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Subject: Re: stream inoculation
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Date: 05/10/01 at 11:22 PM
Posted by: Vikas Goel
In Reply to: Re: stream inoculation posted by sekhar rao on 05/01/01 at 11:00 AM:
In grey and SG iron inoculants help in providing nucleii around which solidification starts and graphite begins to precipitate. Without inoculants there is great possibility of carbide formation in the metal. Normally FeSi based inoculants are used, although neither iron nor silicon act as nucleii. It the trace elements included in the fesi which help in creating suitable nuclei. The exact mechanism of nucleation is not very clearly understood, as calcium etc. present in trace amounts in the inoculant will only nucleate the melt when present in very small amounts and calcium itself will not nucleate if added as pure calcium. Inoculants also help in improving the graphite form and shape so that the mechanical properties are greatly improved. Inoculation is a must do practice to be observed carefully for grey as well as SG irons. Quantities for grey iron vary from 0.1 % to 0.4% depending upon the melt condition and 0.3% to 0.8% for SG irons.
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