Corrosion Behavior of Several Kinds of Steel in NH4Cl Environment

The corrosion behaviors of carbon steel, 321 austenitic stainless steel and 2205 dual phase steel in 5 000 mg/L NH4Cl solution and wet NH4Cl environment were studied. The results showed that in this two kinds of circumstances, carbon steel presented uniform corrosion, ammonium salt deposit corrosion was more serious than the corrosion of aqueous solution. The corrosion intensified with the increase of temperature, the corrosion rate of carbon steel in wet NH4Cl salt at 60 ℃ reached 6.27 mm/a.The uniform corrosion rate of 321 stainless steel was very low, but there were a large number of plaques and corrosion pits on the surface, and no passivation area in the 5 000 mg/L NH4Cl solution. The pitting corrosion resistance of 2205 dual phase steel is superior to that of 321 austenitic stainless steel. The sample surface of 2205 dual phase steel almost was not corroded, but there were a few big and deep pits. The corrosion intensified with the increase of temperature, and there was no Ni content in corroded areas in this two cases, austenite phase was corroded firstly.