Roger W. Staehle

Effect of alloying Cu on the corrosion resistance of stainless steels in chloride media

Abstract In order to explain the effect of alloying Cu on the corrosion resistance of stainless steels in chloride media for both ferritic and austenitic stainless steels, the corrosion behavior of Cu-bearing stainless steels was investigated. Alloying Cu showed beneficial effect in an active potential range and harmful effect in a noble potential range. The beneficial effect of alloying Cu was explained by the stability of deposited Cu on an anodic surface. Difference in the effect of alloying Cu between the ferritic and austenitic steels was ascribed by the differences in their corrosion potentials and the morphology of the deposited Cu.

Intergranular Stress Corrosion Cracking Behavior of Austenitic Stainless Steels in Hydrogenated High-Temperature Water

Abstract The influence of material factors on the intergranular stress corrosion cracking (IGSCC) susceptibility of austenitic stainless steels under hydrogenated high-temperature water were studie...

Effects of the Valence of Sulfur on Passivation of Alloys 600, 690, and 800 at 25°C and 95°C

Abstract Effects of the valence of sulfur, as sulfur oxyanions and sulfide (S2− or HS−), on passivation of alloys 600, 690, and 800 (UNS N06600, N06690, and N08800) in various heat treatments were ...

Comparison of Corrosion Resistance of UNS N06690TT and UNS N08800SN in Simulated Primary Water with Various Concentrations of Dissolved Oxygen

Corrosion behaviors of UNS N06690TT and N08800SN in simulated pressurized water reactor (PWR) primary water containing three concentrations of dissolved oxygen (DO) was studied by open-circuit pote...

Historical Experience Providing Bases for Predicting Corrosion and Stress Corrosion in Emerging Supercritical Water Nuclear Technology: Part 1—Review

This review assesses past experiences from superheated fossil plants, supercritical fossil plants, superheated nuclear plants, and light water reactors from the late 1940s until the present. Data from the development and operation of these plants are directly applicable to supercritical water reactor (SCWR) plants being developed currently. This past work can be applied to the development of current designs in the choice of materials, temperature dependencies, effects of stress, and effects of environments on materials. Some of the past data from light water reactor (LWR) technology can be extrapolated into the present SCWR regimes. The past data are in good agreement among the various previous investigators. These past data are considered with respect to specific components in SCWR: fuel cladding, reactor structurals, reactor vessels, and feedwater heaters. Choosing materials for the SCWR applications must recognize that the materials at nominal outlet temperatures are in a dynamic thermal range, i.e., i...

Coulometric Reduction of Oxides Formed on Copper, Nickel, and Iron

In the atmospheric corrosion of copper, nickel, and iron, the adsorption of water affects the corrosion rates. Knowledge of water adsorption and metal oxyhydroxide formation is important in understanding the atmospheric corrosion process. The adsorption of water on copper, nickel, and iron in humid air is accompanied by oxide formation, and the two processes were separated by combining mass measurements with measurements of the quantity of oxide formed. The thickness of the oxide formed in humid air on copper, nickel, and iron was measured ex situ by coulometric reduction technique. The thickness of the oxide film grown in humid air is a function of both relative humidity and temperature. Since oxides on copper, nickel, and iron are semiconductors and they grow by the diffusion of cation vacancies, the increased growth of the oxides in the presence of adsorbed water is explained in terms of the diffusion by cation vacancies.

Predicting failures in light water nuclear reactors which have not yet been observed -microprocess sequence approach (MPSA)

Publisher Summary An approach, microprocess sequence approach (MPSA), for predicting failures, utilizes sets of elements from the environments and materials where these elements can be identified and quantified, and connected sequentially or in parallel, to provide a scenario leading to the initiation of failure. The idea of microprocesses focuses on specific processes that occur within the domains and have been shown to be critical processes in the nucleation, initiation, and growth of stress corrosion cracking (SCC). The domains provide an intellectual framework for identifying explicitly the sequence of events and for organizing the microprocesses. One of the domains, “Global Domain,” is intended to include microprocesses that apply to all the domains. Another domain, “Bulk Environment Domain,” refers to the primary water, the secondary water, tertiary water, ambient inside the containment or outside, and similar fluids to which components, and materials are exposed. The “Near-Surface Environment Domain” consists mainly of deposits, flow gradients, and electrochemical cells. The “Bulk Metal Domain,” is the “semi-infinite region” of the metal, which, on a gross scale, is homogeneous but on a microscopic and microprocess scale is quite heterogeneous. These local heterogeneities provide paths or influences that affect the development and propagation of corrosion damage.

Effects of Stress and Temperature on Stress Corrosion Cracking of Austenitic Stainless Steels in Concentrated Magnesium Chloride Solutions

Abstract Experimental data from published literature on stress corrosion cracking (SCC) of austenitic stainless steels (SS) as influenced by temperature and stress in concentrated chloride solutions were analyzed using the chemical-mechanical correlation model. Effects of stress and temperature on SCC were analyzed using 63 sets of data for times to failure (tf) from 17 references. The data followed a systematic pattern which was described by the chemical-mechanical correlation model. An equation of tf as a function of stress and temperature was developed using an environmental parameter β that depends upon temperature, molybdenum concentration, and yield strength of the SS.

Engineering with advanced and new materials

Abstract In engineering with advanced and new materials, it is necessary to recognize that they are, like older traditional materials, reactive chemicals which are prone to react and corrode in ambient environments. Engineering with these advanced and new materials to assure their satisfactory performance within their design life is approached by following the ten steps in the “corrosion based design approach.” These steps include environmental definition, material definition, mode and submode definition, superposition, failure definition, statistical definition, accelerated testing, prediction, modification and optimization, and feedback and correction. When this approach is followed rigorously, maximum assurance of satisfactory performance is provided.

Stress Corrosion Cracking Growth of Alloy 800NG in Pressurized Water Reactor Primary Water

The primary purpose of this research is to examine the stress corrosion cracking (SCC) resistance of Alloy 800NG in pressurized water reactor (PWR) primary water and pressurized heavy water reactor (PHWR) primary water. Rates of SCC growth of 20% cold-worked (CW) Alloy 800NG measured over the temperature range between 270°C and 360°C were compared with previously reported results for 20% CW Alloy TT690 and 20% CW Alloy 600 in order to consider which material is the most SCC resistant among materials presently being used for steam generator (SG) tubing worldwide. The secondary purpose is to examine the effect of chromium addition on SCC growth in PWR primary water of a series of alloys based on the Alloy 800 composition. SCC growth measurements were performed in PWR primary water over the chromium concentration range from 16% to 27% to obtain fundamental knowledge useful for considering a future alternative SCC-resistant material for SG tubing in extended life PWRs and PHWRs. The third objective is to exam...