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Author:Jalava, Kalle
Title:Vaihtoehtoiset sylinterikansimateriaalit
Alternative cylinder head materials
Publication type:Master's thesis
Publication year:2014
Pages:(7) + 77 s. + liitt. 10      Language:   fin
Department/School:Insinööritieteiden korkeakoulu
Main subject:Valutuotetekniikka   (Kon-80)
Supervisor:Orkas, Juhani
Instructor:Silvonen, Aulis
Electronic version URL: http://urn.fi/URN:NBN:fi:aalto-201406252237
OEVS:
Electronic archive copy is available via Aalto Thesis Database.
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Location:P1 Ark Aalto  3814   | Archive
Keywords:thermal fatigue
cast iron
ductile iron
thermal conductivity
terminen väsyminen
valurauta
pallografiittirauta
lämmönjohtavuus
Abstract (eng):Aim of this work was to find information on thermal fatigue, alternative cast materials, generally of materials' properties at high temperatures and to possibly find a suitable material or solution to test experimentally.
A potential solution was discovered and experimental castings were made with the aim of increasing spheroidal graphite cast irons thermal conductivity.

Thermal fatigue and thermo-mechanical fatigue are complex failure mechanisms that arise from high temperature loadings.
Heating and cooling cycles fatigue materials and create problems that affect almost every known internal combustion engine.
It is possible to mitigate these problems through material optimization and other means that aim to lessen the stresses in used constructions.
The optimal material properties are unfortunately often conflicting and thus optimization results are always compromises in many ways.

Castings, heat treatments, tensile testing and thermal conductivity measurements were made in the experimental part of this work.
The aim was to study if it was possible to increase spheroidal graphite cast irons thermal conductivity without losing much needed mechanical properties, such as tensile and yield strengths.

It was found that it is possible to increase the studied material's thermal conductivity considerably (~30 %) compared to a reference material through alloying changes and heat treatment.
However, the method decreases some mechanical properties if nothing else is done to remedy the loss of so-lution strengthening.
A potential method to restore the lost strength was discovered during the work and was thus identified as an important further study subject.
Abstract (fin):Työn tavoitteena oli tutkia kirjallisuutta termisestä väsymisestä, sekä mahdollisista uusista valetuista materiaaleista ja niiden ominaisuuksista korotetuissa lämpötiloissa.
Teoriaosuuden tarkoituksena oli etsiä mahdollisia ratkaisuja korotettujen lämpötilojen komponenttien kehityshaasteisiin materi-aaleista tai muista vaihtoehtoisista ratkaisuista.
Selvityksen perusteella tehtiin koesarja pallografiit-tiraudan lämmönjohtavuuden parantamisesta.

Terminen väsyminen on korotettujen lämpötilojen aikaansaamien jännitysten aiheuttamaa vaurioi-tumista.
Se on kuuma-jäähdytys-sykleineen yksi suurimmista polttomoottoreita yleisesti vaivaavista ongelmista.
Optimoimalla materiaaliominaisuuksia on mahdollista lieventää rakenteissa syntyviä käytönaikaisia jännityksiä ja siten vaurioitumisriskiä.
Halutut, optimaaliset materiaaliominaisuudet ovat kuitenkin usein ristiriitaisia toisiinsa nähden, joten saavutettu lopputulos on aina jollain tapaa kompromissi.

Työn kokeellisessa osuudessa keskityttiin kirjallisuusselvityksen perusteella lämmönjohtavuuden parantamiseen pallografiittiselle valuraudalle.
Koekappaleita valettiin, niitä lämpökäsiteltiin ja mitattiin mekaanisia ominaisuuksia, sekä käsittelyillä saavutettuja lämmönjohtavuuksia.

Työssä testatulla keinolla on mahdollista parantaa pallografiittisen valuraudan lämmönjohtavuutta selkeästi, noin 30 %:a, verrattuna käytettyyn referenssimateriaaliin.
Se kuitenkin heikentää mm. lujuutta ilman muita toimenpiteitä.
Lujuuden palauttaminen identifioitiin selkeäksi jatkotutkimusaiheeksi.
ED:2014-08-03
INSSI record number: 49480
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