Erosion mechanisms of nodular and gray cast irons at different impact angles


YILDIZLI K. , Karamis M. B. , Nair F.

WEAR, cilt.261, ss.622-633, 2006 (SCI İndekslerine Giren Dergi) identifier identifier

Özet

The erosion behaviours of the nodular and gray cast irons were studied at an intermediate and normal impact angles via an experimental setup. Erosion tests were carried out at impact angles of 30 degrees, 60 degrees and 90 degrees using angular hard particles. The particle velocity was controlled utilizing the gas pressure and was measured with rotating double discs. The results showed considerable weight loss variation as a function of the impact angles. The highest erosion rate occurred at an impact angle of 30 degrees and then, two types of the cast irons exhibited the least resistance to erosion. While the rate was at an intermediate level at 60 degrees, the lowest rate occurred at normal impact angle. It was found that the erosion rate of the nodular cast iron (NCI) was lower than that of the gray cast iron (GCI) at all impact angles. In all cases, the erosion appeared to have occurred by a ductile process. At oblique impact angles (30 degrees and 60 degrees), hard erodent caused plastic flow in relatively softer surface of nodular cast iron and material removal occurred by microcutting and microploughing. During the erosive wear progress for nodular cast iron, just below the eroded surface, even though the ends of which behaved as crack nucleation agents, the deformed graphite fines were not broken off from the surface in a short time. No remarkable changes were relatively observed in the wear mechanisms. At a normal impact angle, material loss from the nodular cast iron surface occurred via gauging. Deformation spreading was also observed beneath the surface under at all impact tests. As far as gray cast iron is considered, the erodent can cause plastic yielding in the target surface and material removal went on by major ploughing with microcracking and subsurface fatigue. At a normal impact angle, the erosive wear occurred by chipping and small-scale fracture. (c) 2006 Elsevier B.V. All rights reserved.