Developing Fatigue Pre-crack Procedure to Evaluate Fracture Toughness of Pipeline Steels Using Spiral Notch Torsion Test

Wang, Jy-An John ; Tan, Ting ; Jiang, Hao ; Zhang, Wei ; Feng, Zhili

Oak Ridge National Laboratory

关键词: Hydrogen Embrittlement;    Weld Fracture;    Pipeline;    Fracture Toughness;    Spiral Notch Torsion Test;   

DOI  :  10.2172/1055086
RP-ID  :  ORNL/TM-2012/337
RP-ID  :  DE-AC05-00OR22725
RP-ID  :  1055086

美国|英语

来源: UNT Digital Library

【 摘 要 】

The spiral notch torsion test (SNTT) has been utilized to investigate the crack growth behavior of X52 steel base and welded materials used for hydrogen infrastructures. The X52 steel materials are received from a welded pipe using friction stir welding techniques. Finite element models were established to study the crack growth behavior of steel SNTT steel samples, which were assumed to be isotropic material. A series SNTT models were set up to cover various crack penetration cases, of which the ratios between crack depth to diameter (a/D ratio) ranging from 0.10 to 0.45. The evolution of compliance and energy release rates in the SNTT method have been investigated with different cases, including different geometries and materials. Indices of characteristic compliance and energy release rates have been proposed. Good agreement has been achieved between predictions from different cases in the same trend. These work shed lights on a successful protocol for SNTT application in wide range of structural materials. The further effort needed for compliance function development is to extend the current developed compliance function to the deep crack penetration arena, in the range of 0.55 to 0.85 to effectively determine fracture toughness for extremely tough materials.