Phenomenological aspects of the influence of the cyclic loading parameters on corrosion-fatigue crack growth

1984 ◽  
Vol 20 (4) ◽  
pp. 344-348 ◽  
Author(s):  
I. P. Gnyp
Keyword(s):  
Fatigue Crack ◽  
Cyclic Loading ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Corrosion Fatigue ◽  
Corrosion Fatigue Crack ◽  
Corrosion Fatigue Crack Growth

An Engineering Tool for Predicting Corrosion-Fatigue Crack Growth Rates for Structural Steels in Sour Environments

2017 ◽  
Author(s):  
Baotong Lu ◽  
Brian P. Somerday ◽  
Stephen J. Hudak
Keyword(s):  
Fatigue Crack ◽  
Cyclic Loading ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Analytical Model ◽  
Corrosion Fatigue ◽  
Phase 1 ◽  
Structural Steels ◽  
Corrosion Fatigue Crack ◽  
Corrosion Fatigue Crack Growth

Laboratory testing has shown that sour brine environments can reduce the fatigue life of offshore steels by factors of 10× to 50× compared to fatigue lives measured in laboratory air. Thus, in order to ensure safe, reliable, and environmentally-friendly deepwater development, the effect of these sour service environments must be properly accounted for in riser and flowline design. However, to ensure that the environmental effect is fully captured, tests need to be conducted at cyclic loading frequencies representative of those experienced in service (typically 0.1 Hz or less), which makes corrosion-fatigue testing very time-consuming and costly. Consequently, there has been a need for predictive models that can reduce the dependence on extensive long-term testing, while at the same time enable existing data to be interpolated and/or extrapolated over a broad domain of relevant mechanical, environmental, and material variables. In response to this need, a Joint Industry Project (JIP) was organized by Southwest Research Institute® (SwRI®) with the objective of developing and validating an analytical model to predict corrosion-fatigue performance of structural steels in sour brine environments. The resulting model is based on the kinetics of hydrogen generation and transport to a fracture process zone (FPZ), where embrittlement occurs in the hydrostatic stress field ahead of the growing crack. The advantage of this kinetic model is that details of the embrittlement process, which are not presently well defined, need not be included since corrosion fatigue crack growth (CFCG) is governed by the rate-controlling process (RCP) in the elemental kinetic steps that supply hydrogen to the FPZ. A general outline of this model is provided here and its validation against independently generated experimental data is demonstrated. The validated model has been implemented in spreadsheet format for convenience as an engineering tool. Due to the fundamental concepts underpinning the model, the engineering tool is shown to be adaptable to predicting CFCG rates in steels exposed to a variety of other environments — including hydrated and dehydrated sour crude oil, moist H2S gas, sweet brine, and seawater — with and without cathodic polarization. An extension of this Phase 1 model from intermediate to lower CFCG rates is currently underway in Phase 2 of the JIP but will not be discussed in detail in the present paper. The primary objective of this paper is to introduce the engineering tool based on the Phase 1 analytical model and demonstrate its functionality in quantifying CFCG rates over wide ranges of mechanical variables (stress-intensity factor range (ΔK), load ratio (Rσ), and cyclic loading frequency), environmental variables (H2S partial pressure, pH, temperature, applied potential), and material variables (yield strength).

Corrosion-Fatigue Crack Growth in Age-Hardened Al Alloys: Examples of Failures and Explanations for Fractographic Observations

2014 ◽  
Vol 891-892 ◽  
pp. 248-253 ◽  
Author(s):  
Rohan Byrnes ◽  
Noel Goldsmith ◽  
Mark Knop ◽  
Stan Lynch
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Corrosion Fatigue ◽  
Compact Tension ◽  
Al Alloys ◽  
Corrosion Fatigue Crack ◽  
Crack Tips ◽  
Corrosion Fatigue Crack Growth ◽  
Additional Support

The characteristics of corrosion-fatigue in age-hardened Al alloys, e.g. brittle striations on cleavage-like facets, are described, with reference to two examples of component failure. Mechanisms of corrosion fatigue (and explanations for fracture-surface features) are then reviewed. New observations of corrosion-fatigue crack growth for 7050-T7451 alloy compact-tension specimens tested in aqueous environments using a constant (intermediate) ΔK value but different cycle frequencies are then described and discussed. These observations provide additional support for a hydrogen-embrittlement process involving adsorption-induced dislocation-emission from crack tips.

Corrosion-Fatigue Crack Growth Performance of Titanium Grade 29 Welds in Tapered Stress Joints

2021 ◽  
Vol 143 (6) ◽  
Author(s):  
Gabriel Rombado ◽  
David A. Baker ◽  
Lars M. Haldorsen ◽  
Pedro da Silva Craidy ◽  
Jim H. Feiger ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Corrosion Fatigue ◽  
High Strength ◽  
Potential Effect ◽  
Steel Catenary Riser ◽  
Corrosion Fatigue Crack ◽  
Corrosion Fatigue Crack Growth ◽  
Titanium Grade

Abstract Design of a steel catenary riser requires the use of connection hardware to decouple the large bending moments induced by the host floater at the hang-off location. Reliability of this connection hardware is essential, particularly in applications involving high pressure and high temperature fluids. One option for this connection hardware is the metallic tapered stress joint. Titanium (Ti) Grade 29 has been identified as an attractive material candidate for demanding stress joint applications due to its “high strength, low weight, superior fatigue performance and innate corrosion resistance”.2 Titanium stress joints for deepwater applications are typically not fabricated as a single piece due to titanium ingot volume limitations, thus making an intermediate girth weld necessary to satisfy length requirements. As with steel, the potential effect of hydrogen embrittlement induced by cathodic and galvanic potentials must be assessed to ensure long-term weld integrity. This paper describes testing from a joint industry project (JIP) conducted to qualify titanium stress joint (TSJ) welds for ultra-deepwater applications under harsh service and environmental conditions. Corrosion-fatigue crack growth rate (CFCGR) results for Ti Grade 29 flat welding-groove weld (1G/PA) gas tungsten arc welding (GTAW) specimens in seawater under cathodic potential and sour brine under galvanic potential are presented and compared to vendor recommended design curves.

Threshold Corrosion Fatigue Crack Growth in Steels

1978 ◽  
Vol 6 (1) ◽  
pp. 66 ◽  
Author(s):  
RT Horstman ◽  
KC Lieb ◽  
RL Meltzer ◽  
IC Moore ◽  
LKL Tu ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Corrosion Fatigue ◽  
Corrosion Fatigue Crack ◽  
Corrosion Fatigue Crack Growth
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