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Full text of "Metallurgy Of Cast Iron"

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AS.!   VMM   M    ALLOYS    IN    FOLNIHNC,.
as to make the iron of a softer nature. Where the graphite is highest, it will close the grain and give the iron a leaden color and generally decrease its strength; whereas the reverse will generally be true if the combined carbon has overreached that point which would afford the iron the greatest strength. On a whole, aluminum, as far as strength is concerned, is only of value in use with very hard grades of iron, or those1 exceeding 1,05 in combined carbon. The percentage of aluminum which I used would range from one-quarter of one percent, to i } percent. The aluminum was placed in the bottom of the ladle and the molten metal poured over it. I found this plan better than tlirowing it into the molten metal after the ladle had been filled. In both cases the metal would always be stirred with a rod to assist in mixing the metals. Aluminum will increase the fluidity of molten metal, but to obtain the best results in this line it must be used with eaiv and judgment. To secure the greatest fluidity ly means of aluminum depends upon the per-rrnta-jvs of the clrnu'uts which compose the iron de-sigjird to make- it soft or hard. The harder the iron the moiv aluminum can he used to obtain the greatest dcgn-c of lluitlity. With soft grades aluminum, can make tiu* metal sluggish, with excessive dross on its surface, just as can be the case by having too much silicon in a mixt lire.
While flu- way in which aluminum, will generally work in affecting the different percentages of carbon in iron arc above outlined, still, on the whole, it is very erratic and will often act contrary to expectations. Chtr prruliarity about aluminum alloyed with iron, is displayed when* two ladles are used to pour a mould,ole it shows us that