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<p>This study investigates the microstructure and hydrogen embrittlement behavior of weld metals produced by hybrid laser-arc welding (HLAW) and metal active gas (MAG). Cross-sectional SEM analysis revealed that the HLAW process resulted in a significantly higher fraction of acicular ferrite compared to the MAG, promoting a refined grain structure. Electron backscatter diffraction analysis confirmed a greater presence of high-angle grain boundaries (HAGBs) in the HLAW specimens. Slow strain rate tensile testing demonstrated that both welding methods exhibited hydrogen embrittlement in a hydrogen-rich environment, but fracture initiation sites differed. While the MAG specimens mostly&#xa0;fractured within the weld metal under hydrogen exposure, the HLAW specimens failed&#xa0;mostly at the base metal, inferring that the weld section in HLAW had superior resistance to hydrogen-assisted cracking compared to the base metal, whereas in MAG, the weld metal exhibited worsened resistance relative to the base metal. Fractographic analysis further confirmed a transition from ductile fracture in the air to intergranular brittle fracture in the MAG weld section and base metal when exposed to hydrogen. The findings suggest that HLAW provides better hydrogen resistance due to its refined microstructure and increased HAGB density, making it a promising welding technique for hydrogen-related applications.</p>

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Enhancing hydrogen embrittlement resistance in steel pipelines through hybrid welding

  • 期刊论文

  • 出版模式：

    开放获取

  • 发表日期：

    2025年6月4日

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  • Mahdieh Safyari,
  • Donát Horváth,
  • Masoud Moshtaghi

摘要

This study investigates the microstructure and hydrogen embrittlement behavior of weld metals produced by hybrid laser-arc welding (HLAW) and metal active gas (MAG). Cross-sectional SEM analysis revealed that the HLAW process resulted in a significantly higher fraction of acicular ferrite compared to the MAG, promoting a refined grain structure. Electron backscatter diffraction analysis confirmed a greater presence of high-angle grain boundaries (HAGBs) in the HLAW specimens. Slow strain rate tensile testing demonstrated that both welding methods exhibited hydrogen embrittlement in a hydrogen-rich environment, but fracture initiation sites differed. While the MAG specimens mostly fractured within the weld metal under hydrogen exposure, the HLAW specimens failed mostly at the base metal, inferring that the weld section in HLAW had superior resistance to hydrogen-assisted cracking compared to the base metal, whereas in MAG, the weld metal exhibited worsened resistance relative to the base metal. Fractographic analysis further confirmed a transition from ductile fracture in the air to intergranular brittle fracture in the MAG weld section and base metal when exposed to hydrogen. The findings suggest that HLAW provides better hydrogen resistance due to its refined microstructure and increased HAGB density, making it a promising welding technique for hydrogen-related applications.