Crack Branching and Its Effect on Environmentally Assisted Cracking in High Temperature Water Environments

Crack kinking or branching has been observed in laboratory stress corrosion cracking tests and in some components suffering from stress corrosion cracking in nuclear power plant coolants. There are several types of crack branching: i.e., macroscopic multiple branching cracks, local crack branching or the combination of both. Crack branching affects the crack tip stress/strain distribution in terms of stress intensity factor and crack tip strain rate, and consequently affects crack growth behavior. The crack tip mechanical fields in some typical crack branching systems are quantified using empirical, analytical and numerical simulation methods. The effect of crack branching is less significant in contoured double cantilever beam specimens than in compact tension specimens for the same size and configuration of branched cracks. The applications of the analysis results to some observed crack branching phenomena of austenitic alloys in high temperature water environments are discussed based on the theoretical crack growth rate formulation.

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CRACK GROWTH BEHAVIOR FOR STRESS CORROSION CRACKING OF 690 ALLOY IN HIGH TEMPERATURE WATER

ACTA METALLURGICA SINICA ◽

10.3724/sp.j.1037.2010.01267 ◽

2011 ◽

Vol 46 (10) ◽

pp. 1267-1274 ◽

Cited By ~ 1

Author(s):

Tichun DAN ◽

Zhanpeng LU ◽

Jianqiu WANG ◽

Enhou HAN ◽

SHOJI Testuo ◽

...

Keyword(s):

High Temperature ◽

Stress Corrosion ◽

Crack Growth ◽

Stress Corrosion Cracking ◽

Growth Behavior ◽

Corrosion Cracking ◽

Crack Growth Behavior ◽

High Temperature Water ◽

Temperature Water

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Quantifying the Crack Tip Oxidation Kinetics Parameters and Their Contribution to Stress Corrosion Cracking in High Temperature Water

ASME 2010 Pressure Vessels and Piping Conference: Volume 6, Parts A and B ◽

10.1115/pvp2010-25238 ◽

2010 ◽

Cited By ~ 2

Author(s):

Tetsuo Shoji ◽

Zhanpeng Lu ◽

He Xue ◽

Yubing Qiu ◽

Kazuhiko Sakaguchi

Keyword(s):

High Temperature ◽

Water Chemistry ◽

Stress Corrosion ◽

Stress Corrosion Cracking ◽

Oxidation Kinetics ◽

Crack Tip ◽

Corrosion Cracking ◽

High Temperature Water ◽

Austenitic Alloys ◽

Temperature Water

Stress corrosion cracking is the result of the interaction between crack tip oxidation kinetics and crack tip mechanics. Oxidation kinetic processes for austenitic alloys in high temperate water environments are analyzed, emphasizing the effects of alloy composition and microstructure, temperature, water chemistry, etc. The crack chemistry is investigated with introducing the effect of aging on reactivity of crack sides and the throwing power of bulk water chemistry. Oxidation rate constants under various conditions are calculated based on quasi-solid state oxidation mechanism, which are incorporated in the theoretical growth rate equation to quantify the effects of several key parameters on stress corrosion cracking growth rates of austenitic alloys in high temperature water environments, especially the effect of environmental parameters on stress corrosion cracking of Ni-base alloys in simulated PWR environments and stainless steels in simulated boiling water environments.

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Effect of Creep on Stress and Strain at the Tip of Stress Corrosion Cracking in High Temperature Water Environments

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.494-495.651 ◽

2014 ◽

Vol 494-495 ◽

pp. 651-654

Author(s):

He Xue ◽

Jin Tian ◽

Fu Qiang Yang

Keyword(s):

High Temperature ◽

Stress Corrosion ◽

Stress Corrosion Cracking ◽

Crack Tip ◽

Corrosion Cracking ◽

Stress And Strain ◽

Mechanical Parameters ◽

High Temperature Water ◽

High Pressure Environment ◽

Temperature Water

Stress and strain at the crack tip are main mechanical parameters which estimate the stress corrosion cracking rate in metals, and the creep of metals in high temperature and high pressure environment will lead to the redistribution of stress and strain nearby the crack tip. The effects of creep on stress and strain nearby the crack tip are discussed by using 1T-CT specimen and finite element method in this study. The investigated results indicate that both increasing of temperature and stress intensity factor would induce the equivalent creep strain increases at the crack tip.

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Locally Delaminating Stress Corrosion Cracking Growth of Strain-Hardened Austenitic Alloys in Hydrogenated High Temperature Water Environments

Volume 6: Materials and Fabrication, Parts A and B ◽

10.1115/pvp2009-77622 ◽

2009 ◽

Author(s):

Zhanpeng Lu ◽

He Xue ◽

Hiroyoshi Murakami ◽

Tetsuo Shoji

Keyword(s):

High Temperature ◽

Stress Corrosion ◽

Stress Corrosion Cracking ◽

Crack Tip ◽

Corrosion Cracking ◽

Fracture Surfaces ◽

High Temperature Water ◽

Austenitic Alloys ◽

Temperature Water ◽

Crack Tip Stress

Locally delaminating cracks, i.e. cracks that grow along the plane that is parallel to the principal applied loading direction, are observed on the fracture surfaces of heavily strain-hardened austenitic alloys after stress corrosion cracking tests in hydrogenated high temperature water environments. These delaminating cracks often occur locally on mixed intergranular-transgranular stress corrosion cracking fracture surfaces. The crack tip stress field is analyzed by finite element analysis. The physical-chemical degradation effect of stress on oxidation kinetics is formulated. The combinations of local oxidation penetration, relatively slow crack growth on the principal plane, and locally high crack tip stress are favorable for the growth of delaminating cracks. These conditions can be satisfied in stress corrosion cracking for austenitic alloys with heavily deformed microstructures and high strengths in hydrogenated high temperature water environments.

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