Heat Resistant Steel Castings ndi Investment Casting Process

Chitsulo chosagwira kutentha chimatanthawuza chitsulo chokhala ndi kutentha kwakukulu kwa okosijeni komanso mphamvu ya kutentha kwambiri. Kutentha kwakukulu kwa okosijeni kukana ndi chikhalidwe chofunikira kuonetsetsa kuti workpiece imagwira ntchito kwa nthawi yaitali pa kutentha kwakukulu. M'malo okhala ndi okosijeni monga mpweya wotentha kwambiri, mpweya wa okosijeni umakhudzidwa ndi mankhwala ndi pamwamba pachitsulo kuti apange zigawo zingapo za iron oxide. Wosanjikiza wa oxide ndi wotayirira kwambiri, amataya mawonekedwe oyambira achitsulo, ndipo ndiosavuta kugwa. Pofuna kupititsa patsogolo kutentha kwachitsulo kwachitsulo, zinthu zowonjezera zimawonjezeredwa kuzitsulo kuti zisinthe mawonekedwe a oxide. Zomwe zimagwiritsidwa ntchito kwambiri ndi chromium, nickel, chromium, silicon, aluminiyamu ndi zina zotero. Kutentha kwakukulu kwa okosijeni kukana kwachitsulo kumangogwirizana ndi mankhwala.

Kutentha kwakukulu kumatanthawuza mphamvu ya chitsulo chosungira katundu wamakina kwa nthawi yaitali pa kutentha kwakukulu. Pali zotsatira ziwiri zazikulu zachitsulo pansi pa katundu wamakina pa kutentha kwakukulu. Chimodzi ndikufewetsa, ndiko kuti, mphamvu imachepa ndi kutentha kowonjezereka. Chachiwiri ndikukwawa, ndiko kuti, pansi pa kupsinjika kosalekeza, kuchuluka kwa mapindikidwe apulasitiki kumawonjezeka pang'onopang'ono ndi nthawi. The mapindikidwe pulasitiki zitsulo pa kutentha kwambiri amayamba ndi intragranular slip ndi njere malire slip. Kupititsa patsogolo kutentha kwamphamvu kwachitsulo, njira za alloying zimagwiritsidwa ntchito. Ndiko kuti, ma alloying amawonjezeredwa kuchitsulo kuti apititse patsogolo mphamvu yolumikizana pakati pa ma atomu ndikupanga mawonekedwe abwino. Kuonjezera chromium, molybdenum, tungsten, vanadium, titaniyamu, ndi zina zotero, kungathe kulimbikitsa matrix achitsulo, kuonjezera kutentha kwa recrystallization, komanso kupanga ma carbides olimbikitsa kapena ma intermetallic, monga Cr23C6, VC, TiC, ndi zina zotero. khola pa kutentha, musati kupasuka, musati aggregate kukula, ndi kusunga kuuma kwawo. Nickel amawonjezedwa makamaka kuti apezeaustenite. Ma atomu mu austenite amapangidwa molimba kuposa ferrite, mphamvu yolumikizana pakati pa ma atomu imakhala yamphamvu, ndipo kufalikira kwa ma atomu kumakhala kovuta kwambiri. Choncho, kutentha kwamphamvu kwa austenite kuli bwino. Zitha kuwoneka kuti kutentha kwapamwamba kwa chitsulo chosagwira kutentha sikungokhudzana ndi mankhwala, komanso kumagwirizana ndi microstructure.

High-aloyi kutentha zosagwirazitsulo castingsamagwiritsidwa ntchito kwambiri nthawi zomwe kutentha kwa ntchito kumapitilira 650 ℃. Zitsulo zosagwira kutentha zimatanthawuza zitsulo zomwe zimagwira ntchito kutentha kwambiri. Kukula kwa zitsulo zosagwira kutentha kumagwirizana kwambiri ndi kupita patsogolo kwaukadaulo kwa magawo osiyanasiyana a mafakitale monga malo opangira magetsi, ma boilers, ma turbine a gasi, ma injini oyatsira mkati, ndi ma aero engines. Chifukwa cha kutentha ndi zovuta zosiyanasiyana zomwe zimagwiritsidwa ntchito ndi makina ndi zipangizo zosiyanasiyana, komanso malo osiyanasiyana, mitundu yazitsulo zomwe zimagwiritsidwa ntchito ndizosiyana.

Miyezo ya zitsulo zosagwira kutentha m'mayiko osiyanasiyana
1) Chinese Standard
GB/T 8492-2002 "Technical Conditions for Heat-Resistant Steel Castings" imatchula magiredi ndi kutentha kwa chipinda chazitsulo zosiyanasiyana zosagwira kutentha.
2) European Standard
TS EN 10295-2002 Miyezo yachitsulo yosagwira kutentha imaphatikizapo chitsulo chosapanga dzimbiri cha austenitic chosatentha, chitsulo chosapanga dzimbiri cha ferritic ndi austenitic-ferritic duplex chitsulo chosapanga dzimbiri, komanso ma aloyi opangidwa ndi faifi tambala ndi ma aloyi opangidwa ndi cobalt.
3) Miyezo yaku America
Kapangidwe kakemidwe kotchulidwa mu ANSI/ASTM 297-2008 "General Industrial Iron-Chromium, Iron-Chromium-Nickel Heat-resistant Steel Castings" ndiye maziko ovomerezeka, ndipo kuyesa kwamakina kumangochitika pomwe wogula apempha. nthawi yoyitanitsa. Miyezo ina yaku America yokhudzana ndi zitsulo zosagwira kutentha ndi ASTM A447/A447M-2003 ndi ASTM A560/560M-2005.
4) German Standard
Mu DIN 17465 "Technical Conditions for Heat-Resistant Steel Castings", kapangidwe ka mankhwala, zida zamakina pa kutentha kwa firiji, ndi zida zotentha kwambiri zamitundu yosiyanasiyana yazitsulo zosagwira kutentha zimafotokozedwa padera.
5) Japanese Standard
Magiredi mu JISG5122-2003 "Chitsulo chosasunthika" ndi ofanana ndi American Standard ASTM.
6) Russian Standard
Pali zitsulo zokwana 19 zosagwira kutentha zomwe zatchulidwa mu GOST 977-1988, kuphatikizapo zitsulo zapakatikati ndi chromium zosagwira kutentha.

Chikoka cha mankhwala zikuchokera pa moyo utumiki wa zitsulo zosagwira kutentha
Pali zinthu zosiyanasiyana zomwe zimatha kukhudza moyo wautumiki wachitsulo chosagwira kutentha. Zotsatirazi zimawonetseredwa pakukulitsa kukhazikika kwa kapangidwe kake, kuteteza makutidwe ndi okosijeni, kupanga ndi kukhazikika kwa austenite, ndikuletsa dzimbiri. Mwachitsanzo, zinthu zapadziko lapansi zomwe zimasoweka, zomwe zimatsata zitsulo zosagwira kutentha, zimatha kusintha kwambiri kukana kwachitsulo ndi oxidation ndikusintha thermoplasticity. Zida zoyambira zachitsulo chosagwira kutentha ndi ma aloyi nthawi zambiri zimasankha zitsulo ndi ma aloyi okhala ndi malo osungunuka kwambiri, mphamvu zodziyambitsa zokha kapena mphamvu yocheperako. Zitsulo zosiyanasiyana zosagwira kutentha ndi zowonjezera kutentha zimakhala ndi zofunikira kwambiri pazitsulo zosungunulira, chifukwa kukhalapo kwa inclusions kapena zolakwika zina zazitsulo muzitsulo zidzachepetsa mphamvu ya kupirira kwa zinthuzo.

Mphamvu yaukadaulo wapamwamba monga chithandizo chamankhwala pa moyo wautumiki wachitsulo chosagwira kutentha
Kwa zida zachitsulo, kugwiritsa ntchito njira zosiyanasiyana zochizira kutentha kumakhudza kapangidwe kake ndi kukula kwambewu, potero kusintha kuchuluka kwazovuta za kuyambitsa matenthedwe. Pofufuza kulephera kwa kuponyera, pali zinthu zambiri zomwe zimayambitsa kulephera, makamaka kutopa kwamafuta kumabweretsa kuyambitsa ming'alu ndi chitukuko. Mofananamo, pali zinthu zingapo zomwe zimakhudza kuyambitsa ndi kufalitsa ming'alu. Pakati pawo, sulfure ndi yofunika kwambiri chifukwa ming'aluyi imakhala ndi ma sulfide. Zomwe zili sulfure zimakhudzidwa ndi ubwino wa zipangizo ndi kusungunuka kwake. Kwa ma castings omwe amagwira ntchito pansi pa mlengalenga woteteza wa haidrojeni, ngati hydrogen sulfide ili mu haidrojeni, zoponyazo zimakhala ndi sulphurized. Kachiwiri, kukwanira kwa chithandizo chamankhwala kumakhudza mphamvu ndi kulimba kwa kuponyera.