Method for precisely adjusting C and Si before furnace inputting for spheroidal graphite cast iron

Abstract

To achieve optimal control over the content of C and Si of spheroidal graphite cast iron, the invention discloses a method for precisely adjusting C and Si before furnace inputting for the spheroidal graphite cast iron. The method comprises the steps that firstly, according to the final content of C, the content of Si needs to minus Si content increasing ingredients subjected to inoculation, base iron is smelted, and after being smelted, the base iron pours a thermoanalysis empty sample cup and a white cast sample cup; secondly, the activated carbon equivalent (ACEL) of molten iron is determined according to the liquid phase temperature TL of a grey cast cooling curve, the activated silica equivalent (ASiE) is determined according to the eutectic temperature TE of a white cast cooling curve, and the content of activated carbon (AC) is obtained through backstepping; thirdly, the balance temperature Teq of a Si-O-C deoxygenation reaction is calculated through the AC and the ASiE, and the silicon carbon loss state is judged according to the difference of the balancing temperature Teq and the molten iron temperature Ta; fourthly, the empty sample cup is poured again, and C and Si are adjusted according to the ACEL of the molten iron at the time; and fifthly, the ACEL of the finally-nodulized molten iron is verified and can be adjusted again in the next batch. The method is used for the fields of casting detection and metallurgy.

Description

technical field [0001] The invention belongs to the inventions and creations in the field of metallurgy and casting, and in particular relates to a method for precisely adjusting C and Si in front of a nodular cast iron furnace. Background technique [0002] The risk of shrinkage of ductile iron is higher than that of gray cast iron, and the volume expansion effect of spherical graphite is greater than that of flake graphite. Therefore, in order to reduce the scrap rate of incomplete castings and graphite floating and improve its casting performance, nodular cast iron is finally poured into molten iron. The equivalent CE should be in the microeutectic or eutectic state. The degree of graphitization of molten iron is related to the modulus of the casting. For thick ductile iron parts, the cooling speed is slow, and the graphite is fully precipitated. In order to prevent graphite from floating, the carbon equivalent value should be low; while for thin-walled auto ductile iron ...

AI Technical Summary

Problems solved by technology

However, the precipitation temperature of primary austenite on the white cooling curve is the result of the precipitation of eutectic carbon in molten iron in the form of carbides, and does not actually reflect the influence of the precipitation state of eutectic graphite carbon on the real carbon equivalent of molten iron. Activated carbon equivalent, when the molten iron ash solidifies, the test result that deviates from the white curve is relatively large

Thermal analysis determines that carbon has no actual physical meaning, and the gray curve calculation method regards the C content as T L and TE low Although the statistical function of the activated carbon content is given, it is greatly affected by the factors of artificial pouring of the sample cup; the white curve calculation method can only give the total carbon content value (atomic weight ratio of carbon content), and its own accuracy restricted

Silicon is determined by thermal analysis, and the gray curve method is obtained by using the measured ACEL and AC back-calculation; while the white curve method is based on the Si content and the white curve method. T L and T E The statistical function of the calculation, there is still no specific physical meaning

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