Date of Award

11-27-2019

Publication Type

Doctoral Thesis

Degree Name

Ph.D.

Department

Mechanical, Automotive, and Materials Engineering

Keywords

Hypoeutectic Gray Iron, Manganese Sulfide Particles, Phase Diagram Generator, Production Line Thermal Analysis, Quenching Hypoeutectic Gray Iron, Thermal Analysis

Supervisor

Jerry Sokolowski

Rights

info:eu-repo/semantics/embargoedAccess

Abstract

The continuous demand from the automotive industry for enhanced properties in gray cast iron components, such as brake rotors, highlights the need for a faster development cycle for gray iron alloys. Current industrial practice involves producing a large quantity of the proposed composition for a full production run. It is an expensive undertaking due to the raw material and production time used. Physical simulation of the gray cast iron industrial process will decrease the time and cost for development of a new alloy. Current methodologies include thermal analysis and the extraction of mechanical-property samples, which were not developed for physical simulation, and are not flexible enough to reproduce the results of a production component. A primary limiting factor is the lack of any reported data on the actual thermal history of a production cast part. The present work has developed the methodology to obtain in situ thermal traces from a brake rotor in the production line. The data obtained were compared to the results from current methods to identify differences in cooling rate and microstructure. Measurement and analysis required the development of a systematic nomenclature for gray iron thermal analysis. Applying a spline-line smoothing methodology to the industrial thermal traces allowed their incorporation into the control sequence of the High Temperature Universal Metallurgical Simulator Analyzer software for physical simulation. The results obtained by using the same chemical composition and average cooling rate from production reproduced the microstructure from an industrial cast component in a laboratory setting. Having proven the viability of laboratory simulations to model the industrial process, sequential quenching experiments were conducted to study the sequence of microstructural development in hypoeutectic gray cast iron. These experiments support the systematic nomenclature that was developed. Additionally, a five-stage model for (MnX)S development was identified: formation, nucleation, growth, instability, and fragmentation.

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