Research Area 2 combines the topics from the former Areas 2 (High-Temperature Metallurgy) and Area 3 (Processing and Energy Performance) from funding period 1 with some innovative aspects dealing with ferrous and nonferrous applications and processes. Within the ferrous part of Area 2, primary and secondary metallurgy is considered starting from the LD process (LD = Linz-Donawitz) for crude steel production to continuous casting and hot rolling up to steel refining i.e. removal of non-metallic inclusions via Electro Slag Remelting (ESR). Within the nonferrous part, the focus is on alternative reducing agents and process efficiency during copper refining.
Objectives & Motivation
- Further development of the copper refining technology regarding alternative reducing agents and productivity
- Thermodynamic and kinetic modelling of the LD converter process and link to secondary metallurgy (steel cleanness)
- Thermo mechanic modelling of crack formation in steel alloys during continuous casting and hot rolling
- Definition of guidelines for the design of refractory linings in metallurgical aggregates
- Development of innovative and efficiently working mold powders for the continuous casting process
- Influence of slag properties on the remelting energy demand during the ESR process
The research work will contribute to the center’s target of an enhanced know-how related to metallurgical and environmental process optimisation with respect to the material behaviour inside the high-temperature aggregates and the product quality. The copper refining process of our company partner should be further developed whereas it is planned to partially replace carbonaceous agents by natural gas or hydrogen. Therefore, the shaft furnace process needs to be considered.
Deeper understanding regarding the impact of process conditions during steelmaking and refining on the final quality should be generated by investigating the interaction of thermodynamic and kinetics of LD steelmaking to increase the steel cleanness and to reduce the necessary downstream steel refining efforts. A model will be further developed to predict and quantify the involved phenomena (phase interaction inside the converter) and the influence of process parameters on dissolution of calcium and magnesium containing slag additives. In addition, the evolution of non-metallic inclusions during ladle refining will be modelled by employing effective equilibrium zones under usage of FactSage® databases.
Further downstream the metallurgical process chain, surface defect formation during the continuous casting process and the ductility behaviour of different steel grades will be investigated. During this, the further development of the IMC-B (In situ Material Characterization-Bending test as benchmark experiment to quantify the thermal history on the crack susceptibility of steel as well as the refinement of a risk-prediction model is planned.
The Electro Slag Remelting (ESR) process is a secondary metallurgical treatment to reach highest quality steel grades in terms of toughness and corrosion resistance. A suitable composition of ESR slags is necessary for an efficient removal of non-metallic inclusions, and furthermore, ESR slag influences the energy consumption during the re-melting process. In this context, correlations with viscosity and the solidification behaviour and their interrelation with energy consumption should be quantified in Area 2.
Beside the processes itself, investigations regarding refractory materials are in the focus of Area 2. The goal of the investigations is the knowledge-based definition of expansion allowances in refractory linings. For that purpose, Finite Element simulations are planned to analyse thermally loaded refractory linings and to quantify possible damages due to thermomechanical stresses.
In the submerged entry nozzle of a continuous caster, the nozzle wall is equipped with carbon-bound zirconia refractory material between steel and slag (called slag band). In some cases, the corrosion process is enhanced by infiltration of mould slag components into the refractory material due to an oxidation of the carbon. Therefore, alternative mould fluxes with certain compositions will be investigated with respect to an implementation in the casting process.