Cikakke kuma cikakken bayani! Cikakken ilimin kashe ƙarfe!

Ma'anar da manufar kashewa
Ana dumama ƙarfen zuwa zafin da ya wuce ma'aunin Ac3 (ƙarfe hypoeutectoid) ko Ac1 (ƙarfe hypereutectoid), ana ajiye shi na ɗan lokaci don ya zama cikakke ko ɗan austenit, sannan a sanyaya shi a gudun da ya fi saurin kashewa. Tsarin maganin zafi wanda ke canza austenite mai sanyi zuwa martensite ko ƙananan bainite ana kiransa quenching.

Manufar kashe wuta ita ce a canza austenite mai sanyi zuwa martensite ko bainite don samun tsarin martensite ko ƙananan bainite, wanda daga nan za a haɗa shi da tempering a yanayin zafi daban-daban don inganta ƙarfi, tauri, da juriyar ƙarfe. Sauƙin lalacewa, ƙarfin gajiya da tauri, da sauransu, don biyan buƙatun amfani daban-daban na sassa da kayan aiki daban-daban na injiniya. Hakanan ana iya amfani da kashe wuta don biyan buƙatun zahiri da sinadarai na wasu ƙarfe na musamman kamar ferromagnetic da juriyar tsatsa.

Idan aka sanyaya sassan ƙarfe a cikin wani abu mai kashe wuta tare da canje-canje a yanayin jiki, tsarin sanyaya gabaɗaya ana raba shi zuwa matakai uku masu zuwa: matakin fim ɗin tururi, matakin tafasa, da matakin convection.

Taurare na ƙarfe
Taurarewa da taurarewa alamomi ne guda biyu da ke nuna ikon ƙarfe na iya shaƙewa. Su ma muhimman tushe ne na zaɓen kayan aiki da amfani da su.

1. Ma'anonin taurin kai da taurin kai

Taurarewa shine ikon ƙarfe na cimma mafi girman tauri da zai iya samu idan aka kashe shi kuma aka taurare shi a ƙarƙashin yanayi mai kyau. Babban abin da ke ƙayyade taurarewar ƙarfe shine yawan carbon da ke cikin ƙarfe. Don zama daidai, shine yawan carbon da ke narkewa a cikin austenite yayin kashewa da dumamawa. Mafi girman yawan carbon, mafi girman taurarewar ƙarfe. Abubuwan da ke haɗa ƙarfe ba su da tasiri sosai akan taurarewar, amma suna da tasiri mai mahimmanci akan taurarewar ƙarfe.

Taurarewa yana nufin halayen da ke ƙayyade zurfin taurarewa da rarrabawar taurin ƙarfe a ƙarƙashin takamaiman yanayi. Wato, ikon samun zurfin layin taurare lokacin da ƙarfe ya mutu. Yana da wani abu na musamman na ƙarfe. Taurarewa a zahiri yana nuna sauƙin da austenite ke canzawa zuwa martensite lokacin da ƙarfe ya mutu. Yana da alaƙa da kwanciyar hankali na austenite mai sanyi sosai na ƙarfe, ko kuma da mahimmancin saurin sanyaya ƙarfe.

Ya kamata kuma a nuna cewa dole ne a bambanta taurin ƙarfe daga zurfin taurin da ya dace na sassan ƙarfe a ƙarƙashin takamaiman yanayin kashewa. Taurin ƙarfe wani abu ne da ke cikin ƙarfen da kansa. Ya dogara ne kawai da abubuwan ciki nasa kuma ba shi da alaƙa da abubuwan waje. Zurfin taurin ƙarfe mai inganci ba wai kawai ya dogara ne da taurin ƙarfe ba, har ma ya dogara da kayan da aka yi amfani da su. Yana da alaƙa da abubuwan waje kamar matsakaicin sanyaya da girman kayan aiki. Misali, a ƙarƙashin yanayin ƙarfafawa iri ɗaya, taurin ƙarfe iri ɗaya ne, amma zurfin taurin ruwa mai inganci ya fi na kashe mai girma, kuma ƙananan sassa sun fi ƙanƙanta fiye da kashe mai. Zurfin taurin mai mai tasiri na manyan sassa yana da girma. Ba za a iya cewa kashe ruwa yana da taurin ruwa mafi girma fiye da kashe mai ba. Ba za a iya cewa ƙananan sassa suna da taurin da ya fi manyan sassa girma ba. Ana iya ganin cewa don kimanta taurin ƙarfe, dole ne a kawar da tasirin abubuwan waje kamar siffar kayan aiki, girma, matsakaicin sanyaya, da sauransu.

Bugu da ƙari, tunda ƙarfin tauri da ƙarfin tauri ra'ayoyi ne daban-daban guda biyu, ƙarfe mai ƙarfin tauri bayan an kashe shi ba lallai bane yana da ƙarfin tauri mai yawa ba; kuma ƙarfe mai ƙarancin tauri shi ma yana iya samun ƙarfin tauri mai yawa.

2. Abubuwan da ke shafar taurin kai

Tauraron ƙarfe ya dogara ne da daidaiton austenite. Duk wani abu da zai iya inganta daidaiton austenite mai sanyi sosai, ya canza lanƙwasa C zuwa dama, sannan ya rage saurin sanyaya mai mahimmanci zai iya inganta tauraren ƙarfe mai tsayi. Daidaiton austenite ya dogara ne akan sinadaran da ke cikinsa, girman hatsi da kuma daidaiton abun da ke ciki, waɗanda ke da alaƙa da sinadaran da ke cikin ƙarfe da yanayin dumama.

3. Hanyar auna taurin kai

Akwai hanyoyi da yawa don auna ƙarfin ƙarfe, waɗanda aka fi amfani da su sune hanyar auna diamita mai mahimmanci da hanyar gwajin taurarewa ta ƙarshe.

(1) Hanyar auna diamita mai mahimmanci

Bayan an kashe ƙarfen a wani matsakaici, matsakaicin diamita lokacin da zuciyar ta sami dukkan tsarin martensite ko 50% na martensite ana kiransa da diamita mai mahimmanci, wanda Dc ke wakilta. Hanyar auna diamita mai mahimmanci ita ce yin jerin sandunan zagaye tare da diamita daban-daban, kuma bayan an kashe, auna taurin U da aka rarraba tare da diamita akan kowane sashe na samfurin, sannan a nemo sandar da tsarin semi-martensite a tsakiya. Diamita na sandar zagaye Wannan shine diamita mai mahimmanci. Girman diamita mai mahimmanci, mafi girman ƙarfin taurin ƙarfe.

(2) Hanyar gwajin ƙarewa

Hanyar gwajin ƙarewa ta amfani da samfurin da aka yi amfani da shi a ƙarshen ƙarfe (Ф25mm × 100mm). Bayan an yi amfani da shi a ƙarshen ƙarfe, ana fesa ruwa a ƙarshen samfurin a kan kayan aiki na musamman don sanyaya shi. Bayan an sanyaya, ana auna taurin a gefen axis - daga ƙarshen da aka sanyaya ruwa. Hanyar gwaji don lanƙwasa dangantaka ta nesa. Hanyar gwajin ƙarewa ta ƙarshe tana ɗaya daga cikin hanyoyin tantance taurin ƙarfe. Fa'idodinta sune sauƙin aiki da kewayon aikace-aikace.

4. Kashe damuwa, nakasa da fashewa

(1) Damuwar ciki na kayan aikin yayin kashewa

Idan aka sanyaya kayan aikin cikin sauri a cikin yanayin kashewa, tunda kayan aikin yana da takamaiman girma kuma ma'aunin juriyar zafi shima wani ƙima ne, wani ɗan ƙaramin juzu'i na zafin jiki zai faru tare da ɓangaren ciki na kayan aikin yayin aikin sanyaya. Zafin saman yana da ƙasa, zafin zuciyar yana da yawa, kuma yanayin saman da tsakiyar yana da yawa. Akwai bambancin zafin jiki. A lokacin aikin sanyaya kayan aikin, akwai kuma abubuwan da suka faru guda biyu na zahiri: ɗaya shine faɗaɗa zafi, yayin da zafin jiki ke raguwa, tsawon layin kayan aikin zai ragu; ɗayan kuma shine canjin austenite zuwa martensite lokacin da zafin jiki ya faɗi zuwa wurin canza martensite., wanda zai ƙara takamaiman girma. Saboda bambancin zafin jiki yayin aikin sanyaya, adadin faɗaɗa zafi zai bambanta a sassa daban-daban tare da ɓangaren giciye na kayan aikin, kuma za a haifar da damuwa ta ciki a sassa daban-daban na kayan aikin. Saboda wanzuwar bambance-bambancen zafin jiki a cikin kayan aikin, akwai kuma sassan inda zafin jiki ya faɗi da sauri fiye da inda martensite ke faruwa. Sauyi, ƙarar tana faɗaɗawa, kuma sassan da ke da zafin jiki mai yawa har yanzu suna sama da wurin kuma har yanzu suna cikin yanayin austenite. Waɗannan sassa daban-daban kuma za su haifar da damuwa ta ciki saboda bambance-bambance a cikin takamaiman canje-canjen girma. Saboda haka, ana iya haifar da nau'ikan damuwa ta ciki guda biyu yayin aikin kashewa da sanyaya: ɗaya shine damuwa ta zafi; ɗayan kuma shine damuwa ta nama.

Dangane da halayen wanzuwar lokacin damuwa ta ciki, ana iya raba shi zuwa damuwa ta gaggawa da kuma damuwa ta saura. Damuwar ciki da kayan aikin ke haifarwa a wani lokaci yayin aikin sanyaya ana kiranta damuwa ta gaggawa; bayan an sanyaya kayan aikin, damuwar da ta rage a cikin kayan aikin ana kiranta damuwa ta saura.

Damuwar zafi tana nufin damuwa da faɗaɗa zafi mara daidaituwa (ko matsewar sanyi) ke haifarwa saboda bambancin zafin jiki a sassa daban-daban na aikin lokacin da aka dumama shi (ko sanyaya shi).

Yanzu ɗauki silinda mai ƙarfi a matsayin misali don kwatanta ƙa'idodin samuwar da canza yanayin damuwa na ciki yayin aikin sanyaya shi. An tattauna damuwar axial kawai a nan. A farkon sanyaya, saboda saman yana sanyi da sauri, zafin jiki yana ƙasa, kuma yana raguwa sosai, yayin da zuciyar ke sanyaya shi, zafin jiki yana da yawa, kuma raguwar ƙanƙanta ƙarami ne. Sakamakon haka, saman da ciki suna daure juna, wanda ke haifar da damuwa a saman, yayin da zuciyar ke ƙarƙashin matsin lamba. Yayin da sanyaya ke ci gaba, bambancin zafin jiki tsakanin ciki da waje yana ƙaruwa, kuma damuwar ciki ma tana ƙaruwa daidai gwargwado. Lokacin da damuwar ta ƙaru don wuce ƙarfin samarwa a wannan zafin, lalacewar filastik yana faruwa. Tunda kauri na zuciya ya fi na saman, zuciya koyaushe tana raguwa da farko a axial. Sakamakon lalacewar filastik, damuwar ciki ba ta ƙara ƙaruwa ba. Bayan sanyaya zuwa wani lokaci, raguwar zafin saman zai ragu a hankali, kuma raguwarsa kuma zai ragu a hankali. A wannan lokacin, zuciyar har yanzu tana raguwa, don haka damuwar a saman da matsin lamba a kan zuciyar za su ragu a hankali har sai sun ɓace. Duk da haka, yayin da sanyaya ke ci gaba, danshi a saman yana raguwa da ƙasa, kuma adadin raguwa yana raguwa, ko ma ya daina raguwa. Tunda zafin da ke cikin tsakiyar har yanzu yana da yawa, zai ci gaba da raguwa, kuma a ƙarshe za a sami matsin lamba a saman aikin, yayin da zuciyar za ta sami matsin lamba. Duk da haka, tunda zafin yana da ƙasa, nakasar filastik ba abu ne mai sauƙi ba, don haka wannan damuwa zai ƙaru yayin da sanyaya ke ci gaba. Yana ci gaba da ƙaruwa kuma a ƙarshe yana kasancewa a cikin aikin azaman matsin lamba da ya rage.

Za a iya ganin cewa matsin lamba na zafi a lokacin sanyaya da farko yana sa layin saman ya miƙe kuma tsakiyar ya matse, kuma sauran matsin lambar da ya rage shine layin saman da za a matse da kuma tsakiyar da za a miƙe.

A taƙaice, damuwar zafi da ake samu yayin sanyaya kayan aiki yana faruwa ne sakamakon bambancin zafin jiki na sassan jiki yayin sanyaya kayan. Mafi girman saurin sanyaya da kuma girman bambancin zafin jiki na sassan jiki, mafi girman damuwar zafi da ake samu. A ƙarƙashin yanayin sanyaya iri ɗaya, mafi girman zafin zafi na kayan aiki, mafi girman girman, ƙaramar ƙarfin zafin ƙarfe, mafi girman bambancin zafin jiki a cikin kayan aiki, kuma mafi girman damuwar zafi. Idan kayan aikin sun sanyaya ba daidai ba a babban zafin jiki, za su lalace kuma su lalace. Idan damuwar gaggawa da ake samu yayin sanyaya kayan aikin ta fi ƙarfin juriya na kayan aiki, fashewar kashewa za ta faru.

Damuwar canjin lokaci tana nufin damuwa da ke faruwa sakamakon bambancin lokacin canjin lokaci a sassa daban-daban na kayan aikin yayin aikin maganin zafi, wanda kuma aka sani da damuwar nama.

A lokacin kashewa da kuma sanyaya cikin sauri, lokacin da aka sanyaya saman zuwa wurin Ms, canjin martensitic yana faruwa kuma yana haifar da faɗaɗa girma. Duk da haka, saboda toshewar tsakiyar da ba a yi ba tukuna, saman Layer yana haifar da matsin lamba, yayin da tsakiyar yana da matsin lamba. Lokacin da matsin lamba ya yi yawa, zai haifar da nakasa. Lokacin da tsakiyar ya sanyaya zuwa wurin Ms, zai kuma fuskanci canjin martensitic kuma ya faɗaɗa a girma. Duk da haka, saboda ƙuntatawa na saman Layer da aka canza tare da ƙarancin filastik da ƙarfi mai yawa, matsin lambar ƙarshe na ragowarsa zai kasance a cikin nau'in tashin hankali na saman, kuma tsakiyar zai kasance ƙarƙashin matsin lamba. Ana iya ganin cewa canjin da yanayin ƙarshe na matsin lamba na canjin mataki ya saba da matsin lamba na zafi. Bugu da ƙari, tunda damuwar canjin mataki yana faruwa a ƙananan yanayin zafi tare da ƙarancin filastik, nakasa yana da wahala a wannan lokacin, don haka matsin lambar canjin mataki yana iya haifar da fashewar kayan aikin.

Akwai abubuwa da yawa da ke shafar girman matsin lamba na canjin yanayi. Da sauri saurin sanyaya ƙarfe a cikin kewayon zafin canjin yanayi na martensite, girman girman ƙarfen, mafi muni da ƙarfin wutar lantarki na ƙarfe, mafi girman takamaiman girman martensite, mafi girman matsin lamba na canjin yanayi. Girman da yake samu. Bugu da ƙari, matsin lamba na canjin yanayi yana da alaƙa da abun da ke cikin ƙarfe da kuma taurarewar ƙarfen. Misali, ƙarfe mai yawan carbon yana ƙara takamaiman girman martensite saboda yawan carbon da ke cikinsa, wanda zai ƙara matsin lamba na canjin yanayi na ƙarfen. Duk da haka, yayin da yawan carbon ke ƙaruwa, maki na Ms yana raguwa, kuma akwai babban adadin austenite da aka riƙe bayan an kashe shi. Faɗaɗar girmansa yana raguwa kuma matsin lamba na sauran yana ƙasa.

(2) Nakasa a wurin aiki yayin kashewa

A lokacin kashewa, akwai manyan nau'ikan nakasuwa guda biyu a cikin kayan aikin: ɗaya shine canjin siffar geometric na kayan aikin, wanda ake bayyana shi azaman canje-canje a girma da siffa, wanda galibi ake kira nakasuwa mai warping, wanda ke faruwa ta hanyar rage damuwa; ɗayan kuma shine nakasuwa mai girma., wanda ke bayyana kansa a matsayin faɗaɗawa ko raguwar girman kayan aikin, wanda ke faruwa ta hanyar canjin takamaiman girma yayin canjin lokaci.

Nauyin juyawar kuma ya haɗa da nauyin siffar da nauyin jujjuyawar. Nauyin juyawar galibi yana faruwa ne sakamakon rashin sanya kayan aikin a cikin tanda yayin dumamawa, ko rashin maganin siffa bayan gyara nauyin kafin a kashe shi, ko kuma sanyaya sassan kayan aikin daban-daban ba daidai ba lokacin da aka sanyaya kayan aikin. Ana iya bincika wannan nauyin kuma a warware shi don takamaiman yanayi. Mai zuwa galibi yana tattauna nauyin girma da nauyin siffar.

1) Dalilan da ke haifar da nakasa da kuma canje-canjen ƙa'idojinsa

Nakasawar girma da canjin tsari ke haifarwa Yanayin tsarin kayan aikin kafin a kashe shi gabaɗaya yana da siffar pearlite, wato, tsarin gauraye na ferrite da siminti, kuma bayan an kashe shi tsarin martensitic ne. Yawan takamaiman waɗannan kyallen zai haifar da canje-canjen girma kafin da bayan kashewa, wanda ke haifar da nakasa. Duk da haka, wannan nakasawar kawai yana sa kayan aikin su faɗaɗa kuma su yi ƙunci daidai gwargwado, don haka ba ya canza siffar kayan aikin.

Bugu da ƙari, yawan martensite a cikin tsarin bayan maganin zafi, ko kuma yawan sinadarin carbon a cikin martensite, yawan faɗaɗar sa, da kuma yawan austenite da aka riƙe, ƙarancin faɗaɗar sa. Saboda haka, ana iya sarrafa canjin ƙara ta hanyar sarrafa adadin martensite da sauran martensite yayin maganin zafi. Idan aka sarrafa shi yadda ya kamata, girman ba zai faɗaɗa ko raguwa ba.

Nauyin siffar da ke haifar da damuwa ta zafi. Nauyin siffar da ke haifar da damuwa ta zafi yana faruwa a wuraren zafi mai yawa inda ƙarfin yawan amfanin sassan ƙarfe ya yi ƙasa, ƙarfin da ke tattare da shi yana da yawa, saman yana sanyaya da sauri, kuma bambancin zafin jiki tsakanin ciki da wajen aikin shine mafi girma. A wannan lokacin, damuwar zafi ta gaggawa ita ce damuwa ta saman da kuma damuwar matsawa ta tsakiya. Tunda zafin zuciyar yana da yawa a wannan lokacin, ƙarfin yawan amfanin ƙasa ya fi ƙasa da saman, don haka yana bayyana a matsayin nakasa a ƙarƙashin aikin matsin lamba mai yawa, wato, kube ɗin yana da siffar zagaye a alkibla. Bambanci. Sakamakon shine babban yana raguwa, yayin da ƙaramin yana faɗaɗa. Misali, dogon silinda yana gajarta a alkiblar tsayi kuma yana faɗaɗa a alkiblar diamita.

Nauyin siffar da damuwar nama ke haifarwa Nauyin siffar da damuwar nama ke haifarwa kuma yana faruwa ne a farkon lokacin da damuwar nama ta kai matsakaicin girma. A wannan lokacin, bambancin zafin da ke tsakanin sassan ya yi yawa, zafin zuciyar ya fi girma, har yanzu yana cikin yanayin austenite, ƙarfinsa yana da kyau, kuma ƙarfin yawan amfanin ƙasa yana da ƙasa. Nauyin ƙwayar nan take shine damuwa mai matsewa a saman da kuma damuwa mai matsewa a tsakiya. Saboda haka, nauyin yana bayyana ne yayin da tsayin zuciyar yake a ƙarƙashin aikin damuwa mai matsewa a hanyoyi da yawa. Sakamakon shine cewa a ƙarƙashin aikin damuwar nama, babban gefen aikin yana tsawaitawa, yayin da ƙaramin gefen yana raguwa. Misali, nauyin da damuwar nama ke haifarwa a cikin dogon silinda shine tsayin tsayi da raguwa a diamita.

Tebur 5.3 yana nuna ƙa'idodin nakasawa na sassa daban-daban na ƙarfe na yau da kullun.

2) Abubuwan da ke shafar lalacewar nakasa

Abubuwan da ke shafar lalacewar kashe wutar lantarki galibi sune sinadaran da ke cikin ƙarfen, tsarin asali, yanayin sassan da kuma tsarin sarrafa zafi.

3) Kashe fasa

Fashewa a sassa galibi yana faruwa ne a ƙarshen matakin kashewa da sanyaya, wato, bayan an kammala canjin martensitic ko kuma bayan cikakken sanyaya, gazawar karyewa tana faruwa saboda matsin lamba a sassan ya wuce ƙarfin karyewar ƙarfe. Fashewa yawanci suna daidai da alkiblar matsakaicin nakasar tensile, don haka nau'ikan fasawa daban-daban a sassa sun dogara ne akan yanayin rarraba damuwa.

Nau'ikan fasawa da ake yawan yi: Tsagewar dogon zango (axial) galibi ana haifar da su ne lokacin da matsin lamba mai tangential ya wuce ƙarfin karyawar kayan; tsagewar da ke ratsawa ana samun su ne lokacin da babban matsin lamba mai tangential da aka samu a saman ciki na ɓangaren ya wuce ƙarfin karyawar kayan. Tsagewar; fasawar hanyar sadarwa ana samun su ne a ƙarƙashin aikin matsin lamba mai girma biyu a saman; tsagewar da ke barewa tana faruwa a cikin wani siririn Layer mai tauri, wanda zai iya faruwa lokacin da damuwar ta canza sosai kuma matsin lamba mai yawa yana aiki a cikin alkiblar radial. Nau'in tsagewa.

Ana kuma kiran tsagewar tsayi da tsayi da tsagewar axial. Tsagewar tana faruwa ne a matsakaicin matsin lamba kusa da saman ɓangaren, kuma tana da wani zurfin zuwa tsakiya. Alkiblar tsagewar gabaɗaya tana daidai da axis, amma alkiblar kuma tana iya canzawa lokacin da akwai yawan damuwa a cikin ɓangaren ko kuma lokacin da akwai lahani a cikin tsarin ciki.

Bayan an kashe aikin gaba ɗaya, tsagewar tsayin daka na iya faruwa. Wannan yana da alaƙa da babban matsin lamba na tangent a saman aikin da aka kashe. Yayin da yawan carbon na ƙarfe ke ƙaruwa, yanayin samar da tsagewar tsayi yana ƙaruwa. Ƙarancin ƙarfe na carbon yana da ƙaramin adadin martensite da ƙarfin zafi mai ƙarfi. Akwai babban matsin lamba na matsewa a saman, don haka ba shi da sauƙi a kashe shi. Yayin da yawan carbon ke ƙaruwa, matsin lamba na matsewa a saman yana raguwa kuma matsin lamba na tsari yana ƙaruwa. A lokaci guda, matsin lamba na matsewa mafi girma yana motsawa zuwa saman saman. Saboda haka, babban ƙarfe na carbon yana da saurin kamuwa da tsagewar tsayin daka lokacin da aka yi zafi da yawa.

Girman sassan yana shafar girman da rarrabawar damuwa ta saura kai tsaye, kuma yanayin fashewarsa ma ya bambanta. Tsagewar tsayi kuma ana samun sauƙin samu ta hanyar kashewa a cikin kewayon girman giciye mai haɗari. Bugu da ƙari, toshewar kayan ƙarfe sau da yawa yana haifar da tsagewar tsayi. Tunda yawancin sassan ƙarfe ana yin su ne ta hanyar birgima, haɗakar da ba ta zinare ba, carbide, da sauransu a cikin ƙarfe suna rarrabawa a gefen nakasa, wanda ke sa ƙarfen ya zama anisotropic. Misali, idan ƙarfen kayan aiki yana da tsari kamar band, ƙarfin karyewar sa bayan kashewa ya fi ƙanƙanta da kashi 30% zuwa 50% fiye da ƙarfin karyewar tsayi. Idan akwai abubuwa kamar haɗakar da ba ta zinare ba a cikin ƙarfe wanda ke haifar da yawan damuwa, koda kuwa damuwar tangential ta fi ƙarfin axial, tsagewar tsayi tana da sauƙin samuwa a ƙarƙashin yanayin damuwa mai sauƙi. Saboda wannan dalili, sarrafa matakin haɗakar da ba ta ƙarfe ba da sukari a cikin ƙarfe muhimmin abu ne wajen hana kashe tsagewa.

Halayen rarraba damuwa ta ciki na tsagewar da aka yi da kuma tsagewar baka sune: saman yana fuskantar matsin lamba. Bayan barin saman na wani nisa, matsin lamba na canzawa zuwa babban matsin lamba. Tsagewar tana faruwa ne a yankin matsin lamba na tensile, sannan lokacin da matsin lamba na ciki ya bazu zuwa saman ɓangaren kawai idan an sake rarraba shi ko kuma ƙarfin ƙarfe ya ƙara ƙaruwa.

Fashewar da ke juyewa sau da yawa tana faruwa a manyan sassan shaft, kamar na'urori masu juyawa, injin juyawar turbine ko wasu sassan shaft. Halayen fasawar shine suna tsaye a kan alkiblar axis kuma suna karyewa daga ciki zuwa waje. Sau da yawa ana samar da su kafin a taurare su kuma damuwar zafi ce ke haifar da su. Manyan kayan gyarawa galibi suna da lahani na ƙarfe kamar ramuka, abubuwan haɗawa, fasawa da fari. Waɗannan lahani suna aiki a matsayin wurin farawa na karyewa da karyewa ƙarƙashin tasirin matsin lamba na axial. Fashewar baka tana faruwa ne sakamakon matsin lamba na zafi kuma yawanci ana rarraba su a siffar baka a sassan inda siffar sashin ke canzawa. Ya fi faruwa ne a cikin aikin aiki ko kusa da gefuna masu kaifi, ramuka da ramuka, kuma ana rarraba su a siffar baka. Lokacin da sassan ƙarfe masu yawan carbon waɗanda ke da diamita ko kauri na 80 zuwa 100 mm ko fiye ba a kashe su ba, saman zai nuna matsin lamba na matsewa kuma tsakiya zai nuna matsin lamba na matsewa. Damuwa, matsakaicin matsin lamba na matsewa yana faruwa a yankin sauyawa daga Layer mai tauri zuwa Layer mara tauri, kuma fasawa ta baka suna faruwa a waɗannan yankuna. Bugu da ƙari, saurin sanyaya a gefuna da kusurwoyi masu kaifi yana da sauri kuma duk suna kashewa. Lokacin da ake canzawa zuwa sassa masu laushi, wato, zuwa yankin da ba a taurare ba, matsakaicin yankin damuwa mai tauri yana bayyana a nan, don haka fashewar baka tana da saurin faruwa. Saurin sanyaya kusa da ramin fil, rami ko ramin tsakiya na aikin yana da jinkiri, matakin taurare mai dacewa siriri ne, kuma matsin lamba kusa da yankin canji mai tauri na iya haifar da fashewar baka cikin sauƙi.

Fashewar reticular, wanda aka fi sani da fashewar saman, su ne fashewar saman. Zurfin fashewar ba shi da zurfi, gabaɗaya kusan 0.01~1.5mm. Babban halayyar wannan nau'in fashewar ita ce alkiblar da ba ta dace ba ta hanyar da ba ta dace ba ta hanyar da ba ta dace ba da siffar ɓangaren. Fashewar da yawa suna haɗuwa da juna don samar da hanyar sadarwa kuma suna yaɗuwa sosai. Lokacin da zurfin fashewar ya fi girma, kamar fiye da 1 mm, halayen hanyar sadarwa suna ɓacewa kuma suna zama masu karkata ba zato ba tsammani ko kuma waɗanda aka rarraba a tsayi. Fashewar hanyar sadarwa tana da alaƙa da yanayin matsin lamba mai girma biyu a saman.

Sassan ƙarfe masu yawan carbon ko carburized waɗanda aka yi musu laydi mai sassauƙa a saman suna da saurin haifar da tsagewar hanyar sadarwa yayin kashewa. Wannan saboda saman saman yana da ƙarancin sinadarin carbon da ƙaramin ƙarar da ya fi na ciki na martensite. A lokacin kashewa, saman saman carbide yana fuskantar matsin lamba na tauri. Sassan da ba a cire layin rage yawan sinadarin phosphorus gaba ɗaya ba yayin sarrafa injina za su kuma samar da tsagewar hanyar sadarwa yayin kashewa mai yawa ko kuma kashewar saman wuta. Don guje wa irin waɗannan tsagewa, ya kamata a kula da ingancin saman sassan sosai, kuma ya kamata a hana walda oxidation yayin maganin zafi. Bugu da ƙari, bayan an yi amfani da injin ƙirƙirar na ɗan lokaci, tsagewar gajiya mai zafi da ke bayyana a cikin tsiri ko hanyoyin sadarwa a cikin rami da tsagewa a cikin tsarin niƙa sassan da aka kashe duk suna cikin wannan nau'in.

Fashewar barewa tana faruwa a wani yanki mai ƙunci na saman Layer. Damuwar matsewa tana aiki a cikin alkiblar axial da tangential, kuma damuwar matsewa tana faruwa a alkiblar radial. Fashewar suna daidai da saman sashin. Fashewar tauri bayan an kashe saman kuma an sanyaya sassan carburizing na irin waɗannan fasa. Faruwarta tana da alaƙa da tsarin da bai daidaita ba a cikin Layer mai tauri. Misali, bayan an sanyaya ƙarfe mai ƙarfe mai ƙarfe a wani saurin gudu, tsarin da ke cikin Layer mai ƙarfe shine: Layer na waje na pearlite mai kyau + carbide, kuma sublayer shine martensite + residential Austenite, Layer na ciki shine pearlite mai kyau ko tsarin pearlite mai kyau sosai. Tunda samuwar takamaiman girman martensite na sub-layer shine mafi girma, sakamakon faɗaɗa girma shine cewa damuwa mai matsewa yana aiki akan Layer na saman a cikin alkiblar axial da tangential, kuma damuwa mai matsewa yana faruwa a alkiblar radial, kuma maye gurbin damuwa yana faruwa zuwa ciki, yana canzawa zuwa yanayin damuwa mai matsewa, kuma fasawar barewa Yana faruwa a wurare masu siriri sosai inda damuwa ke canzawa sosai. Gabaɗaya, tsage-tsage suna ɓoye a ciki a layi ɗaya da saman, kuma a cikin mawuyacin hali na iya haifar da ɓawon saman. Idan aka hanzarta ko rage yawan sanyaya sassan da aka yi da carburized, ana iya samun tsarin martensite iri ɗaya ko tsarin pearlite mai kyau a cikin layin carburized, wanda zai iya hana faruwar irin waɗannan tsage-tsage. Bugu da ƙari, a lokacin da ake kashe saman mai yawa ko harshen wuta, saman yakan yi zafi sosai kuma rashin daidaituwar tsarin da ke kan layin da aka taurare zai iya samar da irin waɗannan tsage-tsage a saman cikin sauƙi.

Fashewar ƙananan ƙwayoyin cuta sun bambanta da fashewar guda huɗu da aka ambata a baya domin su na faruwa ne sakamakon ƙarfin na'urar microstress. Fashewar ƙananan ƙwayoyin cuta da ke bayyana bayan kashewa, zafi fiye da kima da niƙa ƙarfe mai yawan carbon ko kayan aiki masu ɗauke da carburized, da kuma fashewar da ba a yi amfani da su ba wajen daidaita sassan da aka kashe a kan lokaci, duk suna da alaƙa da wanzuwar ƙananan ƙwayoyin cuta da ke yaɗuwa a cikin ƙarfen.

Dole ne a duba ƙananan fasa a ƙarƙashin na'urar hangen nesa. Yawanci suna faruwa ne a iyakokin hatsi na austenite na asali ko kuma a mahadar zanen martensite. Wasu fasa suna ratsa zanen martensite. Bincike ya nuna cewa ƙananan fasa sun fi yawa a cikin ma'aunin martensite masu ƙyalli. Dalilin shi ne cewa ma'aunin martensite masu ƙyalli yana karo da juna lokacin da yake girma da sauri kuma yana haifar da babban damuwa. Duk da haka, ma'aunin martensite mai ƙyalli da kansa yana da rauni kuma ba zai iya haifar da lalacewar filastik ba yana rage damuwa, don haka yana haifar da ƙananan fasa cikin sauƙi. Hatsin austenite suna da kauri kuma saurin kamuwa da ƙananan fasa yana ƙaruwa. Kasancewar ƙananan fasa a cikin ƙarfe zai rage ƙarfi da ƙarfin sassan da aka kashe sosai, wanda ke haifar da lalacewa da wuri (karyewa) na sassan.

Domin guje wa fashewar ƙananan ƙwayoyin cuta a cikin sassan ƙarfe masu yawan carbon, ana iya ɗaukar matakai kamar rage zafin dumama, samun kyakkyawan tsarin martensite, da rage yawan sinadarin carbon a cikin martensite. Bugu da ƙari, yin zafi a kan lokaci bayan kashewa hanya ce mai tasiri don rage damuwa ta ciki. Gwaje-gwaje sun tabbatar da cewa bayan an yi zafi sosai sama da 200°C, carbide ɗin da ke taruwa a fashewar suna da tasirin "walda" fashewar, wanda zai iya rage haɗarin fashewar ƙananan ƙwayoyin cuta sosai.

Wannan da ke sama tattaunawa ce kan musabbabin da hanyoyin hana fasawa bisa ga tsarin rarraba fasawa. A zahiri, rarraba fasawa ya bambanta saboda dalilai kamar ingancin ƙarfe, siffar sashe, da fasahar sarrafa zafi da sanyi. Wani lokaci fasawa sun riga sun wanzu kafin a yi maganin zafi kuma suna ƙara faɗaɗa yayin aikin kashewa; wani lokacin nau'ikan fasawa da yawa na iya bayyana a cikin wannan ɓangaren a lokaci guda. A wannan yanayin, bisa ga halayen fasawa, nazarin macroscopic na saman karyewa, binciken ƙarfe, kuma idan ya cancanta, ya kamata a yi amfani da nazarin sinadarai da sauran hanyoyi don gudanar da cikakken bincike daga ingancin abu, tsarin ƙungiya zuwa abubuwan da ke haifar da damuwa game da maganin zafi don nemo fasawa. manyan dalilai sannan a tantance ingantattun matakan kariya.

Binciken karyewar fasa hanya ce mai mahimmanci don nazarin musabbabin fasa. Duk wani karyewar fasa yana da wurin farawa. Kashe fasa yawanci yana farawa ne daga wurin haɗuwar fasawar radial.

Idan asalin fashewar ya kasance a saman ɓangaren, yana nufin cewa fashewar ta faru ne sakamakon matsin lamba mai yawa a saman. Idan babu wasu lahani na tsari kamar abubuwan da ke cikin saman, amma akwai abubuwan da ke haifar da damuwa kamar manyan alamun wuka, sikelin oxide, kusurwoyin kaifi na sassan ƙarfe, ko sassan sauye-sauyen tsari, tsagewar na iya faruwa.

Idan asalin fashewar yana cikin ɓangaren, yana da alaƙa da lahani na abu ko kuma yawan damuwa na ciki. Fuskar karyewar da ake samu ta hanyar kashewa ta yau da kullun launin toka ne da ɗan ƙaramin faranti. Idan saman karyewar launin toka ne mai duhu da kauri, yana faruwa ne sakamakon zafi mai yawa ko kuma asalin nama yana da kauri.

Gabaɗaya dai, bai kamata a sami launin iskar shaka a ɓangaren gilashin da ke kashe fashewar ba, kuma bai kamata a sami wani abu da ke kewaye da fashewar ba. Idan akwai wani abu da ke kewaye da fashewar ko kuma wani launi da aka yi wa oxidized a ɓangaren fashewar, yana nuna cewa ɓangaren ya riga ya fashe kafin ya kashe, kuma fashewar ta asali za ta faɗaɗa ƙarƙashin tasirin matsin maganin zafi. Idan aka ga carbide da aka raba da kuma abubuwan da aka haɗa kusa da fashewar ɓangaren, yana nufin cewa fashewar tana da alaƙa da babban rabuwar carbide a cikin kayan da aka samar ko kuma kasancewar abubuwan da aka haɗa. Idan fashewar ta bayyana ne kawai a kusurwoyi masu kaifi ko kuma sassan maye gurbin siffar ɓangaren ba tare da abin da ke sama ba, yana nufin cewa fashewar ta faru ne sakamakon ƙirar tsarin ɓangaren mara kyau ko matakan da ba su dace ba don hana fashewar, ko kuma yawan damuwa game da maganin zafi.

Bugu da ƙari, tsagewar sinadaran da ke magance zafi da kuma sassan kashe saman galibi suna bayyana kusa da tauraruwar Layer. Inganta tsarin Layer mai taurare da rage damuwa game da zafi hanyoyi ne masu mahimmanci don guje wa tsagewar saman.