A systematic assessment of the properties of girth welds, produced by current welding techniques such as Pulsed Gas Metal Arc Welding (PGMAW) and Shielded Metal Arc Welding (SMAW), was carried out on quenched and tempered seamless linepipes, API 5L X65 grade, for offshore applications. The assessment included hardness, Charpy - V testing, and Crack Tip Opening Displacement (CTOD) testing at the fusion line (FL). Detailed metallographic investigation for validation of CTOD results and analysis of Local Brittle Zones (LBZs) was performed. Relevant metallurgical parameters which control toughness in the Heat Affected Zone (HAZ) of multipass weld were identified. PGMAW joints showed excellent CTOD values at - 20 degC in the HAZ/FL, irrespective to steel microalloying design and wall thickness of the pipe. Some small areas which can be considered as potential LBZs have been detected in the Intercritically Reheated - Grain Coarsened HAZ (IR-GCHAZ). However, no detrimental effect of such areas has been found both on CTOD and Charpy toughness. Hardness was within the 250 HV,0 limit in the whole HAZ. SMAW joints showed acceptable Charpy toughness, while somewhat low but still acceptable CTOD values were found in the HAZ/fusion line at 20 degC. This result was related to the presence of LBZs within the IR-GCHAZ. Hardness was not adversely affected by such LBZs and it was found to remain well below the 250 HVIO limit. (Copyright 2003 Stahlinstitut VDEh)
Weldability assessment of offshore seamless linepipes
Bewertung der Schweißbarkeit von nahtlosen Rohrleitungen für den Offshore-Bereich
Conference on Uses of Steel, 1 ; 157-165
2002
9 Seiten, 6 Bilder, 7 Tabellen, 6 Quellen
Conference paper
English
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