Effect of Oxygen Potential on Crack Growth in Alloys for Advanced Energy Systems

2010 ◽  
Vol 132 (10) ◽  
Author(s):  
Julian K. Benz ◽  
Ji Hyun Kim ◽  
Ronald G. Ballinger
Keyword(s):  
Growth Rate ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Crack Growth ◽  
Oxygen Concentration ◽  
Crack Path ◽  
Fatigue Loading ◽  
Effect Of Oxygen ◽  
Static Conditions

The effect of oxygen partial pressure on crack growth rates in Alloy 617 has been studied using both static and fatigue loadings at 650°C over the oxygen partial pressure range 10−19−10−3 atm. Tests were conducted at either the constant stress intensity factor K for static conditions or the constant ΔK in fatigue. Oxygen concentration was measured on both the inlet and outlet of the test retort as well as in situ with a probe located directly at the specimen surface. For fatigue loading the crack path was observed to be transgranular but crystallographic with a decreasing growth rate as the oxygen concentration decreased. However, for static loading the crack path shifted to intergranular at the same Kmax (fatigue) and exhibited what appears to be an increasing crack growth rate with decreasing oxygen concentration.

Effect of Oxygen Potential on Crack Growth in Alloys for Advanced Energy Systems

2008 ◽  
Author(s):  
Julian K. Benz ◽  
J. H. Kim ◽  
Ronald G. Ballinger
Keyword(s):  
Growth Rate ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Crack Growth ◽  
Oxygen Concentration ◽  
Crack Path ◽  
Fatigue Loading ◽  
Effect Of Oxygen ◽  
Static Conditions

The effect of oxygen partial pressure on fatigue and SCC growth rates in alloy 617 has been studied using both static and fatigue loading @ 650°C over the oxygen partial pressure range 10−19–10−2 atm. Tests were conducted at either constant stress intensity factor, K, for static conditions or constant ΔK in fatigue. Oxygen concentration was measured on both the inlet and outlet as well as in-situ with a probe located directly at the specimen surface. For fatigue loading the crack path was observed to be transgranular but crystallographic with a decreasing growth rate as the oxygen concentration decreased. However, for static loading the crack path shifted to intergranular and exhibited an increasing crack growth rate with decreasing oxygen concentration.

Oxygen-Partial-Pressure Dependence of SiC Oxidation Rate Studied by In Situ Spectroscopic Ellipsometry

2008 ◽  
Vol 600-603 ◽  
pp. 667-670 ◽  
Author(s):  
Takeshi Yamamoto ◽  
Yasuto Hijikata ◽  
Hiroyuki Yaguchi ◽  
Sadafumi Yoshida
Keyword(s):  
Growth Rate ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Pressure Dependence ◽  
Oxidation Rate ◽  
Pressure Range ◽  
Empirical Relation ◽  
Oxide Thickness ◽  
Oxide Growth

Real time observations of SiC (000–1) C-face and (0001) Si-face oxidation were performed using an in-situ ellipsometer over the oxygen-partial-pressure range from 0.1 to 1.0 atm. We analyzed the relations between oxide growth rate and oxide thickness by applying an empirical relation proposed by Massoud et al. We found the occurrence of oxidation enhancement in the thin oxide regime also for Si-face as well as for C-face. We have discussed the oxygen-partial-pressure dependence of the oxidation rate constants between SiC C- and Si face, comparing with that of Si.

scholarly journals In-situ SEM and optical microscopy testing for investigation of fatigue crack growth mechanism under overload

2018 ◽  
Vol 165 ◽  
pp. 13013
Author(s):  
Wei Zhang ◽  
Liang Cai
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Optical Microscopy ◽  
Crack Growth ◽  
Load Condition ◽  
Crack Tip ◽  
Initial Crack ◽  
Crack Growth Behavior ◽  
Single Overload

In this paper, the in-situ scanning electron microscope (SEM) and optical microscopy experiments are performed to investigate the crack growth behavior under the single tensile overload. The objectives are to (i) examine the overload-induced crack growth micromechanisms, including the initial crack growth acceleration and the subsequent retardation period; (ii) investigate the effective region of single overload on crack growth rate. The specimen is a small thin Al2024-T3 plate with an edge-crack, which is loaded and observed in the SEM chamber. The very high resolution images of the crack tip are taken under the simple variable amplitude loading. Imaging analysis is performed to quantify the crack tip deformation at any time instant. Moreover, an identical specimen subjected to the same load condition is observed under optical microscope. In this testing, fine speckling is performed to promote the accuracy of digital imaging correlation (DIC). The images around the crack tip are taken at the peak loads before, during and after the single overload. After that, the evolution of local strain distribution is obtained through DIC technique. The results show that the rapid connection between the main crack and microcracks accounts for the initial crack growth acceleration. The crack closure level can be responsible for the crack growth rate during the steady growth period. Besides that, the size of retardation area is larger than the classical solution.

The effect of oxygen partial pressure on the filiform corrosion of organic coated iron

2014 ◽  
Vol 89 ◽  
pp. 46-58 ◽  
Author(s):  
T.M. Watson ◽  
A.J. Coleman ◽  
G. Williams ◽  
H.N. McMurray
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Filiform Corrosion ◽  
Effect Of Oxygen

Effect of Oxygen Partial Pressure on Oxidation of Iron at 573 K

1984 ◽  
Vol 21 (11) ◽  
pp. 844-852 ◽  
Author(s):  
Hitoshi SAKAI ◽  
Toshihide TSUJI ◽  
Keiji NAITO
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Effect Of Oxygen

Characterization of YBa2Cu4O8 high temperature electrical properties and thermodynamic stability

1991 ◽  
Vol 6 (10) ◽  
pp. 2054-2058 ◽  
Author(s):  
B-S. Hong ◽  
T.O. Mason
Keyword(s):  
High Temperature ◽  
Electrical Property ◽  
Electrical Properties ◽  
Seebeck Coefficient ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Pressure Range ◽  
Stability Range

Via in situ electrical property measurements (conductivity, Seebeck coefficient) over the temperature range 500–800 °C and oxygen partial pressure range 10−4-1 atm, the equilibrium transport properties and stability range of YBa2Cu4O8 were determined. YBa2Cu4O8 behaves like the intrinsically mixed-valent compound, magnetite (Fe3O4), with small variations in electrical properties with changes in oxygen partial pressure. The decomposition boundary to YBa2Cu3O6+y (or YBa2Cu3.5O7.5±z) and CuO occurs at log(po2, atm) = −1.24 × 104/T(K) + 11.01(773 ⋚ T(K) ⋚ 1073).

scholarly journals The setup and application of the multi-scale in-situ test system for fatigue damage analysis

2018 ◽  
Vol 165 ◽  
pp. 04005
Author(s):  
Yi Shi ◽  
Xiaoguang Yang ◽  
Guolei Miao ◽  
Duoqi Shi
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Crack Initiation ◽  
Crack Growth ◽  
Test System ◽  
In Situ Test ◽  
Multi Scale ◽  
Macro Scale

This essays aims at introducing the setup for the multi-scale in-situ test system which is applied for the fatigue crack initiation test. The setup of the experiment system is first introduced, including the image capturing system, optical path system, image acquisition and storage system and the three-axis mobile platform. Then the preparation of micro speckle and the corresponding technique for spatial adjustment are improved to realize the DIC measurement in micro scale. Finally three experiments from macro-meso scale to macro scale: fatigue initiation test, the observation of micro crack and the fatigue crack growth rate in macro scale were conducted to verify the application of the system. The test result can indicate the location of crack initiation, the crack growth rate and the evolution of displacement/strain field, etc.

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