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<p>To investigate the causes of corrosion failure in 12CrMoV steel used for the low-temperature reheater of a power plant in Xinjiang, characterization methods such as macroscopic morphology observation, chemical composition analysis, metallographic examination, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were employed. Combined with the actual on-site operating conditions, a systematic analysis of the corrosion failure mechanisms for the 12CrMoV steel in the reheater was conducted. The results show that Tube 1 and Tube 2 meet national standards in terms of chemical composition, metallography and hardness. However, non-metallic inclusions lead to low elongations after fracture, increasing the risk of stress corrosion cracking. For Tube 1, the outer corrosion products on the yellow rust surface consisted of a scale layer composed of CaSO<sub>3</sub>, Ca<sub>2</sub>SiO<sub>4</sub>, and Ca<sub>3</sub>Si<sub>2</sub>O<sub>7</sub>. The hydrolysis of this scale layer generated solutions containing OH<sup>-</sup> that seeped beneath the scale, forming a strongly alkaline environment and causing high-temperature under-scale alkaline corrosion in Tube 1. For Tube 2, the outer corrosion products on the yellow rust surface were a Na<sub>2</sub>SO<sub>4</sub> scale layer. Due to the increased dew point temperature of flue gas containing sulfuric acid vapor, H<sub>2</sub>SO<sub>4</sub> and HCl in the flue gas condensed into acidic liquids, leading to sulfur–chlorine synergistic dew point corrosion in Tube 2.</p>

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Comparative Analysis of Failure Mechanisms in 12CrMoVG Steel Dual Tubes for Boiler Low-Temperature Reheaters

  • 期刊论文

  • 发表日期：

    2025年8月7日

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  • Baojun Dong,
  • Tianfang Jiao,
  • Nan Xiang,
  • Yuhao Liang,
  • Guili Zhang,
  • Fei Kang,
  • Dianyi Wang,
  • Jianyu Chen

摘要

To investigate the causes of corrosion failure in 12CrMoV steel used for the low-temperature reheater of a power plant in Xinjiang, characterization methods such as macroscopic morphology observation, chemical composition analysis, metallographic examination, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were employed. Combined with the actual on-site operating conditions, a systematic analysis of the corrosion failure mechanisms for the 12CrMoV steel in the reheater was conducted. The results show that Tube 1 and Tube 2 meet national standards in terms of chemical composition, metallography and hardness. However, non-metallic inclusions lead to low elongations after fracture, increasing the risk of stress corrosion cracking. For Tube 1, the outer corrosion products on the yellow rust surface consisted of a scale layer composed of CaSO3, Ca2SiO4, and Ca3Si2O7. The hydrolysis of this scale layer generated solutions containing OH- that seeped beneath the scale, forming a strongly alkaline environment and causing high-temperature under-scale alkaline corrosion in Tube 1. For Tube 2, the outer corrosion products on the yellow rust surface were a Na2SO4 scale layer. Due to the increased dew point temperature of flue gas containing sulfuric acid vapor, H2SO4 and HCl in the flue gas condensed into acidic liquids, leading to sulfur–chlorine synergistic dew point corrosion in Tube 2.