Evaluation of chemical heterogeneity of a 90-ton forging ingot

Purpose: This article describes performance of the experimental 90-ton forging ingot casting, the way of cutting, the methodology of chemical analysis and the results of that investigation. Design/methodology/approach: The experimental ingot 8K91SF weighing almost 90 tons was cast due the performance a detailed analysis of the current state of casting and solidification. The ingot was cut and macrostructure and chemical heterogeneity of the ingot was evaluated in detail. The standard method used in metallurgical analytics - analyses using optical emission spectrometers - was not applicable due to the large number of required analyzes. Thus, the mobile optical spectrometer SPECRTOTEST was used. Sulfur prints and fluid penetration tests were performed due to detect macroscopic distribution of sulfur and to locate surface-breaking defects. Findings: Current level of segregations of selected elements in real 90-ton steel ingot was detected. Also mutual mixing of two heats needed for the production of this ingot was verified. Research limitations/implications: Future research is focused on determination of inclusion content in selected parts of experimental ingot and on the level of micro-segregations. We are limited by the accuracy of chosen analytical method, which is also discussed in the paper. Practical implications: The gained knowledge is used to specification of the setting of boundary conditions of the numerical simulations, which should help to optimize the production technology of casting heavy forging ingots and minimize the level of segregation in ingots. Originality/value: New knowledge concerning mutual mixing of two heats needed for bottom casting of heavy forging ingot are presented in this paper. Distribution of segregation in so heavy ingot was detected. Results are the base for further investigations in macro-segregations and for the improving the accuracy of results of numerical simulations.