Fracture Toughness Study on Butt-Welds of Grade X52 Pipeline Steel in Hydrogen Gas at 65 Bar

Abstract This study focuses on the hydrogen (H2) characterization of butt-welded X52 pipeline steel, a material widely used in the oil and gas industry due to its favorable mechanical properties and weldability. The study focused on the effect of the embrittlement of the Hydrogen gas environment at 65 bar(g). Indeed, the effect of different welding processes was investigated and related to the different microstructural zones of the samples and the basic mechanical behavior. Through microstructural analysis, hardness testing, fracture toughness testing in air and H2 environment, the study assesses the susceptibility of the welded joint, particularly the weld metal (WM), heat-affected zone (HAZ), and base metal (BM)—to hydrogen embrittlement. Fracture toughness tests (JIH) in hydrogen gas were conducted to evaluate crack propagation resistance under service-like conditions. The results highlight a different susceptibility of the microstructural zones investigated and helped to assess the structural integrity across the weld region.