O. Bogdan: Optimization of ingot geometry, casting technology and chemical composition of a 20 tones 42CrMo4 ingot to minimise A-segregation and increase material homogeneity; 3rd International Conference on Ingot Casting (ICRF), Aachen, 2018
ICRF2018 - Proceedings Paper Video Presentation Slide Show Presentation

An integrated mold design and the solidification simulation software SimCADE v.2.0 has been used to analyze the solidification and put in evidence the influence of ingot geometry (height/diameter ratio, hot top size, ingot taper), casting variables (pouring temperature, exothermic material) and chemical composition (C, Si, Mn, Cr, Mo) on the size and position of A-segregation area.

In the experiments performed, to get the area affected by segregation, cooling and solidification rate have been correlated with the A-segregation critical value calculated by macrosegregation module of the software, module based on the chemical composition of the steel and method proposed by K.Suzuki and T.Miyamoto.

The results of the experiments we made show that in this particular ingot the homogeneity of the material can be improved if we choose an ingot with high height/diameter ratio, low hot top size, low Carbon and Silicon and high Molybdenum content. The experiments done with various pouring temperatures, ingot taper, and various Mn or Cr content have low or no influence on the A-segregation.

O. Bogdan: Influence of Ingot Size and Mold design on Macro-Segregation in AlSI 4340 Forging Ingots; 1st International Conference on Ingot Casting (ICRF), Aachen, 2012.
ICRF2012 - Proceedings Paper

The analysis goal was to find out if the ingot geometry and mold design of a particular 50 tons ingot offers conditions to avoid macro-segregation and homogeneous mechanical properties in AISI 4340 steel grade forging products. To this purpose, the solidification software SimCADE v.2.0 has been used to analyze the solidification process of the ingot with the same weight but with variation of height/diameter ratio, ingot taper and mold wall thickness. In all experiments performed, the solidification and cooling rate has been used to calculate the A-segregation criterion value for a particular AISI 4340 steel grade chemical composition.

The results show that in the analyzed ingot, the macro-segregation will occur and the material is not homogeneous. The experiments done with a different ingot taper or mold wall thickness show that A-segregation will occur in all these ingots as well. If the ingot height/diameter ratio mold is higher, the ingot will have a lower A-segregation area; ingot taper and mold wall thickness have influence on A-segregation area size but it cannot avoid A-segregation and material heterogeneity completely.

O. Bogdan: Influence of Pouring Technology on Macro-Segregation in AISI 4340 Forgings Products; Industrial Soft
Documentation Paper

The analysis objective was to establish the influence of pouring temperature, hot top size and initial mold temperature on A-segregation in order to increase the homogeneity of AISI 4340 forging products manufactured from 50 tons ingots.

From the analyzed parameters, the hot top size has the biggest influence on the segregation process. A small hot top size is recommended.

O. Bogdan: Influence of Chemical Composition on Macro-Segregation in AISI 4340 Forgings Products
Documentation Paper

The analysis goal was to check if the chemical composition of AISI 4340 steel grade offers conditions to avoid A-segregation and material heterogeneity in forging products made using 50 tons ingots. The analysis shows that if the chemical composition of steel poured into 50 tons ingot with a given geometry is in the limits of AISI 4340 steel grade specification, the steel will develop macro-segregation. Also, the results show that the carbon and silicon content increase the macro-segregation area. Instead, a higher molybdenum content decrease the A-segregation area size.

The results are useful for both, ingot and forging manufacturers or forging products buyers. Using the manufacturing records as input data to segregation analysis, the buyer may choose a forging product with higher homogeneity of mechanical properties.

Industrial Soft: Segregation Control in Steel Ingots - Examples and Applications
Slide Show Presentation

This presentation provides a short description of tools we developed to control macro segregation process: solidification simulation software and segregation analysis module. Then, a few examples demonstrate how and where are the results useful and, at the end, the products we offer based on macro segregation control technique.

A. Gorni, G. Formica, O. Bogdan: Comparaçäo preliminar entre abordagens para o modelmento matemático do perfil térmico de placas durante seu reaquecimento; Revista Escola de Minas - REM, 53:3, Julho-Setembro, 2000, p. 203-209
Magazine Paper - English/Portuguese

An evaluation of performance of Finite Differences Method (FDM) and Finite Element Method (FEM - SimCADE v.2.0) was performed by calculating the evolution of thermal profile over time in selected points of a reheated slab. The results we got from these experiments, without adjustment of the models to the experimental data, revealed that the FEM presented better overall performance and calculates with better accuracy the temperatures. The development of an efficient mathematical model for the automatic control of a plate furnace requires better instrumentation and more data so that the algorithm can be properly adjusted to the operating conditions.