Effect of crack tip stress intensity on the mechanism of stress-corrosion cracking of titanium-6a-4V in methanol

1967 ◽  
Vol 7 (10) ◽  
pp. 721-723 ◽  
Author(s):  
D.A. Meyn
Keyword(s):  
Stress Intensity ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Crack Tip ◽  
Corrosion Cracking ◽  
Crack Tip Stress

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

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.

Stress-Corrosion Cracking and the Interaction Between Crack-Tip Stress Field and Solute Atoms

1970 ◽  
Vol 92 (3) ◽  
pp. 633-638 ◽  
Author(s):  
H. W. Liu
Keyword(s):  
Stress Field ◽  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Solute Atom ◽  
Crack Tip ◽  
Elastic Interaction ◽  
Corrosion Cracking ◽  
Solute Atoms ◽  
Crack Tip Stress

Based on the elastic interaction between a solute atom and a tensile crack-tip stress field, a mechanism of stress-corrosion cracking was proposed and analyzed. This elastic interaction provides a potential for solute atoms to migrate toward the tip of a crack. The elastic interaction and the equilibrium concentration of solute atoms near a crack tip were calculated. The solute atom concentration increases rapidly toward the crack tip if the solute atom is interstitial or if it relaxes the crack-tip stress field. The high concentration of solute atoms at the tip of a crack will enhance the reaction between solute and solvent atoms. The weak fracture strength of the reaction product may cause crack growth. Two crack growth models were analyzed: One is based on the assumption of the “homogeneity” of the fracture and deformation properties of a material, and the other takes a structural size of a material into consideration. The proposed models are compared with available data on magnesium-aluminum alloy, 4340 steel, and soda-lime glass.

Modeling the Interactions of Hydrogen, Stress and Dissolution in Near-Neutral pH Stress Corrosion Cracking of Pipelines

2006 ◽  
Author(s):  
Frank Y. Cheng
Keyword(s):  
Stress Corrosion ◽  
Dissolution Rate ◽  
Crack Growth ◽  
Anodic Dissolution ◽  
Hydrogen Concentration ◽  
Stress Corrosion Cracking ◽  
Crack Tip ◽  
Corrosion Cracking ◽  
Neutral Ph ◽  
Ph Stress

A thermodynamic model was developed to determine the interactions of hydrogen, stress and anodic dissolution at the crack-tip during near-neutral pH stress corrosion cracking in pipelines. By analyzing the free-energy of the steel in the presence and absence of hydrogen and stress, it is demonstrated that a synergism of hydrogen and stress promotes the cracking of the steel. The enhanced hydrogen concentration in the stressed steel significantly accelerates the crack growth. The quantitative prediction of the crack growth rate in near-neutral pH environment is based on the determination of the effect of hydrogen on the anodic dissolution rate in the absence of stress, the effect of stress on the anodic dissolution rate in the absence of hydrogen, the synergistic effect of hydrogen and stress on the anodic dissolution rate at the crack-tip and the effect of the variation of hydrogen concentration on the anodic dissolution rate.

Study on Transition of Stress Corrosion Cracking to Sharp Edge Corrosion for a Liquids Pipeline

2018 ◽  
Author(s):  
Jiajun (Jeff) Liang ◽  
Ziqiang (Alex) Dong ◽  
Mengshan Yu ◽  
Mariko Dela Rosa ◽  
Gurwinder Nagra
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Synergistic Effects ◽  
Management Strategies ◽  
Crack Tip ◽  
Corrosion Cracking ◽  
Lessons Learned ◽  
Sharp Edge ◽  
Maximum Pressure ◽  
Arrest Growth

Although stress corrosion cracking (SCC) growth is attributed to the synergistic effects of stress and corrosion, these two factors can just as easily become competing mechanisms, with stress cycles driving growth (hydrogen, the by-product of corrosion, may facilitate the growth), and corrosion working to blunt the crack tip and arrest growth. It follows that reducing the maximum pressure and cycling severity can slow down the crack growth or even stop it, and aggressive corrosion can further blunt the sharp crack tip. The Authors have observed, on a particular Polyethylene (PE) tape coated pipeline, instances where SCC has exhibited a propensity to corrode and convert into sharp edge corrosion. This is attributed to the combined effects of limited corrosion protection and low stresses. The focus of the paper is to assist operators in recognizing this phenomenon and integrate lessons learned into pipeline integrity management strategies.

The role of crack branching in stress corrosion cracking of aluminium alloys

2015 ◽  
Vol 33 (6) ◽  
pp. 443-454 ◽  
Author(s):  
Timothy L. Burnett ◽  
N.J. Henry Holroyd ◽  
Geoffrey M. Scamans ◽  
Xiaorong Zhou ◽  
George E. Thompson ◽  
...  
Keyword(s):  
Stress Intensity ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Aluminium Alloys ◽  
Compact Tension ◽  
Corrosion Cracking ◽  
Three Dimensions ◽  
Crack Branching ◽  
Test Procedures ◽  
The Many

AbstractStress corrosion cracks of all types are characterised by extensive crack branching, and this is frequently used as the key failure analysis characteristic to identify this type of cracking. For aluminium alloys, stress corrosion cracking (SCC) is almost exclusively an intergranular failure mechanism. For plate and extruded components, this had led to the development of test procedures using double cantilever beam and compact tension precracked specimens that rely on the pancake grain shape to constrain cracking, so that fracture mechanics can be applied to the analysis of stress intensity and crack velocity and the evolution of a characteristic performance curve. We have used X-ray computed tomography to examine in detail SCC in aluminium alloys in three dimensions for the first time. We have found that crack branching limits the stress intensity at the crack tip as the applied stress is shared amongst a number of cracks that are held together by uncracked ligaments. We propose that the plateau region observed in the v-K curve is an artefact due to crack branching, and at the crack tips of the many crack branches, cracking essentially occurs at constant K almost irrespective of the crack length. We have amplified the crack branching effect by examining a sample where the long axis of the pancake grains was inclined to the applied stressing direction. Our results have profound implications for the future use of precracked specimens for SCC susceptibility testing and the interpretation of results from these tests.

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

2010 ◽  
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.

Film Effects On Ductile/Brititle Behavior In Stress-Corrosion Cracking

1995 ◽  
Vol 409 ◽  
Author(s):  
Tong-Yi Zhang ◽  
Wu-Yang Chu ◽  
Ji-Mei Xiao
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Critical Stress ◽  
Fracture Behavior ◽  
Applied Load ◽  
Crack Tip ◽  
Critical Stress Intensity Factor ◽  
Corrosion Cracking ◽  
Dislocation Emission ◽  
Mode Iii

AbstractThe present work analyzes the effects of a passive film formed during stress corrosion cracking on ductile/brittle fracture behavior, considering the interaction of a screw dislocation with a thin film-covered mode III crack under an applied remote load. Exact solutions are derived, and the results show that the crack stress field due to the applied load is enhanced by a harder film or abated by a softer film. The critical stress intensity factor for dislocation emission from the crack tip is greatly influenced by both the stiffness and thickness of the filn. A dislocation is more easily to be emitted from the crack tip if the covered film has a shear modulus larger than that of the substrate. The opposite is also true, i.e., a softer film makes dislocation emission more difficult. Both phenomena become more significant when the film thickness is smaller.

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