The Effect of Cooling Rate-Induced Microstructural Changes on CO2 Corrosion of Low Alloy Steel

The effect of cooling rate-induced microstructural changes on corrosion resistance in a CO2-saturated 3.5 wt% NaCl solution have been explored for the API L80-1Cr steel. The corroded layer majorly contains siderite, akagenite, and undissolved cementite. The amount of FeCO3 in this layer is larger for the water-cooled sample with a martensitic structure, whereas the furnace-cooled sample with a ferritic-pearlitic structure contains a larger amount of akagenite. The retained cementite and the microrough surface of the furnace-cooled sample provide greater anchoring to the scale. Comparing samples cooled at different rates, the furnace-cooled condition appears to provide better CO2 corrosion resistance.