Severe wall thinning is found on the tube of a low-pressure evaporator(LPEVA) module that is used for a heat recovery steam generator(HRSG) of a district heating system. Since wall thinning can lead to sudden failure or accidents that lead to shutdown of the operation, it is very important to investigate the main mechanism of the wall thinning. In this study, corrosion analysis associated with a typical flow-accelerated corrosion(FAC) is performed using the corroded tube connected to an upper header of the LPEVA. To investigate factors triggering the FAC, the morphology, composition, and phase of the corroded product of the tube are examined using optical microscopy, scanning electron microscopy combined with energy dispersive spectroscopy, and x-ray diffraction. The results show that the thinnest part of the tube is in the region where gas directly contacts, revealing the typical orange peel type of morphology frequently found in the FAC. The discovery of oxide scales containing phosphate indicates that phosphate corrosion is the main mechanism that weakens the stability of the protective magnetite film and the FAC accelerates the corrosion by generating the orange peel type of morphology.

Abstract
 1. 서 론
 2. 연구 방법
 3. 결과 및 토론
  3.1 부식 경향 분석
  3.2 부식 생성물 분석
  3.3 단면 미세조직 분석
 4. 결 론
 References

• 홍민기(충남대학교 신소재공학과) | Minki Hong (Department of Materials Science and Engineering, Chungnam National University)
• 채호병(충남대학교 신소재공학과) | Hobyung Chae (Department of Materials Science and Engineering, Chungnam National University)
• 김영수(충남대학교 신소재공학과) | Youngsu Kim (Department of Materials Science and Engineering, Chungnam National University)
• 송민지(충남대학교 신소재공학과) | Min Ji Song (Department of Materials Science and Engineering, Chungnam National University)
• 조정민(충남대학교 신소재공학과) | Jeongmin Cho (Department of Materials Science and Engineering, Chungnam National University)
• 김우철(한국지역난방공사 미래개발원) | Woo Cheol Kim (Frontier Research & Training Institute, Korea District Heating Corporation)
• 하태백(한국지역난방공사 미래개발원) | Tae Baek Ha (Frontier Research & Training Institute, Korea District Heating Corporation)
• 이수열(충남대학교 신소재공학과) | Soo Yeol Lee (Department of Materials Science and Engineering, Chungnam National University) Corresponding author