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A thick-section surfacing test was performed using the gas tungsten arc welding (GTAW) process and evaluated in the as-welded condition. A 40 mm thick overlay was deposited onto an 80 mm thick Q235B steel plate using ERNiCrMo-3 solid wire, which is the filler metal equivalent of Alloy 625. Hot cracks were detected in the outer three-fourths of the deposit. The cracking mechanism was investigated using light optical microscopy (LOM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS). The microstructure featured cellular dendrites and interdendritic solidification cracks aligned with the growth direction. In addition to the commonly reported Ni2Nb Laves phase and NbC-type carbides, δ-Ni3Nb precipitates were also identified. Two solidification paths were distinguished, with the eutectic structure γ + MC + δ + Laves being more susceptible to hot cracking than the γ + MC + Laves composition.

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Microstructural Analysis of Hot Cracking in a 40 mm Thick Alloy 625 Weld Overlay

  • 会议论文

  • 发表日期：

    2026年

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  • Xiao Guo,
  • Ying Han,
  • Elin Marianne Westin,
  • Xiaochun Lv,
  • Yinglong Jiang,
  • Wenjun Fu,
  • He Zhang,
  • Sten Wessman

摘要

A thick-section surfacing test was performed using the gas tungsten arc welding (GTAW) process and evaluated in the as-welded condition. A 40 mm thick overlay was deposited onto an 80 mm thick Q235B steel plate using ERNiCrMo-3 solid wire, which is the filler metal equivalent of Alloy 625. Hot cracks were detected in the outer three-fourths of the deposit. The cracking mechanism was investigated using light optical microscopy (LOM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS). The microstructure featured cellular dendrites and interdendritic solidification cracks aligned with the growth direction. In addition to the commonly reported Ni2Nb Laves phase and NbC-type carbides, δ-Ni3Nb precipitates were also identified. Two solidification paths were distinguished, with the eutectic structure γ + MC + δ + Laves being more susceptible to hot cracking than the γ + MC + Laves composition.