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Effect of silicon on phenomenon and quantity of ferrite in surface structure of gray iron castings Влияние кремния на проявление и количества феррита в поверхностной структуре отливок из серого чугуна Влияние на силиция върху проявяването и качеството на ферита в повърхностната структура на отливки от сив чугун M. TOMOVIC S. MATIJASEVIC |
Ferritic-perlitic layers can often be found on gray iron castings produced under conditions prevailing in foundries. The authors have tried to establish how silicon effects formation of the ferritic-perlitic layers. In the course of investigation of the effect of silicon on the phenomenon and quantity of ferrite in casting surface structure, the percentage of silicon has been changed (1,97 per cent, 2,10 per cent, 2,25 per cent and 2,50 per cent). The castings have been produced in sand moulds. Determination of the depth and quantity of ferritic surface layers has been performed on the castings of the following dimensions: 100, 75, 50, 25, 10 and 5 mm. Pouring temperature varies from 1.370 to 1.400°C. Metallographic examination of surface layers of the castings has confirmed that the influence of silicon in gray iron is significant and an outstanding one in relation to the characteristics of surface structure. |