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Date of Award


Document Type

Campus Access Dissertation

Degree Name

Doctor of Philosophy in Materials Science and Engineering (PhD)

Administrative Home Department

Department of Materials Science and Engineering

Advisor 1

Paul Sanders

Advisor 2

Yong-Ching Chen

Committee Member 1

Gregory Odegard

Committee Member 2

Walter Milligan


Ductile iron powertrain components generally cost less than steel, so there is a demand to enhance ductile iron’s tribological properties such as rolling contact fatigue (RCF) life. One potential strategy to increase RCF life is to increase surface hardness through induction hardening, austempering, and chill casting. These procedures produce drastically different iron microstructures, so common RCF microstructural failure mechanisms have not been observed. Chill casting produces a white iron structure with high hardness and wear resistance while not requiring heat treatment, reducing economic and environmental costs. The focus of this research was on the effect of chill casting on the solidified microstructure, hardness, and RCF life in ductile irons. It was found that the larger the chill, the higher the solidification rate and the better the RCF life. Rapid chilling produced fewer and smaller the discontinuities in ductile irons, such as less primary graphite, carbide, and pearlite, as well as finer eutectic lamellar ledeburite spacing. Higher hardness correlated positively with ductile iron RCF life, similar to steels, however, Vickers or Knoop hardness measured from the subsurface should be used rather than the Rockwell C on the surface by considering the graded structure of chilled ductile iron.