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Date of Award

2016

Document Type

Campus Access Master's Thesis

Degree Name

Master of Science in Mechanical Engineering (MS)

Administrative Home Department

Department of Mechanical Engineering-Engineering Mechanics

Advisor 1

Paul Sanders

Advisor 2

Gregory Odegard

Committee Member 1

Kathy Hayrynen

Abstract

Lightweight materials are an essential component in meeting light vehicle fuel economy standards. Although ductile iron has high strength, toughness, and cost effectiveness, it is usually not thought of for lightweighting solutions because ferrous materials, in general, are thought of as high density. One strategy to address this issue is to produce sound, thin wall ductile iron castings. This study evaluates improvements resulting in alloying of thin wall ductile iron castings. Two, three, four and six-millimeter-thick sections were cast in chemically bonded sand molds and evaluated by optical microscopy, ultrasonic modulus, Brinell hardness and tensile testing. Increasing cooling rates in thin castings will result in a fine, pearlitic lamellar spacing and a fine microstructure. The fast cooling rate inhibits the distance that carbon will diffuse. Fine pearlitic microstructures have shown a promising increase in both yield and tensile strengths. Thin section ductile iron can have increased mechanical properties as opposed to a thicker section size because of a finer microstructure. However, sufficient ductility is challenging. An increase in yield and tensile strength to weight ratio will provide a new approach to not only automotive components but to a wide range of others.

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