| Summary: | 碩士 === 國立中央大學 === 機械工程學系 === 85 === Processing variable of different inoculation techniques,
chemical compositions (0.6%Cu,0.5%Ni0.5%Cu),and filling rates
for producing ductile iron had been evaluatedin this study to
see their effects on the as-cast microstructures of different-
sectionedductile irons.One process used the ladle inoculation
added with ferrosiliconinoculant and 40 ppm bismuth.Another
process used the combination of ladle inoculation and stream
inoculation.Two stepped plate castings(20 and 35mm;35 and 65mm)
werepoured from local foudry shop. The as-cast
microstructures of plate castings were compared.The effect
ofdifferent inoculation treatments on the mechanical properties
of produced platecastings were discussed.Specimens from
different locations of two stepped plate castingswere prepared.
These specimens were used to conducted two different austempered
procedures.One procedure isothermally held at 573K for 180
minutes, and another procedure treatedthe specimens at 663K for
8 minutes and then isothermally holding at 573L for 172 minites,
after the solution treatment at 1173K for 90 minites.Mechanical
properties of tensilestrength,elonation,impact energy and
hardness were tested and compared.
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