I-Austempered Ductile Iron-I-ADI Castings

I-austempered ductile iron, ekwabizwa ngokuba yi-ADI, ibhekisa kwi-ductile cast iron emva kwenkqubo ye-austenitizing ductile iron (850℃-950℃) kwaye emva koko ikhawuleze iyibeke kwindawo yokuhlambela ityuwa (232℃-450℃) yokuguqulwa kwe-isothermal. Ukongeza, kunye nokongezwa kweemali ezaneleyo ze-Cu, i-Ni, i-Mo kunye nezinye izinto, i-austempered austempered austenitic ductile iron inokufumaneka phantsi kweemeko zokupholisa eziqhubekayo.

Intsimbi ye-austempered ductileiicastingszineempawu ezigqwesileyo zoomatshini, kwaye ubunzima beyunithi yabo yokuqina kwesivuno yeyona incinci. Ukufumana amabakala ahlukeneyo entsimbi ye-austempered ductile ixhomekeke kwiqondo lokushisa lokunyuka kwaye alinanto yakwenza nokubunjwa kweekhemikhali. Ngokuqhelekileyo, ukwakheka kweekhemikhali ze-austempered ductile iron ikuluhlu olulandelayo:
C: 3.5% -3.8%
ISi: 2.4%-3.0%
Mnu: ＜0.30%
P: <0.07%
S: <0.02%

I-silicon yenye yezona zinto zibalulekileyo ze-austempered ductile iron. I-Silicon ivimbela ukubunjwa kwe-Bainite carbides, ngaloo ndlela igalelo ekubunjweni kwe-acicular ferrite. Ukonyusa umxholo we-silicon kunokonyusa ukuqina kwempembelelo ye-austempered ductile cast iron kunye nokunciphisa ubude. Indima yeManganese inamacala amabini. Kwelinye icala, kunokuphucula kakhulu ukuqina; kwelinye icala, iManganese iya kukhuthaza ukubunjwa kwee-carbides kwaye ithintele ukuguqulwa kwe-isothermal ngexesha lenkqubo yokuqinisa. Ngoko ke, xa inani lee-graphite spheres liphantsi kwaye ubukhulu bodonga bukhulu, ulwahlulo lwe-manganese kumda wengqolowa kuya kubangela i-shrinkage porosity, i-carbides kunye ne-austenite engazinzanga kwi-ductile iron casting. Ezi ziphene ze-microstructure kunye ne-inhomogeneities ziya kunciphisa i-machinability kunye neempawu zomatshini. Ngoko ke, ipesenti yobunzima bemanganese kufuneka ilawulwe ngaphantsi kwe-3%.

Kwimveliso yokuphosa yokwenyani, ukuze ufumane i-austempered ezinzileyo nekumgangatho ophezului-ductile iron castings, kukho iingongoma ezimbini ezifuna ingqalelo ekhethekileyo:
1) Lawula isakhiwo se-iron ductile iron ngaphambi kokuba unyango lwe-isothermal. Izinga le-spheroidization kufuneka libe phezulu kune-80%. Inani le graphite pheres kufuneka libe ngaphezu kwe 100 nge square millimeter nganye. Ezinye iimeko ziquka: ukwakheka kweekhemikhali ezizinzileyo; i-casting kufuneka ingabikho i-carbides, i-porosity kunye ne-inclusions; kunye nomlinganiselo ozinzileyo wepearlite/ferrite.
2) Ukumisela imilinganiselo yonyango lobushushu olufanelekileyo ngokwendlela yokwakheka kunye nesakhiwo se-ductile iron, kwaye uqhube inkqubo yonyango lobushushu obungqongqo kunye noluzinzileyo.