Effect of Structural State of Austenitic 15-15 Ti Steel on Initiation and Propagation of Solution-Based Corrosion Attack in Flowing Liquid Pb-Bi Eutectic at 400 and 500 °C

2017 ◽  
Author(s):  
Valentyn Tsisar ◽  
Carsten Schroer ◽  
Olaf Wedemeyer ◽  
Aleksandr Skrypnik ◽  
Jürgen Konys
Keyword(s):  
Structural State ◽  
Qualitative Information ◽  
Corrosion Attack ◽  
Flowing Liquid ◽  
Type Distribution ◽  
Initiation And Propagation ◽  
Identical Composition ◽  
Diffusion Paths ◽  
Cold Worked

Investigations of corrosion behavior of austenitic 1.4970 (15–15 Ti) steel in Pb-Bi eutectic at 400–550 °C show an effect of structural state of material with identical composition on the depth of solution-based attack. Structural boundaries play a role of active paths along which the solution-based liquid-metal attack develops preferentially. In this view it is important to have quantitative and qualitative information about grain boundary type distribution in material and state of boundaries with respect to the accumulated strains. The EBSD analysis performed on 1.4970 steel in solution-annealed and cold-worked (40% reduction) states indicates that deformation increases substantially the total length of strained boundaries. The increase in fraction of active diffusion paths results in acceleration of corrosion attack on steel via solution.

Effect of Structural State and Surface Finishing on Corrosion Behavior of 1.4970 Austenitic Steel at 400 and 500 °C in Flowing Pb-Bi Eutectic With Dissolved Oxygen

2018 ◽  
Vol 4 (4) ◽  
Author(s):  
Valentyn Tsisar ◽  
Carsten Schroer ◽  
Olaf Wedemeyer ◽  
Aleksandr Skrypnik ◽  
Jürgen Konys
Keyword(s):  
Oxide Film ◽  
Dissolved Oxygen ◽  
Corrosion Behavior ◽  
Structural State ◽  
Cold Work ◽  
Surface Finishing ◽  
Polished Surface ◽  
Type Solution ◽  
Corrosion Attack ◽  
Cold Worked

The effect of structural state (solution annealed (SA) and after 40% cold work (CW)) and surface finishing (turning, grinding, and polishing) on the corrosion behavior of austenitic 1.4970 (15-15 Ti) steel in flowing (2 m/s) Pb-Bi eutectic containing 10−7 mass% dissolved oxygen at 400 °C and 10−6 mass% O at 500 °C is investigated. At 400 °C for ∼13,000 h, the corrosion losses are minor for steel in both structural states and for surfaces finished by turning and grinding—a thin Cr-based oxide film is formed. In contrast, the polished surface showed initiation of solution-based corrosion attack with the formation of iron crystallites and preferential propagation along the grain boundaries. The depth of corrosion attack does not exceed 10 μm after ∼13,000 h. At 500 °C for 2000 h, the samples in both structural states showed general slight oxidation. Cold-worked steel underwent a severe groove-type and pit-type solution-based attack of 170 μm in maximum depth, while the SA sample showed only sporadic pit-type corrosion attack to the depth of 45 μm in maximum.

An Study of Influence of Imperfections on the Delamination of Diamond-Like Carbon Films

2002 ◽  
Vol 719 ◽  
Author(s):  
Myoung-Woon Moon ◽  
Kyang-Ryel Lee ◽  
Jin-Won Chung ◽  
Kyu Hwan Oh
Keyword(s):  
Cross Sections ◽  
Focused Ion Beam ◽  
Imaging System ◽  
Ion Beam ◽  
Carbon Films ◽  
Diamond Like Carbon ◽  
Glass Substrates ◽  
Atomic Force ◽  
Initiation And Propagation

AbstractThe role of imperfections on the initiation and propagation of interface delaminations in compressed thin films has been analyzed using experiments with diamond-like carbon (DLC) films deposited onto glass substrates. The surface topologies and interface separations have been characterized by using the Atomic Force Microscope (AFM) and the Focused Ion Beam (FIB) imaging system. The lengths and amplitudes of numerous imperfections have been measured by AFM and the interface separations characterized on cross sections made with the FIB. Chemical analysis of several sites, performed using Auger Electron Spectroscopy (AES), has revealed the origin of the imperfections. The incidence of buckles has been correlated with the imperfection length.

scholarly journals The Role of Intersubunit Interactions for the Stabilization of the T State ofEscherichia coliAspartate Transcarbamoylase

2002 ◽  
Vol 277 (51) ◽  
pp. 49755-49760 ◽  
Author(s):  
Robin S. Chan ◽  
Jessica B. Sakash ◽  
Christine P. Macol ◽  
Jay M. West ◽  
Hiro Tsuruta ◽  
...  
Keyword(s):  
Small Angle ◽  
Structural State ◽  
Aspartate Transcarbamoylase ◽  
Wild Type ◽  
X Ray ◽  
X Ray Scattering ◽  
Intersubunit Interactions ◽  
T State ◽  
Ray Scattering

Homotropic cooperativity inEscherichia coliaspartate transcarbamoylase results from the substrate-induced transition from the T to the R state. These two alternate states are stabilized by a series of interdomain and intersubunit interactions. The salt link between Lys-143 of the regulatory chain and Asp-236 of the catalytic chain is only observed in the T state. When Asp-236 is replaced by alanine the resulting enzyme exhibits full activity, enhanced affinity for aspartate, no cooperativity, and no heterotropic interactions. These characteristics are consistent with an enzyme locked in the functional R state. Using small angle x-ray scattering, the structural consequences of the D236A mutant were characterized. The unliganded D236A holoenzyme appears to be in a new structural state that is neither T, R, nor a mixture of T and R states. The structure of the native D236A holoenzyme is similar to that previously reported for another mutant holoenzyme (E239Q) that also lacks intersubunit interactions. A hybrid version of aspartate transcarbamoylase in which one catalytic subunit was wild-type and the other had the D236A mutation was also investigated. The hybrid holoenzyme, with three of the six possible interactions involving Asp-236, exhibited homotropic cooperativity, and heterotropic interactions consistent with an enzyme with both T and R functional states. Small angle x-ray scattering analysis of the unligated hybrid indicated that the enzyme was in a new structural state more similar to the T than to the R state of the wild-type enzyme. These data suggest that three of the six intersubunit interactions involving D236A are sufficient to stabilize a T-like state of the enzyme and allow for an allosteric transition.

The Role Of Microstructures And The Diffusion Of Hydrogen In A Plain Carbon Eutectoid Steel For Pressure Vessels

2012 ◽  
Author(s):  
Ronnie Higuchi Rusli
Keyword(s):  
Hydrogen Embrittlement ◽  
Room Temperature ◽  
Pressure Vessels ◽  
Electrochemical Technique ◽  
Eutectoid Steel ◽  
Chemical Pressure ◽  
Hydrogen Retention ◽  
Cold Worked ◽  
Diffusion Of Hydrogen

An electrochemical technique was used to measure the room temperature diffusivity and trapping of hydrogen in a 0.82%C steel for chemical pressure vessels in two micro structural conditions (a) the cold worked pearlitic state and (b) the hardened and tempered state. Trapping of hydrogen occurs in both structures but with more traps in the cold worked structure. Base on experimental results and observation, different hydrogen retention (trapping) behavior operates in the two structures. It was also found that patented and cold worked steels are much less susceptible to hydrogen induced embrittlement than similar steels in the hardened and tempered condition. Key words: Diffusivity of hydrogen; hydrogen embrittlement; cold–worked

Shear Cavitation

2005 ◽  
Author(s):  
P. A. Kottke ◽  
S. Bair ◽  
W. O. Winer
Keyword(s):  
Normal Stress ◽  
Hydrodynamic Pressure ◽  
Local Flow ◽  
Flowing Liquid ◽  
Principal Normal Stress ◽  
State Of Stress ◽  
Nucleation Sites ◽  
Theoretical Foundations ◽  
Viscous Stresses

The importance of cavitation in lubrication hydrodynamics is well recognized. Cavitation can also act as a source of experimental error in rheological measurements. Therefore, the ability to understand and predict cavitation is important for tribology. Nearly all models for cavitation prediction are based on the local hydrodynamic pressure. The appropriateness of this approach when viscous stresses are of the order of the hydrodynamic pressure is questionable. One cavitation model that considers the state of stress in a flowing liquid is the principal normal stress cavitation criterion (PNSCC), which proposes that cavitation will occur when the most tensile principal normal stress exceeds some critical value. Although this hypothesis can accommodate many experimental observations, its theoretical foundations are weak. In particular, it fails to account for the tensile strength of liquids and resulting need for nucleation sites; it neglects the role of transport of dissolved gases; and it does not consider the effect of a growing bubble on the local flow, and hence local state of stress. We demonstrate cavitation in low Reynolds number Couette flow, and present a model for cavitation in shear in the limit of creeping (Stokes) flow, which corrects for the theoretical failures of the PNSCC. We use numerical simulation to analyze cavitation onset, and obtain a more general cavitation criteria from which the PNSCC is recovered under certain conditions.

Role of Cavity Formation in Crack Initiation of Cold-Worked Carbon Steel in High-Temperature Water

CORROSION ◽  
10.5006/0821 ◽  
2013 ◽  
Vol 69 (5) ◽  
pp. 487-496 ◽  
Author(s):  
Koji Arioka ◽  
Tomoki Miyamoto ◽  
Takuyo Yamada ◽  
Masanori Aoki
Keyword(s):  
High Temperature ◽  
Carbon Steel ◽  
Crack Initiation ◽  
Cavity Formation ◽  
High Temperature Water ◽  
Cold Worked ◽  
Temperature Water
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