Yield strength mis-match effect on fracture performance of girth welded joints of Grade 550 pipeline steel
- Osaka Univ. (Japan). Dept. of Welding and Production Engineering
- Sumitomo Metal Industry, Osaka (Japan)
- NOVA Gas Transmission Ltd., Calgary, Alberta (Canada)
- Univ. of Toronto, Ontario (Canada). Dept. of Metallurgy and Materials Science
The fracture behavior of girth welded joints with a surface notch in the weld metal has been investigated using wide plate testing and 3D FE-analyses. The base steel used was a Grade 550 pipeline steel, and overmatched, matched and undermatched weld metals were evaluated. The problem is that undermatched welded joints require a larger crack tip opening displacement (CTOD) than matched and overmatched welded joints. Nevertheless, an undermatched weld metal can be utilized during girth welding, provided that it retains sufficient toughness to meet the required deformation. The present paper develops a procedure to determine the fracture toughness level in undermatched weld metal needed to guarantee the deformation required by the design solution. Through a collaborative program the fracture behavior of girth welded joints with a surface notch in the weld metal have been investigated using wide plate testing and 3D FE-analysis. The approach uses the distinction between the 3-point bend CTOD and the CTOD of the wide plate test and the concept of an equivalent CTOD. At the same CTOD level, the 3-point bend specimen generally produces a markedly higher near crack-tip stress than in the wide plate. The paper describes how the equivalent bend toughness can be determined and shows how the required toughness can be determined from the equivalent bend CTOD (which provides a near-tip stress field compatible with the wide plate test) at the required deformation level.
- OSTI ID:
- 205463
- Report Number(s):
- CONF-950695--; ISBN 0-7918-1311-8
- Country of Publication:
- United States
- Language:
- English
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