Elevated temperature thermal conductivities of some as-cast and austempered cast irons

ABSTRACT

The aim of this study was to provide insight on thermal conductivity of three cast iron groups, namely lamellar, compacted and spheroidal graphite irons at elevated temperatures up to 673 K (400°C) in as-cast and austempered states. Austempering treatments increased mechanical properties of all the studied materials while decreasing thermal conductivity across the line. The effects of austempering on conductivity were lower for grey and compacted graphite iron than for spheroidal graphite irons. The results indicate that heat treating can be a viable option in increasing cast iron performance in thermally stressed applications. One ferritic low-silicon spheroidal graphite iron surpassed lamellar graphite iron in conductivity at elevated temperatures, while high-silicon spheroidal graphite irons exhibited low conductivities.

KEYWORDS:

• Cast iron
• thermal conductivity
• spheroidal graphite
• compacted graphite
• lamellar graphite
• elevated temperature
• austempering

Acknowledgements

This study was made as part of the DIMECC (Digital, Internet, Materials & Engineering Co-Creation) project ‘Breakthrough steels and applications: Novel Cast Materials’. The authors would like to thank the project leaders for permission to publish the results.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Tekes.