Abstract
The presented work is aimed at developing a mould geometry suitable for casting both low- and high-alloy steel grades into 500 kg experimental ingots. The high Height-to-Diameter (H/D)-ratio mould currently used in COMTES FHT Inc. served as a reference and for finite element method simulations (FEM) of the filling and solidification process. The optimized mould geometry, balancing the porosity and segregations, was determined using MAGMA software. Four different steel grades were defined for the simulation. Case studies were carried out for 34CrNiMo6 (W.Nr. 1.6582), DHQ8, CB2 and borated stainless steel grades ranging from low-alloy steel to high-alloy steel. Extended user-defined criteria and verified boundary conditions were used to predict the formation of A-segregations in cast steel. Both primary (PDAS) and secondary (SDAS) arm spacings were modelled as well. The optimized mould shape and the casting assembly were designed based on the simulation results.
Highlights
Jose Torralba andThe development of new iron-based alloys with strict requirements on the internal quality of a product is forcing manufacturers to optimize every step of the whole metallurgical process
In addition to widely used approaches to design, both primary (PDAS) and secondary (SDAS) arm spacings and Suzuki criteria for A-segregation [5] are taken into account
Where σ represents the component of external stress, p is the pressure, ρ is the density of a fluid and u is the velocity vector. This mathematical description is in accordance with the Law of Conservation of Mass including those terms describing the flow of molten metal needed for the calculation of the thermal fields during the filling (Equation (4)) [10]
Summary
The development of new iron-based alloys with strict requirements on the internal quality of a product is forcing manufacturers to optimize every step of the whole metallurgical process. A Height-to-Diameter ratio (H/D) reaches a critical value of 4.25 and a draft angle of 2◦ Such geometry promotes a high chemical homogeneity. Poor internal quality is a limiting factor in subsequent initial stages of the hot working process, especially when considering highly alloyed experimental materials. In addition to widely used approaches to design, both primary (PDAS) and secondary (SDAS) arm spacings and Suzuki criteria for A-segregation [5] are taken into account. These criteria are fundamental to subsequent material processing to achieve the desired final structure of the product. To the best of the authors’ knowledge, there is no previously published work presenting the medium-sized mould design in such a comprehensive manner
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