Date of Award

Fall 11-15-2025

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Materials and Infrastructure Systems

First Advisor

Henry Cardenas

Abstract

Corrosion fatigue remains a critical durability challenge for steels used in boiler tubes and other safety-critical components, where the interaction of cyclic stresses and corrosive environments accelerates material degradation. This dissertation comprises three experimental studies aimed at advancing mitigation strategies and test methodologies: (1) enhancing corrosion resistance through electrodeposited Fe-Ni anodic coatings, (2) inducing synthetic crack closure to suppress fatigue crack growth, and (3) developing an accessible, low-cost, automated testing system to investigate environmentally assisted cracking (EAC) under controlled laboratory conditions. The first study examined the corrosion behavior of Fe and Fe-Ni electrodeposits synthesized from sulfate-based baths and applied to carbon steel substrates. Specimens immersed in oxygen-saturated, alkaline solution (pH 9.5–10.0) were evaluated using electrochemical methods. Increasing the Ni²⁺/Fe²⁺ ratio reduced porosity, surface cracking, and galvanic corrosion while increasing the temperature dependence of general corrosion between 20–60 °C. These findings indicate the potential of Fe-Ni coatings in boiler water environments, though further work is needed to assess performance under elevated pressures and temperatures. The second study investigated Fe-Ni electrodeposits as a means of inducing crack closure in ASTM A36 steel compact tension specimens. Treatments achieved complete arrest of fatigue cracks for significant load cycles, though effectiveness diminished as cracks lengthened. Crack reinitiation life following arrest was quantified and modeled using a Huang-modified Correia equation. Electrodeposit composition and morphology confirmed alloy composition control in the electrochemical codeposition process and informed interpretation of fatigue suppression mechanisms. The third study focused on the design and validation of an accessible, low-cost, automated test system integrating mechanical loading, environmental control of pH and temperature, and compliance-based crack length measurement calibrated by finite element analysis. Validation tests on carbon steel in acidic chloride solution and PMMA in xylene-ethanol solvents demonstrated accurate load control, stable environmental regulation, and sensitivity to crack growth and closure. Collectively, these studies advance the scientific foundation and practical tools needed to mitigate corrosion fatigue in steels. They represent the first demonstration of an electrodeposited alloy specifically engineered to deliver sacrificial cathodic protection while simultaneously suppressing fatigue crack propagation. The findings clarify the role of Fe-Ni electrodeposits in extending component life and establish an accessible testing framework to accelerate future research on environmentally assisted cracking across diverse materials and environments.

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