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Meeting 2018 TMS Annual Meeting & Exhibition
Symposium Environmentally Assisted Cracking: Theory and Practice
Presentation Title Environmental Cracking: Theory Depends on Practice
Author(s) Peter L. Andresen
On-Site Speaker (Planned) Peter L. Andresen
Abstract Scope Environmental cracking has been with us for centuries, and it was during the industrial revolution in the 1850s, with the widespread use of steam boilers, that the heavy consequences of failures demanded attention. In a single year in the U.S. over 50,000 deaths and 2,000,000 injuries from steam boiler failures occurred, and this was the motivation behind the slow process of developing pressure vessel and boiler codes – first issued ~60 years later in 1914 and developed by mechanical engineers to address overload and fatigue design. While helpful, the dominant cause of the failures was stress corrosion cracking (SCC) and corrosion fatigue (CF), terms that were unfamiliar terms to engineers of that era. The greater complexity of environmental effects made it difficult to address, with the Code simply mandating that SCC be avoided. This relegated the issue to the designers, who interpreted the Code to mean that regions of SCC immunity exist, and can be identified with simple tests representing <0.2% of a 40+ year design life. While the Code has been successful in reducing mechanical failures, now, ~165 years later, it has never seriously addressed the original problem of environmental cracking. Failures thus continue and our grasp of environmental cracking is stunted. Simple, short-term tests are generally only able to identify severe SCC susceptibility, and tend to focus on initiation with its inherent ambiguity, reliance on near-surface conditions that are not well understood, and uncertain relevant to plant components whose surfaces and stresses are poorly characterized. If they were successful, the design codes would have prevented failures, however extensive cracking has occurred, and life evaluation codes were developed to address cracks detected by leakage, inspection, etc. Resolution of environmental cracking will only come with the recognition that the design codes are a starting point, and other codes, standards and/or guidelines are needed to manage design and fabrication to address environmental effects. Major sources of vulnerabilities include weak material specifications and associated inhomogeneities; welding, fabrication and grinding; and boiling, creviced, aggressive, and upset operating environments – if these were optimized, perhaps 99% of SCC incidents would cease. Our belated efforts to quantify and predict environmental cracking are complicated by experimental challenges, very long plant life (>80 years), complexities of the metallurgical – environmental – mechanical factors in components, and the rich diversity of the kinetics and possible mechanisms of cracking. Models tend to assume what controls environmental cracking, generally avoiding rigorous evaluation of their assumptions and ramifications. Our basic understanding of environmental cracking – especially immunity – hinges on incisive experiments, including an ability to detect very low crack growth rates. This talk highlights our dependency on the highest quality experiments to discern the nature and kinetics of environmental cracking. Examining only very aggressive situations that would induce failures in months is an inadequate approach to defining safe operation for many decades, or understanding the nature of environmental cracking. The possibility that immunity or thresholds exists in stress intensity factor, corrosion potential, water purity, temperature, metallurgical state, etc. need to be evaluated against sophisticated experiments able to discern subtleties of behavior. Some examples of such experiments will be given. The reality is that SCC often occurs over a very broad spectrum of conditions, including very resistant materials, high purity water, low corrosion potential, low stress, etc. Both plant experience and careful laboratory observation have altered our understanding of environmental cracking, and eroded much of the lore surrounding immunity and thresholds. This is especially true in high temperature water environments, the conditions associated with the original industrial problem.
Proceedings Inclusion? Planned: Supplemental Proceedings volume

OTHER PAPERS PLANNED FOR THIS SYMPOSIUM

3D Microstructural and Electrochemical Characterization of Accelerated Corrosion in Aluminum Alloys
Characterization of Stress Corrosion Cracking of 304 Stainless Steel Using High-energy Synchrotron X-ray Microtomography
Comparative Assessment of the Fracture Behaviour of API 5L X65 and Micro-alloyed Steels in E80 Simulated Fuel Ethanol Environment
Comparison of Hydrogen Introduction Techniques for In-situ TEM Straining Experiments
Correlative 3D Imaging of Iodine-induced Stress Corrosion Cracks in Zr Alloys
Corrosion Crack Propagation Modeling Using Meshless Peridynamics Approach
Cracking Behavior and Fracture Toughness of Irradiated Austenitic Stainless Steels in LWR Environments
Dealloying Induced Stress Corrosion Cracking
Dispelling Myths about Gaseous Hydrogen Environmental Fracture and Fatigue
EAC Behavior of Modified Duplex Stainless Steel Bars in Seawater
Effect of 3D Crystallographic Orientation and Microstructure on the Evolution of Corrosion in Aluminum Alloys
Effect of Frequency on Corrosion Fatigue Behavior of Steel 1.4016 in E85 Biofuel up to the Very High Cycle Fatigue Regime
Effect of Hydrogen on Ideal Shear Strength of Metals: An Ab-initio Study
Effect of Mechanical Deformation on the Corrosion Behavior in Al 7075 – Ti6Al4V Galvanic Joint
Effect of Titanium Contents on Hydrogen Induced Cracking Susceptibility and Hydrogen Permeation Characteristic of X80 Pipeline Steel
Electrochemical-mechanical Interactions in an Aluminum Alloy under Slow Strain Rate Stress Corrosion Cracking
Environment Induced Degradation in Maraging Steel Grade 18Ni1750
Environmental Cracking: Theory Depends on Practice
Evaluating the Effect of Sensitizing Time on the Hydrogen Embrittlement of Austenitic Stainless Steels
From First Discoveries in the Late 1800s to Mechanistic Understanding and Radiation Effects in the Early 2000s: Over 140 Years of Stress Corrosion Cracking Research
Fundamental Mechanisms of Preventing Stress Corrosion Cracking of Austenitic Alloys by Laser Shock Peening
Hydrogen-dislocation Interaction Revisited by Quantitative Mechanical Tests inside TEM
Hydrogen and Dislocation Assisted Grain Boundary Crack Initiation Mechanism
IASCC Behavior of Additively Manufactured 316L Stainless Steel in Light Water Reactor Environments
Incorporating Detailed Experimental Grain Boundary β-phase (Mg2Al3) Observations to Improve Sensitization Modeling of Aluminum AA5XXX Alloys
Influence of MC Carbides and γ’ on Hydrogen Trapping in Nickel Alloys and Superalloys: Experiment and Alloy Design
Mechanisms of High Temperature Stress Corrosion Crack Initiation in Austenitic Alloys
Metallurgical Factors and Changes Driving Susceptibly to Environment Assisted Cracking in Aluminum Alloys
Phase Field Modeling of Pitting & Crevice Corrosion
Role of Nitrogen on Hydride Nucleation and Stability in Pure Niobium by First-principles Calculations
SCC Property Evolution of X70 Pipeline Steel in Simulated Deep-sea Environments
Sensitization Effects on Tensile Behavior in 5XXX Series Aluminum Alloys: Environmentally Enhanced Cracking
The Effects of Grain Boundary Structure on the Intergranular Stress Corrosion Cracking Initiation Susceptibility of Alloy 690 in High Temperature Water
The Stress Corrosion Cracking Mechanism of a Cu-free Al-Zn-Mg Alloy in Sodium Chloride Solutions
Trapping against Hydrogen Embrittlement

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