Incazelo kanye nenhloso yokucima
Insimbi ishiswa ibe yizinga lokushisa elingaphezu kwe-critical point Ac3 (insimbi ye-hypoeutectoid) noma i-Ac1 (insimbi ye-hypereutectoid), igcinwa isikhathi esithile ukuze ikwazi ukuqiniswa ngokuphelele noma ngokwengxenye, bese ipholiswa ngesivinini esikhulu kunesivinini sokucima okubalulekile. Inqubo yokwelapha ukushisa eguqula i-austenite epholile kakhulu ibe yi-martensite noma i-bainite ephansi ibizwa ngokuthi i-quenching.
Inhloso yokucima i-austenite ukuguqula i-supercooled austenite ibe yi-martensite noma i-bainite ukuze kutholakale isakhiwo se-martensite noma se-bainite esiphansi, esihlanganiswa nokushisa emazingeni okushisa ahlukene ukuze kuthuthukiswe kakhulu amandla, ubulukhuni, kanye nokumelana kwensimbi. Ukuguguleka, amandla okukhathala kanye nokuqina, njll., ukuze kuhlangatshezwane nezidingo ezahlukene zokusetshenziswa kwezingxenye namathuluzi ahlukahlukene emishini. Ukucima i-iron kungasetshenziswa futhi ukuhlangabezana nezakhiwo ezikhethekile zomzimba nezamakhemikhali zezinsimbi ezithile ezikhethekile njenge-ferromagnetism kanye nokumelana nokugqwala.
Uma izingxenye zensimbi zipholiswa endaweni yokucima enezinguquko esimweni somzimba, inqubo yokupholisa ngokuvamile ihlukaniswe ngezigaba ezintathu ezilandelayo: isigaba sefilimu yomhwamuko, isigaba sokubilisa, kanye nesigaba sokudlulisa uketshezi.
Ukuqina kwensimbi
Ukuqina nokuqina kuyizinkomba ezimbili zokusebenza ezichaza ikhono lensimbi lokucinywa. Futhi ziyisisekelo esibalulekile sokukhethwa nokusetshenziswa kwezinto.
1. Imibono yokuqina nokuqina
Ukuqina yikhono lensimbi lokufinyelela ubulukhuni obuphezulu kakhulu elingabufinyelela uma iqedwa futhi iqiniswa ngaphansi kwezimo ezifanele. Isici esiyinhloko esinquma ukuqina kwensimbi okuqukethwe yikhabhoni kwensimbi. Ukuze kube sobala kakhudlwana, okuqukethwe yikhabhoni okuncibilikisiwe ku-austenite ngesikhathi sokucima nokushisa. Uma okuqukethwe yikhabhoni kuphakeme, kulapho ukuqina kwensimbi kuphakeme. . Izinto ezixubayo ensimbini azinawo umthelela omkhulu ekuqineni, kodwa zinomthelela omkhulu ekuqineni kwensimbi.
Ukuqina kubhekisela ezicini ezinquma ukujula kokuqina kanye nokusatshalaliswa kokuqina kwensimbi ngaphansi kwezimo ezithile. Okungukuthi, ikhono lokuthola ukujula kwengqimba eqinile lapho insimbi icishwa. Kuyimpahla engokwemvelo yensimbi. Ukuqina empeleni kubonisa ukulula lapho i-austenite iguquka ibe yi-martensite lapho insimbi icishwa. Kuhlobene kakhulu nokuzinza kwe-austenite epholile kakhulu yensimbi, noma izinga lokupholisa elibucayi lensimbi.
Kufanele futhi kuphawulwe ukuthi ukuqina kwensimbi kumele kuhlukaniswe nokujula kokuqina okusebenzayo kwezingxenye zensimbi ngaphansi kwezimo ezithile zokucima. Ukuqina kwensimbi kuyimpahla engokwemvelo yensimbi ngokwayo. Kuxhomeke kuphela ezintweni zayo zangaphakathi futhi akuhlangene nhlobo nezici zangaphandle. Ukujula kokuqina okusebenzayo kwensimbi akuxhomekile kuphela ekuqineni kwensimbi, kodwa futhi kuncike ezintweni ezisetshenziswayo. Kuhlobene nezici zangaphandle njenge-cooling medium kanye nosayizi we-workpiece. Isibonelo, ngaphansi kwezimo ezifanayo zokuqinisa, ukuqina kwensimbi efanayo kuyafana, kodwa ukujula kokuqina okusebenzayo kokucinywa kwamanzi kukhulu kunokokucima uwoyela, kanti izingxenye ezincane zincane kunokucima uwoyela. Ukujula kokuqina okusebenzayo kwezingxenye ezinkulu kukhulu. Lokhu akunakushiwo ukuthi ukucima amanzi kunokuqina okuphezulu kunokucima uwoyela. Akunakushiwo ukuthi izingxenye ezincane zinokuqina okuphezulu kunezingxenye ezinkulu. Kungabonakala ukuthi ukuze kuhlolwe ukuqina kwensimbi, ithonya lezinto zangaphandle ezifana nesimo se-workpiece, usayizi, i-cooling medium, njll. kumele lisuswe.
Ngaphezu kwalokho, njengoba ukuqina nokuqina kuyimiqondo emibili ehlukene, insimbi enokuqina okuphezulu ngemva kokucinywa akusho ukuthi insimbi enokuqina okuphezulu; kanti insimbi enokuqina okuncane ingase futhi ibe nokuqina okuphezulu.
2. Izici ezithinta ukuqina
Ukuqina kwensimbi kuncike ekuqineni kwe-austenite. Noma yisiphi isici esingathuthukisa ukuzinza kwe-austenite epholile kakhulu, sishintshe ijika le-C liye kwesokudla, ngaleyo ndlela sinciphise izinga lokupholisa elibalulekile singathuthukisa ukuqina kwensimbi ephezulu. Ukuqina kwe-austenite kuncike kakhulu ekwakhekeni kwayo kwamakhemikhali, usayizi wezinhlamvu kanye nokufana kokwakheka, okuhlobene nokwakheka kwamakhemikhali kwensimbi kanye nezimo zokushisa.
3. Indlela yokulinganisa yokuqina
Kunezindlela eziningi zokulinganisa ukuqina kwensimbi, ezisetshenziswa kakhulu yindlela yokulinganisa ububanzi obubalulekile kanye nendlela yokuhlola ukuqina kokuphela.
(1) Indlela yokulinganisa ububanzi obubalulekile
Ngemva kokuba insimbi icishiwe endaweni ethile, ububanzi obukhulu lapho ingaphakathi lithola yonke i-martensite noma isakhiwo se-martensite esingu-50% sibizwa ngokuthi ububanzi obubalulekile, obumelelwa yi-Dc. Indlela yokulinganisa ububanzi obubalulekile ukwenza uchungechunge lwezinduku eziyindilinga ezinobubanzi obuhlukene, futhi ngemva kokucima, linganisa ijika lobunzima be-U elisakazwa ngobubanzi esigabeni ngasinye sesampula, bese uthola induku enesakhiwo se-semi-martensite phakathi nendawo. Ububanzi benduku eyindilinga Lobo ububanzi obubalulekile. Uma ububanzi obubalulekile bukhulu, kulapho ukuqina kwensimbi kuphakama khona.
(2) Indlela yokuhlola yokuqeda ukucima
Indlela yokuhlola yokucima ukuphela isebenzisa isampula yokuvala ukuphela enobukhulu obujwayelekile (Ф25mm × 100mm). Ngemva kokuvuselelwa, amanzi afafazwa kolunye uhlangothi lwesampula kumishini ekhethekile ukuze iphole. Ngemva kokupholisa, ubulukhuni bulinganiswa eceleni kwe-axis - kusukela ekugcineni okupholiswe ngamanzi. Indlela yokuhlola ijika lobudlelwano bebanga. Indlela yokuhlola ukuqina kokuphela ingenye yezindlela zokunquma ukuqina kwensimbi. Izinzuzo zayo ukusebenza okulula kanye nobubanzi bokusetshenziswa.
4. Ukuqeda ukucindezeleka, ukuguqulwa kanye nokuqhekeka
(1) Ukucindezeleka kwangaphakathi kwento yokusebenza ngesikhathi sokucima
Uma i-workpiece ipholiswa ngokushesha endaweni yokucima umlilo, njengoba i-workpiece inosayizi othile kanye ne-coefficient yokushisa nayo iyinani elithile, kuzovela i-gradient ethile yokushisa engxenyeni engaphakathi ye-workpiece ngesikhathi senqubo yokupholisa. Izinga lokushisa lobuso liphansi, izinga lokushisa lobuso liphezulu, kanti izinga lokushisa lobuso nelobuso liphezulu. Kukhona umehluko wokushisa. Ngesikhathi senqubo yokupholisa ye-workpiece, kukhona futhi izinto ezimbili ezibonakalayo: enye ukwanda kokushisa, njengoba izinga lokushisa lehla, ubude bomugqa we-workpiece buzoncipha; enye ukuguqulwa kwe-austenite ibe yi-martensite lapho izinga lokushisa lehla liye endaweni yokuguqulwa kwe-martensite. , okuzokwandisa ivolumu ethile. Ngenxa yomehluko wokushisa ngesikhathi senqubo yokupholisa, inani lokwanda kokushisa lizohluka ezingxenyeni ezahlukene eceleni kwengxenye ye-workpiece, futhi ukucindezeleka kwangaphakathi kuzokhiqizwa ezingxenyeni ezahlukene ze-workpiece. Ngenxa yokuba khona komehluko wokushisa ngaphakathi kwe-workpiece, kungase kube nezingxenye lapho izinga lokushisa lehla ngokushesha kunendawo lapho kwenzeka khona i-martensite. Ukuguquka, ivolumu iyakhula, futhi izingxenye ezinokushisa okuphezulu zisephezulu kunephuzu futhi zisesesesimweni se-austenite. Lezi zingxenye ezahlukene zizophinde zikhiqize ukucindezeleka kwangaphakathi ngenxa yokwehluka kwezinguquko ezithile zevolumu. Ngakho-ke, izinhlobo ezimbili zokucindezeleka kwangaphakathi zingase zikhiqizwe ngesikhathi senqubo yokucima nokupholisa: enye ukucindezeleka kokushisa; enye ukucindezeleka kwezicubu.
Ngokwezimpawu zesikhathi sokuba khona kokucindezeleka kwangaphakathi, kungahlukaniswa futhi kube ukucindezeleka okusheshayo kanye nokucindezeleka okusele. Ukucindezeleka kwangaphakathi okudalwa yi-workpiece ngesikhathi esithile ngesikhathi senqubo yokupholisa kubizwa ngokuthi ukucindezeleka okusheshayo; ngemva kokuba i-workpiece isipholile, ukucindezeleka okusele ngaphakathi kwe-workpiece kubizwa ngokuthi ukucindezeleka okusele.
Ukucindezeleka kokushisa kubhekisela ekucindezelekeni okubangelwa ukwanda kokushisa okungaguquki (noma ukufinyela okubandayo) ngenxa yokwehluka kwezinga lokushisa ezingxenyeni ezahlukene zomsebenzi lapho ushiswa (noma upholisiwe).
Manje thatha isilinda esiqinile njengesibonelo ukuze ubonise ukwakheka nokushintsha kwemithetho yokucindezeleka kwangaphakathi ngesikhathi senqubo yokupholisa. Kuxoxwa ngokucindezeleka kwe-axial kuphela lapha. Ekuqaleni kokupholisa, ngoba ubuso buphola ngokushesha, izinga lokushisa liphansi, futhi lincipha kakhulu, kuyilapho umongo upholisiwe, izinga lokushisa liphezulu, futhi ukuncipha kuncane. Ngenxa yalokho, ubuso nangaphakathi kuyavinjelwa, okuholela ekucindezelekeni kokuqina ebusweni, kuyilapho umongo ungaphansi kwengcindezi. Njengoba ukupholisa kuqhubeka, umehluko wokushisa phakathi kwangaphakathi nangaphandle uyanda, kanti nokucindezeleka kwangaphakathi nakho kuyanda ngokufanele. Lapho ukucindezeleka kukhuphuka ukuze kudlule amandla okukhiqiza kuleli zinga lokushisa, kwenzeka ukuguqulwa kwepulasitiki. Njengoba ukujiya kwenhliziyo kuphakeme kunokobuso, inhliziyo ihlala incipha nge-axial kuqala. Ngenxa yokuguqulwa kwepulasitiki, ukucindezeleka kwangaphakathi akusakhuli. Ngemva kokupholisa kuze kube yisikhathi esithile, ukwehla kwezinga lokushisa lobuso kuzoncipha kancane kancane, futhi ukuncipha kwalo kuzoncipha kancane kancane. Ngalesi sikhathi, umongo usancipha, ngakho ukucindezeleka kokuqina ebusweni kanye nokucindezeleka kokucindezela umongo kuzoncipha kancane kancane kuze kunyamalale. Kodwa-ke, njengoba ukupholisa kuqhubeka, umswakama womphezulu uba phansi kakhulu, futhi inani lokuncipha liyancipha kakhulu, noma liyeke ngisho nokuncipha. Njengoba izinga lokushisa elingaphakathi lisephezulu, lizoqhubeka nokuncipha, futhi ekugcineni kuzokwakhiwa ukucindezeleka okucindezelayo ebusweni bento yokusebenza, kuyilapho ingaphakathi lizoba nokucindezeleka kokudonsa. Kodwa-ke, njengoba izinga lokushisa liphansi, ukuguquguquka kwepulasitiki akulula ukwenzeka, ngakho-ke lokhu kucindezeleka kuzokwanda njengoba ukupholisa kuqhubeka. Kuyaqhubeka nokwanda futhi ekugcineni kuhlala ngaphakathi kwento yokusebenza njengokucindezeleka okusele.
Kungabonakala ukuthi ukucindezeleka kokushisa ngesikhathi senqubo yokupholisa kuqala kubangela ukuthi ungqimba olungaphezulu lunwetshwe kanye nomgogodla ucindezelwe, kanti ukucindezeleka okusele okusele ungqimba olungaphezulu olucindezelwe kanye nomgogodla ocindezelwe.
Ngamafuphi, ukucindezeleka kokushisa okudalwe ngesikhathi sokupholisa ngokucisha kubangelwa umehluko wokushisa ophakathi kwesigaba ngesikhathi senqubo yokupholisa. Uma izinga lokupholisa lilikhulu futhi umehluko wokushisa ophakathi kwesigaba umkhulu, kulapho ukucindezeleka kokushisa okudalwe khona kukhulu. Ngaphansi kwezimo ezifanayo zokupholisa, lapho izinga lokushisa lokushisa lengxenye yokusebenza liphakeme, usayizi ukhulu, ukuhanjiswa kokushisa kwensimbi kuncane, umehluko wokushisa ngaphakathi kwengxenye yokusebenza ukhulu, futhi ukucindezeleka kokushisa kukhulu. Uma ingxenye yokusebenza ipholisiwe ngokungalingani ekushiseni okuphezulu, izophambuka futhi iguquguquke. Uma ukucindezeleka kokucindezela okusheshayo okudalwe ngesikhathi senqubo yokupholisa yengxenye yokusebenza kukhulu kunamandla okucindezela ezinto ezibonakalayo, kuzovela imifantu yokucima.
Ukucindezeleka kokuguqulwa kwesigaba kubhekisela ekucindezelekeni okubangelwa izikhathi ezahlukene zokuguqulwa kwesigaba ezingxenyeni ezahlukene zomsebenzi ngesikhathi senqubo yokwelapha ukushisa, okwaziwa nangokuthi ukucindezeleka kwezicubu.
Ngesikhathi sokucisha nokupholisa okusheshayo, lapho ungqimba olungaphezulu lupholiswa endaweni ye-Ms, kwenzeka ushintsho lwe-martensitic futhi lubangele ukwanda kwevolumu. Kodwa-ke, ngenxa yokuvinjelwa kwengqikithi engakashintshi, ungqimba olungaphezulu ludala ukucindezeleka okucindezelayo, kuyilapho ingqikithi inokucindezeleka kokudonsa. Uma ukucindezeleka kukhulu ngokwanele, kuzobangela ukuguqulwa. Lapho ingqikithi ipholisiwe endaweni ye-Ms, izophinde iguqulwe i-martensitic futhi ikhule ngevolumu. Kodwa-ke, ngenxa yemingcele yengqimba engenhla eguquliwe ene-plasticity ephansi namandla aphezulu, ukucindezeleka kwayo kokugcina okusele kuzoba ngesimo sokucindezeleka kobuso, kanti ingqikithi izobe ingaphansi kwengcindezi. Kungabonakala ukuthi ushintsho kanye nesimo sokugcina sokucindezeleka kokuguqulwa kwesigaba kuphambene ngqo nokucindezeleka kokushisa. Ngaphezu kwalokho, njengoba ukucindezeleka kokushintsha kwesigaba kwenzeka emazingeni okushisa aphansi ane-plasticity ephansi, ukuguqulwa kunzima ngalesi sikhathi, ngakho-ke ukucindezeleka kokushintsha kwesigaba kungenzeka kakhulu ukuthi kubangele ukuqhekeka kwento yokusebenza.
Kunezici eziningi ezithinta usayizi wokucindezeleka kokuguqulwa kwesigaba. Uma izinga lokupholisa lensimbi lishesha kakhulu ebangeni lokushisa lokuguqulwa kwe-martensite, usayizi wengcezu yensimbi uba mkhulu, ukuguquguquka kokushisa kwensimbi kuba kubi kakhulu, umthamo othize we-martensite uba mkhulu, ukucindezeleka kokuguqulwa kwesigaba kuba kukhulu. Uma kuba kukhulu. Ngaphezu kwalokho, ukucindezeleka kokuguqulwa kwesigaba kuhlobene nokwakheka kwensimbi kanye nokuqina kwensimbi. Isibonelo, insimbi ene-alloy ephezulu enekhabhoni ephezulu ikhulisa umthamo othize we-martensite ngenxa yokuqukethwe kwayo okuphezulu kwekhabhoni, okufanele kwandise ukucindezeleka kokuguqulwa kwesigaba kwensimbi. Kodwa-ke, njengoba okuqukethwe kwekhabhoni kukhuphuka, iphuzu le-Ms liyancipha, futhi kukhona inani elikhulu le-austenite egciniwe ngemva kokucinywa. Ukwanda komthamo wayo kuyancipha futhi ukucindezeleka okusele kuphansi.
(2) Ukuguqulwa kwento yokusebenza ngesikhathi sokucima
Ngesikhathi sokucisha, kunezinhlobo ezimbili eziyinhloko zokuguquka kwesimo sejiyometri yento yokusebenza: enye ushintsho esimweni sejometri yento yokusebenza, olubonakala njengoshintsho ngobukhulu kanye nesimo, oluvame ukubizwa ngokuthi ukuguqulwa kwe-warping, okubangelwa ukucindezeleka kokucima; enye ukuguqulwa kwevolumu. , okuzibonakalisa njengokwanda okulinganiselwe noma ukuncipha kwevolumu yento yokusebenza, okubangelwa ushintsho lwevolumu ethile ngesikhathi sokushintsha kwesigaba.
Ukuguquguquka kwesimo okugobile kuhlanganisa nokuguquguquka kwesimo kanye nokuguquguquka kokugoba. Ukuguquguquka kwesimo okugobile kubangelwa kakhulu ukufakwa okungafanele kwento yokusebenza esithandweni somlilo ngesikhathi sokushisa, noma ukuntuleka kokwelashwa kokubumba ngemva kokulungiswa kokuguquguquka ngaphambi kokucima, noma ukupholisa okungalingani kwezingxenye ezahlukene zento yokusebenza lapho into yokusebenza ipholile. Lokhu kuguquguquka kungahlaziywa futhi kuxazululwe ezimweni ezithile. Okulandelayo kuxoxa kakhulu ngokuguquguquka kwevolumu kanye nokuguquguquka kwesimo.
1) Izimbangela zokuqeda ukuguquka kanye nemithetho yayo eshintshayo
Ukuguquguquka kwevolumu okubangelwa ukuguqulwa kwesakhiwo Isimo sesakhiwo sento yokusebenza ngaphambi kokucima ngokuvamile siyi-pearlite, okungukuthi, isakhiwo esixubile se-ferrite ne-cementite, futhi ngemva kokucima kuyisakhiwo se-martensitic. Amavolumu ahlukene ala mathishu azokwenza ushintsho lwevolumu ngaphambi nangemva kokucima, okuholela ekuguqukeni. Kodwa-ke, lokhu kuguquguquka kubangela kuphela ukuthi into yokusebenza yande futhi inciphe ngokulinganayo, ngakho-ke ayishintshi ukuma kwento yokusebenza.
Ngaphezu kwalokho, uma i-martensite iningi esakhiweni ngemva kokwelashwa ngokushisa, noma uma okuqukethwe kwekhabhoni ku-martensite kuphakeme, kulapho ukwanda kwevolumu yayo kukhula khona, futhi lapho inani le-austenite egciniwe likhula khona, ukwanda kwevolumu kuyancipha. Ngakho-ke, ushintsho lwevolumu lungalawulwa ngokulawula okuqukethwe okuhlobene kwe-martensite kanye ne-martensite esele ngesikhathi sokwelashwa ngokushisa. Uma kulawulwa kahle, ivolumu ngeke ikhule noma inciphe.
Ukuguquka komumo okubangelwa ukucindezeleka kokushisa Ukuguquka komumo okubangelwa ukucindezeleka kokushisa kwenzeka ezindaweni ezishisa kakhulu lapho amandla okukhiqiza ezingxenye zensimbi ephansi, i-plasticity iphakeme, ubuso buphola ngokushesha, futhi umehluko wokushisa phakathi kwangaphakathi nangaphandle kwento yokusebenza mkhulu kakhulu. Ngalesi sikhathi, ukucindezeleka kokushisa okusheshayo ukucindezeleka kokucindezela kobuso kanye nokucindezeleka kokucindezela komgogodla. Njengoba izinga lokushisa lomgogodla liphezulu ngalesi sikhathi, amandla okukhiqiza aphansi kakhulu kunobuso, ngakho-ke kubonakala njengokuguquka ngaphansi kwesenzo sokucindezeleka kokucindezela okuqondiswe ngezindlela eziningi, okungukuthi, i-cube iyindilinga ohlangothini. Ukuhlukahluka. Umphumela uba ukuthi enkulu iyancipha, kuyilapho encane ikhula. Isibonelo, isilinda eside siyafinyela ohlangothini lobude futhi sanda ohlangothini lobubanzi.
Ukuguquka komumo okubangelwa ukucindezeleka kwezicubu Ukuguquka komumo okubangelwa ukucindezeleka kwezicubu kwenzeka futhi ngesikhathi sokuqala lapho ukucindezeleka kwezicubu kuphezulu kakhulu. Ngalesi sikhathi, umehluko wokushisa wesigaba esiphambene mkhulu, izinga lokushisa eliyinhloko liphakeme, lisesesimeni se-austenite, i-plasticity ilungile, futhi amandla okukhiqiza aphansi. Ukucindezeleka kwezicubu okusheshayo ukucindezeleka kokucindezela okuphezulu kanye nokucindezeleka kokucindezela okuyinhloko. Ngakho-ke, ukuguquka kubonakala njengokwandiswa komgogodla ngaphansi kwesenzo sokucindezeleka kokudonsa okuqondiswe ngezindlela eziningi. Umphumela uba ukuthi ngaphansi kwesenzo sokucindezeleka kwezicubu, uhlangothi olukhulu lomsebenzi luyanwebeka, kuyilapho uhlangothi oluncane lufinyela. Isibonelo, ukuguquka okubangelwa ukucindezeleka kwezicubu kusilinda eside kuwukunwebeka ngobude kanye nokunciphisa ububanzi.
Ithebula 5.3 libonisa imithetho yokushintshashintsha kokucima izingxenye zensimbi ezijwayelekile.
2) Izici ezithinta ukuguqulwa kokucima
Izici ezithinta ukuguqulwa kokucima ikakhulukazi ukwakheka kwamakhemikhali kwensimbi, isakhiwo sokuqala, i-geometry yezingxenye kanye nenqubo yokwelapha ukushisa.
3) Ukucima imifantu
Imifantu ezingxenyeni yenzeka kakhulu esigabeni sokugcina sokucinywa nokupholisa, okungukuthi, ngemva kokuguqulwa kwe-martensitic sekuqediwe noma ngemva kokupholisa ngokuphelele, ukwehluleka kokuqhekeka kwenzeka ngoba ukucindezeleka kokudonsa ezingxenyeni kudlula amandla okuphuka kwensimbi. Imifantu ivame ukuqonde ngqo ohlangothini lokuguquguquka okukhulu kokudonsa, ngakho-ke izinhlobo ezahlukene zokuqhekeka ezingxenyeni zincike kakhulu esimweni sokusabalalisa ukucindezeleka.
Izinhlobo ezivamile zokuqhekeka kokucima: Ukuqhekeka kwe-longitudinal (axial) kukhiqizwa kakhulu lapho ukucindezeleka kokudonsa kwe-tangential kudlula amandla okuphuka kwezinto; ukuqhekeka okuphambene kwakheka lapho ukucindezeleka okukhulu kokudonsa kwe-axial okwakhiwa ebusweni bangaphakathi bengxenye kudlula amandla okuphuka kwezinto. Ukuqhekeka; ukuqhekeka kwenethiwekhi kwakheka ngaphansi kwesenzo sokucindezeleka kokudonsa okunezinhlangothi ezimbili ebusweni; ukuqhekeka okuxebukayo kwenzeka ungqimba oluqinile kakhulu, okungenzeka kwenzeke lapho ukucindezeleka kushintsha kakhulu futhi ukucindezeleka kokudonsa ngokweqile kusebenza ohlangothini lwe-radial. Uhlobo lokuqhekeka.
Imifantu ye-longitudinal ibizwa nangokuthi imifantu ye-axial. Imifantu yenzeka ngokucindezeleka okukhulu kokudonsa eduze kobuso bengxenye, futhi inobubanzi obuthile obuqonde enkabeni. Indlela imifantu eqondiswa ngayo ngokuvamile ihambisana ne-axis, kodwa indlela ingashintsha futhi uma kukhona ukugcwala kokucindezeleka engxenyeni noma uma kukhona amaphutha angaphakathi kwesakhiwo.
Ngemva kokuba umsebenzi usucishiwe ngokuphelele, imifantu emide ivame ukwenzeka. Lokhu kuhlobene nokucindezeleka okukhulu kokudonsa okubonakalayo ebusweni bomsebenzi ocishiwe. Njengoba okuqukethwe kwekhabhoni kwensimbi kuyanda, ukuthambekela kokudala imifantu emide kuyanda. Insimbi ephansi yekhabhoni inomthamo omncane othize we-martensite kanye nokucindezeleka okunamandla okushisa. Kukhona ukucindezeleka okukhulu kokucindezela okusele ebusweni, ngakho akulula ukucishwa. Njengoba okuqukethwe kwekhabhoni kuyanda, ukucindezeleka kokucindezela kobuso kuyancipha futhi ukucindezeleka kwesakhiwo kuyanda. Ngesikhathi esifanayo, ukucindezeleka kokudonsa okuphezulu kuya ngasengqimbeni engaphezulu. Ngakho-ke, insimbi ephezulu yekhabhoni ivame ukucishwa imifantu emide uma ishiswa kakhulu.
Ubukhulu bezingxenye buthinta ngqo usayizi kanye nokusatshalaliswa kokucindezeleka okusele, futhi ukuthambekela kwayo kokuqhekeka kokucima nakho kuhlukile. Imifantu ye-longitudinal nayo yakhiwa kalula ngokucisha ngaphakathi kobubanzi obuyingozi be-cross-section. Ngaphezu kwalokho, ukuvaleka kwezinto zokusetshenziswa zensimbi kuvame ukubangela imifantu ye-longitudinal. Njengoba izingxenye eziningi zensimbi zenziwa ngokugoqa, ukufakwa okungeyona igolide, ama-carbide, njll. ensimbini kusatshalaliswa ngendlela yokuguquka, okwenza insimbi ibe yi-anisotropic. Isibonelo, uma insimbi yamathuluzi inesakhiwo esifana nebhendi, amandla ayo okuqhekeka okuphambene ngemva kokucisha angaphansi kuka-30% kuya ku-50% kunamandla okuqhekeka kwe-longitudinal. Uma kunezici ezifana nokufakwa okungeyona igolide ensimbini okubangela ukugcwala kokucindezeleka, noma ngabe ukucindezeleka kwe-tangential kukhulu kunokucindezeleka kwe-axial, imifantu ye-longitudinal kulula ukwakheka ngaphansi kwezimo zokucindezeleka okuphansi. Ngenxa yalesi sizathu, ukulawulwa okuqinile kwezinga lokufakwa okungeyona insimbi kanye noshukela ensimbini kuyisici esibalulekile ekuvimbeleni imifantu yokucima.
Izici zokusatshalaliswa kokucindezeleka kwangaphakathi kwemifantu ewela phansi kanye nemifantu ye-arc yilezi: ubuso bungaphansi kokucindezeleka kokucindezela. Ngemva kokushiya ubuso ibanga elithile, ukucindezeleka kokucindezela kuyashintsha kube ukucindezeleka okukhulu kokucindezela. Ukuqhekeka kwenzeka endaweni yokucindezeleka kokucindezela, bese kuthi lapho ukucindezeleka kwangaphakathi kusakazeke ebusweni bengxenye kuphela uma isatshalaliswa kabusha noma ubuthakathaka bensimbi bukhula kakhulu.
Imifantu eguquguqukayo ivame ukwenzeka ezingxenyeni ezinkulu ze-shaft, njenge-roller, i-turbine rotors noma ezinye izingxenye ze-shaft. Izici zemifantu ukuthi iqonde ngqo eqondweni le-axis futhi iyaphuka kusukela ngaphakathi kuya ngaphandle. Ivame ukwakheka ngaphambi kokuba iqiniswe futhi ibangelwa ukucindezeleka kokushisa. Ama-forging amakhulu avame ukuba namaphutha e-metallurgical njenge-pores, i-inclusions, imifantu yokubopha kanye namabala amhlophe. La maphutha asebenza njengendawo yokuqala yokuqhekeka nokuphuka ngaphansi kwesenzo sokucindezeleka kokudonsa kwe-axial. Imifantu ye-arc ibangelwa ukucindezeleka kokushisa futhi ivame ukusakazwa ngesimo se-arc ezingxenyeni lapho isimo sengxenye sishintsha khona. Kwenzeka kakhulu ngaphakathi kwe-workpiece noma eduze kwemiphetho ebukhali, imifantu kanye nezimbobo, futhi isakazwa ngesimo se-arc. Lapho izingxenye zensimbi enekhabhoni ephezulu enobubanzi noma ubukhulu obungu-80 kuya ku-100 mm noma ngaphezulu zingacinywanga, ubuso buzobonisa ukucindezeleka okucindezelayo futhi isikhungo sizobonisa ukucindezeleka kokudonsa. Ukucindezeleka, ukucindezeleka okukhulu kokudonsa kwenzeka endaweni yokuguquka kusukela kungqimba oluqinile kuya kungqimba olungelukhuni, futhi imifantu ye-arc iyenzeka kulezi zindawo. Ngaphezu kwalokho, izinga lokupholisa emaphethelweni abukhali nasemakhoneni liyashesha futhi konke kuyacinywa. Uma ushintshela ezingxenyeni ezithambile, okungukuthi, endaweni engaqinisiwe, indawo yokucindezeleka okuphezulu kakhulu ivela lapha, ngakho-ke imifantu ye-arc ivame ukwenzeka. Izinga lokupholisa eduze kwembobo yephini, umsele noma imbobo ephakathi yento yokusebenza lihamba kancane, ungqimba oluqinisiwe olufanayo luncane, kanti ukucindezeleka kokucindezeleka eduze kwendawo yokuguquka eqinile kungabangela kalula imifantu ye-arc.
Imifantu eqondile, eyaziwa nangokuthi imifantu engaphezulu, imifantu engaphezulu. Ukujula komfantu akujulile, ngokuvamile kuzungeze u-0.01 ~ 1.5mm. Isici esiyinhloko salolu hlobo lomfantu ukuthi isiqondiso esingenanjongo somfantu asihlobene nokuma kwengxenye. Imifantu eminingi ixhunywe komunye nomunye ukuze yakhe inethiwekhi futhi isakazeke kabanzi. Lapho ukujula komfantu kukhulu, okungaphezu kuka-1 mm, izici zenethiwekhi ziyanyamalala futhi zibe imifantu eqondiswe ngokungahleliwe noma esakazeke ngobude. Imifantu yenethiwekhi ihlobene nesimo sokucindezeleka kokucindezelwa okunezinhlangothi ezimbili ebusweni.
Izingxenye zensimbi ezinekhabhoni ephezulu noma i-carburing enesendlalelo esikhishwe i-carburing ebusweni zivame ukwakha imifantu yenethiwekhi ngesikhathi sokucinywa. Lokhu kungenxa yokuthi ungqimba olungaphezulu lunokuqukethwe okuphansi kwekhabhoni kanye nevolumu encane ethile kunesendlalelo sangaphakathi se-martensite. Ngesikhathi sokucinywa, ungqimba olungaphezulu lwe-carbide lubhekene nokucindezeleka kokudonsa. Izingxenye ungqimba lwazo lwe-dephosphorization olungasuswanga ngokuphelele ngesikhathi sokucutshungulwa kwemishini nazo zizokwakha imifantu yenethiwekhi ngesikhathi sokucinywa kobuso obunamaza aphezulu noma obunamalangabi. Ukuze kugwenywe imifantu enjalo, ikhwalithi yobuso bezingxenye kufanele ilawulwe ngokuqinile, futhi ukushiswa kwe-oxidation kufanele kuvinjelwe ngesikhathi sokwelashwa kokushisa. Ngaphezu kwalokho, ngemva kokuba i-forging die isetshenziswe isikhathi esithile, imifantu yokukhathala kokushisa evela emigqeni noma kumanethiwekhi emgodini kanye nemifantu enkambisweni yokugaya yezingxenye ezicinyiwe konke kungokwalolu hlobo.
Ukuqhekeka kwenzeka endaweni encane kakhulu yesendlalelo sobuso. Ukucindezeleka okucindezelayo kusebenza eziqondisweni ze-axial kanye ne-tangential, kanti ukucindezeleka kokudonsa kwenzeka ohlangothini lwe-radial. Ukuqhekeka kufana nobuso bengxenye. Ukuqhekeka kwesendlalelo esiqinile ngemva kokucima ubuso kanye nezingxenye ze-carburizing kungokwemifantu enjalo. Ukuvela kwayo kuhlobene nesakhiwo esingalingani esendlalelo esiqinile. Isibonelo, ngemva kokuba insimbi ye-alloy carburised ipholile ngesivinini esithile, isakhiwo esendlalelo se-carburised singu: ungqimba lwangaphandle lwe-pearlite enhle kakhulu + carbide, kanti i-sublayer yi-martensite + i-Austenite esele, ungqimba lwangaphakathi luyi-pearlite enhle kakhulu noma isakhiwo se-pearlite esihle kakhulu. Njengoba ivolumu ethile yokwakheka kwe-martensite ye-sub-layer iyona enkulu kunazo zonke, umphumela wokwandiswa kwevolumu ukuthi ukucindezeleka okucindezelayo kusebenza osendlalelo sobuso eziqondisweni ze-axial kanye ne-tangential, kanti ukucindezeleka kokudonsa kwenzeka ohlangothini lwe-radial, futhi kwenzeka ushintsho lokucindezeleka ngaphakathi, kuguqukela esimweni sokucindezeleka okucindezelayo, kanye nokuqhekeka kwemifantu Kwenzeka ezindaweni ezincane kakhulu lapho ukucindezeleka kushintsha khona ngokushesha. Ngokuvamile, imifantu ifihlakele ngaphakathi eduze kobuso, futhi ezimweni ezimbi kakhulu ingabangela ukuxebuka kobuso. Uma izinga lokupholisa lezingxenye ezifakwe i-carburite lishesha noma lincishisiwe, isakhiwo se-martensite esifanayo noma isakhiwo se-pearlite esicwebezelayo kakhulu singatholakala kungqimba olufakwe i-carburite, okungavimbela ukwenzeka kwemifantu enjalo. Ngaphezu kwalokho, ngesikhathi sokucima umphezulu onamaza amaningi noma ilangabi, umphezulu uvame ukushisa kakhulu futhi ukungalingani kwesakhiwo kungqimba oluqinile kungakha kalula imifantu enjalo yomphezulu.
Ama-microcrack ahlukile kuma-crack amane ashiwo ngenhla ngoba abangelwa yi-microstress. Ama-crack aphakathi kwe-granular avela ngemva kokucima, ukushisa ngokweqile kanye nokugaya insimbi yamathuluzi enekhabhoni ephezulu noma izinto zokusebenza ezifakwe i-carburized, kanye nama-crack abangelwa ukungashintshwa ngesikhathi kwezingxenye ezicinyiwe, konke kuhlobene nokuba khona kanye nokwanda okulandelayo kwama-microcrack ensimbini.
Ama-microcracks kumele ahlolwe ngaphansi kwe-microscope. Ngokuvamile avela emingceleni yokuqala yezinhlamvu ze-austenite noma lapho kuhlangana khona amashidi e-martensite. Amanye ama-cracks angena kumashidi e-martensite. Ucwaningo lubonisa ukuthi ama-microcracks avame kakhulu kuma-martensite ama-flaky twinned. Isizathu ukuthi i-martensite e-flaky iyashayisana lapho ikhula ngesivinini esikhulu futhi idala ukucindezeleka okuphezulu. Kodwa-ke, i-martensite e-twinned ngokwayo iyaphuka futhi ayikwazi ukukhiqiza ukuguquguquka kwepulasitiki okuphumuza ukucindezeleka, ngaleyo ndlela kubangele kalula ama-microcracks. Ama-austenite grains aqinile futhi ukuthambekela kuma-microcracks kuyanda. Ukuba khona kwama-microcracks ensimbini kuzonciphisa kakhulu amandla kanye nokuqina kwezingxenye ezicinyiwe, okuholela ekulimaleni kokuqala (ukuphuka) kwezingxenye.
Ukuze kugwenywe ukuqhekeka okuncane ezingxenyeni zensimbi ezinekhabhoni ephezulu, kungasetshenziswa izindlela ezifana nokushisa okuphansi kokucima, ukuthola isakhiwo esihle se-martensite, kanye nokunciphisa okuqukethwe kwekhabhoni ku-martensite. Ngaphezu kwalokho, ukupholisa ngesikhathi esifanele ngemva kokucima kuyindlela ephumelelayo yokunciphisa ukucindezeleka kwangaphakathi. Ukuhlolwa kuye kwafakazela ukuthi ngemva kokupholisa ngokwanele ngaphezu kuka-200°C, ama-carbide aqhuma emifantwini anethonya "lokushisela" imifantu, okunganciphisa kakhulu izingozi zemifantu emincane.
Lokhu okungenhla kuyingxoxo yezimbangela nezindlela zokuvimbela imifantu ngokusekelwe kuphethini yokusatshalaliswa kwemifantu. Ekukhiqizweni kwangempela, ukusatshalaliswa kwemifantu kuyahlukahluka ngenxa yezici ezifana nekhwalithi yensimbi, ukuma kwengxenye, kanye nobuchwepheshe bokucubungula ukushisa nokubanda. Ngezinye izikhathi imifantu isivele ikhona ngaphambi kokwelashwa kokushisa futhi yanda kakhulu ngesikhathi senqubo yokucisha; ngezinye izikhathi izinhlobo eziningana zemifantu zingavela engxenyeni efanayo ngesikhathi esifanayo. Kulesi simo, ngokusekelwe ezicini zesimo somfantu, ukuhlaziywa kwe-macroscopic kobuso bokuqhekeka, ukuhlolwa kwe-metallographic, futhi uma kudingeka, ukuhlaziywa kwamakhemikhali nezinye izindlela kufanele kusetshenziswe ukwenza ukuhlaziywa okuphelele kusukela ekhwalithini yezinto ezibonakalayo, isakhiwo senhlangano kuya ezimbangeleni zokucindezeleka kokwelashwa kokushisa ukuthola umfantu. Izimbangela eziyinhloko kufanele zinqunywe.
Ukuhlaziywa kokuqhekeka kwemifantu kuyindlela ebalulekile yokuhlaziya izimbangela zokuqhekeka. Noma yikuphi ukuqhekeka kunesiqalo sokuqhekeka. Ukucima imifantu ngokuvamile kuqala endaweni yokuhlangana kwemifantu yemisebe.
Uma umsuka woqhekeko ukhona ebusweni bengxenye, kusho ukuthi uqhekeko lubangelwa ukucindezeleka okukhulu kokuqina kobuso. Uma kungekho ziphazamiso zesakhiwo ezifana nokufakwa ebusweni, kodwa kunezici zokuhlushwa kwengcindezi njengezimpawu zommese ezinzima, isikali se-oxide, amakhona abukhali ezingxenye zensimbi, noma izingxenye zokuguqulwa kwesakhiwo, kungenzeka imifantu.
Uma umsuka woqhekeko ungaphakathi kwengxenye, uhlobene nokukhubazeka kwezinto noma ukucindezeleka okukhulu kwangaphakathi okusele. Ubuso boqhekeko bokucima okuvamile bumpunga futhi buyi-porcelain encane. Uma ubuso boqhekeko bumpunga omnyama futhi buqinile, bubangelwa ukushisa ngokweqile noma izicubu zokuqala zijiyile.
Ngokuvamile, akufanele kube nombala we-oxidation engxenyeni yengilazi yoqhekeko lokucima, futhi akufanele kube khona ukuhlukaniswa kwe-carburization ezungeze uqhekeko. Uma kukhona ukuhlukaniswa kwe-carburization ezungeze uqhekeko noma umbala we-oxidized engxenyeni yoqhekeko, kubonisa ukuthi ingxenye yayivele inemifantu ngaphambi kokucima, futhi imifantu yokuqala izokhula ngaphansi kwethonya lokucindezeleka kokwelashwa kokushisa. Uma ama-carbide ahlukanisiwe kanye nokufakwa kubonakala eduze kwemifantu yengxenye, kusho ukuthi imifantu ihlobene nokuhlukaniswa okukhulu kwama-carbide ezintweni zokusetshenziswa noma ukuba khona kwezinto ezifakiwe. Uma imifantu ibonakala kuphela emakhoneni abukhali noma izingxenye zokuguqulwa kwesimo sengxenye ngaphandle kwesenzakalo esingenhla, kusho ukuthi ukuqhekeka kubangelwa ukwakheka kwesakhiwo okungenangqondo kwengxenye noma izinyathelo ezingafanele zokuvimbela imifantu, noma ukucindezeleka okukhulu kokwelashwa kokushisa.
Ngaphezu kwalokho, imifantu ekwelashweni kokushisa ngamakhemikhali kanye nezingxenye zokucima ubuso ngokuvamile ivela eduze kwengqimba eqinile. Ukuthuthukisa isakhiwo sengqimba eqinile nokunciphisa ukucindezeleka kokwelashwa kokushisa kuyizindlela ezibalulekile zokugwema imifantu ebusweni.
Isikhathi sokuthunyelwe: Meyi-22-2024