chromium suna ba da damar ɗimbin simintin gyare-gyare (misali, mai ɗaukar nauyi mai nauyin ton 10) ya zama simintin yashi, yayin da chromium yana rage yawan sanyaya da ake buƙata don samar da carbides ta mafi girman kauri na abu.Chromium kuma yana samar da carbide tare da juriya mai ban sha'awa.Wadannan galoli masu girma-chromium suna dangana mafi girman taurinsu ga kasancewar chromium carbides.Babban nau'in waɗannan carbides sune eutectic ko na farko M₇C₃carbides, inda "M" ke wakiltar ƙarfe ko chromium kuma zai iya bambanta dangane da abun da ke ciki.The eutectic carbides suna zama a matsayin daure na sanduna hexagonal mara kyau kuma suna girma daidai da jirgin basal mai hexagonal.Taurin waɗannan carbides suna cikin kewayon 1500-1800HV.

Ƙarfin simintin gyare-gyare

Ƙarfe mai ƙyalƙyali yana farawa azaman simintin ƙarfe na farin ƙarfe wanda sai a ji zafin rana ɗaya ko biyu a kusan 950 °C (1,740 °F) sannan a sanyaya sama da kwana ɗaya ko biyu.A sakamakon haka, carbon a cikin baƙin ƙarfe carbide ya canza zuwa graphite da ferrite da carbon (austenite).Tsarin jinkirin yana ba da damar tashin hankali na saman don samar da graphite zuwa barbashi spheroidal maimakon flakes.Saboda ƙananan yanayin yanayin su, spheroids suna da ɗan gajeren gajere kuma suna da nisa daga juna, kuma suna da ƙananan ɓangaren giciye vis-a-vis mai yaɗa fasa ko phonon.Hakanan suna da iyakoki mara kyau, sabanin flakes, wanda ke rage matsalolin damuwa da ake samu a cikin baƙin ƙarfe mai launin toka.Gabaɗaya, kaddarorin simintin gyare-gyaren simintin gyare-gyare sun fi kama da na ƙarfe mai laushi.Akwai iyaka ga yadda za a iya jefa babban sashi a cikin baƙin ƙarfe mai yuwuwa, kamar yadda aka yi shi daga farin simintin ƙarfe.

Ƙarfin simintin gyare-gyare