Cailiao Baohu (Dec 2023)

Corrosion Behavior of 2Cr-1Ni-1.2Mo-0.2V Steel in 120 mmol/L NH<sub>4</sub>H<sub>2</sub>PO<sub>4</sub> Solution

  • WANG Tong, LI Quande, LI Zhi, CHEN Ruifang, GONG Xianlong, DAI Jun, NI Rong, GONG Xiufang, LONG Bin, MENG Huimin

DOI
https://doi.org/10.16577/j.issn.1001-1560.2023.0303
Journal volume & issue
Vol. 56, no. 12
pp. 179 – 187

Abstract

Read online

In order to analyze the impact of the waste heat utilization environment in phosphate compound fertilizer industrial production on the corrosion behavior of steam turbine rotors, various methods such as the mass loss method, laser scanning confocal microscopy (CLSM), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS) and electrochemical tests were employed. The corrosion behavior and patterns of the steam turbine rotor material, 2Cr-1Ni-1.2Mo-0.2V steel in 120 mmol/L NH4H2PO4 solution at an external temperature of 25 ℃ were investigated. Results showed that 2Cr-1Ni-1.2Mo-0.2V steel underwent uniform corrosion. The corrosion rate first rapidly decreased and then slowly decreased, gradually stabilizing towards 0.2 mm/a. When the NH4H2PO4 concentration was 120 mmol/L and the temperature was 25 ℃, the service life of 2Cr-1Ni-1.2Mo-0.2V steel was determined to be 7.5 a. The corrosion product film of 2Cr-1Ni-1.2Mo-0.2V steel in NH4H2PO4 solution was composed of Fe3(PO4)2, FePO4, Fe(OH)3, FeOOH, and Fe3O4. As the immersion time prolonged, the coverage, compactness and thickness of the corrosion product film were observed to increase, and Cr was found to be enriched in the corrosion product film, thereby enhancing the corrosion resistance of 2Cr-1Ni-1.2Mo-0.2V steel.

Keywords