抄録
As to the change in the characteristics of Mg-treated spheroidal graphite iron, the effects of remelting temperature and duration of molten state after remelting are reported in the present paper. Th results obtained are summarizede as follows. (1) The decrease of the residual Mg content due to remelting was faster at the earlier stage of remelting, but became gradually slower. (2) The initial spheroidal grpahite changed to nodular, and then, to irregular quasi-flaky graphite with the decrease of the residual Mg content in proportion to the duration after remelting. (3) At this stage a ledeburite structure appeared in the matrix and then its amount increased.It was an interesting phenomena that this chilled effect appeared with the decrease of the residual Mg content. (4) However, when the initial spheroidal graphite was remelted perfectly into molten iron, the chilled effect disappeared and suddenly changed to the D-type undercooled graphite structure, and then, gradually to the normal flaky graphite structure, (5) The structural change above mentioned became faster with higher remelting temperature. (6) Reappearance of spheroidal graphite iron due to remelting in the air can hardly be expected.
