Hello Researchers,
To conduct fracture toughness tests for pipeline material how do you machine specimen using pipelines with small thicknesses (ex 7mm)?
According to ASTM E399, how do you satisfy the ligament length condition with a smaller specimen?
Thank you
According to ASTM A370, the standard specimen size for Charpy impact testing is 10 mm × 10 mm × 55 mm. Subsize specimen sizes are: 10 mm × 7.5 mm × 55 mm, 10 mm × 6.7 mm × 55 mm, 10 mm × 5 mm × 55 mm, 10 mm × 3.3 mm × 55 mm, 10 mm × 2.5 mm × 55 mm. Details of specimens as per ASTM A370 (Standard Test Method and Definitions for Mechanical Testing of Steel Products).
Fo low wall thickness pipes, itis possible only the longitudinal impact test (the length of the specimen is aligned with pipe axis)
To get fracture toughness, for line pipe about 0.25" wall, you should use ASTM E1820 to measure Jc or CTOD. There are validity check list in this standard. We measured J-integral on line pipe before. We converted the critical J value to K fracture toughness and use the value in the fitness-for-service assessment. ASTM E399 should not be used for ductile line pipe materials.
Hello Dr. Eliseo Galli,
Thank you for your reply. However, for my study I'm conducting in-situ embrittlement studies Therefore I'm unable to use the standard tensile specimen and Charpy impact test.
Hello Dr. Hillary Yin
Thank you for your reply. I'm currently reviewing the E1820 standard. Would you be kind enough to let me know the following?
1) Due to several restrictions, I can only use Arc-shaped bend specimen type for my testing. However in the E1820 standard it does not have the above mentioned specimen type, above-mentioned, Will it be an issue?
2) Why do you say E399 cannot be used for ductile pipeline material?
Thank you
Rashiga Walallawita Ductile line pipe materials do not meet the plane-strain condition required in E399, because the materials are too ductile and is outside the linear-elastic fracture mechanics theory.
What was the reason why you cannot not use CT or bend specimens as given in E1820? If you want to use a specimen geometry that is not included in E1820, you can run FEA analysis of you specimen geometry to determine the J-internal equation for your specimen.
Dr Hillary Yin ,thanks again.
The reason for the inability to use CT or bend specimens is the lack of ligament length. The pipeline specimen I have is 6.7 mm in thickness and 12.75 in diameter.
Thank you for the suggestion I will use that method to obtain J-integral.
Article Correlation of Pipe Ring Notched Bend (PRNB) specimen and Si...
Article Proposal of New Pipe-Ring Specimen for Fracture Mechanics
https://www.sciencedirect.com/science/article/abs/pii/S0013794418304119
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