Research & Projects
Modelling of Materials and Process Parameters
No. 120-1201780-1779; 2007-2011.
Senior researcher: Tomislav Filetin
Financed by Ministry of Science, Education and Sports of the Republic of Croatia, (MZOŠ)
Computer simulations of processes, material properties and material selection reduce the time necessary to develop and apply materials, to define and optimise the required parameters of the production processes. Mathematical modelling is applied to formalize and simulate electromagnetic phenomena, thermodynamic processes of heat transfer and microstructure transformation as well as the predictable properties in various processes of casting, heat treatment and surfaces modification treatment. The study of the possibilities and limitations of applying artificial intelligence methods for predicting the material properties and production process parameters and their optimisation, as well as decision-making at the material selection, has only just started. The previous own results show that these methods can be successfully applied in cases of knowledge processing about materials and production processes, with lacking quantitative data or the impossibility to exactly physically describe the processes. Neural networks, genetic algorithms and genetic programming, and fuzzy logic help in developing the models for predicting the properties and behaviour of material based on the known composition and microstructure, as well as expert systems for the selection and application of materials. The design of databases and knowledge base about the properties and application of advanced materials and processes is planned. The device for hardenability testing of steels when cooling in high pressure gas quenching with high velocity gas stream will be reconstructed and the model for prediction of hardness distribution along the cross-section of the axially-symmetric work- pieces will be developed. Simulation programmes and expert systems will be developed for the prediction of material properties and casting parameters, precipitation hardening, vacuum furnace cooling, surface modification and coating of metals – particularly induction hardening, duplex process of carburising and vanadising, etc. Expert systems are to be developed for the selection and application of material and surface modification treatment. The results of the study and mathematical formalization of the electromagnetic phenomena, thermodynamic processes and microstructure transformation during casting, rapid heating and cooling of materials, have a general significance for the similar thermal processes.
Investigation and research
Investigation of heat transfer data at quenching (heat flux density; heat transfer coefficient) of real axially symmetric engineering components is based on experiments with a cylindrical probe of 50 mm Dia. × 200 mm, having three thermocouples, by applying the Temperature Gradient Method. Relevant probes for other shapes (plates, rectangular bodies, rings…) are optional.
Besides own proprietary software, other well-known software packages (Matlab, SYSWELD, COMSOL, FLUENT) are used to calculate and predict the microstructure transformation, the as-quench hardness, the stress-strain development with residual stresses and distortions. Quenching intensity and results of quenching depend, in every case, on: specific characteristic of the quenchant, its temperature and its agitation rate i.e. flow velocity. Because the above described facilities enable to change all of these conditions, every mathematical model and simulation can be experimentally validated. Quenching Research Centre is devoted primarily to steels, but it deals equally with aluminium and other light metals hardened by precipitation.
QRC is offering the following services
- Selection of the optimal quenchant and quenching conditions for real workpieces based on the relevant drawing and required properties. Planning of quenching operation within the whole manufacturing process.
- Analysis of the quenching process by heat flux density and heat transfer coefficient as well as other thermodynamic functions, based on the cooling intensity measured by the proprietary probe of 50 mm Dia. × 200 mm.
- Prediction of the hardness distribution through the whole volume of axially–symmetric workpieces of any complex shape, after quenching and after tempering, based on workpiece drawing and experimentally established heat transfer coefficient (HTC).
- Mathematical modelling of microstructure, as-quenched hardness, residual stresses and distortions, based on known HTC, with experimental validation.
- Testing of new, improved, or used quenchants under different quenching conditions, based on the method used for real workpieces.
- Improve existing or design new quenching equipment based on CFD analysis in real conditions.
Long-term activities of the QRC
- To establish a data base of quenching intensities for different quenchants and quenching conditions in order to enable their mutual comparison.
- Further development and application of new quenching techniques:
- Intensive Quenching;
- Controllable Delayed Quenching;
- Gas-Nozzle Quenching (with or without transient spraying of liquid Nitrogen).
- Development of the method for hardenability measurement of gas quenched steels (continuation of the research started at Institute of Materials Science, IWT – Bremen).