Doctoral Dissertations

Keywords and Phrases

Metallurgy

Abstract

“Eglin steel was developed by the U.S. Air Force and Ellwood National Forge Company as a cost-effective, ultrahigh strength steel for use in armament, aerospace, and commercial applications. Eglin steel has been successfully substituted for high alloy steels, such as AF1410 and HP-9-4-20/30, to produce the casing for “bunker buster” bombs where penetration of concrete barriers and rock at high velocity ( > 1000 ft/sec) is desired. Unlike AF1410 and HP-9-4-20/30, Eglin steel is low nickel (nominal 1 wt.%) and contains no cobalt. Given the successful performance of Eglin steel in the casings applications, the Department of Defense has directed that further development of Eglin steel as a cast product should be conducted.

The goal of the research reported here was to use existing knowledge and practices of producing Eglin steel as a basis and to advance the science and the physical metallurgy of cast Eglin steel to produce a more consistent material that meets current performance requirements by optimizing chemical homogeneity, and thermal processing.

A novel heat treatment was designed which reduced the prior austenite grain size from 283 ± 74 µm to 58 ± 17 µm, and increased Charpy impact energy at -40° F/C from 34 ± 4 ft-lbs to 40 ± 11 ft-lbs. Porosity and Cleanliness Limitations were investigated, and it was found porosity must be restricted to less than 0.05% to obtain elongations to failure of 10% or greater. A general model for the notch effect of a large pore was formulated and shows that shrinkage pores must be restricted to less than 400 µm in length to eliminate brittle behavior induced by porosity. Finally elevated temperature normalization at 2250°F for up to 11 hours was explored in which it was concluded that for Eglin steel, homogeneity is a secondary consideration to casting porosity, cleanliness, and martensitic substructure”--Abstract, page iv.

Advisor(s)

Van Aken, David C.

Committee Member(s)

O'Malley, Ronald J.
Richards, Von
Huebner, Wayne
Baird, Jason, 1955-

Department(s)

Materials Science and Engineering

Degree Name

Ph. D. in Metallurgical Engineering

Comments

This work has been supported under the Steel Founders’ Society of America (SFSA) program on Casting and Advanced Steel Technology that has been funded by the Army Research Laboratory under the provisions of cooperative agreement W911NF-12-2-0033.

Publisher

Missouri University of Science and Technology

Publication Date

Fall 2015

Journal article titles appearing in thesis/dissertation

  • An Innovative Heat Treatment to Improve the Ductility of High Strength Steels
  • Grain Refinement Strategies in High Strength Cast Steel
  • Porosity and Cleanliness Limitations on High Strength Steel
  • Normalization of High Strength Steels to Improve Homogeneity and Mechanical Properties
  • Evaluating Chemical Homogeneity in the Performance of Eglin Steel

Pagination

xxii, 222 pages

Note about bibliography

Includes bibliographic references.

Rights

© 2015 Terrell Owen Webb, Jr., All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 11814

Included in

Metallurgy Commons

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