Award Date

12-2004

Degree Type

Dissertation

Degree Name

Doctor of Philosophy in Mechanical Engineering

Department

Mechanical Engineering

Advisor 1

Ajit K. Roy, Chair

First Committee Member

Anthony E. Hechanova

Second Committee Member

Brendan J. O'Toole

Third Committee Member

Mohamed B. Trabia

Graduate Faculty Representative

Jacimaria Batista

Number of Pages

189

Abstract

This investigation is focused on the evaluation of stress corrosion cracking (SCC), localized corrosion, and hydrogen embrittlement (HE) susceptibility of martensitic Alloy EP-823 in neutral and acidic solutions at ambient and elevated temperatures. While no failures were observed in smooth specimens in the neutral solution, failures were noticed in the 90°C acidic solution at constant-load (CL) leading to a threshold stress (O'th) of 102 ksi. The presence of a notch reduced the O'th value to 91 ksi in a similar environment. The ductility (%El and %RA), time-to-failure (TTF), and true failure stress (O'r) were gradually reduced in both environments with increasing temperature during SSR testing. The presence of a notch, however, enhanced the O'r value. All polarized specimens exhibited localized attack. The application of a controlled cathodic potential further reduced the ductility, TTF and O'r showing the characteristics of more brittle failures. Metallographic and fractographic evaluations revealed secondary cracks along the gage section, and combination of ductile and brittle failures at the primary fracture face, respectively. Ill

Keywords

Harry Reid Center; Martensitic stainless steel – Cracking; Metals – Hydrogen embrittlement; Strains and stresses; Stress corrosion

Disciplines

Materials Science and Engineering | Mechanical Engineering | Mechanics of Materials | Nuclear Engineering

Language

English

Comments

Refer to PDF file for exact formulas