Fatigue crack growth law of API X80 pipeline steel under various stress ratios based onJ-integral

2014 ◽  
Vol 37 (10) ◽  
pp. 1124-1135 ◽  
Author(s):  
L. Li ◽  
Y. H. Yang ◽  
Z. Xu ◽  
G. Chen ◽  
X. Chen
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Pipeline Steel ◽  
X80 Pipeline Steel ◽  
Stress Ratios

Fatigue Performance of Sour Deepwater Riser Welds: Crack Growth vs. Endurance

2011 ◽  
Author(s):  
Colum M. Holtam ◽  
David P. Baxter
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Pipeline Steel ◽  
High Stress ◽  
Fatigue Loading ◽  
Stress Intensity Factor Range ◽  
Valuable Insight ◽  
Stress Ratios ◽  
Fatigue Endurance

Steel catenary risers (SCRs) are increasingly used in deepwater oil and gas developments. SCRs can be subject to low-stress high-cycle fatigue loading, for example from wave and tidal motion, vortex induced vibration (VIV) and operating loads, and corrosive environments (internal and external). When the production fluids are sour, higher fatigue crack growth rates (FCGRs) are expected and therefore shorter overall life compared to performance in air, as a result of the interaction between fatigue crack growth and sulphide stress cracking. Successful design of risers is critically dependent on the availability of appropriate experimental data to quantify the extent to which fatigue lives are reduced and rates of fatigue crack growth are increased. Historically there has been a discrepancy between experimental sour fatigue endurance data and fracture mechanics-based estimates of the corresponding stress-life (S-N) curves. This paper summarises the results of recent sour FCGR tests on C-Mn pipeline steel. Tests were performed under conditions of increasing applied stress intensity factor range (ΔK), on specimens containing shallow initial flaws and at very high stress ratios (R), to obtain data close to threshold. In many cases it is material behaviour at these low values of ΔK that dominate the fatigue life (e.g. VIV loading). The FCGR data are then compared to sour fatigue endurance data, both published and from a TWI Joint Industry Project (JIP). The observed environmental reduction factor (ERF) for endurance tests is compared to that expected from the difference in fatigue crack propagation rates, to examine whether FCGR data might provide an alternative means of predicting ERFs. This paper offers valuable insight into current best practice methods for generating sour FCGR data when qualifying girth welds for sour service, and the relationship between fatigue crack growth and fatigue endurance.

Fracture Resistance and Fatigue Crack Growth of X80 Pipeline Steel in Gaseous Hydrogen

2011 ◽  
Author(s):  
Chris San Marchi ◽  
Brian P. Somerday ◽  
Kevin A. Nibur ◽  
Douglas G. Stalheim ◽  
Todd Boggess ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fracture Resistance ◽  
Pipeline Steel ◽  
Low Cost ◽  
Petroleum Products ◽  
Gaseous Hydrogen ◽  
X80 Pipeline Steel ◽  
Crack Growth Rates

Gaseous hydrogen is a convenient medium to store and transport energy. As existing petroleum-based platforms are electrified, such as with the growth of fuel cell systems, hydrogen is becoming an attractive fuel which must be distributed, stored and dispensed. Hydrogen is used extensively in refining of petroleum products, and often distributed by pipeline. However, there remains a need to quantify the mechanical properties of low-cost steels in gaseous hydrogen and to relate the measured performance to the variety of microstructures that characterize steels. This study is part of a larger effort to characterize a broad range of steels manufactured for pipelines and to measure their fracture and fatigue resistance in gaseous hydrogen. The fracture resistance and fatigue crack growth rates of two microstructural variations of X80 pipeline steel were measured in gaseous hydrogen at pressure of 21 MPa. The performance of these steels was found to be similar to the performance of other ferritic steels that are currently used to distribute gaseous hydrogen.

Experimental Study of Fatigue Crack Overload Retardation in X80 Grade Steel

2008 ◽  
Author(s):  
Qingquan Duan ◽  
Hong Zhang ◽  
Feng Yan
Keyword(s):  
Fatigue Crack ◽  
Crack Growth ◽  
Oil And Gas ◽  
Prediction Models ◽  
Pipeline Steel ◽  
Compact Tension ◽  
X80 Pipeline Steel ◽  
Oil And Gas Pipelines ◽  
Crack Retardation ◽  
Grade Steel

The tests of fatigue crack overload retardation were performed to gain a some what deeper understanding of overload retardation. We present an experimental investigation of fatigue crack retardation behavior caused by intermediate single peak tensile overload under constant amplitude cyclic loading. The compact tension (CT) specimens of API grade X80 pipeline steel were used in fatigue test. The results show there was an instant crack extension during overloading for the tested overload ratios. As soon as the overload cycle was removed, instant delay in crack growth occurred. The results should be of interest for fracture mechanics prediction models on fatigue crack growth under variable amplitude loading and overloading effect for oil and gas pipelines.

Near-Threshold Fatigue Crack Growth Behavior of ECAPed Ultrafine-Grained Copper

2021 ◽  
Vol 1016 ◽  
pp. 1193-1198
Author(s):  
Shou Dao Qu ◽  
Ze Sheng You
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Threshold ◽  
Coarse Grained ◽  
Crack Growth Behavior ◽  
Fatigue Crack Growth Resistance ◽  
Ultrafine Grained ◽  
Stress Ratios ◽  
Near Threshold

Fatigue crack growth resistance of ultrafine grained Cu processed by equal channel angular pressing (ECAP) was investigated. Particular emphasis was devoted to the effects of microstructure evolution on fatigue crack growth in the near-threshold regime. The ultrafine grained Cu exhibits a lower fatigue threshold than coarse-grained Cu at stress ratios of 0.1 and 0.7. Fatigue induced coarsening of the UFG structure near the fatigue crack and intergranular fatigue crack growth are observed.

Sign in / Sign up

Export Citation Format

Share Document