scholarly journals The Initiation of Environmentally Assisted Cracking in Semi-Elliptical Surface Cracks

1998 ◽  
Vol 120 (2) ◽  
pp. 200-206
Author(s):  
L. A. James
Keyword(s):  
Experimental Test ◽  
Surface Crack ◽  
Compact Tension ◽  
Initial Crack ◽  
Surface Cracks ◽  
Test Results ◽  
Low Oxygen ◽  
Type Specimens ◽  
Environmentally Assisted Cracking ◽  
Access To Water

A Criterion to predict under what conditions EAC would initiate in cracks in a high-sulfur steel in contact with low-oxygen water was recently proposed by Wire and Li (1996). This EAC initiation criterion was developed using transient analyses for the diffusion of sulfides plus experimental test results. The experiments were conducted mainly on compact tension-type specimens with initial crack depths of about 2.54mm. The present paper expands upon the work of Wire and Li by presenting results for significantly deeper initial semi-elliptical surface cracks. In addition, in one specimen, the surface crack penetrated weld-deposited cladding into the high-sulfur steel. The results for the semi-elliptical surface cracks agreed quite well with the EAC initiation criterion, and provide confirmation of the applicability of the criterion to crack configurations with more restricted access to water.

Corrosion Fatigue Crack Growth in Clad Low-Alloy Steels—Part I: Medium-Sulfur Forging Steel

1997 ◽  
Vol 119 (3) ◽  
pp. 249-254 ◽  
Author(s):  
L. A. James ◽  
T. A. Auten ◽  
T. J. Poskie ◽  
W. H. Cullen
Keyword(s):  
Fatigue Crack ◽  
Corrosion Fatigue ◽  
Compact Tension ◽  
Initial Crack ◽  
Aqueous Environment ◽  
Low Alloy Steels ◽  
Surface Cracks ◽  
Low Oxygen ◽  
Corrosion Fatigue Crack ◽  
Alloy Steels

Corrosion fatigue crack propagation tests were conducted on a medium-sulfur ASTM A508-2 forging steel overlaid with weld-deposited alloy EN82H cladding. The specimens featured semi-elliptical surface cracks penetrating approximately 6.3 mm of cladding into the underlying steel. The initial crack sizes were relatively large with surface lengths of 30.3–38.3 mm, and depths of 13.1–16.8 mm. The experiments were conducted in a quasi-stagnant low-oxygen (O2 < 10ppb) aqueous environment at 243°C, under loading conditions (ΔK, R, and cyclic frequency) conducive to environmentally assisted cracking (EAC) in higher-sulfur steels under quasi-stagnant conditions. Earlier experiments on unclad compact tension specimens of this heat of steel did not exhibit EAC, and the present experiments on semi-elliptical surface cracks penetrating cladding also did not exhibit EAC.

Mechanism of Delamination and Its Effects on Fracture of Surface Crack Bodies in Ductile Pipeline Steel

2005 ◽  
Vol 297-300 ◽  
pp. 1235-1240
Author(s):  
Hui Ru Dong ◽  
Wanlin Guo ◽  
Zheng Yang
Keyword(s):  
Fracture Toughness ◽  
Surface Crack ◽  
Safety Assessment ◽  
Pipeline Steel ◽  
Three Dimensional ◽  
Stress Constraint ◽  
Surface Cracks ◽  
Test Results ◽  
Real Material ◽  
Cracked Specimens

The effects of three-dimensional crack configurations and delaminations on fracture mechanism and fracture toughness Jc of pipeline steel were investigated experimentally by use of tensile specimens having surface cracks of different depth to length ratio. Comparison with test results of through-thickness cracks and mechanism analyses are made as well. When 3D stress constraint is larger than the strength in the thickness direction the delamination forms. As no delamination occurs in the interior of a surface crack, the constraint is higher and the fracture toughness is lower than that of the through-thickness cracks. Therefore, the nominal fracture toughness obtained from through-thickness cracked specimens is not a real material constancy, and not suitable for safety assessment of pipelines.

Development of Burst Pressure Estimation Equations for Steam Generator Tubes With Multiple Axial Surface Crack

2018 ◽  
Author(s):  
Ji-Seok Kim ◽  
Myeong-Woo Lee ◽  
Jin-Weon Kim ◽  
Yun-Jae Kim
Keyword(s):  
Steam Generator ◽  
Surface Crack ◽  
Burst Pressure ◽  
Damage Analysis ◽  
Surface Cracks ◽  
Test Results ◽  
Estimation Equations ◽  
Pressure Estimation ◽  
Steam Generator Tubes ◽  
Axial Surface

In this paper, the burst pressure estimation equations for steam generator tubes with multiple axial surface cracks are proposed based on the local collapse load approach concept. The proposed equations are for a single axial surface crack, two collinear axial surface cracks and two non-aligned axial surface cracks. The proposed equations are validated against experimental tube burst test results and finite element damage analysis for twin cracks. Predicted burst pressures agree well with the experimental results and FE analysis results, suggesting validity of the proposed equations to estimate burst pressures for twin axial surface cracks.

scholarly journals The Effect of Water Flow Rate Upon the Environmentally Assisted Cracking Response of a Low-Alloy Steel

1995 ◽  
Vol 117 (3) ◽  
pp. 238-244 ◽  
Author(s):  
L. A. James ◽  
G. L. Wire ◽  
W. H. Cullen
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
Water Flow Rate ◽  
Surface Cracks ◽  
Low Alloy Steel ◽  
Compact Type ◽  
Type Specimens ◽  
Linear Elastic ◽  
Effect Of Water ◽  
Environmentally Assisted Cracking

The effect of water flow rate upon the environmentally assisted cracking (EAC) response of a high-sulfur ferritic steel was studied at a temperature of 243°C. In contrast to earlier studies which employed compact-type specimens, this study employed relatively large tight semi-elliptical surface cracks tested under generally linear-elastic conditions. Flow velocities parallel to the crack as low as 1.58–1.84 m/s were effective in mitigating EAC.

Advanced railgun experimental test results and implications for the future

1992 ◽  
Author(s):  
M. HOLLAND ◽  
P. EGGERS ◽  
S. GUINTO ◽  
R. STEVENSON ◽  
GREGORY COLOMBO
Keyword(s):  
Experimental Test ◽  
Test Results ◽  
The Future

On axial compressive behavior of steel fiber reinforced concrete confined by FRP

2021 ◽  
pp. 136943322098165
Author(s):  
Hossein Saberi ◽  
Farzad Hatami ◽  
Alireza Rahai
Keyword(s):  
Reinforced Concrete ◽  
Experimental Test ◽  
Steel Fiber ◽  
Experimental Tests ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Test Results ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Frp Confinement

In this study, the co-effects of steel fibers and FRP confinement on the concrete behavior under the axial compression load are investigated. Thus, the experimental tests were conducted on 18 steel fiber-reinforced concrete (SFRC) specimens confined by FRP. Moreover, 24 existing experimental test results of FRP-confined specimens tested under axial compression are gathered to compile a reliable database for developing a mathematical model. In the conducted experimental tests, the concrete strength was varied as 26 MPa and 32.5 MPa and the steel fiber content was varied as 0.0%, 1.5%, and 3%. The specimens were confined with one and two layers of glass fiber reinforced polymer (GFRP) sheet. The experimental test results show that simultaneously using the steel fibers and FRP confinement in concrete not only significantly increases the peak strength and ultimate strain of concrete but also solves the issue of sudden failure in the FRP-confined concrete. The simulations confirm that the results of the proposed model are in good agreement with those of experimental tests.

Experience of Using Complex Modifiers to Increase Corrosion Resistance of Pipe Steels

2021 ◽  
Vol 316 ◽  
pp. 369-374
Author(s):  
Aleksey N. Shapovalov ◽  
Roman R. Dema ◽  
Sergey P. Nefed'ev
Keyword(s):  
Corrosion Resistance ◽  
Rare Earth Metals ◽  
Test Results ◽  
Pipe Steels ◽  
Low Oxygen ◽  
Thermal Expansion Coefficients ◽  
Barium Strontium ◽  
Metallic Inclusions ◽  
Expansion Coefficients ◽  
Increase Corrosion Resistance

The article presents the test results of complex microcrystalline modifiers containing calcium, barium, strontium, rare earth metals. Complex modifiers were used in the processing of steel for 17G1S-U pipes in order to reduce its contamination with non-metallic inclusions, including corrosive ones. The use of modifiers allowed to reduce metal contamination by non-metallic inclusions of all kinds. The most experimental non-metallic inclusions were obtained during metal processing with INSTEEL®5.1 and INSTEEL®9.4 modifiers. In addition, the use of experienced modifiers ensured the production of complex oxysulfides of calcium, cerium and lanthanum with low oxygen content and thermal expansion coefficients, which increases the corrosion resistance of steel.

Fatigue of Stabilized SS and 316 NG Alloy in PWR Environment

2006 ◽  
Author(s):  
Jussi P. Solin
Keyword(s):  
Stainless Steels ◽  
Fatigue Tests ◽  
Test Results ◽  
Constant Amplitude ◽  
Low Oxygen ◽  
Variable Amplitude ◽  
Variable Amplitude Fatigue ◽  
Reduction Factors

Strain controlled constant and variable amplitude fatigue tests for 316NG and Titanium stabilized stainless steels in low oxygen PWR waters were performed. The stabilized steel has been plant aged for 100 000 hours. Constant amplitude test results at 0,01 Hz sinusoidal straining comply with predicted lives according to the Fen approach for both materials. Spectrum straining both in air and in environment caused predicted life reduction factors (about 3) for the stabilized steel, but for the 316NG steel spectrum straining in environment resulted to a larger reduction in life.

Predicting the Brittle-to-Ductile Transition Temperatures for Surface Cracks in Pipeline Girth Welds: It’s Better Than You Thought

2008 ◽  
Author(s):  
Gery Wilkowski ◽  
David Rudland ◽  
Do-Jun Shim ◽  
David Horsley
Keyword(s):  
Transition Temperature ◽  
Surface Crack ◽  
Master Curve ◽  
Crack Depth ◽  
Temperature Shift ◽  
Transition Temperatures ◽  
Surface Cracks ◽  
Line Pipe ◽  
Brittle To Ductile Transition ◽  
Girth Welds

A methodology to predict the brittle-to-ductile transition temperature for sharp or blunt surface-breaking defects in base metals was developed and presented at IPC 2006. The method involved applying a series of transition temperature shifts due to loading rate, thickness, and constraint differences between bending versus tension loading, as well as a function of surface-crack depth. The result was a master curve of transition temperatures that could predict dynamic or static transition temperatures of through-wall cracks or surface cracks in pipes. The surface-crack brittle-to-ductile transition temperature could be predicted from either Charpy or CTOD bend-bar specimen transition temperature information. The surface crack in the pipe has much lower crack-tip constraint, and therefore a much lower brittle-to-ductile transition temperature than either the Charpy or CTOD bend-bar specimen transition temperature. This paper extends the prior work by presenting past and recent data on cracks in line-pipe girth welds. The data developed for one X100 weld metal shows that the same base-metal master curve for transition temperatures works well for line-pipe girth welds. The experimental results show that the transition temperature shift for the surface-crack constraint condition in the weld was about 30C lower than the transition temperature from standard CTOD bend-bar tests, and that transition temperature difference was predicted well. Hence surface cracks in girth welds may exhibit higher fracture resistance in full-scale behavior than might be predicted from CTOD bend-bar specimen testing. These limited tests show that with additional validation efforts the FITT Master Curve is appropriate for implementation to codes and standards for girth-weld defect stress-based criteria. For strain-based criteria or leak-before-break behavior, the pipeline would have to operate at some additional temperature above the FITT of the surface crack to ensure sufficient ductile fracture behavior.

FRP Reinforcement to Retrofit Bridge Pier After Repair: Experimental Test Results

2021 ◽  
pp. 449-458
Author(s):  
Junqing Xue ◽  
Davide Lavorato ◽  
Gabriele Fiorentino ◽  
Alessandro Vittorio Bergami ◽  
Bruno Briseghella ◽  
...  
Keyword(s):  
Experimental Test ◽  
Bridge Pier ◽  
Test Results ◽  
Frp Reinforcement
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