Density and thermal expansion coefficients of liquid and austenite phase in lamellar cast iron

Abstract

Volume change related defects formation mechanisms are an important detracting phenomenon in production of complex shaped cast components. Among different technical alloys, cast iron behaves in a complex manner due to the combined volume change of the formed phases. The liquid and the austenitic phase are contracting while the graphite phase is expanding during the solidification. The complex volume change in combination with complex casting shapes causes a considerable deviation from isotropy in the solidification domain. The mentioned difficulties are considered the main reason why an extensive research work is condensed in the literature within this topic. The multitude of reported experimental set up and the various efforts to interpret the volume change phenomena in terms of density and thermal expansion coefficients makes the results difficult to compare from different sources. With these difficulties in mind, the present paper presents a broad experimental series and measures unidirectional linear deformation of an industrially spread lamellar cast iron alloy system (Fe-C-2Si) using the push-rod based dilatometer technique. The measurements are divided into two major groups with respect to the liquid iron deformation over the liquidus temperature line, and the austenite deformation below the solidus temperature line. The obtained results are interpreted as thermal expansion coefficients, density variation slopes, and density data at the liquids and solidus temperature. The obtained results are compared with literature data and with calculated values by the Thermo Calc software.

Keywords

• density; thermal expansion coefficient; dilatometer; cast iron; fe-c-2si; calphad