Doctoral Dissertations

Keywords and Phrases

Deoxidation; High strength steel; Impact wear; Mechanical properties; Porosity; Toughness

Abstract

"Ground Engaging Tools (GET) are the expendable replacement parts used in heavy machinery used with mining or construction equipment. GET’s protect the expensive machine components from the wear and tear found common in high-impact or high-abrasion environments. The goal of this project is to develop advanced next-generation alloy choices that outperforms the existing GET materials. A method of predicting tempered hardness of mixed microstructures was formulated. Using this model, two alloy series viz. Cr-Ni-Mo and Mn-Si-Mo-V were proposed and experimented with the goal of obtaining a high strength and impact resistant cast steel. Cast iterations of Cr-Ni-Mo alloy series were used to develop a low nitrogen induction melting practice (N< 80 ppm) along with an effective deoxidation. Size of ground Si-Zr addition controls final ZrN particle size. Good mechanical properties can be obtained if ZrN particle size is limited to 2μm. A high oxygen melt practice gave 35% improvement in notch toughness. A Mn-Si-Mo-V steel was formulated to minimize solidification shrinkage porosity. Steels were heat treated to a lath martensitic microstructure, and a Stage-I tempered hardness of 53-55 HRC. Yield strength and ultimate tensile strength averaged 1482 MPa and 1930 MPa. Tensile ductility decreased with increasing porosity. Porosity should be limited to 0.04% to get elongation of 10% or more. Manganese and Nickel additions lowered the yield strength. Lowered yield to tensile strength ratio resulted in up to 46% improvement in impact wear simulated using a gouging abrasion test relative to steels currently employed. Recommendations for further cast alloy iterations, wear performance study and characterization are provided"--Abstract, page iv.

Advisor(s)

Van Aken, David C.

Committee Member(s)

O'Malley, Ronald J.
Bartlett, Laura
Xu, Mingzhi
Chandrashekhara, K.

Department(s)

Materials Science and Engineering

Degree Name

Ph. D. in Metallurgical Engineering

Publisher

Missouri University of Science and Technology

Publication Date

Fall 2019

Journal article titles appearing in thesis/dissertation

  • On predicting quenched and tempered hardness of mixed microstructures using steel chemistry
  • Empirical methods of predicting quenched and tempered hardness
  • Controlling nitrogen pick-up during induction melting low alloy steels
  • Effect of deoxidation and pouring practice on the mechanical properties of Stage-I tempered Cr-Ni-Mo steel
  • Mechanical properties and impact wear resistance of 540 Brinell hardness Mn-Si-Mo-V steel

Pagination

xviii, 161 pages

Note about bibliography

Includes bibliographic references.

Rights

© 2019 Viraj Ashok Athavale, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 11614

Electronic OCLC #

1139525622

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Metallurgy Commons

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