Investigation of the Difference Between Carbon Equivalent from Carbon Saturation Degree and that from Liquidus

Abstract

Carbon equivalent of cast iron is known as the following equation: CE = [%C] ? (1/3) [%Si]. This equation is basically calculated from the carbon solubility in hypereutectic composition. On the other hand, liquidus from hypoeutectic to eutectic composition in Fe-C phase diagram is well known. Liquidus temperature (hereinafter referred to as T L ) can be measured easily with thermal analysis by focusing primary crystallization temperature. In this study, the effects of elements on T L and carbon equivalent in cast iron were examined from the view point of cooling curve, carbon flotation, and internal shrinkage, and a more accurate equation for calculating carbon equivalent is suggested. It is revealed by the experiment that the relationship between T L and elements from hypoeutectic to eutectic composition is as follows; T LDividing this equation by carbon coefficient, the carbon equivalent equation of liquidus (hereinafter referred to as CE L ) from hypoeutectic to eutectic composition is obtained as follows: CE L = [%C] ? 0.23 [%Si] -0.03 [%Mn] ? 0.32 [%P] ? 0.64 [%S] ? 0.02 [%Ni] ? 0.06 [%Cr]. This CE L is different from the commonly used CE since it is determined from liquidus. We investigated how the difference of carbon equivalent (CE/CE L ) application in the range of hypoeutectic to eutectic composition affected on the cast iron and revealed that CE L = [%C] ? 0.23 [%Si] should be applicable.

Cast Iron Parts Obtained in Ceramic Molds Produced by Binder Jetting 3D Printing—Morphological and Mechanical Characterization

“…Based on the values resulting from the chemical analyzes for the two types of cast iron, the EC carbon equivalent (or degree of carbon saturation) indicating the nature of the cast iron was calculated for each. The carbon equivalent is calculated from relation (6) [ 45 ] where C represents the amount of carbon, S represents the amount of sulfur and P represents the amount of phosphorus. If EC = 2.08 ÷ 4.26%, then cast iron is hypoeutectic.…”

“…Based on the values resulting from the chemical analyzes for the two types of cast iron, the EC carbon equivalent (or degree of carbon saturation) indicating the nature of the cast iron was calculated for each. The carbon equivalent is calculated from relation (6) [45] EC = C + 0.31•S + 0.27•P [%],…”

Application of thermal analysis in ferrous and nonferrous foundries

“…It is also essential for a fine tuning of their casting temperature during ladle treatment. Both liquidus and solidus temperatures are critical parameters for proper adjustment of physical and numerical modelings, significantly affecting the final quality of the as cast steel parts [20]. Liquidus temperatures of various steel grades are commonly determined using cooling curve analysis.…”

Archives of Foundry Engineering

“…Researchers analyzed the liquidus temperature of a cooling curve using thermal analysis of the cast iron and derived a new Carbon equivalent equation CEL that closely meets the practical findings. Here coefficient of the silicon varies 0.22 to 0.25, CEL = [%C] +0.23[%Si] is the recommended Carbon equivalent equation [17]. For this reason, it is needed to define an actual carbon equivalent by using a proper thermal analysis system to determine the type of gray iron) [16].…”