| dc.description.abstract | The influence of some process variables like casting size, initial mould temperature,
mould wall thickness, inoculation and composition on microstructure, hardness and
tensile strength of gravity die cast grey irons were investigated.
The microstructures were observed using light microscopy. Tensile tests were
carried out at room temperature using universal testing machine. Hardness tests
were carried out at room temperature on as-cast specimens.
Increasing casting size resulted in decreased tensile strength and decreased ascast
BHN. Increasing initial mould temperature resulted in increased tensile strength
and increased as-cast BHN. Increased mould wall thickness resulted in increased
as-cast BHN but decreased tensile strength. Inoculation increased as-cast BHN and
percentage of type A graphite. Mixed graphite sizes were observed in all the as cast
specimens. However, the reversal of some of the trends are attributed to the
interplay of notch sensitivity factors, namely: coarseness of graphite, coarseness of
ferrite, increased pearlite spacing and the way the graphite flakes merges with the
matrix.
This study was initiated with a long term aim of furthering the studies on the subject
of gravity die casting of grey irons. It is expected that future studies will obtain more
results and conclusions. | en |
