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Dokumenten-Nummer: 57829
Tagungsbeitrag
Selin, Martin
Publikationssprache: Englisch
Using Regression Analysis to Optimize the Combination of Thermal Conductivity and Hardness in
Compacted Graphite Iron
Nutzung der Regressionsanalyse zur Optimierung der Kombination von thermischer Leitfähigkeit und Härte bei
Gusseisen mit Vermiculargraphit
In cast iron there is a contradictory relationship between thermal conductivity and strength. In many applications it is
desirable to optimize the material properties to obtain both sufficiently high thermal conductivity and sufficiently high
strength. The aim of this paper is to investigate how various microstructure parameters and alloying elements affect
thermal conductivity and hardness in compacted graphite irons. It was found that the fraction of ferrite, the fraction of
cementite, nodularity and content of carbon and silicon are parameters that influence the thermal conductivity and
hardness the most. Based on these five key parameters linear regression equations were created for calculation of
thermal conductivity and hardness. Ferrite and carbon have a positive influence on the thermal conductivity, while
silicon, cementite and nodularity have a deleterious effect. All parameters except ferrite have a positive influence on the
hardness. This is because the thermal conductivity is dependent on the movement of free electrons, and therefore
unfavourable growth directions and grain boundaries which impede the electron movement will reduce the thermal
conductivity. Ferrite has quite high thermal conductivity, while cementite has poor thermal conductivity, due to an
unfavourable crystal structure. Nodular shaped graphite has a lower thermal conductivity than compacted graphite
which explains the deleterious influence of nodularity. The soft ferrite phase will reduce the hardness value, while
increasing the fraction of harder graphite nodules and harder cementite phase will increase the hardness. To investigate
how these five parameters affect the combination of hardness and thermal conductivity, values for hardness and
thermal conductivity were calculated for all combinations of key parameters in given intervals, using two linear
regression equations. From these it is possible to predict the combination of parameters which gives a particular
combination of hardness and thermal conductivity in compacted graphite iron.
Jönköping University, SE
Erscheinungsjahr 2010
S. S.337-342
Seiten/Bilder/Tabellen/Quellen: 6S
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