Development of a rapid stress corrosion test for aluminum alloys Annual report, 1 Mar. 1966 - 1 Mar. 1967
Accelerated stress corrosion tests for aluminum alloys
CORROSION TEST↗
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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Stress corrosion cracking of titanium alloys - Electrochemical mass transport kinetic model, metallurgical and mechanical effects, and proposed relation of electrochemical, metallurgical and mechanical effects Quarterly progress report, 1 Apr. - 30 J
Electrochemical mass transport kinetic model used to study metallurgical and mechanical effects of titanium alloy stress corrosion cracking
ELECTROCHEMICAL CORROSION↗
Stress corrosion cracking of titanium alloys.
Stress corrosion cracking of titanium alloys, noting tensile test data, crack propagation in salt solution and in pure solvents and metallurgical and electrochemical factors
METAL CRYSTAL↗
Corrosion Protection for Increased Resiliency of NASA's Launch and Ground Support Equipment
This presentation provides an overview of NASA's corrosion protection practices and technology development efforts throughout the history of the U.S. Space Program.
Coatings↗
Microstructure and Corrosion Behavior of the Cu-Pd-X Ternary Alloys for Hydrogen Separation Membranes
CuPd alloys are among the most promising candidate materials for hydrogen separation membranes and membrane reactor applications due to their high hydrogen permeability and better sulfur resistance. In order to reduce the Pd content and, therefore, the cost of the membrane materials, efforts have been initiated to develop CuPdM ternary alloys having a bcc structure. The advantages of having Pd as a hydrogen separation membrane are: (1) high hydrogen selectivity; and (2) high hydrogen permeability. The disadvantages are: (1) high cost; (2) hydrogen embrittlement ({alpha} {yields} {beta} Pd hydride); and (3) sulfur poisoning. Experiments (XRD, SEM/EDS) verified that Mg, Al, La, Y and Ti are promising alloying elements to expand the B2 phase region in Cu-Pd binary system. HT-XRD showed that the B2 to FCC transition temperatures for Cu-Pd-X (X = Mg, Al, La, Y and Ti) are higher than that of Cu-Pd binary alloys. While the Cu-50Pd alloy had the highest corrosion resistance to the H2S containing syngas, the Cu-Pd-Mg alloy had a comparable resistance.
08 HYDROGEN↗
Flow Accelerated Erosion-Corrosion (FAC) considerations for secondary side piping in the AP1000{sup R} nuclear power plant design
The issue of Flow Accelerated Erosion-Corrosion (FAC) in power plant piping is a known phenomenon that has resulted in material replacements and plant accidents in operating power plants. Therefore, it is important for FAC resistance to be considered in the design of new nuclear power plants. This paper describes the design considerations related to FAC that were used to develop a safe and robust AP1000{sup R} plant secondary side piping design. The primary FAC influencing factors include: - Fluid Temperature - Pipe Geometry/layout - Fluid Chemistry - Fluid Velocity - Pipe Material Composition - Moisture Content (in steam lines) Due to the unknowns related to the relative impact of the influencing factors and the complexities of the interactions between these factors, it is difficult to accurately predict the expected wear rate in a given piping segment in a new plant. This paper provides: - a description of FAC and the factors that influence the FAC degradation rate, - an assessment of the level of FAC resistance of AP1000{sup R} secondary side system piping, - an explanation of options to increase FAC resistance and associated benefits/cost, - discussion of development of a tool for predicting FAC degradation rate in new nuclear power plants. (authors)
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
Corrosion Behavior of Zinc-Nickel and Graphene Layered Structures on Steel Substrates
Large–area single layers of graphene are synthesized using chemical vapor deposition techniques and are assembled onto steel substrates that are finished with a thin layer of electrodeposited zinc–nickel (ZnNi). Atomic force microscopy combined with Raman spectroscopy is used to determine the number of the assembled graphene layers and to characterize the defects in their crystal structure. The graphene–ZnNi–steel layered specimens are exposed to a salt–fog environment. The defects in the structure of the graphene single layers are found to accelerate corrosion and the formation of a resistive oxide layer. The chemical composition and element map of the reacted surfaces are studied by x–ray photoelectron spectroscopy. In conclusion, the electrical properties of the samples before and after the salt–fog testing are evaluated using sheet resistance measurements.
36 MATERIALS SCIENCE↗
Accumulation of Corrosion-Fatigue Damage by Hydro Turbine Equipment Elements
Questions are considered for evaluating material damage and substantiation of life on the basis of corrosion-fatigue crack development kinetics. Linear fracture mechanics are used for this approach suitable for large and small cracks, which makes it possible to include a nominal initial crack l0 among basic material properties. Calculated curves for fatigue in an aqueous medium based on 1010 cycles, and the curves for fatigue damage accumulation corresponding to 106 and 1010 cycles are provided for specimens with a cross section of 180X200 mm of steel 06Kh12N3D in rolled and cast conditions. Results are provided for evaluation of the life of during action of two-stage loading and repeated overloading.
42 ENGINEERING↗
Effect of Post-deformation Annealing Treatment on the Microstructural Evolution of a Cold-Worked Corrosion-Resistant Superalloy (CRSA) Steel
The post-deformation annealing treatments of a commercial cold-worked corrosion-resistant superalloy steel (Sanicro 28 steel) were carried out at different temperatures in the range of 900-1100 °C for different holding durations of 5, 10, and 15 min. The effects of post-deformation annealing time and temperature on the microstructural evolution and subsequent mechanical properties of the processed Sanicro 28 steel were investigated. The observations indicated that twin–twin hardening in cold deformation condition mainly correlates with abundant nucleation of mechanical twins in multiple directions resulting in considerable strain hardening behavior. Microstructural investigations showed that the static recrystallization takes place after isothermal holding at 900 °C for 5 min. Increasing the annealing temperature from 900 to 1050 °C leads to recrystallization development and grain refinement in the as-recrystallized state. In addition, an increase in annealing duration from 5 to 15 min leads to subgrain coarsening and subsequently larger recrystallized grains size. The occurrence of large proportion of the grain refinement, which is achieved in the first annealing stage at 1050 °C after 5 min, is considered as the main factor for the maximum elongation at this stage.
36 MATERIALS SCIENCE↗
Pitting Corrosion of Supermartensitic Stainless Steel in Chloride Solutions Containing Thiosulfate or H{sub 2}S
Deepwater oil and gas extraction environment have high salinity, low oxygen content, and the presence of carbon dioxide and hydrogen sulfide (H{sub 2}S). Handling of H{sub 2}S-containing gaseous mixtures should be carried out in laboratories with special installations, owing to the high toxicity of this gas. An alternative is the use of non-toxic substances that can generate H{sub 2}S in the medium, such as sodium thiosulfate. The objective of this work is to study the viability of substituting H{sub 2}S by thiosulfate for the evaluation of the susceptibility to pitting corrosion in sour environments of the supermartensitic stainless steel (SMSS). The electrochemical behavior of SMSS in NACE TM0177-2016 solution C solution containing different concentrations of H{sub 2}S or thiosulfate ions at 10{sup −3} mol/L was performed by using cyclic potentiodynamic polarization (CPP). The condition of shorter OCP time (300 s) prevents the formation of a passive layer and allows the generation of H{sub 2}S due to the reaction of the solution with the metal surface. The CPP curves of SMSS in the media containing 3% H{sub 2}S/Ar (2.96 kPa) and 10{sup −3} M of thiosulfate ions (OCP 300 s) were similar, the pitting potential was about − 322.5 ± 8.7 and − 338.8 ± 11.4 mV{sub Ag/AgCl}, respectively, and the pit morphology showed several small pits on the steel surface in both conditions, suggesting the viability of the use of thiosulfate-containing brines to simulate H{sub 2}S solutions.
36 MATERIALS SCIENCE↗
Influence of Rust Permeability on Corrosion of E690 Steel in Industrial and Non-industrial Marine Splash Zones
The corrosion behaviour of E690 steel in industrial and non-industrial marine splash environments was studied by environmental testing, morphology analysis, electrochemical measurements, and scanning Kelvin probe microscopy. Chloride and sulphide anions were found to diffuse across the rust layer following the evaporation of seawater splashed on the steel’s surface. The cation-selective permeability of the rust layer resulted in an anion concentration gradient across the rust layer, which was more significant in the presence of sulphur dioxide. In addition, sulphur dioxide enhanced the formation of α-FeOOH, which led to the formation of distinct anode and cathode areas at the rust/steel interface.
36 MATERIALS SCIENCE↗
Effect of Overaging on Fatigue Crack Propagation and Stress Corrosion Cracking Behaviors of an Al-Zn-Mg-Cu Alloy Thick Plate
The fatigue property as well as stress corrosion cracking (SCC) resistance of an Al-Zn-Mg-Cu alloy thick plate in peak-aged and overaged tempers (T7351 and T7651) is systematically investigated by fatigue crack propagation (FCP) test and slow strain rate test (SSRT). Microstructural characterization is examined by transmission electron microscopy and scanning electron microscopy. Results reveal that the T7351 alloy has lower strength but higher electrical conductivity as compared to T7651 alloy. The FCP resistance of T7351 alloy is superior to that of the T7651 alloy due to the coarser precipitates in the highly overaged alloy in which the strain localization is reduced by promoting homogeneous slip. In addition, the SSRT test suggests a higher SCC resistance in T7351 alloy. The enhanced SCC resistance is found to depend on grain boundary precipitate characteristics and crack propagation resistance of the alloys.
36 MATERIALS SCIENCE↗
Corrosion Behavior of Sm{sub y}(Fe{sub x}Ni{sub 1−x}){sub 4}Sb{sub 12} (0.40 ≤ x ≤ 0.80) in NaCl Solutions Studied by Electron Microscopy and ICP-AES
Filled skutterudites are currently studied as thermoelectric materials to be used in the automotive and nautical field; the study of their resistance to a saline environment is therefore mandatory. To this purpose, the corrosion behavior of several compositions belonging to the Sm{sub y}(Fe{sub x}Ni{sub 1−x}){sub 4}Sb{sub 12} skutterudites system was investigated by immersing samples in differently concentrated (0.1 and 0.5 M) NaCl solutions. The effect of the treatment was analyzed both by SEM–EDS on the sample surface and at fixed times by ICP-AES on the solution. The formation of an oxide layer was observed on the surface of all the samples: the film results uniformly grown on specimens treated in NaCl at the lower concentration, while it is cracked and not spread over the whole surface in the other samples. Relying on the oxide layer thickness, the oxidation resistance results to increase with increasing the Fe content; correspondingly, the Sb concentration in the more diluted solution decreases at each time considered with increasing the Fe amount, pointing at a strict correlation between the cationic release and the oxide formation, and suggesting a possible mechanism for the growth of the protective film.
36 MATERIALS SCIENCE↗
Pitting Corrosion of 10Ni8CrMoV High-Strength Steel Induced by a Potential Perturbation
Pitting corrosion of high-strength steel 10Ni8CrMoV under square wave polarization (SWP) in simulated deep-sea environment is investigated and the possible mechanism is proposed. The results show that potential perturbation generates periodic intensification effect on both anodic and cathodic processes by frequently breaking the electrode equilibrium state. The intensity of periodic intensification effect essentially depends on the concentration gradient of Fe{sup 2+} cations at the steel/solution interface which acts as the forced electrochemical oscillator. The concentration gradient and the resulting concentration polarization effect increase periodically with the increase in SWP potential range. The morphology observation of the pitting and electric charge calculation indicate that the periodic intensification effect can promote the initiation and growth of pits by enhancing the anodic dissolution even under cathodic protection, but it is ineffective below the hydrogen evolution potential. The decrease in either upper or lower potential can mitigate anodic dissolution. Through the statistical analysis of pitting size, it is found that the wide potential range tends to activate the metastable pitting formed under hydrostatic pressure, forming densely distributed pitting. Meanwhile, it is more favorable to the formation of fully grown pits with high size dispersion degree when the proportion of electric charge in the anodic process is higher.
36 MATERIALS SCIENCE↗
Sulfide Stress Corrosion Cracking Behavior of G105 and S135 High-Strength Drill Pipe Steels in H{sub 2}S Environment
Slow strain rate testing was employed to investigate the sulfide stress corrosion cracking (SSCC) behavior of low-carbon high-strength drill pipe steels (G105 and S135) in the simulated drilling environment containing H{sub 2}S. Results reveal that both G105 and S135 steels have a high SSCC susceptibility in the simulated drilling environment containing H{sub 2}S. In the range of experimental slow strain rate, the SSCC sensitivity of drill pipe steel increases with the decrease in slow strain rate, and the ductility and fracture properties of drill pipe steels also decrease obviously. With the increase in the steel strength, the SSCC sensitivity of the drill pipe steel increases, and the S135 drill pipe steel has higher SSCC sensitivity than G105. There is no obvious plastic deformation on the fracture surface of G105 and S135 steels in H{sub 2}S solution. The cracks of fracture sprout on the surface of the specimen, the instantaneous fracture zone is in the middle, and the fracture can be divided into the cracking and the final fracture zone. The SSCC mechanisms of two drill pipe steels are hydrogen embrittlement. The hydrogen enters the steel and reduces the binding force of the iron atom, resulting in cleavage fracture.
36 MATERIALS SCIENCE↗
Corrosion Fatigue Behaviors of Type 316 LN Cold-Worked Stainless Steels in Acidified Chloride Environment
The effect of cold work (CW) on the microstructure and corrosion fatigue (CF) resistance of 316 LN stainless steel (SS) using microscopic, electrochemical and surface analytical methods was investigated. The CF resistance increases with CW. The fractographs revealed that the crack growth zone was minimum for the base metal as compared to CW SS. Fatigue-tested sample revealed a slip offset was high for as-received, while not much significant difference for 5 and 20% CW SS at low mean stress levels. The presence of NH{sub 4} improved passivity by the formation of nitrate ions that inhibits anodic dissolution.
36 MATERIALS SCIENCE↗
Effect of AC Current Density on the Stress Corrosion Cracking Behavior and Mechanism of E690 High-Strength Steel in Simulated Seawater
In this work, we studied the impact of alternating current (AC) density on the stress corrosion cracking (SCC) behavior and mechanism of E690 high-strength steel in simulated seawater with electrochemical measurements, U-bend immersion tests and slow strain rate tensile tests. Results demonstrate that AC enhances both anodic and cathodic processes, especially localized anodic dissolution and hydrogen evolution, which manifests as the increase in i{sub corr} with AC current density rising. Therefore, AC leads to higher SCC susceptibility. Accordingly, SCC is dominated by anodic dissolution (AD) at low AC current density while in a mixed control of AD and hydrogen embrittlement (HE) at high AC current density as a result of increasing hydrogen concentration. Besides, 50 A/m{sup 2} corresponds to the threshold hydrogen concentration of the “hydrogen-induced plasticity to HE” transformation, which is due to the different interactions of dislocation and hydrogen.
36 MATERIALS SCIENCE↗
Towards Automated Design of Corrosion Resistant Alloy Coatings with an Autonomous Scanning Droplet Cell
We present an autonomous scanning droplet cell platform designed for on-demand alloy electrodeposition and real-time electrochemical characterization. Automation and machine learning are currently driving rapid innovation in high-throughput and autonomous materials design and discovery. We present two alloy design vignettes: one focusing on a multi-objective corrosion resistant alloy optimization and a study highlighting the complexity of the multimodal characterization needed to provide insight into the underlying structural and chemical factors that drive observed material behavior. This motivates a close coupling between autonomous research platforms and scientific machine learning methodology that blends mechanistic physical models and black box machine learning models. Lastly, we reflect on our early efforts in on-demand alloy deposition, highlighting some of the challenges. This emerging research area presents new opportunities to accelerate materials synthesis, evaluation, and hence discovery and design.
36 MATERIALS SCIENCE↗