Yiziphi izimbangela ze-cast steel crack defects?

Ukuvela kokukhubazeka kokuqhekeka ezingxenyeni zensimbi ekhonjiwe kuyinkinga evamile futhi eyinkimbinkimbi, ehlanganisa lonke uchungechunge lokukhiqiza kusukela ekuncibilikeni, inqubo yokuphonsa kuya ekwelapheni okulandelayo. Imifantu idalwa ngokuyisisekelo ukucindezelwa kwangaphakathi (ikakhulukazi ukushisa nokuncipha) okudlula umkhawulo wamandla wento kulelo zinga lokushisa.

Ngokuvamile, imifantu ihlukaniswa izigaba ezimbili: imifantu eshisayo nemifantu ebandayo.

1, Ukuqhekeka okushisayo kwenzeka ekupheleni kwesikhathi noma ngokushesha ngemva kokuqina kwensimbi encibilikisiwe, lapho insimbi isesimweni sokuhlalisana okuqinile koketshezi namandla aphansi kanye nepulasitiki. Izinga lokushisa lokwenzeka: ngokuvamile eduze komugqa we-solidus (cishe u-1300-1450 ° C). Izici: Ingxenye yokuqhekeka i-oxidized kakhulu, ibonakala imnyama noma eluhlaza okwesibhakabhaka, enomumo ohlukumezayo futhi ongajwayelekile.

imbangela enkulu:

1. Idizayini yesakhiwo yokulingisa: Umehluko owedlulele ekujikeni kodonga kanye nokuguquguquka okungalingani ekuxhumekeni kubangela ukupholisa okungalingani kanye nengcindezi enkulu yokushisa.

2. Idizayini engenangqondo yesistimu yokuthela: I-sprue igxile kakhulu noma ibekwe ngendlela engafanele, okuholela ekushiseni okweqile kwendawo, okugcina kuqina kuleyo ndawo.

Ayikwazi ukuthola ukucindezela nokusekelwa.

3. Ukuhlehla okungekuhle kwesikhunta/umgogodla wesihlabathi: Amandla esikhunta sesihlabathi aphakeme kakhulu, okuvimbela ukushwabana kwaso kwamahhala ngesikhathi sokuqiniswa nokuncipha, okuholela ekucindezelekeni okuqinile nokuqhekeka. Lesi yisizathu esivame kakhulu.

4. Ukwakheka kwamakhemikhali engxubevange: Okuqukethwe okuphezulu kwezinto eziyingozi njengesulfure (S) ne-phosphorus (P): Zakha ama-sulfide ancibilikayo aphansi nama-phosfide, zakha amafilimu amancane awuketshezi emingceleni yokusanhlamvu, okwenza buthaka kakhulu amandla okuhlanganisa ama-intergranular, futhi ziyizici ezibaluleke kakhulu eziholela ekuqhekekeni okushisayo. Okuqukethwe kwekhabhoni (C): Ngokuqukethwe kwekhabhoni ephezulu, izinga lokushisa lokuqina liyaba banzi, ama-dendrites abe mahhadla, futhi kuba nokuthambekela okukhulayo kokuqhekeka okushisayo. 5. Ukusetshenziswa ngendlela engafanele kwesikhuphukeli nensimbi yokupholisa: Uma isikhuphukeli sentamo siside kakhulu noma sisifishane kakhulu, futhi i-ayina yokupholisa ingafakwanga kahle, izokwandisa ukupholisa okungalingani.

2, Ukuqhekeka okubandayo kwenzeka ngemva kokuba ukubunjwa kuqiniswe ngokuphelele futhi kupholiswe esimweni esinwebekayo, ngokuvamile esiteji sokushisa okuphansi ngaphansi kuka-600 ° C. Izinga lokushisa lokuvela: izinga lokushisa eliphansi. Izici: Isigaba sokuqhekeka sihlanzekile, sinokucwebezela kwe-metallic noma umbala we-oxidation omncane, futhi ukuqhekeka kuqondile futhi kuyaqhubeka kumugqa oqondile.

imbangela enkulu:

1. Ingcindezi yokusakaza eyedlulele: Ingcindezi yokushisa: okubangelwa amazinga okupholisa angahambisani ezingxenyeni ezihlukahlukene zokusakaza. Ingcindezi yokuncipha: Izithiyo zemishini ekwakhiweni kokuncipha okubangelwa isikhunta, ama-sand cores, ama-sprue systems, nezitobhi zamabhokisi. Ukucindezeleka kokuguqulwa: Ukucindezeleka okukhiqizwa ukuguqulwa kwevolumu ethile phakathi nenqubo yokupholisa lapho kukhona ukuguqulwa kwesakhiwo (njengokuguqula i-austenite ibe yi-martensite).

2. Ikhwalithi yensimbi yensimbi: Okuqukethwe kwegesi ephezulu, ikakhulukazi i-hydrogen (H), kungabangela "ukuqhekeka okwenziwe yi-hydrogen" futhi kunciphise ukuqina kwento. Kunezinto eziningi ezifakiwe ezingezona ezensimbi: njengamaphoyinti okugxilisa ingqondo, ukufakwa kunganciphisa kakhulu amandla nokumelana nokuqhekeka kwezinto.

3. Ukufaka isihlabathi ngaphambi kwesikhathi ngesikhathi sesibhakela: Ukulingisa akukakapholi kuze kufike ezingeni lokushisa eliphansi ngokwanele, futhi ukucindezeleka kwangaphakathi akukaqedwa ngokuphelele ngaphambi kokudlidliza ngaphambi kwesikhathi kanye nesihlabathi kungabangela kalula ukuqhekeka okubandayo.

4. Inqubo yokwelapha ukushisa okungafanele: Izinga lokushisisa ngokweqile noma lokupholisa: Ikakhulukazi phakathi nokwelashwa kokucwiliswa kwe-anneal kanye nokujwayelekile, uma ukushisisa noma ukupholisa kungalingani, kuzodala ingcindezi enkulu yokwelashwa kokushisa, okuzokwedlula ingcindezi yokuqala yokuphonsa futhi kubangele ukuqhekeka.

I-Quenching crack: Lolu uhlobo olukhethekile lokuqhekeka okubandayo, okwenza i-martensite yobulukhuni obukhulu ngenxa yezinga lokupholisa ngokushesha lokucisha, elihambisana nokucindezeleka okukhulu kwesakhiwo, okwenza kube lula kakhulu ukuqhekeka.

Isifinyezo nemibono yesixazululo

Lapho ukuqhekeka kutholakala ezingxenyeni zensimbi ekhonjiwe, izizathu kufanele ziphenywe ngokuhlelekile kulezi zici ezilandelayo:

1. Ukwakheka kwamakhemikhali: Lawula ngokuqinile okuqukethwe kwezinto eziyingozi ezifana no-S no-P.

2. Inqubo yokuncibilikisa: Izindlela zokucwenga zisetshenziselwa ukunciphisa okuqukethwe kwamagesi kanye nokufakwa ensimbi encibilikisiwe. 3. Isakhiwo sokulingisa: Lungiselela idizayini ukuze ugweme izinguquko ezingazelelwe ekujimeni kodonga futhi usebenzise ukuguqulwa okuyindilinga.

4. Inqubo yokusakaza: i-sprue kanye nesistimu yesikhuphukeli: Idizayinelwe ngokunengqondo ukuze kufinyelelwe ukuqina okulandelanayo noma ukuqina ngesikhathi esisodwa, ukugwema ukushisa okweqile kwasendaweni. Isihlabathi sokubumba/isihlabathi esiwumgogodla: Qinisekisa ukuvunwa okwanele nokugoqeka. Insimbi ebandayo nesikhuphukeli: Ukusetshenziswa ngendlela efanele ukulawula ukulandelana kokupholisa.

5. Ukususwa nokuhlanzwa kwesihlabathi: Qinisekisa ukuthi ukulingwa kupholiswe ezingeni lokushisa eliphansi ngokwanele (njengangaphansi kuka-400 ° C) esibunjeni sesihlabathi ngaphambi kokushaya isibhakela. Lapho usika izikhuphukeli kanye nokulungiswa kokushisela, kuyadingeka futhi ukugwema ukukhiqiza izingcindezi ezintsha.

6. Inqubo yokwelapha ukushisa: Yenza izichasiselo zokwelashwa kokushisa okunengqondo, ikakhulukazi lawula amazinga okushisa nawokupholisa. Ezingxenyeni eziyinkimbinkimbi noma izingxenye zensimbi ye-alloy ephezulu, sebenzisa isinyathelo sokushisisa nendlela yokupholisa kancane.

Ukuze unqume ngokunembile imbangela ethile, ngokuvamile kuyadingeka ukuhlanganisa ukuhlaziywa kwe-macroscopic kanye ne-microscopic morphology yokuqhekeka (ukuhlolwa kwe-metallographic), ukubuyekezwa kwenqubo, nokuhlaziywa kokwakheka kwamakhemikhali ukuze wenze isinqumo esibanzi.