论文信息 - Weld crack assessments in API X65 pipeline: Failure assessment diagrams with variations in representative mechanical properties

Weld crack assessments in API X65 pipeline: Failure assessment diagrams with variations in representative mechanical properties

Applying accurate material properties to failure assessment diagrams (FAD) for flaw assessment has been problematic, particularly for welded joints in structures such as natural gas pipeline. In a study of API X65-graded natural gas pipeline, we evaluated material properties such as tensile properties and fracture toughness for the base metal, weld metal and heat-affected zone (HAZ), and investigated the influence on flaw assessment of variations in material properties of three regions. In particular, microtensile tests and crack-tip-opening-displacement (CTOD) tests made it possible to construct an HAZ-focused FAD reflecting HAZ properties. It was found that, when crack-like flaws exist in the HAZ, the HAZ-focused FAD yields a more accurate assessment than FADs constructed according to current codes.

[1] Standard Test Methods for Tension Testing of Metallic Materials 1 , 2022 .

[2] J. R. Gordon,et al. A Review of Fracture Assessment Procedures and Their Applicability to Welded Structures , 1993 .

[3] G. Reddy,et al. Heat-affected zone softening in high-strength low-alloy steels , 1999 .

[4] Zhiliang Zhang,et al. Application of local approach to inhomogeneous welds. Influence of crack position and strength mismatch , 1999 .

[5] Dongil Kwon,et al. Determination of welding residual stress distribution in API X65 pipeline using a modified magnetic Barkhausen noise method , 2003 .

[6] G. Reddy,et al. Ballistic performance of high-strengh low-alloy steel weldments , 1996 .

[7] David A. Osage,et al. API 579 : a comprehensive fitness-for-service guide , 2000 .

[8] Robert A. Ainsworth,et al. The assessment of defects in structures of strain hardening material , 1984 .

[9] D. Kwon,et al. Effects of microstructural change on fracture characteristics in coarse-grained heat-affected zones of QLT-processed 9% Ni steel , 2003 .