Austempered Ductile Iron – ADI Castings

Austempered ductile iron, kuma aka sani da ADI, yana nufin ductile simintin ƙarfe bayan aiwatar da austenitizing ductile iron (850 ℃-950 ℃) sa'an nan da sauri ajiye shi a cikin wani gishiri wanka (232 ℃-450 ℃) domin isothermal canji. Bugu da ƙari, tare da ƙarin isassun adadin Cu, Ni, Mo da sauran abubuwa, ana iya samun baƙin ƙarfe austenitic ductile baƙin ƙarfe a ci gaba da sanyaya yanayi.

Austempered ductile ironsimintin gyare-gyaresuna da kyawawan kaddarorin inji, kuma nauyin rukunin su na ƙarfin yawan amfanin ƙasa shine mafi ƙanƙanta. Samun nau'o'i daban-daban na baƙin ƙarfe austempered ductile baƙin ƙarfe ya dogara da zafin jiki na austempering kuma ba shi da dangantaka da sinadaran sinadaran. Gabaɗaya magana, sinadarai na baƙin ƙarfe austempered ductile iron yana cikin kewayon mai zuwa:
C: 3.5% - 3.8%
Si: 2.4% - 3.0%
Mn: % 0.30
P: <0.07%
S: <0.02%

Silicon yana ɗaya daga cikin mahimman abubuwan ƙarfe na baƙin ƙarfe austempered. Silicon yana hana samuwar Bainite carbides, don haka yana ba da gudummawa ga samuwar acicular ferrite. Ƙara abun ciki na siliki na iya ƙara tasirin taurin simintin simintin gyare-gyare da kuma rage tsawo. Matsayin manganese yana da bangarori biyu. A gefe guda, yana iya haɓaka ƙarfin ƙarfi sosai; a daya hannun, Manganese zai inganta samuwar carbides da kuma hana isothermal canji a lokacin solidification tsari. Saboda haka, lokacin da adadin graphite spheres low kuma bango kauri ne babba, da rabuwa na manganese a hatsi iyaka zai haifar da shrinkage porosity, carbides da m austenite a cikin ductile baƙin ƙarfe simintin gyaran kafa. Waɗannan lahani na microstructure da inhomogeneities za su rage machinability da kayan aikin injiniya. Don haka, yawan adadin manganese ya kamata a sarrafa shi ƙasa da 3%.

A ainihin samar da simintin gyare-gyare, don samun karɓuwa da inganci mai inganciductile baƙin ƙarfe simintin gyaran kafa, akwai abubuwa guda biyu masu buƙatar kulawa ta musamman:
1) Sarrafa tsarin as-castile iron ductile iron kafin maganin isothermal. Yawan spheroidization ya kamata ya zama sama da 80%. Yawan graphite pheres ya kamata ya zama fiye da 100 a kowace murabba'in milimita. Sauran sharuɗɗan sun haɗa da: ingantaccen tsarin sinadaran; simintin gyare-gyare ya kamata ya kasance ba tare da carbides ba, porosity da inclusions; da daidaiton abun ciki na pearlite/ferrite.
2) Ƙayyade ƙayyadaddun ƙayyadaddun maganin zafi masu dacewa bisa ga abun da ke ciki da tsarin simintin simintin ƙarfe na ductile, da aiwatar da ingantaccen tsarin kula da zafi mai ƙarfi.