I-Austempered Ductile Iron - I-ADI Castings

I-Austempered ductile iron, eyaziwa nangokuthi i-ADI, isho i-ductile cast iron ngemva kwenqubo ye-austenitizing ductile iron (850℃-950℃) bese iyibeka ngokushesha endaweni yokugeza usawoti (232℃-450℃) ukuze kuguqulwe isothermal. Ngaphezu kwalokho, ngokungezwa kwenani elanele le-Cu, i-Ni, i-Mo nezinye izakhi, i-austempered austenitic ductile iron ingatholakala ngaphansi kwezimo zokupholisa eziqhubekayo.

I-Austempered ductile ironukusakazababe nezakhiwo ezinhle kakhulu zemishini, futhi isisindo seyunithi samandla esivuno sincane kakhulu. Ukuthola amamaki ahlukene e-austempered ductile iron kuncike ekushiseni kwe-austempering futhi akuhlangene nokwakheka kwamakhemikhali. Ngokuvamile, ukwakheka kwamakhemikhali e-austempered ductile iron ikuluhlu olulandelayo:
C: 3.5%-3.8%
Isilinganiso: 2.4%-3.0%
Mnu: ＜0.30%
P: <0.07%
S: <0.02%

I-silicon ingenye yezinto ezibaluleke kakhulu ze-austempered ductile iron. I-silicon ivimbela ukwakheka kwe-Bainite carbides, ngaleyo ndlela ibe nomthelela ekwakhekeni kwe-acicular ferrite. Ukwandisa okuqukethwe kwe-silicon kungakhuphula ukuqina komthelela we-austempered ductile cast iron futhi kunciphise ubude. Indima yeManganese inezinhlangothi ezimbili. Ngakolunye uhlangothi, kungathuthukisa kakhulu ukuqina; ngakolunye uhlangothi, iManganese izokhuthaza ukwakheka kwama-carbides futhi ivimbele ukuguqulwa kwe-isothermal ngesikhathi senqubo yokuqinisa. Ngakho-ke, lapho inani lama-graphite sphere liphansi futhi ubukhulu bodonga bukhulu, ukuhlukaniswa kwe-manganese emngceleni wokusanhlamvu kuzodala ukuncipha kwe-porosity, ama-carbides kanye ne-austenite engazinzile ekubunjweni kwe-iron ductile. Lezi zinkinga ze-microstructure kanye ne-inhomogeneities zizonciphisa ukusebenza kwemishini kanye nezakhiwo zemishini. Ngakho-ke, iphesenti elikhulu le-manganese kufanele lilawulwe libe ngaphansi kuka-3%.

Emkhiqizweni wokulingisa wangempela, ukuze uthole i-austempered ezinzile nesezingeni eliphezului-ductile iron castings, kunamaphuzu amabili adinga ukunakwa okukhethekile:
1) Lawula ukwakheka kwe-as-cast ductile iron ngaphambi kokwelashwa kwe-isothermal. Izinga le-spheroidization kufanele libe ngaphezu kwama-80%. Inani lama-graphite pheres kufanele libe ngaphezu kwe-100 ngemilimitha yesikwele ngayinye. Ezinye izimo zihlanganisa: ukwakheka kwamakhemikhali okuzinzile; ukubunjwa kufanele kungabi nama-carbides, i-porosity kanye ne-inclusions; kanye nesilinganiso esizinzile sokuqukethwe kwe-pearlite/ferrite.
2) Thola ukucaciswa okufanele kokwelashwa kokushisa ngokuya ngokwakheka kanye nesakhiwo se-ductile iron, futhi wenze inqubo yokwelapha ukushisa okuqinile nezinzile.