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Evolution of Microstructure in Directionally Solidified Cast Iron Treated with Cerium and Magnesium

  • Subhojit Chakraborty
  • Saurabh Gadkari
  • Philipp Steinmetz
  • Charles A. Monroe
  • Amber L. GenauEmail author
Article
  • 29 Downloads

Abstract

Cast iron is a eutectic alloy consisting primarily of iron, carbon, and silicon. Depending on the composition and solidification conditions, the carbon can solidify either as cementite or graphite with a variety of morphologies. Because the microstructure directly influences the mechanical properties and the performance of the macroscopic part, a deeper understanding of the solidification behavior of the material is required. In this work, the solidification velocity and composition were independently and systematically varied in a well-controlled environment. Near-eutectic samples with varying amounts of Mg, Ce, and Si were directionally solidified with velocities from 10 to 30 \( \frac{{\mu {\text{m}}}}{{\text{s}}} \) in a Bridgman furnace. White cast iron was used as a starting material, which effectively suppressed flotation of graphite, so that a uniform composition and microstructure along the length of the samples was achieved. A range of morphologies were observed, including spheroidal austenite–graphite colonies, austenite–cementite eutectic, nodular graphite, and two distinct types of austenite dendrites. These structures were qualitatively and quantitatively assessed, and compared with a recently published schema describing the solid/liquid interface behavior of cast iron as a function of cooling rate and nodularizing elements.

Notes

Acknowledgments

Initial melts were prepared at the UAB Materials Processing and Application Development Center (MPAD) as part of the project DE-EE0005980 through the USA Department of Energy and Caterpillar Inc. Foundry activities occurred under the guidance of John Griffin with support from the entire UAB MSE metal casting group. Additional project support was provided by the National Science Foundation under Grant No. 1554856. The authors thank Dr. Robin Foley for many fruitful discussions.

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Copyright information

© The Minerals, Metals & Materials Society and ASM International 2019

Authors and Affiliations

  • Subhojit Chakraborty
    • 1
  • Saurabh Gadkari
    • 1
  • Philipp Steinmetz
    • 1
  • Charles A. Monroe
    • 1
  • Amber L. Genau
    • 1
    Email author
  1. 1.Department of Materials Science and EngineeringUniversity of Alabama at BirminghamBirminghamUSA

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