Abstract
This study was undertaken to determine the effects of some variables, such as aluminum content, pouring temperature, mold temperature and addition elements, on the fluidity of Zn-Al alloys by the spiral-form metallic mold testing apparatus.
The results obtained are summarized as follows :
(1) For Zn-Al binary alloys, the fluidity value is approximately in inverse proportion to the freeziing range, and alloy containing about 30%Al shows the lowest fluidity value.
(2) The coarse porosities appear in the fluidity specimen having narrow freezing range such as pure metals and eutectic composition, the microporosities dispersed in the alloys having long freezing range.
(3) The relations between fluidity value and superheat of pouring temperature and mold temperature may be shown as the following equation :
L=A⋅ΔT+B
where, L is fluidity value in cm, T is superheat of pouring temperature or mold temperature in °C, A is constant in cm/°C, B is constant in cm.
(4) For the effects of addition elements on the fluidity of high Al-Zn alloy with long freezing range, the fluidity may be improved by adding Mg, Si, V and Cu, and decreased by adding Cr, Zr, Ti, Ni and Mn in the range of less than 0.5%.
(5) In Zn-22% Al-1% Cu and Zn-22% Al-3% Cu alloys, the fluidity value may be increased by adding Si, and decreased by adding Mg. In Zn-22% Al-3% Cu-1% Mg alloy, the fluidity valuie decreases by adding Si more than 0.5%.
