Authors
University of Technology
Abstract
The wear and erosion-corrosion resistance of gray and ductile cast irons
were studied for their important in most applications. The wear tests were carried
out using a pin-on-disc machine by applying different loads (10,20 and 30 N). The
wear rate was measured using weighting loss method.
Erosion-corrosion rate measurements for both types of cast iron in
(0.01%,0.58% and3.5%) NaCl solutions using a rotating disc of 450 rpm indicate
that erosion-corrosion resistance of ductile iron is better than that of gray cast iron.
Microstructure observations after erosion-corrosion indicate that it plays a
role in erosion-corrosion ; the predominant ductile matrix on the microstructure of
ductile iron is at lower erosion-corrosion rate than that of gray cast iron .
Localized attack usually has bright surfaces free from corrosion product. Pits are
often observed on the line flow direction on these materials. These pits have a
characteristic horse shoes shape for both types of cast irons. Optical microscope
examination for the specimens indicates the presence of white and dark areas
which refer to graphitization and pitting corrosion respectively. The wear rate is
influenced by the form of phases therefore the flake graphite form in gray acts
more like a lubricant film between two contact surfaces than spheriodal
graphite. Brinell hardness measurements for both materials show that gray iron has
higher hardness than ductile iron so that wear tests at different loads (10, 20 and 30
N) for both materials indicate that gray iron has high wear resistance than ductile
iron and the wear rate increases sharply after (20N) for ductile iron. These results
are related to high hardness and graphite phase form on the microstructure of gray
iron.
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