Masters Theses

Keywords and Phrases

Cold shut; P900

Abstract

"This work investigated the liquid metal treatment and molding practices for Fe- 30wt.%Mn-9wt.%Al-1wt.%Si-0.9wt.%C-0.5wt.%Mo steel. The goal of this research was to determine the process conditions that would produce a tough Fe-Mn-Al-C alloy and the appropriate mold design to produce a defect-free P900 plate.

Notch toughness of age-hardenable Fe-Mn-Al-C alloys decreases as phosphorus increases. Thermodynamic calculations and experimental work show that additions of Ca followed by Ce can be used to mitigate the deleterious effects of phosphorus, and the addition of Ar-stirring can be used to decrease the number of harmful aluminum nitride inclusions. In the solution-treated and aged condition (Brinell hardness 317-330), the room temperature Charpy Vnotch (CVN) impact energies increased from 33 J to 92 J as a result of ladle refinement using calcium wire, misch metal additions, and argon stirring with a lance. The addition of Ar-stirring decreased the number of inclusions by more than 90% when compared with the untreated heat.

Liquid Fe-Mn-Al-C alloys have casting characteristics significantly different from regular carbon steel; specifically, the high aluminum content promotes a strong tendency to re-oxidize and form surface films during mold filling. These melt properties promote the formation of oxide film laps and cold shuts in thin-walled castings. This research used MagmaSoft modeling software in conjunction with experiments to study the castability of Fe-Mn-Al-C steel P900 armor plates. The effects of superheat and venting procedures were evaluated for different molding techniques including bonded olivine sand molds tilted at both 0⁰ and 15⁰ from horizontal and preheated investment shell molds vertically oriented with a bottom-filled gating system. The best castings were produced in vertically oriented, bottom-filled, ceramic investment shell molds with a superheat of 300C⁰ and poured directly from the furnace into a preheated investment shell at 800⁰C. Successful P900 castings were also obtained from the tilted bonded olivine sand molds when poured with a superheat above 300C⁰"--Abstract, page iv.

Advisor(s)

Van Aken, David C.
Richards, Von

Committee Member(s)

Peaslee, Kent D., 1956-2013

Department(s)

Materials Science and Engineering

Degree Name

M.S. in Metallurgical Engineering

Sponsor(s)

United States. Army Research Office
Leonard Wood Institute

Publisher

Missouri University of Science and Technology

Publication Date

Spring 2010

Journal article titles appearing in thesis/dissertation

  • Phosphorus mitigation in cast lightweight Fe-Mn-Al-C steel
  • Modeling for improved casting quality of high aluminum steels

Pagination

xi, 63 pages

Note about bibliography

Includes bibliographical references (pages 60-62).

Rights

© 2010 Angella Marie Schulte, All rights reserved.

Document Type

Thesis - Open Access

File Type

text

Language

English

Library of Congress Subject Headings

Aluminum castings
Manganese
Phosphorus
Steel-aluminum alloys

Thesis Number

T 9628

Print OCLC #

692197388

Electronic OCLC #

752151305

Included in

Metallurgy Commons

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