Hydrogen Embrittlement Characteristics in Irradiated Stainless Steel

2020 ◽  
Author(s):  
Sarah Khalil ◽  
Tarek M. Hatem
Keyword(s):  
Stainless Steel ◽  
Nuclear Reactors ◽  
Early Stage ◽  
Cooling Water ◽  
Dislocation Loops ◽  
Dynamics Model ◽  
Defect Migration ◽  
Corrosion Reaction ◽  
Hydrogen Vacancy ◽  
Clustering Behavior

Abstract Hydrogen is produced in nuclear reactors as a by-product of the corrosion reaction between the pressure vessel and the cooling water, where hydrogen produced may enter the metal in atomic form. During operation a reactor vessel is exposed to avalanche of neutron irradiation fluxes, in addition to corrosion from cooling water. A novel cluster dynamics model that accounts for off-stoichiometry of clusters and matrix was developed and applied to investigate the clustering behavior of Hydrogen-vacancy and Hydrogen-interstitial clusters in proton irradiated stainless steel has been developed. The differences in point defect migration energies and binding energy of H to lattice defects, makes it possible to have vacancy and interstitial clusters having compositions different from those of pure iron. The model predicts populations of Defect-Hydrogen complexes in iron. The model is applied to the early stage formation of voids and dislocation loops in stainless steel in the presence of atomic hydrogen. This study investigates the effect of irradiation dose and temperature on the concentration of vacancy-Hydrogen (VmHn) and Intersitial Fe-H (FemHn) complexes on bulk α-Iron. The re

Nucleation and amorphization of radiation-produced phases in a modified austenitic stainless steel during Ni-ion irradiation

1988 ◽  
Vol 3 (5) ◽  
pp. 840-844 ◽  
Author(s):  
E. H. Lee ◽  
E. A. Kenik
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Ion Irradiation ◽  
Amorphous State ◽  
Dislocation Loops ◽  
Nickel Ion ◽  
Carbide Phases ◽  
Direct Formation ◽  
Radiation Induced ◽  
Lower Temperature

The nucleation and amorphization of radiation-induced (G) and radiation-enhanced (η) phases in a silicon- and titanium-modified austenitic stainless steel have been studied under nickel-ion irradiation. These silicon- and nickel-enriched phases form under high-temperature (950 K) irradiation as the result of radiation-induced segregation to radiation-produced interstitial dislocation loops. Availability of carbon promotes the formation of η phase relative to G phase. Under lower temperature (450 K) irradiation, G and η phases are amorphized without significant change in composition of metallic elements. Two carbide phases (MC, M23C6) remain crystalline for the same irradiation conditions. The amorphization of the silicides may result from (1) radiation damage increasing their free energy above that of the amorphous state or (2) direct formation of the amorphous phase in the damage cascade.

Evaluation of the Tube to Tubesheet Joining Process in an AL6XN® Feedwater Heater

2017 ◽  
Author(s):  
Eric Svensson ◽  
Michael Catapano
Keyword(s):  
High Pressure ◽  
Stainless Steel ◽  
Cooling Water ◽  
Intimate Contact ◽  
Pull Out ◽  
Digital Microscope ◽  
304 Austenitic Stainless Steel ◽  
Type 304 ◽  
Tube Expansion ◽  
Joining Process

Type 304 austenitic stainless steel is the most common tube material utilized for nuclear feedwater heaters, however, some utilities have experienced problems with Stress Corrosion Cracking (SCC), especially when they utilize brackish cooling water and have experienced condenser tube leaks. This has forced some utilities to explore other options when it comes to high pressure feedwater heaters (HP FWH) tubing materials. AL6XN® is considered a “super” stainless steel that is resistant to (SCC), however, it is not immune (AL6XN is a trademark of ATI Technologies). Based on the relative inexperience and unknowns related to the use of AL6XN tubing in high pressure, nuclear feedwater heater applications, a detailed mock-up procedure was outlined as part of the replacement heater specification which would allow the evaluation of the tube to tubesheet joining processes. Since AL6XN can still be affected by SCC; steps were taken in order to minimize the imposed stress levels and any potential for the inadvertent inclusion of contaminants during the fabrication steps at the tube mill and at the feedwater heater Manufacturer’s shop. The desire to minimize stresses also applies at the tube to tubesheet joint, therefore, it was desired not to stress the tube more than absolutely necessary in achieving a reliable, leak tight joint. The mock-up details and procedures were therefore generated with these objectives in mind, so as to give consideration for the ability to check different configurations in order to determine the most efficient tube to tubesheet joining process. Several tubes in the mock-up were subjected to a pull out test in order to quantify the joint strength in the different configurations. The mockup was then sectioned and inspected under a digital microscope to verify intimate contact between the tube and the tubesheet. Once the optimal procedure was identified, four identical HP FWHs were constructed utilizing AL6XN tubing. During heater production, over 30,000 tube ends were expanded, however, two tubes were identified to have failures as part of the tube expansion process. This paper shall describe the procedures utilized in developing and analyzing the tubesheet mock-up as well the actions taken to identify the root causes of the tube failures.

Effect of Self-Interstitial Diffusion Anisotropy in Electron-Irradiated Zirconium. A Cluster Dynamics Modeling

2005 ◽  
Vol 237-240 ◽  
pp. 659-664
Author(s):  
Frédéric Christien ◽  
Alain Barbu
Keyword(s):  
Point Defects ◽  
Thin Foil ◽  
Elastic Interaction ◽  
Dislocation Loops ◽  
Considerable Influence ◽  
Dynamics Modeling ◽  
Dynamics Model ◽  
Diffusion Anisotropy ◽  
Vacancy Loops ◽  
Transmission Electron

Irradiation of metals leads to the formation of point-defects (vacancies and selfinterstitials) that usually agglomerate in the form of dislocation loops. Due to the elastic interaction between SIA (self-interstitial atoms) and dislocations, the loops absorb in most cases more SIA than vacancies. That is why the loops observed by transmission electron microscopy are almost always interstitial in nature. Nevertheless, vacancy loops have been observed in zirconium following electron or neutron irradiation (see for example [1]). Some authors proposed that this unexpected behavior could be accounted for by SIA diffusion anisotropy [2]. Following the approach proposed by Woo [2], the cluster dynamics model presented in [3] that describes point defect agglomeration was extended to the case where SIA diffusion is anisotropic. The model was then applied to the loop microstructure evolution of a zirconium thin foil irradiated with electrons in a high-voltage microscope. The main result is that, due to anisotropic SIA diffusion, the crystallographic orientation of the foil has considerable influence on the nature (vacancy or interstitial) of the loops that form during irradiation.

A New Dislocation-Dynamics Model and Its Application in Thin Film-Substrate Systems

2005 ◽  
Vol 875 ◽  
Author(s):  
E.H. Tan ◽  
L.Z. Sun
Keyword(s):  
Thin Films ◽  
Mechanical Performance ◽  
Dislocation Motion ◽  
Dislocation Dynamics ◽  
Dislocation Segment ◽  
Dislocation Loops ◽  
Dynamics Model ◽  
Proposed Model ◽  
Simulation Results ◽  
Film Substrate

AbstractBased on the physical background, a new dislocation dynamics model fully incorporating the interaction among differential dislocation segments is developed to simulate 3D dislocation motion in crystals. As the numerical simulation results demonstrate, this new model completely solves the long-standing problem that simulation results are heavily dependent on dislocation-segment lengths in the classical dislocation dynamics theory. The proposed model is applied to simulate the effect of dislocations on the mechanical performance of thin films. The interactions among the dislocation loops, free surface and interfaces are rigorously computed by a decomposition method. This framework can be used to simulate how a surface loop evolves into two threading dislocations and to determine the critical thickness of thin films. Furthermore, the relationship between the film thickness and yield strength is established and compared with the conventional Hall-Petch relation.

Magnetic Barkhausen Noise Technique for Early Stage Fatigue Prediction in Martensitic Stainless-Steel Samples (invited)

2021 ◽  
pp. 1-18
Author(s):  
Zi Li ◽  
Bharath Basti Shenoy ◽  
L. Udpa ◽  
Yiming Deng
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Power Plants ◽  
Early Stage ◽  
Fatigue Cracks ◽  
Turbine Blades ◽  
Barkhausen Noise ◽  
Magnetic Barkhausen Noise ◽  
Operating Cycle ◽  
Microstructure Changes

Abstract Martensitic grade stainless steel is generally used to manufacture steam turbine blades in power plants. The material degradation of those turbine blades, due to fatigue, will induce unexpected equipment damage. Fatigue cracks, too small to be detected, can grow severely in the next operating cycle and may cause failure before the next inspection opportunity. Therefore, a nondestructive electromagnetic technique, which is sensitive to microstructure changes in the material, is needed to provide a means to estimate the specimen’s fatigue life. To tackle these challenges, this paper presents a novel Magnetic Barkhausen noise (MBN) technique for garnering information relating to the material microstructure changes under test. The MBN signals are analyzed in time as well as frequency domain to infer material information that are influenced by the samples’ mate- rial state. Principal Component Analysis (PCA) is applied to reduce the dimensionality of feature data and extract higher order features. Afterwards, Probabilistic Neural Network (PNN) classifies the sample based on the percentage fatigue life to discover the most correlated MBN features to indicate the remaining fatigue life. Furthermore, one criticism of MBN is its poor repeatability and stability, therefore, Analysis of Variance (ANOVA) is carried out to analyze the uncertainty associated with MBN measurements. The feasibility of MBN technique is investigated in detecting early stage fatigue, which is associated with plastic deformation in ferromagnetic metallic structures. Experimental results demonstrate that the Magnetic Barkhausen Noise technique is a promising candidate for characterizing.

New corrosion inhibitor for 13Cr stainless steel in 20% HCl solution

2020 ◽  
Vol 67 (6) ◽  
pp. 557-564
Author(s):  
Pingli Liu ◽  
Yanhua Zhu ◽  
Liqiang Zhao
Keyword(s):  
Stainless Steel ◽  
Corrosion Inhibitor ◽  
Mannich Reaction ◽  
Corrosion Mechanism ◽  
Oil Well ◽  
Content Type ◽  
Layer Function ◽  
Corrosion Reaction ◽  
Hydrogen Evolution Reactions ◽  
Hcl Solution

Purpose A novel compound was synthesized by cyclohexylamine, acetophenone and cinnamaldehyde through Mannich reaction in laboratory to use as corrosion inhibitor for steel in acidification process. Design/methodology/approach The corrosion and inhibition of 13Cr stainless steel in conventional acidification solution were investigated by electrochemical measurements and soaking experiments. The corrosion appearance was observed with scanning electron microscope on the whole surface of 13Cr stainless steel in 20% HCl solution, and the protection film was confirmed on the surface in presence with inhibitor. Findings Results manifested that the inhibitor C23H27NO can effectively inhibit the corrosion reaction by forming an adsorption layer function as a barrier. Polarization curves indicated that the mixed inhibitor can reduce anodic dissolution and cathodic hydrogen evolution reactions simultaneously. The results of impedance measurements indicated that this inhibitor cannot change the corrosion mechanism of 13Cr stainless steel in 20% HCl solution. The results of the study can provide a theoretical basis for the application of 13Cr stainless steel in conventional acidification solutions during oil well acidification construction process. Originality/value A novel compound was synthesized by cyclohexylamine, acetophenone and cinnamaldehyde through Mannich reaction in laboratory to use as corrosion inhibitor for steel in acidification process. The corrosion and anti-corrosion mechanism of 13Cr steel in acid solution was proposed.

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