Abstract
Erosion-corrosion behaviours of a carbon steel and a stainless steel were studied by electrochemical measurements in “jet-in-slit” sand-erosion testing. The test was conducted under the condition of slurry flow rates lower than 5m/s, pH range 1.5-7.0 and alumina particle of 4×10-5m diameter. The erosion-corrosion rate was evaluated in terms of the corrosion rate obtained by the electrochemical measurement and the erosion rate. The following results were obtained. (1) The erosion-corrosion rate of the stainless steel increases in proportion to the 4-5 powers of the flow rate. The corrosion rate, which amounts to 10-30% of the erosion-corrosion rate, increases also in proportional to the 4-5 powers of the flow rate. The corrosion is accelerated by the breakdown of passive films due to the slurry flows. (2) The erosion-corrosion rate of the carbon steels is 15-300 times higher than that of the stainless steel, and increases in proportion to the 0.5-1.0 powers of the flow rate. The corrosion rate amounts to almost all of the erosion-corrosion rate. The acceleration of the corrosion is due to the diffusion of disolved oxygen enhancement by the slurry flow. (3) Under the cathodic protection, the erosion-corrosion rate of the carbon steel decreases dramatically resulting about the same rate with the stainless steel.
