The corrosion behavior of 15CrMo used for water-wall tubes was studied in various urea-containing solution to determine the corrosion problem of water-wall tubes caused by urea in a coal-fired power plant. Urea decomposition tests, together with corrosion experiments, were carried out. The temperature was 320 °C, and the concentrations of urea were 70, 140, 280, 560 and 840 mg/L. Weight loss experiments and surface analysis indicated that the corrosion of 15CrMo steel is mainly manifested as localized corrosion. The corrosion rate of 15CrMo steel increased with the increase of urea concentration, and the maximum value reached 0.686 mm/y (mm per year) when the urea concentration was 840 mg/L. Electrochemical analysis suggested that the corrosion rates of 15CrMo were enhanced substantially by urea decomposition products. The results of UPLC-ESI-MS, infrared spectroscopy and X-ray diffraction showed that urea solution produced corrosive ions NH 2 COO − during the decomposition process, which caused the corrosion of 15CrMo. Results provided evidence as relevant explanation for the corrosion behavior of 15CrMo in urea solution.

中文翻译：

---

尿素及其副产物存在下火电厂水冷壁管用15CrMo钢的腐蚀行为

在各种含尿素的溶液中研究了用于水冷壁管的15CrMo的腐蚀行为，以确定燃煤电厂中由尿素引起的水冷壁管的腐蚀问题。进行了尿素分解试验和腐蚀试验。温度为320℃，尿素浓度为70、140、280、560和840mg / L。失重实验和表面分析表明，15CrMo钢的腐蚀主要表现为局部腐蚀。15CrMo钢的腐蚀速率随尿素浓度的增加而增加，当尿素浓度为840 mg / L时，最大值达到0.686 mm / y（每年mm）。电化学分析表明，尿素分解产物可显着提高15CrMo的腐蚀速率。UPLC-ESI-MS的结果，红外光谱和X射线衍射结果表明，尿素溶液在分解过程中产生腐蚀性离子NH 2 COO-，引起15CrMo的腐蚀。结果为15CrMo在尿素溶液中的腐蚀行为提供了相关解释。