Experimental characterization of dynamic fracture toughness behavior of X80 pipeline steel welded joints for different heat inputs

Abstract

Structural integrity of oil and gas pipelines depends on fracture toughness and metallurgical properties of pipeline steel welded joints. Dynamic fracture toughness (J(Id)) is an important parameter to measure structural integrity in terms of fracture toughness of pipeline steel welded joints under impact loading. Welding input parameters such as current (A), voltage (V), and travel speed (cm/m) significantly affect the mechanical and metallurgical properties of the weldments; therefore, to study the cumulative effect of these parameters, author(s) used different heat input (kJ/cm) as an input parameter in the present work. In the present work, three different levels of heat input such as low heat input (LHI)15 kJ/cm, medium heat input (MHI)20 kJ/cm, and high heat input (HHI) 25 kJ/cm were employed for the fabrication of X80 pipeline steel welded joints. Thereafter, mechanical and metallurgical behavior of different locations (Fusion line (FL), FL + 1 mm, FL + 2 mm, and FL + 3 mm) in multi-pass X80 pipeline steel weld joint was investigated under cold climatic conditions (- 20 degrees C). The dynamic fracture toughness was measured from instrumented Charpy impact test results using three different estimation methods. Furthermore, a finite element model was developed to simulate the Charpy impact test and validate the experimental results, using the Johnson-Cook constitutive model.