Austempered Ductile Iron – ADI Castings

ʻO Austempered ductile iron, i ʻike ʻia ʻo ADI, pili i ka ductile cast iron ma hope o ke kaʻina o ka austenitizing ductile iron (850 ℃-950 ℃) a laila hoʻokomo koke iā ia i loko o ka ʻauʻau paʻakai (232 ℃-450 ℃) no ka hoʻololi isothermal. Eia kekahi, me ka hoʻohui ʻana i ka nui o Cu, Ni, Mo a me nā mea ʻē aʻe, hiki ke loaʻa i ka hao austenitic ductile austempered ma lalo o nā kūlana hoʻomaha mau.

Austempered ductile haohoolei analoaʻa nā waiwai mechanical maikaʻi loa, a ʻo kā lākou paona o ka ikaika hua ka mea liʻiliʻi loa. ʻO ka loaʻa ʻana o nā māka like ʻole o ka hao ductile austempered e pili ana i ka mahana o ka austempering a ʻaʻohe mea pili i ka haku mele. ʻO ka ʻōlelo maʻamau, ʻo ka haku mele ʻana o ka austempered ductile iron aia i loko o ka pae aʻe:
C: 3.5%-3.8%
Aia: 2.4%-3.0%
Mn: ＜0.30%
P: <0.07%
S: <0.02%

ʻO Silicon kekahi o nā mea koʻikoʻi o ka hao ductile austempered. Kāohi ʻo Silicon i ka hoʻokumu ʻana o nā carbide Bainite, a laila e hāʻawi i ka hoʻokumu ʻana o ka ferrite acicular. Hiki i ka hoʻonui ʻana i ka ʻike silika ke hoʻonui i ka paʻakikī o ka austempered ductile cast iron a hōʻemi i ka elongation. ʻElua ʻaoʻao ka hana a Manganese. Ma kekahi ʻaoʻao, hiki iā ia ke hoʻomaikaʻi nui i ka hardenability; ma ka ʻaoʻao ʻē aʻe, e hoʻolaha ʻo Manganese i ka hoʻokumu ʻana o nā carbide a keʻakeʻa i ka hoʻololi isothermal i ka wā o ke kaʻina paʻa. No laila, ke emi ka helu o ka graphite spheres a nui ka mānoanoa o ka pā, ʻo ka hoʻokaʻawale ʻana o ka manganese ma ka palena o ka palaoa e hoʻohaʻahaʻa i ka porosity, carbide a me ka austenite paʻa ʻole i ka ductile hao. ʻO kēia mau hemahema microstructure a me nā inhomogeneities e hōʻemi i ka machinability a me nā waiwai mechanical. No laila, pono e mālama ʻia ka pākēneka o ka manganese ma lalo o 3%.

Ma ka hana hoolei maoli, i mea e loaa ai ka austempered pa'a a me ka maikaihao ductile, aia ʻelua wahi e pono ai ka nānā kūikawā:
1) E hoʻomalu i ke ʻano o ka as-cast ductile iron ma mua o ka mālama isothermal. Pono ka nui o ka spheroidization ma mua o 80%. ʻOi aku ka nui o nā graphite pheres ma mua o 100 no ka millimeter square. ʻO nā kūlana ʻē aʻe e pili ana: ka haku mele paʻa; pono ʻole ka hoʻolei ʻana i nā carbide, porosity a me nā inclusions; a me ka ratio paʻa pearlite/ferrite maʻiʻo.
2) E hoʻoholo i nā kikoʻī hoʻomaʻamaʻa wela kūpono e like me ke ʻano a me ka hoʻokalakupua o ka hao ductile, a hoʻokō i kahi kaʻina hana mālama wela austempering paʻa a paʻa.