EFFECT OF 20 ADDING ELEMENTS ON SILUMIN

Abstract

Effect of Ca, Ti, P, S and C, which will possiblly be alloyed in Silumin from the raw material; Silicon, on Silumin has already been reported. In this report effects of other 20 adding elements (Ag, B, Ba, Be, Bi, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Sb, Sn, V, W and Zn) on the hardness, microstructure and casting surface of Silumin has been studied. Relations between the content of additional elements and the Rockwell hardness (B scale) of Silumin are shown in Table 2 and Fig. 1a-d. Microstructures of slowly cooled or chillcast specimens are shown in Photo. 1-92, and the casting surfaces are also shown in Photo. 96-115. The results of observations may be summarized as follows;(1) The most effective element to increare the hardness of Silumin is found to be Mg followed by Cu, although the addition of Co, Cr, Ni and Mn are found also to be very effective, and the effect of Ba, Bi, Ag, Fe and Mo is not so conspicuous. Zn, Cd and Pb have little or no effect.(2) Ba, Sb, Bi and Mg modify the structure of Silumin especially as chilled but their modifying power is not so strong as Na. The microstrcture of Silumin modified by these elements are not so fine as modified by Na especially as slow cooled.(3) Ba, Sb, Bi and Mg make the casting surface of Silumin like toad's skin which is disliked by founder. This phenomenon is a result of feeble modification in which Al dendrites grow rectangular to the casting surface.