Slurry erosion wear of high chromium cast iron samples from a slurry pump impeller. Effect of impact angle variation

Abstract

In this work, the impact angle effect on the erosive wear resistance of high chromium cast iron (HCCI) samples from a slurry pump impeller was evaluated. For this purpose, equipment was designed and built to carry out wet erosion tests. Erosion tests were carried out at angles of 30°, 45°, 60° and 90° using an erosive slurry with a concentration of 20%, by weight, of silica sand. The results indicated that the erosive wear rate followed the classic behavior of variation with the impact angle for ductile materials. There was an increase in the erosion rate with increasing angle until reaching the peak wear at 45°, followed by a decrease in wear down to the minimum wear rate at 90°. Significant differences were observed in the mass loss of the HCCI samples: the samples eroded at 45° showed a mass loss 2.7 times greater than the eroded condition at 90°, indicating that, due to the condition of slurry contact with the surface of the samples, erosive and abrasive mechanisms acted synergistically favoring wear at 45°. On the other hand, samples eroded at 30° and 60° showed similar and intermediate mass losses. In general, for the samples eroded at a normal angle (90°) the mechanisms of wear due to plastic deformation of the matrix and carbide fracture were observed, while for smaller angles, the mechanisms of micro cutting and micro grooving were more evident.